10m Is At It Again.

After a low in solar activity it is now up again. Solar flux 121 that last two days is quite a bit, and a daily sunspot number of over 100.

10 has seriously woken up this week end.

From East Asia in the morning and almost until noon, Australia morning/noon, and fro the first time I have seen it in Cycle 25. my receiver spotted New Zealand. 

Around noon the 4X6TU was through, and in the mid afternoon the South Americans were there, lots of them.

Then, still mid afternoon I heard the 4U1UN beacon in New York was there while I was elsewhere in the house. Checking the PSK-reporter, yes, sure enough there were several spots from the East Coast of  the US. 

Then a bit quiet in the early evening, and suddenly spots from near the West Coast of the US, around 9PM local time here. This looks very much like trans-polar propagation, not unheard of at this time of the year.

Definitely an interesting day on 10m.

Rough Layout for a 2.4GHz Transverter - "LEGO-Style".

After yesterday's test I found a shielded box with dividing walls that should be usable for starting the build of a 2.4GHz transverter and/or QO-100 up-converter. 

2 amplifiers are added to the design, one for receiving and one for transmitting, and a further filter for transmitting. The extra TX filter might be better placed in an amplifier box, we shall see. This might provide a better balance in the filter/amplifier gain/attenuation, maybe even a better LO and image rejection. 

What I did is simply putting the "LEGO" modules in their approximate places. Of course, the modules will be mounted parallel to the surfaces of the box, but the picture below gives an idea of what the layout should be. 

The mixer, filters and the hybrid will be placed at the bottom of the box, the two amplifiers at the sides inside the box.

The image gives a rough idea of the layout. The bigger casing next to the module box is the LO,  a non modified 2009MHz oscillator, at this moment. Initial tests, like the test yesterday, will be with my signal generator at 391MHz, and with a receiver capable of 391MHz.

Modifications of the LO will come later It needs to generate a 1968MHz signal for converting between 2400 and 432MHz.

I would expect the TX output of this to be around -10dBm (100uW), and the RX sensitivity not too good. With the modified LO, however, it could be used for a short range experiment on 2400MHz.

Now for some mechanical work, and that takes me longer, then some tests of the set-up.

For the record: The idea is not my own, I first heard about it from OZ2OE, Ole. The mechanical set-up is my own, though ;) .

Quick Experiment With the LO Module and Some Chinese Modules. 2.4GHz signal achieved.

 Today I got a quick set-up to see how some of the modules I have could be used as a transverter or up-converter from 432MHz to 2400MHz.

Here are the parts:

- the 2009MHz oscillator module I tested a few days ago

- a mixer PCB module, IF DC-1.5GHz, RF/LO 1.5-4.5GHz

- a 2.4GHz filter PCB module using "hairpin" resonators

- a Wilkinson combiner/divider hybrid PCB module

All this was just lying loose on the lab desk, connected with SMA cables with the first port to the 35-4400MHz spectrum analyzer and the second port of the hybrid terminated with a 50 Ohm load. The second port is intended for use in 2.4GHZ reception

For the test I set my signal generator to a 391MHz IF, mixing with 2009MHz to get 2400MHz out.

The raw signal out of the mixer was as expected, a bit of 2009MHz LO feed through with LO +/- IF signals about 30dB stronger

Adding the filter (and the hybrid) provided a solid signal on 2400MHz. The LO signal was about 45dB down, and the image frequency was about 55dB down.

The results are encouraging. I would expect the stray LO and image signals would be better attenuated when the mixer/filter/hybrid  modules are mounted in a shielded casing, but for the transmitter path I intend to mount a second filter between some of the amplifier stages, in a second shielded casing.

For a receive path in a transverter A second filter is probably also a good idea, but at present it may not be necessary. In principle this is a very low powered and very insensitive 391/2400MHz transverter.

What comes next (in no particular order)?

- modifying the LO module to generate 1968MHz, so a 432MHz  can be used as the IF.

- building an amplifier chain, so I can get a minimum of about 500-800mW output.

- building the modules into shielded casings Except the LO, it is already in an excellent shielded box.

- Start mounting this arrangement into a sufficiently large casing

- adding circuitry for supplying and controlling the LNB used for QO100 reception. Right now the QO100 set-up has separate transmitter and receiver.

- adding receive amplification/filtering for 2.4GHz.

- adding control circuits, such as T/R switching, band switching etc.

- adding a second down converter, so the LNB's IF signal can be received on 144 or 139MHz

- maybe a bit more when I can think of it.

Results of the Solar Panel Relocation.

After relocation the illumination of the panel is clearly improved. Last year, at this time of the year, the battery got too discharged, as it was supplying the charge controller.

This year, after relocating, and making sure that snow was removed from the panel, the voltage has been kept above 12V, often around 13V. A considerable improvement over last year's performance.

In the spring I should get more set up, along with a lot of maintenance of my antenna system.

It looks like next year will have much more outdoor activities for me.

Testing A 2GHz Brick Oscillator, And My Microwave Testing Limitations.

Some time ago I purchased a few surplus 2GHz oscillator modules fro RF-Microwaves in Italy, designated SU-03. They are now sold out, but I finally got to start testing a few of them.

Those are synthesized modules operating on 2009MHz, with a reference crystal of 8MHz. From the description it is indicated that with a modified reference frequency the unit could be modified to operate in the 1960 - 2035MHz band.

The SU-03 requires a dual power supply of +/- 12V. For the test I used my standard variable lab PS with 12V, and a set of 3 Li Ion cells to provide the negative voltage. The negative voltage is needed, as the unit has 2 GaAsFETs that need a negative gate bias.

Power output is specified to 10dBm (10mW), so to be sure not to over-load (and destroy) the probe of my old HP432 I connected a 10dB attenuator at the SU-03 output. That was good, as the measured output turned out to be +15dBm (30mW, well above the spec of the thermistor probe). Better safe than sorry. I now have 3 units tested and in-spec for the +10dBm output. This should be quite sufficient for use with a passive (diode) mixer. 

Next step: Look at the spectrum coming out of the SU-03. Here is where I think that the limitations of the low cost Chinese spectrum analyzer, covering 35 - 4400MHz comes in. This is a device costing less than $100, so how can we expect miracles? Well, we can't.

First of all, the maximum scan bandwidth of the spec-an is 350MHz with a 500kHz "IF" bandwidth, so in order to "see" the full spectrum I need to look at 300MHz at a time, then switching to the next segment, etc. It takes some time, and it is tedious, but it can be done. 

Second limitation I see is, as I suspect, the local oscillator - I guess an ADF4351 (or a clone) - has a square wave output, so subharmonics of the original input frequency show up on the display (1GHz, 666MHz, 500MHz) quite strongly. Well, knowing the limitation is half of getting more reliable results. 

Between 2GHz and 4GHz I see no spurious coming out of the oscillator, at least they are about 60dB or more down from the wanted signal. Also, between 1 and 2 GHz I see no spurious signals. This indicates that the output from the oscillator is rather spurious free.

When looking at a more narrow frequency span, the limitations of the low cost spectrum analyzer really shows. The curve is no longer a curve, but has steps of about 5dB in the in the spectrum, and further it is possible to see the effect of the direct conversion design in the analyzer, in that the center null is somewhat visible. 

When looking at a moderate bandwidth,  some asymmetric sideband noise is visible. I can not se if this comes from the oscillator block or the local oscillator in the spectrum analyzer, but I suspect it comes from the low cost local oscillator in the analyzer.

Clearly, the low cost solution, while not useless, is not very efficient, but for now it will have to do, as I do not have a (more expensive) analyzer covering up to 2GHz or above. What I do have is a rather old (analog) model covering up to 1.5GHz. With that I can test for spurious output(s) below 1.5GHz, that's all.

Next test of the oscillator will be a frequency test. While I do have a frequency counter covering up to 2.4GHz it is not locked to a frequency standard, neither does it have an input for doing so. So high precision frequency measurements are not possible.

The frequency counter that does have such an input just covers up to 1.3GHz. What will be necessary to use my GPS controlled 10MHz source is a divide-by-10 (counter), because this particular counter requires a 1MHz external reference frequency. Some soldering work needed.

There is, however, the possibility of adding a pre-scaler to it so all is not lost. It looks like I should get the soldering iron going again, so I can get a divide-by-4 pre-scaler up and running, with that one I should be able to measure frequencies up to 3.5GHz (with the use of an added calculator) with good precision. .More soldering work. Also, this would be my first (fully) microwave construction, not just using modules or adding modulators or doing small modifications. Now it gets interesting (hopefully not in the Chinese sense of the word ;) )

What is this (modified) oscillator brick useful for? Let me see, with modifications:

- 1968MHz is within the range of operation of the VCO, so a local oscillator for a 432 < - > 2400MHz transverter (or QO100 up converter) is possible

- possibly a base oscillator for a 10GHz transverter (followed by a x5 frequency multiplier, e.g. 1987.2 x5 -> 9936MHz - LO for a 10368/432MHz conversion)

- a precise 2000MHz oscillator for down conversion of 2400MHz to frequencies that a better spectrum analyzer or frequency counter. Possibly with a divider to 1GHz and/or a frequency multiplier for higher frequencies. We shall see. what I do

Small update: 

I tested the oscillator with the old spectrum analyzer (up to 1500MHz) No subharmonic signals could be seen. The oscillator is free of spurious signals from 0 - 1.5GHz on this one. Nothing could be seen from 1-2GHz and 2-4GHz. My conclusion is that this oscillator module is very clean, at least with regard to spurious signals. I cannot measure phase noise, but I can probably get that done at a ham radio friend with better instruments. 

This looks like an excellent candidate for 2.4 and 10GHz transverters with 432MHz IF. It is fair to say that a ham radio friend recommended this at a small ham meeting, so I mostly expected this.

The interesting part comes when I try a modification for an external reference frequency signal, how much it depends on the purity of the reference signal.

More on that later.

Idea Box: Putting the 10GHz Amplifiers to Good Use.

Now that I have some decent amplifiers, it is time to make a project to make good use of them. since they have a high gain it is essential to avoid over-driving them. 

Here are some ideas:

The easiest modules to employ are the 2-400mW modules, as they only need a single, +15V power supply. The modules are rather small, and heat up quickly, so some kind of heat sink is necessary for those. Not unexpected when I saw the size, and they do have holes for mounting on a heat sink.

The 1-2W module needs a -12V and a +12V supply, as does the amplifiers in the up-converter module I have tested earlier. Those units *need* the -12V to be supplied before the +12V, so some kind of sequencing/safety circuit is necessary.  

For this reason the first construction tests will be done with the low power modules. Here are some options for experiments. 

1) a WBFM modulated DRO, such as a modified HB-100 module driving the amplifier. The HB100 module needs to be modified for use as an exciter for the amplifier, and a modulator is needed, too. The modification would consist in disconnecting the RX mixer circuit and the transmit antenna on the PCB, adding a semi-rigid cable at the "antenna output" and building the HB100 into a shielded box. One more thing is needed, an attenuator in order to avoid over-driving the amplifier.

Adding the attenuator has one more advantage, it provides some isolation of the DRO, giving less drift and external influences.

Such a transmitter can be used together with a satellite LNB and a WBFM capable scanner running in the 600-700MHz range. Separate antennas can be used for simplicity.

It could also be used as aWBFM test TX ("Beacon") when used with an audio frequency keyed system, e.g. with a microprocessor, such as the Arduino with a suitable program. Of course, this could also include a keyer input for manually keying the audio tone.

The range with such a transmitter will be significantly improved when compared to a simple system with the HB100 "stand-alone".

2) A set-up using a cheap 70cm transceiver as the source for the TX signal. This is a bit more involved, but some of the circuitry can be used for other experiments later.

The circuit needed is a frequency multiplier chain, for example 432x2 -> 864x2 ->1728x2 ->3456x3 ->10368MHz (x24 multiplication, so other orders of the multipliers could be useful). A bit of offset from 432 would be good, as I want to avoid running WBFM in the narrow band segment. The advantage of this will be the improved frequency stability, as the reference frequency is usually synthesized. Yes, an attenuator is needed after the 70cm TX, but that is not too difficult, since such a TX can run a power as low as 0.5-1W, and the load impedance is not overly critical for the TX.

Otherwise the multiplied and filtered signal can be used as in example 1 above.

This was all wideband, and this does have its limitations with respect to range, so I would like to use the amplifiers for narrow band transmission as well.

3) Narrow band CW (FM) transmitter. Using the multiplier from example 2 it is then a matter of generating a 432MHz signal with sufficient stability. For a simple, single frequency CW TX, e.g. a "beacon", I have some TXCOs running on 14.4MHz. As those oscillators are likely to generate a square wave, taking out the 5th harmonic on 72MHz and amplifying it should not be tricky. After that a frequency doubler, followed by a tripler will generate a signal on 432MHz. As I have done a bit of VHF construction before I would not expect this to be too difficult, especially as this comes after trying making the higher frequency multipliers. Good shielding and decoupling is a known construction technique for me. Keying can be done in one of the multiplier stages, and this can also be used as marker signals for 2m, 70cm, and 23cm.

200mW CW should be quite good from a hill top.

Because I do not know any people near me running WBFM, this might be a better option to make a first QSO on 10GHz, if I do not build a second simple WBFM set, or find someone who has one or wants to build his or her own.

Now, although I know some, not all people doing microwaves can do CW, so what comes next?

4) Up-converter from a VHF or HF station, so all modes are possible. The receive side can still be a satellite LNB (modified for better reference frequency), so here goes:

Among the stuff I ebay'd lately, there is also a 10-11GHz mixer circuit. The IF connector is not a standard SMA, so it looks like I am going to make a modification so that all three connectors will be SMA. Otherwise I can use the one from the up-converter I already have (and tested), modified, so that the DRO is removed and a multiplier chain (as above) is used in stead. I will probably need a new multiplier chain, but that should be doable, if I can get the first version (above) working. In the up-converter there is (what looks like) a decent band pass filter centered on about 10330MHz. This has to be re-tuned as 10368 is outside the band pass.The amplifier chain in the up-converter as it originally was, is quite bulky, and could be replaced by the 2-400mW amplifier. I suspect there will be sufficient gain.

All in all, it will be interesting to see what I can do with the surplus equipment/modules I have got now. A bit more is on the way, more on that later. There is enough work for quite some time with the speed I normally build stuff. For now, the HB100 modulator is back in the front again. I received some (SMD) 4001s, so the morse tone generator can be made, even if I need to use an adapter from SMD to "normal" (old fashioned) PCB soldering.

Solar Panel Re-Location.

For a while I have had a 50W solar panel running with a sealed (gel) lead-acid battery indoors, running with a charge controller.

Last year I realized that the panel was part in the shade during the deep of winter,  and the battery had been discharged, just by supplying the controller. but at the time it was too late already, so nothing was done.

Looking outside today around noon I saw that the panel was only  about 2/3 illuminated, so I got to change it. 

The panel is now about 1m above ground level, and placed a bit further from the building shading it. Yes, the sun is very low above the horizon at this time of the year here, somewhere around 10-15 deg. at winter solstice, so it does not take much to put the panels in shade.

There will only be a few hours of charging, but it is dfinitely better than at the previous position.

This brings me to another project that should be worked on this winter (apart from the 10GHz equipment). I have been working on re-conditioning some gel-batteries, but they are not yet ready for deployment. I have now decided that as a start, I will get some new batteries, so I can increase the storage capacity,.

Apart from this, I do have a small store of a few 30W (small, flexible) panels, and some very small solar panels. Some of the smaller panels I should use with some LiIon cell chargers (yes they are with BMS) to supply some low power consumption stuff, like a HB100 TX or the like.

The aim is to have some simple low power equipment for monitoring purposes powered entirely by solar, and with the panels and batteries I already have that should be possible.

To be sure, this location of the panel is temporary, and a more permanent location (more mechanically stable) is needed.

Oh, well. I am probably never running out of things to do or try. No time to be bored here. Was there ever?

Successful Test of Amplifiers for 10GHz.

Recently I received some amplifiers capable og working on 10GHz:

Having finished the test set-up I could finally make a rough test. Here are the results.

One claimed to deliver 2W (33dBm) with a gain of 47 dB.

My test resulted in an output of close to 1W (30dBm), with a gain beteween 40 and 45dB. 

A couple claimed to deliver 400mW (26dBm) with a gain of 47dB.

My test result showed about 200mW (23dBm) with a similar gain as the "2W" amplifier above.

Admittedly, the calibration of my test equipment may be about +/- 3dB off when the accuracy of attenuators, and most likely some loss in a SMA to N transition. Given that both tests showed less output I am willing to accept that the result may easily be up to the specification. Until I gan get it measured on a better calibrated set of instruments I will accept that the amplifiers are probably within 1-2dB of the specification.

Now I need to create a good signal, so I can put the amplifiers to good use. 

More 6GHz Attenuators Tested on 10GHz.

 More attenuator testing of nominal 6GHz attenuators measured on 10GHz with the up-converter and the HP432 power meter :

- 10dB attenuators: 2 of them very close to the 10dB mark, the 3rd 9.5dB

- 20dB attenuators: All 3 within 0.5dB of the 20dB mark

- 30dB attenuators: All within 1.5dB of the 30dB mark

All this is good enough for my amateur radio lab. Part of the purpose is avoiding overdrive and/or destruction of input devices in sensitive microwave amplifiers, as well as getting estimated gain figures.

Not bad for relatively low cost attenuators, tested out-of-spec. Now some rough gain testing of amplifiers can be done. Those 6GHz attenuators are now all in the box with 10GHz test equipment.

Error #40 ;) .

 We all do it from time to time. Error #40, also known as "User Error".

Today it was mu turn (again) (Nothing was destroyed).

When testing attenuators for 10GHz I was setting all up (I thought). setting output power of the signal generator, sending the signal through the up converter, got the DC power connected - sending the output to the power meter, and - no power out... Did I break the up-converter? 

No! I had forgotten to set the frequency to 70MHz. The generator starts up with a default 300MHz. the resulting mixed frequency on 10GHz is far outside the 10GHz band pass filter, so no output could be detected. (This does show that the filter is quite good, so there is that).

Set the frequency to the "ordained" 70MHz, and all was good.

I chuckled and got started with the testing of the attenuators (see previous post)

Rough Calibration of Attenuators When Used on 10GHz.

 

A bit of activity in the lab today:

While I have two SMA attenuators capable of working at 10W with 10dB nominal on 10GHz, I wanted to test some lower cost attenuators specified up to 6GHz. How to test that without a true, calibrated 10GHz signal generator. Some thinking was needed. Here is what I did:

Using my calibrated (well enough for me) RF generator on 70MHz entering the signal into the up-converter described a few days ago, except omitting the output (2-stage) amplifier, just using the DRO/Mixer and the first (buffer) stage module.

This got me an output on 10GHz close to the output on 70MHz, e.g. 0dBm on 70MHz -> 0dBm +/- 1dB on 10GHz. It looks like the buffer on 10GHz essentially compensated for the loss in the (passive) mixer. OK, now I have a reference signal, showing -1.5dBm on the HP432 power meter.

Here are the values measured with the HP432:

10W/10GHz/10dB:-10.5dBm   ->9dB

2W/6GHz/10dB:    -11dBm      ->9.5dB

2W/6GHz/6dB:      - 7.5dBm    ->6dB

Non-brand

6Ghz/6dB:             - 9.5dBm    ->8dB

Return loss has not been tested, so the impedances are not well known, but given  the values I got from the brand attenuators I used, those are probably close enough for my purposes.

So now I have a good set of SMA attenuators capable of handling up to 10W, and with sufficient attenuation to avoid destroying the thermistor mount of my HP432 power meter.

Before anyone aks: Yes, I did terminate the input and output of the 200mW output stage, to avoid those stages oscillating. They might be unconditionally stable, but I do not know. With components/modules like this, better safe than sorry.

All this took some time because I removed +12V DC power from the unit every time I changed attenuators etc.

I do have 2 more attenuators capable of operating on 10GHz, those have N-connectors. They will be tested together later, as one of them is mounted in my 2.4GHz up-link transmitter system. Now, at least I know that I can safely measure power with sufficient accuracy on 10GHz.

Why do all this? Today I received a 2W amplifier from another seller in Italy, and I do want to test that one.

New 10GHz Modules Are In. One Tested.

A little while ago I found some 10GHz modules at an Italian seller on Ebay:

- high gain amplifier, 47dB gain, claimed 26dBm out, covering 4 - 10GHz

- a 10GHz passive mixer module

- a tuneable filter, w/cavities

- a TX up-converter module claimed power output 22dBm

All are announced to be tested, but I should test them all.

Some of those need work, some not:

The high gain amplifier is complete with a single supply and SMA connector, so no mod needed

The IF port connector of the mixer needs to be changed into the SMA type, so I can make decent measurements on it with my test equipment.

The tuneable filter should be re-tuned to 10368MHz

The TX up-converter needs a b it more, but I got started with testing it. It is built with modules mounted on a "sandwich" of 2 PCBs.

First of all. The converter uses a dielectric resonator oscillator, so unmodified it is only useful for wideband applications Specifications:

-70MHz IF

- 10240MHZ output

- DRO tuneable from 10.2 - 10.8GHz, so frequencies above 10270MHz all the way up to the 10500MHz band edge should be possible to generate.

- The mixer output is filtered through a 4 or 5-cavity filter. I suspect it will be tuneable in the whole specified frequency range After the filter there are 2 amplifier blocks:

a) what looks like a single stage amplifier in aluminium casing, probably milled. Likely gain about 10dB.

b) the next amplifier module was opened (Taking the lid off, and contains 2 stages, likely gain: 15-20dB

c)  the specified output of the unit is 22dBm (about 150mW)

- the unit needs both +12V and -12V

Knowing that GaAsFETs need to have the negative gate bias before applying the drain voltage, for "proper use" I will need to make a DC voltage sequencer in order to protect the amplifier(s)

Test equipment:

Recently I purchased two attenuators capable of working on 10GHz, with 10dB attenuation and a 10W rating each. With this I can test/measure up to 1W output without destroying the thermistor mount for my old HP432 bolometer. Since the claimed output is 22dBm/about 150mW this should be no problem for testing the up-converter.

For the initial test the 70MHz exciter is my signal generator, capable of an output level of +5dBm, just what the mixer needs, so the test set-up is:

1) signal generator

2) the up converter module supplied with +12V and -12V, using two 3-cell battery cases with each 3x 18650 cells

3) the two 10dB attenuators daisy-chained

4) the HP432 bolometer with a probe capable of measuring on 10GHz

Here are the initial test results:

Entering +5dBm (70MHz) at the mixer gives 200mW (23dBm) output, so the power specification holds, within the estimated accuracy of my test equipment. changing the IF frequency from the signal generator shows about 1dB higher output at 60 and 80MHz, and about 3dB less around 55 and 85MHz, indicating a filter bandwidth of about 30MHz. Not bad if a higher IF is used.

When changing the IF power level the linearity below 150mW looks good, so with a different local oscillator (synthesizer) there should be no problems running SSB/CW through this up-converter. This is definitely encouraging. A relatively simple 200mW WBFM transmitter using this module with a WBFM modulated oscillator on 70 - 80MHz and using a satellite LNB as down converter should provide a decent basis for wide band experiments with a bit more power than the low cost HB100 module.

This first lab test is a success, More experimentation with this module is in order, but that is foe a bit later. The first of those new tests would be a different LO, and a re-tuned filter, so the module can be used at 10360 or nearby. More to come later.

The 10m Band, Update.

 Last night I forgot to switch off my receiver for the International Beacon Project frequency on 28.200MHz. As a result, about 0815 local time, 0715 UTC the 4X6TU beacon popped up with a good signal.

With the FT8 monitoring (24/7), every day for the last month or more, the band has shown spots at my receiver from several continents, many days for 6 continents. North America is the most tricky, because it requires a higher solar flux than the others at my Northern latitude.

South America has not failed on any day, with PY being there daily, and often LU and CX. Some days also CE. and a few times YV, PZ and HC were spotted.

On 28.200 the 4X6Tu has essentially been heard every day, often peaking at S9. Other beacons heard fairly often are rhe ZS6DN and CS3B. A few times the RR9 and the VK6 have been heard. 

Sometimes I hear some signals with a long dash followed by a 2 or 3 letter ID in morse code. As far as I know these are buoys used by fishermen in the Mediterranean Sea. Not quite according to the rules, but a good propagation monitoring tool. One of those was spot on 28.200 one day.

The OTHR (over the horizon) radar systems are now active on 10m, and sometimes obliterating all other signals in a 30kHz or more wide band.

A week or so ago I worked a few North American stations with CW.

Oh, yes, 10m has woken up, and I will expect regular openings for the next few years during the solar maximum.

A Bit of Progress With the HB100 Modulator(s).

Just to remind possible readers of this blog, much of what I write is also a store of ideas and information that I want to be able to find again.

Lately I have not been so active with the soldering. However, since the first test of a modulator I have built another one on a new PCB. This one is a version shown on the website of F6HCC .

My version is simplified, as the idea was to use it with one of my MP3 players for modulating a test signal. This could be voice or (WBFM) modulated morse code.

As far as I know there is a kit out there for the F6HCC modulator, but I built my version on an experimental PCB, as modifications are a lot easier than on such a board.

Compared to the original F6HCC I omitted the (microphone) audio amplifier stage, assuming that the MP3 player should have sufficient output for modulating the HB100. 

The initial test, like the test of the first modulator, shows that the output of the IC-821 transceiver when using the CW side tone, works nicely, and can be adjusted to a voltage deviation of +/-100mV at 4.9VDC.  This looks like a good start. Now, the MP3 players seem to have a too low output for the purpose, at least for the modified F6HCC modulator. Now I have two options:

1) Add the second audio amplifier stage, or

2) Build the "digital" morse generator. This could be:

- a keyed CMOS oscillator, like the F6HCC one, but with a simple keying circuit. I have ordered some CMOS 4001 (NOR gates) IC. Amazing that I did not have any in my stock of components, but they are on the way.

- a simple beep-beep generator as described in the F6HCC modulator, or

- the CMOS oscillator with a microprocessor generating a repeated CW keying signal. Somewhere I should have a program for that in a PICAXE. The other option is using the Arduino. I think I found a program for a "beacon keyer" with dual output, a simple CW key output and a (side) tone output. With a (hardware or software) modification a simple input for a CW keyer, even a straight key, is possible. The microprocessor road will require me to learn to set up programming of the processors, and I have to learn some programming, too. The PICAXE with the BASIC programming language that I have a decent grasp of, is probably the simplest way, and the smallest of the PICAXE processors is an 8-pin DIL package, so there is plenty of space on the PCB to have that as well as the keyed oscillator.

It looks like I will be building a third modulator PCB on a slightly larger PCB, because this time I want the full circuit on the PCB, with space to spare. The very first modulator used an external AF amplifier for modulation, but I want to avoid that for mechanical simplicity - and also avoid lots of wires between PCBs, switches etc.

The end result will have the microphone amplification, so it is likely to be usable for the MP3 player, too.

Later, I expect to make myself a "WBFM modulated CW beacon", that I can set up in the garden and test the range of the setup. That could be a simplified version using the microprocessor keyer/audio generator and the F6FCC modulator without the extra audio amplification.

The microprocessor should also be usable as a true CW beacon keyer.

Oh, yes, I do need to (re)learn some programming and get the things set up for PICAXE and/or Arduino programming. Everything takes time.

Idea Box: Single Band SDR Receiver With Old SDR Kits.

 

I have some old "single XO" SDR kits from Germany. I think I have some Softrock kits somewhere, too, they use discrete crystal oscillators.

As indicated they have a canned (DIP/DIL) crystal oscillator running on 4x the RX operating frequency, and the quadrature signals are generated using a 74AC74 dual flip-flop as divider/phasing, providing quadrature local oscillator signals on the receiver boards. 

The receivers cover only one small frequency range around the LO frequency, so with a 48kHz sound card interface the max bandwidth covered is a bit less than 48kHz. Sound cards with higher sampling frequencies can, of course provide more coverage, but the 48kHz sampling frequency is now ubuquitous in computer sound systems.

Here is the idea. Not particularly complicated or original, but this could make better use of those old kits.

My intention is to replace the fixed XO with a Si5351 module controlled by Arduino. This could be programmed in, say 10kHz steps for the LO, or indeed for a single frequency. There are several Arduino programs for making a VFO with the Si5351, so I should be able to modify the program to suit this purpose. 

I have one finished kit of this kind, and a few (2 or 3) not yet assembled, so I should be able to make simple SDR system for rarely changed frequencies, such as beacon frequencies or digital mode frequencies. All for monitoring purposes.

In addition, if all the wanted frequencies are within 45kHz, the system could be used as-is for a few frequencies, branching out the "stereo" I/Q outputs to more than one sound card/computer for dual monitoring, or alternatively, use a local webSDR server. 

I think that the splitting of I/Q signals is the simplest solution to this, though.

The single frequency can be generated by a suitable XO, if that cannot be found, the Si5351/Arduino can be used to generate a single frequency.

I do have a finished kit for 80m, and I will check if I have a suitable XO for covering the FT8, JS8, WSPR/QRSS frequencies. It does look like a 14318kHz XO is usable for covering these frequencies with the 48kHz sampling frequency, although JS8 could be a bit tricky.

Major Solar Flare and Some Good High Band HF Propagation.

 The sun has done it again.

After more than a week with good strong solar activity, solar flux up to over 100, the activity jumped up to about 110, the 10m band is pretty good with openings detected, using FT8 as a monitor, to all continents.

After several days of solid solar activity, yesterday one of the sunspot groups unleashed an X-class solar flare, X1 - the highest category. This is not, by far, the strongest solar flare recorded, that happened in 2001, when the X-ray sensors on the NOAA satellites were saturated. Actually, I was watching the website when the flare started, and grew and grew in intensity, then the graph flattened at the X17, and I thought that the flare had finished, but when the graph stayed at X17 for more than 10 minutes I realized that this was much more than X17. It was later estimated to have been at the X28 level, and that is the official record. An X28 flare is 28 times stronger than X1.

Looking at the website it was clear that the sunspot group had already produced several major - M-class -  when it erupted, and there is still activity in the sunspot group. When it erupted there was a short wave black-out - SID (Sudden Ionospheric Disturbance) on the day time side of Earth.

When I received the mail from Spaceweather.com I took a look at the short GIF of the flare in UV light, and there was a clearly visible darkening of the sun spreading fast from the flare site. This is something I had not noticed before, so I had to watch it a few times to be sure that it was not my imagination. But no, this was definitely visible.

The X1 flare from yesterday happened just when the sunspot group was close to the center of the sun's disk as seen from Earth, so the CME (Coronal Mass Ejection) is moving towards us. The expected impact time is likely to be around the night Saturday to Sunday, although the timing can be off.

What does the impact mean? If the direction of the magnetic field is "correct" we may get good mid-latitude aurora activity, with visible, or at least photographic aurora and a strong geomagnetic storm - the alert says up to the G3 level, if it is not, we get a lesser geomagnetic storm. 

What does this mean for HF propagation? As I see it the CQWW SSB contest this week end might have very poor propagation, maybe even with periods of the bands almost closed.

Longer term, if the solar activity stays at this level, approaching winter, we could have some strong day time openings on the high HF bands 15 - 12 - 10m. I would not be surprised if we get strong F2 openings between Northern Europe and the East coast on North America - if the geomagnetic activity does not get too high. I will not be surprised if we will have good 10m opening all the way through winter and well into the spring here. It may disappoint, who knows?

Idea Box: More Simple HF CW Transceiver(s).

 Here is another one for the idea box.

While I am doing stuff for much higher frequencies I am still thinking of this in connection with my "one QSO per band with home made gear" challenge. I was thinking of using a kit (or two) for a simple HF CW transceiver using a direct conversion receiver.

Some examples of those kits are the Pixie, the Rockmite, the Frog Sound and the 49'er. I have a box with some of those kits, and some of them should be quite easy to convert to HF bands up to 18MHz without too much loss of performance.

For higher frequencies I suspect that the receiver sensitivity will be insufficient for efficient work on those bands (21/24/28MHz). Here it is probably a good idea to use two kits, one for TX and one for RX, adding a preamplifier for improved RX sensitivity, and possibly a PA for higher TX power.

Each transceiver would be modified to use a SI5351 synthesizer board. This board should be controller (programmed) by, e.g. an Arduino, so I will have to learn another skill: Micro-controller programming. There are libraries and some programs in existence, but the programming skill will come in handy if I want to extend functions.

A simple 28MHz model could possibly be used as base transceiver for transverters to higher bands. This would not need RX modifications and could possibly be using just a simple TRX kit. I am well aware of the lack of CW activity, especially on the VHF/UHF/SHF bands, but a single QSO, or a few, should be possible.

I do have two other kits for CW transceivers, the QRP Labs' QCX+, with components for 20m and 60m. Still need to be built, but that is a matter of finding time to add those.

Do I have too many kits and projects? Yes, but I will not have any time to be bored, that is certain ...

Another one of the ideas stacking up ;)

World Wide Propagation on 10m.

The solar cycle 25 has started in earnest, and seems to be ramping up activity. We have already had a few days with the 2800MHz solar flux exceeding 100. Here is to hoping that it will pass 200 (or more) this cycle. That is not guaranteed, hope is all we have.

The past week or so 10 meters has been a band with world wide propagation.

My FT8 monitoring has shown spots form essentially all continents, every day. The past few days signals have been mounting from North America.

Signals from most of the Eastern United States have been coming in here, from the North West all the way down to Texas. 

Today I went on CW and worked barefoot with my R6000 vertical antenna. 3 US stations and also a single PY was what I could work after coming home late afternoon from a birthday party.

Since 10m is my favourite HF band I am quite happy that it is open with F2 propagation again. I have not heard the band like this in about 6 years.

Batteries for Portable and Fixed Use.

Today I brought my hand held VX-5 on my walk. Yes, I am trying to work myself up to a daily walk of at least 2km. I thought the battery was well charged, and all was fine just operating in stand-by. Having a local chat with the highest power level ... oops! Battery died. Maybe this is because the battery is fairly old. I am now going to check the state of the battery (Li-Ion type, 7.2V)

I may have to purchase a couple of spares, because it is a nice little radio. The standard battery is rated to 1100mAh.

For now, I am thinking of making a battery pack with 3 18650 Li-Ion cells and a cord/connector, just to be sure to have some spare capacity. This way I have can always have a fully charged battery, and I can change the cells when it goes too low. The cells are used, but tested cells with more than 2000mAh, so even with full power (5W) I should have enough juice for some local chatting. I **could** use lead acid batteries, but I don't want a hole in my pocket or rucksack after all those batteries are heavy as lead ;)

I have a good supply of Li-Ion cells and battery cassettes, so I expect to use those for several portable experiments, including going to local hills with the 10GHz WBFM experiments.

In China I found 2 solar chargers with a 3-cell (18650) battery casing, and including a BMS system, possibly fine for portable work.

At home I am slowly building some battery supply, charged mostly by solar panels, but in winter time it is probably necessary to add some juice from the mains power.

Initially this is intended for very low power equipment, such as a 28200 simple beacon receiver and some other simple monitor receivers that should run 24/7, and preferably also when mains supply fails, even if that does not happen often here.

For some of the computing the plan is to use some Raspberry Pi boards. The idea is using this for both WSPR/FT8 propagation monitoring and QRSS. 

As usual, ideas a-plenty, now it is about making time to do something with them.

Outdated Computers - Spare Parts?

Over time I have collected a bunch of old laptop computers, all too old to run just about anything remotely modern, even decent Linux distributions.

So what to do with this? 

One of the older laptops has 2GB memory and a Pentium 4 (2.4GHz), I could probably run a Windows XP with some "Windows only" programs that I still want to use, e.g. the control program for the 35 - 4400MHz signal generator, some spectrum analyzer software etc, possibly WSJT or QRSS software.

The processors of those old laptops simply don't run fast enough, and the RAM is too low to run any modern applications, so that is really useless. 

What else can be used of such old laptops? 

Batteries can always be disassembled, and the cells used for rechargeable battery packs, providing that the cells have not died. Some testing of their capacity will be needed.

Old hard disks should be checked for usable information on them, and backed up. Really old ones, i.e. used PATA disks should probably be discarded and disassembled for parts. (Stepper motors and magnets come to mind, maybe a few more items.)

From the main boards a few components could be of interest as spare parts. Switch transistors, possibly some capacitors or inductors for the switch mode circuits.

A few modules, such as WiFi modules could possibly be used elsewhere

I would save some small speakers from laptops.

One thing seems quite useful: The laptop screens. With an interface they should be useful for some Raspberry Pi projects. I have a few from old netbook PCs with only 1024x600, a 800x480, and one 1366x768 screen from a recently disassembled defective machine.

With all the propagation monitoring I want to do those screens should prove useful in the shack, and in the lab.

Right now I have two dead Asus machines (one with dual core i5 and one with quad core i7). absolutely nothing happens when the (19V) power supply is connected, and the PS is working. From the description of other faulty laptops etc I suspect one or two defective switch transistors, as I have have had some power cuts with possible transient voltages. Here the disassembled old laptop main boards might provide spare parts. If not I should try to get some replacements.

Fault finding and repair is something I have not done a lot of, but learning something new is always of interest, especially if I can get some useful equipment up and running again. Yes, I have had the tendency to just buy new (or good used) stuff, but the stock is quite high now, so I should get to use more of what I have.

Additionally, I have some very old - and very large/heavy - test equipment. I have got some new and smaller equipment, so the really old/heavy stuff, like an ancient 1.7 - 4GHz signal generator with a **klystron** is not too useful. Very heavy and bulky, and unstable. The new ADF4351 based generator is much better and takes up a fraction of the space. Any useful parts from the generator, like the attenuator(s), will, of course, be salvaged, as they are useful in the lab. 

So this is an effort combining tidying the lab, making space and improving my test equipment, all while I am building some ham radio projects. Absolutely no time to be bored (what is "bored?)

Especially the lab is in an attic with essentially no useful vertical walls, so space is at a premium. Also, while the newer/smaller test equipment is not of professional standard, it will work nicely for my amateur use.

Slow Progress on the 10HGz WFM Project.

 The past few weeks I have been working a bit on the modulator for the 10GHz HB100 module. The modulator worked, but I needed to build it up on some prototype PCBs and that is almost there. A CW (audio) generator is under way, and then it needs to go into a box, so it can be operated portable.

I may also make myself a test TX ("beacon") with the HB100 and just a CW audio generator. I think I have found some directions where I can test the TX on top of a 12m telescopic fibreglass mast and then walk on road and path to test the path for (near) line-of-sight propagation. First tests will be in the garden, of course, with a max range of about 35m ;)

Then I will have to take some walks, I suspect that I have found a possible distance of about 600m, and maybe one of about 1.6km. 

This will all be using the HB100 with the built-in dual patch antenna on the PCB, and the LNB just with the integrated feed horn. Not a lot of gain, but some people have claimed the range of such a simple arrangement to be 8, maybe 15km. The distance to a fellow amateur who is interested in participating is less than 10km, and we suspect that we could possibly make a line-of-sight contact from garden to garden.

Initially I just build a single TX and RX, but having made one set it is not too difficult to make another.

For longer distances some improved antennas or higher power is needed for WFM contacts.

I hope to be able to make the first one-way tests in my garden this week end, and hope for some decent weather to make the tests on longer distances.

I will need the weather to be dry and not too windy for these experiments, as the HB100 module(s) need to be in the open air, or at least with very low loss material in front of the patch antennas.

Now we start the idea box:

Improved antennas can be the following:

- mounting the HB100 and the LNB (or just the LNB) on a dish. Not easily portable if I need to up a steep road to a hilltop, or up a narrow staircase to a watch tower or the like. Also, for the dish a tripod is needed, and it should not be too flimsy.

- The second option involves more work: Horn antennas. In this case both the HB100 and the LNB need to be "connected" to horn antennas. For this some coax-to-waveguide transitions are needed. I have one.

It may be possible to "glue" a horn antenna in front of the LNB. I will have to test how efficient that will be.

The HB100 *could* be mounted inside a "horn". I do not know how efficient that will be, so modifying a HB100 with a connector/coax to the coax/WG transition.

- The other option for keeping the size/bulk of the equipment low also involves more work: Going narrow band. This could be NBFM as we use it on 2m and 70cm, or it could be a CW transmitter, to keep it as simple as possible. Both would likely involve generating a much lower frequency, and using frequency multipliers to get to 10GHz. Much more complex electronically, but still relatively simple mechanical construction.

We shall see what we will do, but first some short range tests will be done, likely this autumn.

10 Meters Is Opening, Slowly, But Surely.

 For the last few weeks I have been monitoring 10m FT8, and lately the beacons on 28.200.

A few weeks ago the band started opening to South America from here. There has not been a day within the last 3 -4 weeks without receiving SA stations, mostly from Brazil, and often stations were also coming in from Southern Africa. I suspect that some of this propagation was trans-equatorial propagation (TEP). This fits well into the pattern of TEP being strongest around the Equinox times.

Then stations started coming in from the Far East and Oceania, and the South American stations started coming in during day time, and several stations from Australia. 

The past week the propagation has moved closer to the North American continent, Northern part of South America, and Caribbean stations coming in, and the past few days South Eastern and also North Eastern United states have come through, as well as regular propagation to the Middle East and Atlantic islands like the Canaries and the Azores. These are clearly single hop F2 propagation  

The past week or so I have re-started monitoring 28.200, and  daytime propagation has been detected on this frequency. Almost daily signals from CS3B and ZS6DN, and occasionally very strong signals from the 4X6TU beacon.

To me this means that the F2 propagation on 10m has returned after the deep solar minimum, and I am happy that my favourite HF band is coming to life again.

I suspect that we will see more North Atlantic propagation in the next few months, unless the sun goes very quiet again. That may happen in short periods, but I suspect that we will have good, maybe excellent 10m propagation the next 3 - 5 years or so. Who knows, with the new weak signal digital modes we may even see weak F2 propagation on 6m. That would be exciting. 

The most general predictions for the next solar maximum (cycle 25) is much like the previous cycle, but we can always hope that it will be larger. As a Danish poet said about 100 years ago: "Prediction is difficult, especially about the future" ;)

Spectrum Analyzer Extender Using the HB100 Module as Down Converter.

Tonight I made a test of using the HB100 module as a down converter, so I should be able to "see" 10GHz band signals on my (low-cost) Tiny SA spectrum analyzer.

I have a few of the modules, so here goes:

With a previous test I had used a LNB with a more expensive spectrum analyzer I had access to. I tuned some HB100 modules to different frequencies, so I had some simple signal sources on frequencies from 10300 up to 10500MHz in 25MHz steps. I also made one for 10368MHz (narrow band) and for 10489MHz (QO100 segment).

Today I wanted to test how the HB100 module did as a simple dowm converter. Because it has been used with (broadcast) FM band receivers I am aware that it can be used as a general down converter, and sure enough, using a 10450MHz HB100 and a 10375MHz module, connecting the spectrum analyzer to the IF output of the module produced a 75MHz IF output. It does work as I expected.

However, I do not know the RF or IF) bandwidth of the module, so I have not checked that.

The base bandwidth of the Tiny SA is 350MHz, so I tested with a 10300 module and a 10600 module, and got a nice 300MHz signal. Using the modules is a bit tricky because the apparent output varies a lot when tuning.

Using a 10600MHz module should make "seeing" 10300 - 10900MHz with a small gap around 10600 (zero IF). Not too bad for a $5 module. For the putpose I also made a 10500MHz module (10200 - 10800MHz coverage) a 10300MHz module can be added for coverage all the way down to the 10000MHz band edge (10000 - 10600MHz)

I am well aware that I do not have any image rejection, but as long as I can calculate expected frequencies I should be able to estimate the spectrum of an oscillator or a transmitter.

The Tiny SA has a base bandwidth of 350MHz (LOW input), but also has an extended coverage up to 960MHz, so it should be possible to see more than 1800MHz with a single module. The question is how much IF bandwidth the module can provide. 

SM6WHY estimates on his blog that the IF bandwidth of the HB100 might be up to 2GHz. I have my doubts, but if that is the case I might try using my Chinese 35 - 4400MHz (primitive) spectrum analyzer which uses direct conversion to sweep the band. If I recall correctly, only 350MHz can be displayed at a time, but the 10500MHz version then might be able to cover 8500 - 12500MHz with a small gap around 10500.

Even if this is far from calibrated, it is much better than not being able to see anything.

For the initial test I just used the modules lying on the desk, with the antennas there. I do think that removing/disconnecting the antenna(s) and adding connectors, and put the module in a stable casing will improve the set-up considerably, both with respect to stability and reliability.

What do you think? a spectrum analyzer extender to the 10GHz band for about $5? Not bad. 

Mini-Lab Downstairs.

While I do have a mostly complete lab upstairs, it will be nice to do some home construction at the operating position downstairs, and have at least some test equipment there. This mostly for simple constructions and kit building.

Here is an overview of what I have for work downstairs, with a few ideas for improvements.

- Soldering iron and antistatic mats.

- 2 Multimeters (DMM).

- single channel portable oscilloscope (100MHz?, more like 30MHz, but OK)

- LCR-multimeter (not for very low L and C values, but a start, a better one is upstairs)

- Nano VNA (900MHz Fundamental wave generator up to 300MHz)

- Nano VNA (SAA2) (3Ghz)

- (Both Nano VNAs need to be tested with a simple diode multiplier for signal generation above 3GHz, e.g. 3.4, 5.7 and 10GHz)

- Tiny SA, low cost spectrum analyzer up to 960MHz, base scan about 300MHz. (The bigger/better one is upstairs, anyway).

- frequency counter, up to 1.3GHz. Under warm-up-test. Looks like it needs a bit of burn-in to age the OCXO crystal a bit more. It has moved 5Hz @ 10MHz for now, and seems fairly temperature stable at normally changing room temperatures, < +/- 1Hz. If better stability is needed, a GPSDO can be adapted (10MHz out to 1MHz in as counter reference frequency).

- a GPSDO, 10MHz and a distributor/extra OCXO. More power supply needed.

- (I should set up some more power supply downstairs for testing. I have an older one (up to 1A w/fold-back at over-current/short circuit) that needs to be tested. Output voltage should be 10 - 15V. Claimed max current 2.5A, but looks like insufficient cooling for that.)

- (For more test equipment a 12V (not 13.8) supply with several Ampere output should be available. Must be linear to avoid noise/ripple on the output.) (Also usable for the microwave converters/transverters.) Some equipment does not like the 13.8V, and should have just a 12V supply voltage.

- for now, a few battery cases with 3x 18650 Li-Ion cells (9.5 - 12.5V), and a few Ni-MH rechargeable sets are available. (4.8V, 7.2V, 9.6V available, a casing for 10 cells (12V) can be made.)

- Charging for Ni-MH cells set up.

- (Charging for Li-Ion cells needs to be set up.)

- I think I will need a more advanced linear power supply for the downstairs lab. (There is one upstairs) I should go see if I can find something suitable. Something with both voltage and current limiting. A simple SMPS or DC/DC converter with those functions may be sufficient for quick experiments. I think I can find one in my pile of modules - 12V input buck/boost converter with 3 - 24 (30) V out, with digital meters and settings ;).

- A small set of components for experimentation.

If you can think of further improvements please consider leaving a comment.

I do have more test equipment upstairs, and that will come into use for more elaborate testing and building. It does need some (a lot of) tidying there, though.

10GHz HB 100 Test With Modulation.

 Today was an active day with the soldering iron.

As the very first test I just connected the HB100 modules, preset to 10375MHz and 10450MHz on the desk, just to see if I could hear the carrier with my LNB mounted outside the house, and pointing away from the house. This is the LNB I have used for beacon monitoring, so I know that it works.

A primitive modulator using the LM386 PCB module with gain control (from China) connected to the 5V power supply (yes, 7805) was tested, making sure that the peak voltage would not be too high for the transistor in the HB100 module. This initial test was done with a 150 ohm "DC-dummy-load" in place of the HB100, and the LM386 input was connected to the earphone/headphone connector of a transistor radio. The voltage swing was about 50mVpp, so well within the limit.

Time for an on-air test. I connected my QO-100 base radio for TX, without RF output, and used the CW side tone to modulate the system on 10450MHz. When the HB100 was in an optimal position the wideband FM modulated CW signal was loud and clear in the receiver. Not very strong, but with significant quieting and a clear CW. My callsign has been sent out on 10GHz.

What I need to do now is getting the system into a box with switches, a tone generator the modulator, likely an electret microphone and a bias tee for the LNB, plus connectors for getting signals and DC out to the LNB and HB100, and the IF signal in from the LNB, and I should have a working system.

Right now I do not have any stations to test with, but a local amateur has a HB100 module and LNB somewhere, so he might be available. Otherwise I may have to build another system, so I can get some tests done.

The transmission distance tested right now is about 8m, so there is plenty of room for improvements.

First HB100 Tests on 10GHz. Simple Low Cost Field Strength Meters.

 The first experiment with very simple equipment, using the low cost HB100 Doppler radar module has been completed: A simple field strength meter (FSM). The idea comes from F6HCC's website http://f6hcc.free.fr/10ghz.htm .

A non-functioning HB100 (with no output when supplied with 5V supplied) was modified according to F6HCC. Another as yet untested HB100 module was used as a source.

But the initial test was done by using a 2m/70cm hand held radio near the module's receive antenna. The "IF" output of the module uses a 10nF capacitor (non-critical, F6HCC uses 22nF) as decoupling for the RF to the meter. The meter used is a low cost digital multimeter (DMM) from the local DIY (home improvement) store. 

The reading with 10cm distance from the source (TX antenna) to the sensor (FSM RX antenna), and the reading is a modest 5mV, clearly seen when changing the distance.

Because most hams do have a DMM this provides for a low cost method of testing the functioning of a 10GHz transmitter and/or antenna. The HB100 module can still be had for less than $5, and the modification is simple and well described (with images) by F6HCC. Admittedly, the sensitivity of this meter is low, but it does work.

On the same page F6HCC also describes a more elaborate FSM for 10GHz, involving a diode inside a wave guide, and an amplifier for an analog meter.

However, for a much more sensitive FSM I would likely use a low cost (surplus) low noise block converter LNB, usually used with a satellite TV receiver dish. This has lots of gain, and you can probably salvage one from a discarded satellite dish. The signal on 10GHz is amplified and converted to a much lower frequency, usually around 250 - 750MHz, where a diode detector is much easier to make. Also a simple multimeter (analog or digital) can easily be used in this application. 

For measuring close to the lower band edge (about 10.0GHz) it may be a good idea to modify the LNB with an external DC supplied, not via the IF cable, but directly through a hole in the casing, and disconnect the DC "RF-choke" on the PCB from the IF connector.

Further, if there is a filter on the 11-12GHz side, it may be an advantage to by-pass this for greater bandwidth.

The gain in such an arrangement may be rather high - too high - but reducing gain in a system like this is easy. Just put some RF (microwave) lossy material between the LNB and the signal source...

There is, of course, the possibility of bypassing the RF (10GHZ) amplifier and the RF filter in the LNB, and connect the sensor antenna directly to the mixer via a piece of coax (semi-rigid coax will be the best choice), thereby reducing the gain.

If you do this, you might salvage some useful GaAsFETs, if you can avoid destroying them with static electricity.

New "Toy": NanoVNA V2 Plus4

 The latest version of the NanoVNA just arrived.

The model is the NanoVNA V2Plus4. I features a 4 inch screen and it is supported by the NanoVNA-Saver program freely available.

This is a considerably improved version, capable of running up to 4.4GHz and displaying 400 test points on the built-in screen. The dynamic range is improved, too, with up to 80dB range up to 3GHz, when using 5x averaging, otherwise 70dB. Below 1GHz, and with 20x averaging all the way up to 90dB.

This makes this VNA very interesting as a stand-alone unit.

As with all the previous versions, this version can be used as a simple RF signal source, up to 4.4GHz.

There is always a catch. It appears that the people behind this design are working on a new version (v3) capable of measuring up to 6GHz. Not (yet) available, and probably more expensive, but probably worth it for me if I continue to want to build microwave equipment.

Now the question is, when will there be a version capable of measuring the 10GHz amateur band? It will not surprise me if we see a v4 with that capability in the not too far future (5 years?).

Flea Market in Frederikssund and Test equipment.

 This was the first larger arrangement I have attended since the corona closed down everything social, sort of.

I am still glad that this was an outdoor event.

It was good to meet some old and new friends. I had been talking to a local on the QO100 satellite, and finally we got to meet in person.

I did not bring too much back home, as the house is quite full of stuff. What I did get, was some good quality attenuators (10W/10GHz/10dB) and an older frequency counter capable of 1300MHz.

The counter has been under test a while, testing the reading of my 10MHz GPSDO. After close to 2 days (warming up the reference oscillator) it looks like the reference frequency oscillator is 2Hz off on 10MHz. Not too bad for HF/VHF, but insufficient for UHF and microwaves. The variation with temperature (there is a simple OCXO inside) seems to be less than 1Hz after warm-up, so stability is quite good.

Reference frequency alignment is in my future. 

The counter does have a 1MHz reference frequency input, so it will also be possible to lock the reference to a GPSDO for the best possible stability and accuracy.

Update of "Shack Corner". Mostly Operational Again.

First stage of the "shack corner" update is done. 

I can now slide the desktop plate in and out, so I can get better access to radios and cables behind the radios. The plate itself is 200x60cm, but part of it slides between shelves, so I have about 140x60cm of desktop available.

The shack computer, a Raspberry Pi 4 (8GB RAM) is set up with a 1080p monitor, so I have the log program running again. The log program is, at the moment, storing all (digitally entered) logs, with the exception of the log for QO-100. The log program cannot yet handle that.

There will be more computing there, I want to get some FT8 monitoring up and running again, on different bands. Some more Raspberry Pi's are available for this, and I expect (long term) to be running those remote controlled from the main computer/screen (if the Raspi4/8GB can handle the load).

The QO-100 setup is up and running again, including a manipulator keyer connected to the radio, so I can run SSB/CW on the satellite.

Newly built: Long ago I had made my own memory keyer, capable of being programmed from a straight key. It had several switching arrangements, but it is 40 years old, so I pulled out the electronics of it and just connected a few of the toggle switches. The switch box can now handle 4 radios - one at a time, using 3 toggle switches. In addition, the switch box has 2 inputs in parallel, one for the memory keyer, and one for a straight key. I have a Swedish Key that works very nicely for hand keying.

I got some cables made, and 4 radios are connected:

- IC-7600 connected to the 6m part of my 6/2/70 vertical (V-2000) and my R-6000 for 10/12/15/17/20m.

- IC-7300 connected to my low hanging multi-dipole, runnnig 80/40/20/15/10/6/4m. Not very good on 6 and 4, but a poor antenna is better than none.

- IC-7100 connected to a power amplifier and the 2m Big Wheel antenna.

- IC-703 connected to a 10m vertical.

The HF PA is up on the shelves again, but still needs to be connected - I am still considering which radio to connect ...

Receive antennas and receivers still need to be connected, but it is good to be able to operate again, and to have the soldering iron in use again.

Update (2) Reorganization of Equipment.

Quick update the 19th:

I tested if the desk plate can be fitted in between existing shelves, and it is (just) possible.

The 8GB Raspberry Pi 4 is now connected and in working order, so the logbook program can be started. With the narrow shelf it is possible to do some operation on VHF, HF and the QO-100.

Things in the reorganization now go a bit slower, so other necessary activities can be done.

Quick update the 15th:

This is a lot of work, even with some decent planning.

The shelf arrangement as such is essentially in place, and some radios initially connected to power and antenna. I can listen to some HF, VHF and the QO-100 satellite.

An initial narrow shelf has been placed, so a bit of operation can be done. 

The evening was used for transferring some radio stuff from storage boxes to the shelves, initially just up on the shelves, but for later positioning and connection when more antennas and signal distribution is available. Before the end of this week I need to decide on the next project build. Antenna maintenance, a new 25MHz frequency reference for the QO-100 receiver or ... ?

The satellite system does run, but the receive sensitivity, or at least the system gain seems to be lower than before the reorganization started. This will have to be looked into, but that is for later.  The local 2m multimode radio is fully running, one HF/6m radio is connected to the R6000 antenna and to the 50MHz part of the V-2000 antenna (with a triplexer). The IC-7300 is connected to the multiband dipole, and can run 80/40/20/15/10/6/4m, though not with any impressive signals. 

The full desk top plate (60x200cm) will have to wait until the correct antenna cabling from the radios to the accessible side of the arrangement has been done. Power cables and power supply units need to be arranged, also with respect to the cables.

A bit of HF listening and SSB work can be done on HF/6/4m, and with the vertical V2000 on 2m.

Laters...

Reorganization of the Radio Equipment.

 Finally, I got started with a major reorganization of the equipment.

The radio corner downstairs, where the main operation activity is going on, had been more and more disorganized, and moving some of the heavier stuff, like PAs, for improved ease of operation is needed.

Most of the equipment is now removed from the shelves (the living room is now full of radio stuff everywhere), and the remaining radios will be removed and re-placed on other shelves this week. The build-up will take a while, but I plan to get the most essential equipment moved, so the down time can be minimized.

Because I am doing this on my own, it is more time consuming than with assistance. I do prefer doing most things myself, but heavy lifting (HF PA) will require some assistance (no problem with that).

When the new "shack" is ready, the operation should be a good deal easier.

At the same time, there is some necessary antenna work to be done this (remaining) summer and in the autumn/fall.

When that is (more or less) done, the lab upstairs is due for some tidying.

Test Equipment, Part 1a: Idea Box: Using Nano VNA as a Portable RF Signal Generator.

 Not everyone can afford expensive RF signal generators, or even several less expensive ones, so here are some thoughts on how to make simple signal generation with a Nano VNA, probably the least expensive piece of test equipment with excellent functionality for the amateur who wants to build some equipment, or even just as an antenna analyzer.

In my case I want to be able to check receivers up to the 10GHz band, maybe higher, so what to do with a simple Nano VNA?

I have been looking a bit around to see what others have done in this regard, so here is my 

Up to the 70cm band.

For the 2200m to 70cm bands, even the oldest version of the Nano VNA can be used directly. Even though it does not have a calibrated output (amplitude or frequency) It will provide a (not very clean) signal, but if you know which frequency your receiver is set to, it will work fine. If the signal is too strong it is possible to use attenuators, for the HF bands and lower they can be home made, it is more difficult on higher frequencies. 

It is also possible to use the VNA as a "personal beacon" test generator, though a keying circuit (and amplifier) has to be added. What about your own low power CW transmitter? Mind you, some filtering will be necessary, as the VNA signal is not really clean, but for an experiment it will work.

Higher bands.

The simplest way to generate signals on the microwave bands will be a simple diode multiplier (comb generator).

So here we go: Add an amplifier followed by a 3 - 6dB attenuator to the signal generator output. It is likely a good idea to add a simple band pass filter as well. Then connect a diode across the output of the attenuator.

Why the attenuator, you may ask. This is in order to have a good load of the amplifier, giving a more stable output.

Next question: Which kind of diode can we use? Given what others have done, with sufficient input power into the diode, PA3FYM reports + 7dBm is sufficient to generate a 10GHz signal using a standard (dirt cheap) 1N4148 silicon diode, so that is what I would try first. Others suggest using step-recovery diodes for generating stronger harmonics, but why do that if the low cost solution works.

With a 432MHz (filtered) signal from the Nano VNA, signals should be generated on 1296, 5760 and 10368MHz, providing signals for narrow band receivers. About 437MHz will provide a signal in the QO-100 satellite downlink band on 10GHz, and should be within range of the band pass filter.

With 400MHz a 2400MHz signal can be generated.

With 425MHz a 3400MHz signal can be generated.

This covers all amateur band allocations (up to and including the 10GHz band) available to me, and should be sufficient to check receivers on all bands, if no other (better) RF signal generator is available.

Given the relative simple design of this I might try it out. I can test the 10GHz signal with a (synthesized) Satellite LNB, initially I will test without a filter on 432MHz, just to see if it is necessary. I might even try to connect the diode directly to the output of the Nano VNA Simplicity rules ;)

All this is with the cheapest version of the Nano VNA. As you may be aware, there are versions with a larger frequency range. The SAA2 (Nano VNA v.2) works up to 3GHz. More expensive, but much easier to work with, up to and including the 2400MHz amateur band. The diode multiplier should also be useful with this model.

The Tiny SA (spectrum analyzer) should be able to work as an RF signal generator, so this might be useful as well, if you have one.

One other option may be using the generated signal from a scalar network analyzer (35 - 4400MHz. I do not know if the spectral purity is sufficient for those PCBs, or if the frequency can be set to a fixed value, but I guess this has to be tested, too. First more research on the Internet. If this one works, the 3400MHz band will be included, but no HF/MF/LF. Everything is a compromise.

2m Es Continues.

 This year's sporadic E season could turn out to be the best in my experience.

Yesterday, June 11th, I had the highest number of Es QSOs in a single day on 2m.

4 different stations in Southern France, one in SSB, the others in FT8, and a single Spanish station, EA1SA in IN83.

I am hopeful there will be more. 

This year I have been focusing more on the 2m band than on 4m and 6m when the chances look good, and it has been successful, even if I have missed openings - sometimes by mere minutes.

I have made good use of PSK-reporter and DX-Maps. Even when I was not at the radios, I can monitor the propagation on a separate screen in the house, and that pays off nicely. Of course, when I am away from the house I cannot immediately go to the radio, but at least I know if something interesting has happened while away.

Of course I want to make some contacts with this rare propagation, but I do not want to be tied to the radios all the time.

2m Sporadic E, and a Transatlantic Opening on 6m.

 The late afternoon today had a nice Es opening on 2m. Stations received were EA1. EA3, EA6 and IS0.

I managed a single QSO with EA6SA, and I was called by another EA6, but no complete QSO.

All with my omnidirectional "Big Wheel" antenna, so I am not complaining at all.

After finishing reading a book I noticed that the 6m band was open to North America. While I did not work any of the stations with my limited power, 80W into an omnidirectional vertical, the Diamond 3-band antenna "V2000", A lot of stations from Florida and Texas in the South to Wisconsin and further East in the North.

I really need a better antenna for 6m, one that can take the power from a power amplifier. I do have one, but it has been put away for the time being, because the antenna is only rated to 150W, and I do not want to lose it.

All in all a very interesting day of sporadic E.

Here is a thought. When looking at my logs through the years, there is a tendency to have 2m Es openings  at my place more often around two sets of dates, about 8th - 10th June and 8th - 10th July. This could be a coincidence, but it does coincide with meteor showers at those dates, so who knows? I do not.

I am well aware that the cause of sporadic E has many other (unknown) factors, but it is a thought I have had for some time.

The Sun Is Awake!

 This past week end we got the clear sign that Cycle 25 has arrived.

Saturday we had the first X-class solar flare of the cycle. The X-class flares are the strongest category of solar flares, and if they are located near the centre of the solar disk, they can create strong auroras and other disruption in HF propagation.

This flare was near the edge of the disk, and will not produce auroras. Id did, however create a sudden ionospheric disturbance (SID), in essence a short wave radio black-out in the day time zone of the planet.

This time the timing created the black-out in trans-Atlantic propagation.

While the cycle has let us wait quite a while, I think that this autumn/fall we will see the higher HF bands (10 - 20m) wake up and become very good. 

With the advent of weak signal modes I think that world wide openings will be quite common on the 10m band, and CW QSOs will certainly be there some of the time.

According to predictions the maximum should arrive in about 3 - 4 years, so I am looking forward to better days for HF propagation on the higher bands.

Who knows, with weak signal modes like FT8, we may see openings appear in the 6m band during the maximum. 

Some 2m Sporadic E (Es).

 Yesterday my FT8 monitoring system detected a single Italian station, most likely a short Es opening, or a long meteor burst.

Then this morning I went to the radios and found that 10 minutes before there had been Es signals on 2m. 2 stations in Southern France and 4 stations in Northern Spain were detected with up to +11dB S/N.

Away from the station I have set up a rudimentary 2m Es monitoring system using the PSK-reporter and the DX-maps websites showing my own 2m FT8 spots and the Es-MUF map for Europe, as well as stations spotted on 6m FT8.

This monitoring system has been running essentially 24/7during the Es season, and I would like to be able to add to the system, so I can monitor 28(/40)/50/70/144MHz 24/7, especially during the Es season, so here is an addition to the "Idea Box":

For this I do have usable receivers, but the antenna system is not yet ready for this. For the purpose I am thinking of mounting a TFD (Terminated Folded Dipole) vertically, with an added broad band amplifier, hidden in the trees at the far end of my garden, at least for the 28 - 70MHz bands, and probably some kind of wideband antenna, usable for the FM broadcast band, air-band, 137MHz satellite band and 2m, also with a preamp.

An alternative for 2m would be a simple vertical or a horizontal V-dipole or a halo, with a narrow band preamp for 2m.

Home Antenna Considerations, Part 1.

 I am doing some considerations on a re-design of my antennas in and around the house. Right now I have a more or less functioning system, because during the pandemic I have not had the option of people coming to assist in antenna installations. 

The antenna system was due some maintenance the last 2 years, so now is probably the time to get started again.

This is my existing antenna system:

1) RX-ant:

- Active Mini-whip: 10kHz - 25MHz (needs some distribution/filter circuit(s))

- Indoor loop: 500kHz - 30MHz (lower than 500kHz w/amplification?)(needs distribution/filters)

- Loop on ground (30 - 160m, maybe MW/NDB bands w/ amplification?) (needs distribution/filters)

2) TRX-ant:

- R6000 (10 - 20m) (6m poor(RX only?)). In working order, but guy wires need to be replaced.

- Low 5B dipole (10-15-20-40-80m). Not very efficient due to the low height.

- V2000 (6/2m/70cm vertical). This is in working order.

- Corner vertical (mounted at the corner of the garden). This antenna has lost the top. I will have to check if the telescopic fiberglass mast has partly collapsed, or if it is broken. Originally this antenna worked in varying degrees on 160 - 30m, but it has certainly lost the 160m capability. Most definitely needs maintenance or re-design.

- Big Wheel, 2m (could possibly do 70cm) Omnidirectional, horizontal polarisation. This is generally in working order, but in rainy conditions it seems to deteriorate. Probably leaking, so needs maintenance.

- 10m 1/2 wave antenna. In working order.

- Low 2m/70cm vertical w/lossy cable. 

I am trying to make the antenna system as unobtrusive as possible, still with the functionality I want, so here are some requirements:

TRX Operation possible on following bands:

- preferably a possibility og making at least one QSO on 2200 and 630m. This may be tricky, but should be tested.

- 10 - 160m, reasonably well.

- 10m good (minimum as good as a vertical 1/2 wave).

- 4/6m needs to be improved (probably with Moxon, capable of running more power)

- 2m added gain, horizontal

- 70cm horizontal gain

- 23cm vertical and horizontal w/ some gain

- 13cm vertical and horizontal w/ some gain

- 9cm ???

- 6cm (maybe "14dB" patch array)

- 3cm 15/17dB horn or small (35cm?) dish

- probably some antennas should be capable of more than one band.

Diverse RX antennas: 

- Mini-Whip (2 pcs?). Will need distribution/filters

- Indoor WB loops for MW/HF. Will need distribution/filters

- Outdoor WB loop for MW/HF. Will need distribution/filters

- Outdoor loop for MF/LF(/VLF?). Will need distribution/filters

- Loop on ground antenna for MF/low HF bands. Will need distribution/filters

- other possible RX antennas may be considered, e.g. 4/6/10m RX antenna, 137/145/250MHz, 432MHz, 23/13/3cm monitor antennas.

I do have some ideas, but I think I will have to take yet another look at the garden and assess the possible solutions, so this is all for today.

More 2m Es.

 2m is at it again. The DX Maps' MUF chart had lots of red patches, and some really high MUF spots (>200MHz).

I have not worked anything, the "high MUF" spots are either too close or too far. As is classic, at the moment of signals from EA3, EA5, I was in the shower. There is a reason it is named **Sporadic** E.

Update 1538UTC:

IK7JNM in JN80 worked.

Update 1830UTC:

IK7UXW. also in JN80 a bit later, and even later

EA2BFM in IN83. Some EA4 also heard, but not worked.

Update 1900UTC:

IU0LLD in JN61FU

Considering that I am working with a simple omnidirectional antenna (Big Wheel) this is not bad. I think I need to get my preamplifier sequencing  working, so my "ears" will improve.

Most Active Es Day For Me This Year.

Today was quite a day for sporadic E propagation (Es).

2m:

While I have received Es on 2m a few days ago, I worked my first 2m Es today. One Russian and one Italian. Both were worked with FT8 because I only had low power available at those moments. I discovered the opening to Italy a bit late when I checked the PSKreporter while in a local QSO, then I got busy. I probably missed the main opening, but at least I got one.

Here is the map of received stations via 2m Es today. Quite a bit of propagation.

Initially I tried to work SSB or CW, but at that moment the PA went on strike. After the openings I checked, and with a power disconnect-reconnect it works again. I suspected the RF input level to the PA was too high in SSB, so played with the levels for DIGI modulation and Mic Gain, as well as limiting the RF output level of the radio, and now all works nicely again.

4m:

The other day I worked a single station on Es, today there was a bit more (yes, just two). The antenna used is still the HF dipole. not ideal, but it does provide QSOs.

6m:

This band has been humming with signals every day the past week. Today I got just under 20 QSOs on 6m, all with trying 2 and 4m in the mean time.

Oh, the weather was perfect for working on the radio, raining much of the day.

Week End Activity, P.3: Loop on Ground Receive Antenna Experiment.

 The loop antenna adventure continues.

This time I revised the Loop on Ground (LoG) setup.

Some time ago I tried out a LoG made with field telephone cable. This cable is mostly made of steel wires, but with a few strands of tinned copper wire, in a 4x5m configuration. Probably not the best material for antennas, and the results were disappointing, and the experiment was halted. Now it continues.

After cutting the grass (first time this year, so it took some effort) I found some thin wire to lay down. It may be replaced with weatherproof wire later, but I got to test the system, this time the wire is a bit longer, the configuration is about 5x8m, so the highest band expected to work properly is 30m. I use pegs to hold down the wire, the type used to hold wires for robotic lawn mowers.

The box with the transformer had to be repaired, too, one of the transformer wires had disconnected since I last made the experiment.

I am testing with the IC-7600. Here are the first test results:

Initially the noise level all over the bands was poor, but winding part of the cable a round a ferrite rod near the radio improved that. A better common mode choke is desirable. Now I need even more ferrite (toroids and other stuff) for reducing RFI all over the house.

MW/LW sounds quite noisy and with low S/N reception. Not as good as the small NCPL (w/amplifier at the radio), and certainly not as good as the Mini-Whip.

160m sounds OK-ish with no preamp, not spectacular

80m sounds good, signals weaker than on the low hanging dipole, but noise lower, too. Almost equal, but I suspect that the 

60m sounds good, not spectacular, looks like it is a bit noisier than the dipole (using Shannon Volmet and FT8 as test signals), but then again, the dipole is not resonant on 60m.

40m weaker than the dipole, but sounds quite good. Comparable S/N.

30m looks quite sensitive, no resonant antenna to compare with yet, but it sounds like a decent receive antenna

20m: Looks like S/N is worse than the R6000. No surprise, as the Loop on Ground is too large for 20m

I suspect that the best band for this antenna will be 80m. 40/60/160 are probably OK with a better set of common mode chokes at antenna and radio.

On all the bands the noise floor of the receiver increased when the antenna was connected, so the IC-7600 receiver is sufficiently sensitive on all the bands I intend to use it for. It should also prove a decent receive antenna for use from 1.6 - 12MHz. I think I shall keep it and probably replace the wire, then get it closer to the ground, maybe a few cm under ground level. With some weatherproofing this should prove an interesting low band receive antenna in the winter season.

Week End Activity, P.2: QO-100.

This Saturday we had the CW challenge on QO-100.

This was running from Sat. 1800Z to Sun. 0600Z.

I started close to the 1800 mark, working the stations as I found them "on the dial". A bit tricky, because I use completely separate transmitter and receiver systems, so the transmitter has to be tuned when I find a signal on the receiver. This is a bit slow, but it works.

After running up the dial for the stations I found a frequency and started my own CQ. 

My signal on the satellite is not the strongest, but I can run SSB comfortably, so CW is not a problem, my signal can be seen on the waterfall of SDR receivers.

I had good fun and worked 35 unique stations in on/off activity of a total of 5 hours.

Week End Activities, P.1: Sporadic E.

 This week end has provided some sporadic E propagation on 10m and the lower VHF bands

My 4m vertical is still not functional, so I tested my low hanging 5-band HF dipole, and with the tuner in the IC-7300 it could be used on both 4 and 6m. At least, I could try to work on 4m, so I set the receiver to monitor 70.200, and sure enough, on Thursday (13th) a signal popped up. S57L called CQ in CW. I got the key connected in time, and made the QSO. Yes, I know! I need a better system to use my memory keyer for more than one radio.

I have now made my first 4m Es QSO of this season.

After this I went on 6m, still keeping an eye, well ear, on 4m.

8 QSOs in SSB and CW were made.

The rest of the week end I had the radio monitoring 6m FT8, and there have been signals every day, but not enough time to work QSOs.

Amplified RX Loop Test and a Little Outdoor Antenna Work.

 This week end I have been active with antenna work.

Small Receiving Loop.

The first was a test using a low cost Chinese amplifier for the NCPL (loop).

The amplifier is actually "overkill", stated gain/bandwidth is 32dB/1-2000MHz. Not surprising, the gain is too high, both attenuators are in action on the FRG-100 receiver, and the base noise level (not interference), especially on 5-10MHz, is still very high.

Considering that the antenna is till tested indoors in the noise field I would expect things to improve when the antenna (properly weather proofed) is placed outdoors, but there is still one problem. The high gain causes intermodulation, maybe also cross modulation. I have not tested this, but in addition it is possible that the amplifier is oscillating in the UHF range. 

Which signals cause the intermod etc? I suspect it can be the MW broadcast band, but given the bandwith/gain of the amplifier it could be FM broadcast stations, too.

As I suspected this type of amplifier is simply unsuitable for such low frequencies, but I had to test it.

A simple 2 transistor with negative feedback is in my thoughts, along with a pre-selector. N1KPR has published a simple design that could be made on simple perf-board. 

Outdoor antennas.

The weather was pleasantly warm today, so a little outdoor antenna work was done. Since I do it all alone things may take a bit longer.

First outdoor thing was removing the lowered 6m half wave vertical antenna. There was a bit of rust, so the WD-40 was in action. This antenna was mounted on a satellite dish mount on the lawn, so this is now freed for other antennas. In addition, the cable was freed as well, and put to good use.

The 5 band dipole (10-15-20-40-80) had been connected together with the 4m vertical (now partly lowered) with a HF/VHF diplexer, which this was removed. The dipole is now connected to the old 6m antenna cable. Testing from indoors, the dipole/cable system seems capable of operating on 6m and 4m, so for the moment the dipole is used for 4m, because the 6m reception is quite noisy. The performance is expected to be quite poor on 4 and 6m, but until a better solution is available this will have to do.

The (partly taken down) 4m antenna is now connected to the old cable, running indoors, so a very limited 4m reception is possible, until another 4m(6/10/30m) antenna can be tested. At the moment only a transceiver capable of running a repeater is connected.

For now the 4m will be run on the IC-7300 with the dipole, and 6m on the IC-7600 with the V-2000 vertical.

It looks like the weather will be quite good tomorrow, too, so I may find time for more antenna work.

4m Antenna System Temporarily Out of Order

 Because I have the intention to replace my 4m vertical with a multiband vertical the antenna has been partly taken down.The mast is standing/lying in about a 45 deg. angle, so while it is connected, it is useless right now. When the weather permits I will seek to change that situation.

Initially I should test a set-up of a 30m vertical (GP) which will resonate on 30, 50 and 70MHz. This could, initially (tor testing) be set next to the tree where the old 4m antenna is now quite useless.

As soon as the weather permits this is the next stage of outdoor antenna experiments.

My Home Made NCPL (YouLoop Clone).

 I made a prototype version of the NCPL (Noise Cancelling Passive Loop) receiving antenna.

This version is the same size as the YouLoop, but made with RG-58 cable, cross soldered (shield to inner and inner to shield at the top, then pushed through a hula hoop plastic tubing.

The ends of the tubing are inserted into a distribution box for electric wiring at the bottom. The shields are soldered together there, and the inner conductors are fed to a transformer made with 2x4 windings on a type 73 binocular ferrite core, one end connected to the shields and to the ground part of a SMA connector, the other end to the center of the coax connector. A better mechanical construction is needed, but a preliminary outdoor test can be made when the weather permits.

Testing:

Under test the home made loop behaved, essentially, as the commercial loop with respect to frequency response and signal strength. Not unexpected, and encouraging for the next experiment with NCPLs, another loop almost 2.5x the size of the original.

Due to the small size of the loop, signal strength on the lower bands is quite low. Experiments with amplification are in order.I suspect that the S/N can be improved significantly on MW/LW for this antenna, because many receivers/transceivers have low sensitivity below 1.6MHz, and the atmospheric noise is quite high on the low frequencies. I found a simple 2 transistor design presented by N1KPR, with 15-20 dB gain and a reasonable dynamic range, and I think this should be the first test with low frequency amplification, and probably be mounted outdoors near the position of the antenna. After this I can think of making an indoor distribution system with some band splitting, more amplification (pet band) and possibly a pre-selector system for the receivers. 

For the larger NCPL the intention is to use the thin Teflon coax cable (RG-316(?)) for inserting in the tubing, because the fitting holding the tubing parts together will probably not have enough space to fit the cross connected pieces of RG-58 inside. The thin RG-174 could probably be used, but the Teflon cable is more heat resistant when soldering, and more mechanically stable. Experiments with a different transformation ratio and some amplification should be made to see if the VLF band (down to about 10kHz) can be covered with sufficient sensitivity.

Because the system will be more usable in the winter half of the year, there is no great haste needed, but the bigger loop should definitely be made and tested. After that, I should focus on 2, 4, 6 and 10m. The Sporadic E season is right around the corner.

Beginning of the Sporadic E Season.

Monitoring FT8 signals on 10m has shown me two things:

1) F2 propagation is slowly starting after the deep solar minimum. I regularly detect signals form South America, a bit of the Middle East and a a few stations from Oceania, mainly Indonesian stations. I am looking forward to be able to work stations world wide with CW (and maybe SSB) on 10m, maybe even with QRP.

2) Most days I detect signals from all over Europe, mostly at distances of more than 1200km. Soon I will have to change the monitoring to 6m and maybe 4m. 

At the same time I am trying to reduce the visual impact of my antenna system as much as possible.

Last year I had separate vertical antennas for 6m, 4m and 10m. Not very good for low visual impact. This year I am planning to test an unusual antenna for multiband use: A 10MHz ground plane antenna. This will have a low impedance resonance on 30 (workable on 28MHz with a tuner), 50 and 70MHz, with some low angle radiation. What remains to be seen is whether this will work well for 6 and 4m, if it does I will keep that as a vertical for 4 bands. With a frequency multiplexer I should be able to use the antenna simultaneously for all 4 bands. I have a diplexer separating HF and VHF, so that is a start. But before I can do this I will have to dismantle my separate 4m vertical, and that is too difficult without assistance. I hope that the COVID restrictions will ease sufficiently for that to be possible, very soon, so I do not miss too much of the Es season.

There is more antenna maintenance needed, but this has a rather high priority.

I have some ideas for making a very modest rotatable antenna system for 6/4/2m and 70/23/13/3cm. For 3cm DX I know I will need something larger, but I have to start somewhere. More on this project later.

The Small Loop RX Antenna Adventure Continues.

Slightly updated.

 This is another attempt to achieve a good receive antenna system for monitoring different frequencies in as many (ham) bands as possible.

Stage one was the experiment with the Mini-Whip described in recent posts.

The active Mini-Whip did provide some decent to good reception on frequencies ranging from 16kHz up to 18MHz.

Not bad for such a small antenna.

Now the experiments have started for a small passive wideband loop antenna. The main idea is not new (at least 60 years old), but there has been a resurgence of interest since SDRs with good sensitivity and with reception capability on VLF have started becoming available at reasonable prices.

Looking at the "YouLoop" antenna made for use with the Air-Spy SDR I decided to look into this. 

This is in essence a "Moebius Loop" type antenna, a design invented in the 1960s, as far as I know. A version is available at the well known auction site, so I took the lazy way and purchased one, just to see what all the fuss was about.

This is the initial result of a quick comparison of the Mini-Whip and the YouLoop:

First I want to point out that the YouLoop as purchased is not suitable for outdoor use - no waterproofing.

This means that the Mini-Whip is mounted outdoors in one of the least noisy places I could find in my garden, furthest from houses, mine or neighbours' houses, and the YouLoop was hung inside the house, in the noise field.

Because the Mini-Whip is active the signal level is much higher than from the small loop. However, whereas some signals were audible with the active Mini-Whip and too weak to be heard on the loop, others were swamped in noise on the Mini-Whip and weaker, but clear with the loop. 

I am aware that the loop might benefit from a sensitive preamplifier, especially on low frequencies and with low sensitivity receivers. This I need to test.

Signals on the loop were a bit weak and noisy on medium wave, and somewhat comparable in S/N to the Mini-Whip on 1.8 to 10MHz. Above this the loop did not increase the receiver's noise when connected, indicating either insufficient sensitivity of the receiver (possible) or simply a too low output of the loop. MW was full of rather strong signals with the Mini-Whip, and considerable weaker (and more noisy) signals came from the loop.

I suspect that a low noise preamplifier at the loop will improve this, especially if a long cable is used. Oh, darn! more projects ;)

Having seen the results I decided to make my own (weather proofed) version of the loop. I already had some hula-hoops (yes the children's toy ones) stored and found a few of them. The first test will be a loop of similar size to the original "YouLoop" (My YouLoop clone). Using two lengths of RG-58 soldered together crossing the shield and inner conductor at the top of the loop, feeding the inner conductors at the bottom to a 1:1 transformer (type 73 binocular ferrite core), and connecting the shields together at the bottom. Here is a description already made, so I will not repeat everything. I will report back when the test has been done

I will have to check whether or not a connection of the feed cable shield to the common shield is beneficial wrt noise performance. I suspect it will be.

I have two more (larger) hula-hoops, so I intend to test a larger (2.5x or so) version of the loop for getting higher signal strength.

The loop antennas do have another advantage over the Mini-Whip: They are directional and have a null, making it possible to reduce interference/noise by turning the loop. For now I intend to use both the Mini-Whip and loop antenna, and switch between them to get the best possible S/N on a given signal.

Using separate receive antennas is beginning to take shape, and with the addition of a distribution system,  preselector/filters/amplifiers a decent propagation monitoring system, such as FT8/WSPR and/or beacon/QRSS monitoring.