2019-07-11

Building My Own Website.

I do have an extremely simple page on https://qsl.net/oz9qv/
This may grow a bit, but I have just got the domain where the main (detailed) parts should be.
It should also host the contents of this blog.
When it becomes active, it will be at http://oz9qv.dk When I find out how to set it up it will be at
https://oz9qv.dk https://oz9qv.dk

It will take time to get everything in there, but I should get there along the way.

Next post will be #100, so I will see if I can make a good one ...
(A good opportunity to launch the new website/blog.)

2019-07-09

10GHz Horn Antennas and Update on the LNB RX Experiment.

I have a number of horn antennas.
I am well aware that horn antennas of these sizes for 10GHz are a compromise. Small size is used, sacrificing gain, as compared to dish antennas.
Today I found a horn antenna calculator , so I can see what I should expect of the different sizes.
The calculations are like this:

- The largest horn (145x115mm): 20dBi
- Two slightly smaller horns (120x115mm) 19dBi
- Two metallised plastic horns purchased new: 17dBi. Same as specified by manufacturer
- a tiny horn with a (Gunn or detector?) diode in an integrated waveguide: 10dBi

I should be able to find more horn antennas when I get access to the rest of the storage - if I have brought them home when I moved, that is.
The three larger horns were painted when I got them, so I hope the paint is not too lossy.
For the 3 larger horn antennas I need to make a coax to WR75 transition. The 2 standard 17dBi horns need WR90. It should be possible to use the WG transition from some ancient single polarization LNBs I have, or, in the first instance, maybe use the preamplifier in the LNB as a 10GHz preamplifier. Still, a modification is needed, and the noise figure is expected to be about 1.5dB. Not as good as it could be, but still in the acceptable range.

It looks like I may have to create a 10GHz antenna "test range" in my garden, so I can check the gain figures. It is a good thing that I now have a set of 17dBi reference horn antennas, so I can get some relatively reliable gain indications. I know, a test field is not ideal in a garden, due to reflections etc, but it is better than nothing. Yes, coax to WG transitions needed there, too.
Initially I expect to use a HB100 as the signal generator, and test, if I can find log detector covering 10GHz. I am trying to make it simple. It may be possible to use an old (low gain) LNB for converting 10GHz and use log detector for a lower frequency. More tests to do.

Finally, a small update of the LNB receive experiment:
I looked up today to see that the direction of the horn is about 60deg. off the heading to the local beacon. Impressive that I still get a signal at 36km.

2019-07-06

A Bit of Work to Get a Workshop Up and Running.

The last few days I have worked a bit more in my "out-house" (40 sqm), to get a better organized space. The plan is getting to one section for storage with a small desk, one section with mechanical tools, and a section for other activities.

It is slow work, because there is a lot of stuff to move around, but right now I have done the beginning of the storage space, not yet with the desk space. A lot of stuff has been discarded, and more will come.

There is a fair bit of good quality tools that I inherited from my father when he passed and I took over the house, but it has been out of use for a while. Some of it probably needs maintenance. I will get there eventually.

Right now the corner section with shelves (and space for the desktop plate) is partly done. Some old stuff needs to be moved, so that more of the shelf space can be made ready and orderly. Next should be the workshop getting ready. A slow process, but it is progressing, along with all the other projects.

6m JA "Heard" - and a bit of rain scatter on 10GHz.

I got up late this morning and I could see on the PSK Reporter that I had received several JA stations on 50MHz this morning (50.313). The best signal was about -10dB, so quite good. I might have been able to work that station.
On top of this, I had received a few South Korean stations.
Interesting propagation at the bottom of the solar cycle. Who knows if the same propagation is seen at solar maximum. I am not sure.

In the afternoon some showers passed across the island of Zealand (Sjælland), and two beacon signals were audible. In addition to OZ9GHZ that I seem to hear at all times, OZ7IGY came through with the characteristic rain scatter sound.


2019-07-05

Update: Local 10GHz Beacon Monitoring.

Here is a quick update on the LNB receiving experiment.

The LNB is just mounted to the mast with duct tape with no dish reflector, and just in a fixed direction.
Here are the reception results after some tropo days and days with more or less flat conditions:
The beacon OZ9GHZ can always be found when tuning around for the drifting. It varies in strength from a solid S5-7 sometimes with short fade-outs of less than a second.
OZ7IGY is still out of reach for this setup.
I suspect that the part sea path for OZ9GHZ with few obstructions, and the landscape being against my signal, is the reason for the difference, in spite of the OZ7IGY being located closer to me.

At least, it looks like I have a stable 10GHz signal source to test basic reception on the band.

2019-07-04

Antennas: The Right Tool for the Purpose. Part 1.

Over the past few years I have been working a bit of everything on every band I could.
Just over 4 years ago I returned to my native Denmark after 25 years working abroad.
I moved back to my childhood home and started re-building my antenna system which had deteriorated a lot over time. That process is far from finished, and I suspect it will never be, due to new projects and interests in the ham radio field.

#1: Getting some local VHF FM system working. I chose the Diamond V-2000 antenna, because it had 3 bands available: 6m, 2m and 70cm. 6m has been a great interest of mine ever since I the band started becoming available in Europe.
So, why use a simple vertical omnidirectional antenna for a band like 6m? You can work so much more with a beam. The simple answer is that I wanted to get started quickly, because the Sporadic E season had just started, and getting a beam and rotator would take too long.
I had been working a fair amount of DX on 2m, 70cm and 23cm before, so that was not high priority, and I wanted to have some antenna for local FM traffic.
The V-2000 simply fits the bill very nicely, and easy to mount on my mast going up through an apple tree. the 6m capability was a great bonus, though.

#2: In my years since I got licensed in 1973, I have worked very little HF, but I would like to try out more. The exception was 10m, I have worked a lot on that band, especially in the summer Sporadic E seasons. The choice was a 5 band dipole for 10-15-20-40-80m. I tuned the antenna for the low parts of the bands, because I worked mostly CW and later digital modes. I managed to work DX on 80m, like the US and Japan, in the deep of winter, so the antenna was working, at least.
10m was OK-ish, but not too good for my taste hence:

#3: 10m vertical. I purchased a low-cost 27MHz end-fed half wave antenna and got it mounted about 6m above ground. Even in the rapidly deteriorating solar activity I was able to work some DX on 10 most of the year. This has, of course not been quite as good right now, as we are in the deepest low of solar activity. Only the sporadic E season is really any good on 10m, but I know things will improve when the sun gets going again. The 10/11m vertical does work on some lower bands, using the built-in antenna tuner of the radio. Suddenly I was able to work on 30m, even if that was bot the best antenna in the world.

This is what happened with my antennas the first year or so after I returned home. More happened later, but this is sufficient for now.
At the least this got me going on most of the bands from 80m to 70cm.

2019-06-29

Local Beacon Monitoring on 10GHz.

I recalled that I had a "free" cable to add another LNB.

I found one of the inexpensive ones I had, a single IF output version, unmodified as yet.
I mounted it with duct tape, just below my 6/2m/70cm vertical, about 6m above ground, and just the feed horn pointed in the direction of the local beacon I have heard earlier. Yes just testing without any substantial gain.
Of course, it drifts with temperature, but I found the OZ9GHZ beacon easily, at a distance of 36km (just around 23 miles), and without line-of-sight, but the landscape has a downward slope from my antenna, down to a part of the path (about 20km) over water.
I am aware that there may be some tropo involved, but I can, at least test that now. The signal strength varies from S3 to S7, as estimated by ear.

Now I just have to wait and see if I can hear it at all times, and see if other beacons in a similar direction will pop up at some time.

Successful 144MHz Tropo from my station.

Last night and this morning we had strong tropospheric propagation on 144MHz.
Half a score of G stations,,  a few DL, PA, LA and SPs. have been worked with my Big Wheel antenna. Yes, I still do not have any beam antenna mounted for 144MHz, just the omnidirectional

The Big Wheel is not really an ideal antenna, but much better than a vertical for working DX on 2m, and it can take more power than the vertical. I was working with about 200W at the antenna.

This morning I noticed that DL7QY in Southern Germany was reporting "my" local 10GHz beacon OZ9GHZ. I still have the 10GHz RX setup used for QO100 only, but at some time I must mount some (at least) RX setup for 10GHz terrestrial listening.

2019-06-25

Partly Successful 10GHz Reception Test With Small Dish. Updated.

Today I tested beacon reception with a small dish antenna and an unmodified PLL LNB.
The test was done in my garden with obstructions all the way round.

I have done reception tests before, but this had two limitations:
- Polarization was vertical, while the beacons transmit with horizontal polarization.
- The 60cm dish is fixed, pointing to the satellite.

The limitation of today's test was that the dish is smaller (35cm) and mounted even lower than the dish for OSCAR100. Just a tripod.
Antenna polarization for this test is horizontal, which should be a significant advantage.

As before, I hear no sign of OZ7IGY at 26km distance, with a heavily obstructed path, both by trees at the edge of the garden, and the landscape rising about 20-30m. OZ7IGY has not yet been heard without the aid of rain scatter.

OZ9GHZ at 36km, but in a different direction with much less obstruction. The worst part is probably a bit of forest about 100m away but no landscape obstructions I can think of, and the middle of the path there are some km of sea. This should prove much better, and indeed it does.

With the correct polarization and the dish pointing closer to the horizon I found a gap between two houses (the neighbour's and mine), and got the dish aligned, and voilà !
The signal is always audible in spite of the lack of line-of-sight, and it is the strongest signal I have heard on 10GHz yet. Stronger than the OSCAR100 beacon, indeed!

A test with the LNB without the dish still provides a clearly readable signal. I am wondering if I am experiencing some "local tropo" propagation. Time and more tests will show.

The experiment is a qualified success, and gives me hope that I can work some 10GHz from home when a corresponding transmitter becomes available.

At the moment I can not use this setup permanently, it uses the setup for the OSCAR100, and the cable comes in through an open window. I should test if the LNB behind a window will work. More experiments to do.

Update: The LNB behind the window is not that good. Probably coating in the windows

I am thinking of mounting a horn antenna as high as possible, hopefully looking above (most of) the local obstructions, and a dish in a lower position. This is in order to reduce visibility and wind load, and is for a later consideration.

A fixed box with a few LNBs pointing in different directions, and mounted as high as possible is also under consideration.

One thing is sure, I need some modification of the LNBs, so I can connect an external reference, the drift I have with the unmodified LNB is too high for weak signal work.

Microwave Parts and Modules Part 2: Surplus PCBs and Modules.

Some weeks ago I went to a small ham gathering at the site of a  local repeater.

I had a talk with local hams about uplink equipment to the QO100 satellite. Many people are planning getting active on the satellite, so equipment for the 2400MHz band is in higher demand.
I had been planning to use some cheap Chinese modules for the local oscillator, but one suggested to find some better modules with Franco, alias RF-Microwaves.

Looking at the site I found that they have a lot of interesting stuff, especially in their surplus dept. Here are a few examples:
- A local oscillator module running at 2009MHz with the standard 8MHz crystal
- Some LNB modules without feed horn, but with input connectors
- PCBs with 4 HEMT FETs, where the PCB is arranged, so that it is possible to cut out two low noise amplifiers
- WLAN PCBs with several good components, including some 2.4GHz band pass filters
- 15GHz oscillator modules with several 10s of mW output.

I ordered a few of each, and some microwave absorbing foam. The service from Franco is excellent, I ordered one afternoon, and 2 days later, in the morning, the goods were delivered. The exception would if he is at a ham gathering, such as the Friedrichshafen Ham Meeting, probably the biggest in Europe.

Now for the goods, some of which are the last few left.

The 2GHz local oscillator module (about €20):
This is a complete module with casing and mounted with vibration absorption. Looks really good. On the website there is some modification information. The VCO can be used from about 1960 - 2040MHz, and the modification consists of making an external reference oscillator, replacing the internal 8MHz crystal oscillator. The external reference can be made with a well filtered DDS module.
For the IF of 432MHz the LO frequency should be 1968MHz, which is in the VCO range

As s second use of the LO module, it should be feasible to add a multiplier x5, for a local oscillator for a linear 10GHz transverter/converter.

A brief description of the LO module is on Franco's website.

LNB module (about €3):
This is a DRO controlled down converter module for satellite TV, with the mixer/oscillator in a single chip.
F6CXO has proposed the use of this module as a down converter for a (lower frequency) spectrum analyzer. The modification involves removing the 11/12GHz amplifiers and the filter. This cannot remove the image frequencies, so one needs to be aware of the frequencies that can be generated by the circuit you are testing. For amateur use, it does present a possibility to see what is going on in the 10GHz band, without having a more expensive spectrum analyzer. Mine covers up to 1.7GHz, so with a LO tuned to 11GHz the frequency range of 9.3 - 12.7GHz can be monitored.
Max RF input for the converter is about 0dBm (1mW). The RF input connector should be changed to a SMA, for the original ones it is probably very expensive or difficult to find a source for them.
The modification, if done carefully and with antistatic precautions, should provide you with 3 working GaasFETs, apart from the intended converter. I would probably make 2 converters, the second one using the lower LO frequency of about 9.7GHz, thus covering 8.0 - 12.7GHz with my analyzer.
A description of this modification is posted at Franco's website.
I would propose a few uses for the module, apart from sourcing components:
- Using the converter as it is, as a WBFM down converter to the 600 - 800MHz range.
- Adding a connector to the output of the 10/12GHz  preamplifier (before or after the (modified) band pass filter, providing a simple 10GHz amplifier with a gain of 15 - 20dB, likely with 20-30mW output.
- It might be possible to add injection locking to one of the DROs, if so the converter could be used as a simple narrow band down converter for 10GHz.
- Using the LNB as it is, for rather unstable down converter for wideband FM.
- Using the casing (moulded aluminium?) as it is for other modules I should build
I am sure other uses, apart from being a source of components, will turn up ...
Not bad for a €3 module.

PCBs with 4 HEMT FET amplifiers:
There is a document on this PCB, too, on Franco's website.
Here are some uses the document suggests:
- A low noise 10GHz LNA from a cut-out piece of the PCB. Each PCB could provide two of those in a relatively easy way, also salvaging two HEMT FETs. Yes, the board has 4 amplifiers, it looks like it has come from a dual head LNB. A negative supply for the gate of the FETs is necessary to add to the simple amplifier.
- Using a piece of the 50ohm stripline as a piece of test equipment, e.g. a component tester or for a bias-tee. The PCB material is good for up to 20GHz.
- Making 1 12/24GHZ doubler.
- The FETs are useable on 24GHz with up to +13dBm output and a gain of about 7dB.
This looks like an excellent source for building microwave stuff.
Like with the "connector-LNB", you get a lot for €3.

The WLAN PCB looks like a good source of components for building some 2.4GHz transverters/converters.
I was buying them, mostly for the 2.4GHz filters, but there is a PLL IC, a prescaler, and other good components there.

The last one, the LO PCB:
This contains two LO chains for around 14/15GHz:
- A straightforward receiver LO, starting on around 2.5GHz, adding multipliers. A tripler for 7.5GHz and a doubler for 15GHz
- A TX LO which also includes a modulator, meaning that it looks useable as a (WB)FM modulated transmitter, with a suitable PLL oscillator modification of the 2.5GHz part.
The output transistors, (two) coupled with a hybrid, are supposed to be capable of delivering about 100mW on 14GHz. I am now wondering if the hybrid is broadbanded enough to cover 10GHz, but that is something that needs to be tested. Also the 14/15GHz filters should probably be bypassed and replaced with some 5 and 10GHz filtering. I am hoping to be able to use a modified version of this PCB as a 10GHz power amplifier with 100mW output, if the hybrids have sufficient bandwidth. It may, however be necessary to design a separate PCB or set of PCBs, using the output FETs. With that, I will have to ask someone with **much** more experience than I have. I know, my general knowledge will probably not be sufficient for such a design ... yet.
- Also, an excellent source of components, FETs, MMICs etc.

Oh, well, so many ideas to try out, and lots of other activities. It will take time, and learning some new skills, but, as a start, I have a few of those modules

2019-06-22

Getting More Tidy?- and TV Tuner Modules.

With a house full of stuff it is not the easiest thing to keep tidy.
Here is an on-going project that started right after my move back to Denmark, and with a break because of a serious illness.

I am - slowly - beginning to know where more of my (radio) stuff is, but there is a long way yet.
It looks like I need to make some sort of inventory (what do I have, and where?).

This week I found some old TV tuner modules which may be useful for converting the IF signals from a satellite TV LNB down to a second IF, where a WBFM demodulator (or base receiver) can operate. Some of those are synthesized with the synthesizer on board, others just have VCOs which may or may not be PLL controllable (with or without modifications).

In any case, some low cost 10GHZ system looks feasible with the tuners, others may have  interest in using them, too.
The old fashioned TV tuners are getting more tricky to find.

Why not use the cheap USB TV tuner modules, like the RTL-SDR, you may ask. Well such a tuner needs a computer and SDR program, so the complexity goes up right there. A simple PLL can be programmed by a small single chip processor, like the PIC/PICAXE or the Arduino, drawing much less power. Certainly a high priority if you want to go portable.



2019-06-18

Microwave Parts and Modules, Part 1: Old 10GHz Stuff.

Lately, I have purchased a fair amount of microwave components and (PCB) modules, as well as some stuff I have had for a long time, before I moved back to Denmark.
Unfortunately I may not have brought everything (I now want to use) with me, so it was time to take stock of what I have available.
I have already written some posts about the 10GHz HB100 module, and that should result in some wideband FM equipment at some stage.

Last week I ordered some surplus boards from rf-microwaves.it .
Along with that some bonus parts were in the package, some of them not yet identified, so I have more to sort out.

First stage was a box with some old 10GHz parts. Some of those were not really suitable for 10GHz, waveguides (WG) too big or too small, but here is a list of some useable stuff:

Two small horns (probably 15dBi) and a slightly larger one (probably near 20dBi) fit a WG17/WR75 waveguide, as does a slightly larger one. Both appear to be made from PCB material, and all have a WR75 flange.
Two horn antennas (probably about 15dBi) with WR90 flanges.

A bit of WR90 waveguide material, e.g. some twisted WG with flanges.

a DRO with a WR75 flange. This is built into the casing for an older LNB, and there could be enough space for building a 10GHz power amplifier, up to a few 100s of milliwatts.

3 old single band LNBs with WR75 flanges. those could most likely be used as a preamplifier for a separate receiver. If the DRO in it can be frequency locked, it may be possible to use it as a simple converter for narrow band, maybe for an experiment with a "local rain scatter" monitor with a horn pointing up into the sky.
Maybe, with another PCB, it could be used as a 30-50mW amplifier for a transmitter.
If nothing else, it may be used as a coax-to-WG transition. A bit of matching with a screw or two may be needed for that.

If I got it back to Denmark at the move, I may find some more old 10GHz stuff, like:
- a simple tiny WG/horn with a Gunn oscillator, another small horn with a detector diode
- some Doppler Gunn modules with a tiny, tiny horn antenna.
- some Gunn oscillator/detector with small horn antennas, probably 10dBi
- one or two Gunn/detector modules without  horn antenna, but with a flange.
- I seem to recall a small double-horn Doppler module.
Some of this would probably be useable for making coax-to-WG transitions, if I can find it.
All this may have been discarded at the move, but it may also be inaccessible at this time, due to a major reorganization (well slowly tidying up) in the big shed.

I am - slowly - finding more radio stuff after the move, so I may still find this, exactly.

2019-06-15

10GHz Reception: Update

The rain scatter seems to be gone for now, but it looks like reception of the OZ9GHZ beacon is still possible with the dish pointing at about 25 degrees elevation.
At least, I hear it now, weak, with a tropo scatter-like signal with an occasional short burst of an increased signal. I am not sure what the burst was, but I suspect a plane reflection is the most likely explanation, given the high elevation of the beam.
I am aware that the reception mentioned above may not be completely reliable, but time will tell, at least I have some new monitoring to try out.

Because the main use for this dish is reception of the  QO-100 downlink I did make a system capable of using a signal splitter, so more receivers, e.g. a SDR, can be connected to the same LNB.

I am thinking of adding 3 SDRs:
- one for monitoring QO-100
- one for monitoring the 10GHz beacon band (10368.800 - 10369.000)
- one for monitoring the low band where most of the narrow band activity is expected to take place (10368.000 - 10368.250)

A set of 3 Raspberry Pi 3+s with RTL-SDR should be sufficient for this kind of monitoring. Later on, I may try to mount a modest receiving setup with a smaller antenna - maybe even just the LNB with is feed horn, or a system with a higher gain horn, just to see what I can hear with that system. This should preferably happen before the end of summer, and the rain scatter season, but given other projects it may have to wait. After all, setting up GNU Radio is not for the faint of heart, as I understand it.

There is more than enough room for more technical-scientific experimentation.

10GHz Reception: Terrestrial Mode: Rain Scatter

As you may know, I have been listening to the QO-100 satellite downlink on 10GHz for a while.
At the moment some heavy rain showers are approaching my area. I tried to re-tune my receiver to
the terrestrial narrow band segment of the band.
Nothing heard around 10368.100 yet, but the nearest beacon, OZ7IGY on 10368.920 about 26km from here, with no line of sight, has been heard for 1/2 to 1 hour here.
The propagation mode is known as "rain scatter", something that can happen when the signals pass via heavy rain showers with rather large rain drops.
further, a weaker signal from about 30km away is also being heard, albeit weaker OZ9GHZ in a somewhat different direction.

The rain scatter signals have a significant Doppler spread, and a bit of Doppler shift, and sound like something I got used to many years ago: Aurora signals.

This is my first reception of terrestrial signals on 10GHz, so something of a mile stone for me.

This makes me want to get to transmit on 10GHz narrow band (as well as wideband), even if it is with a small station. It should be possible to build something with my current components/modules, running up to about 500mW, maybe 1W. For more power I will need to purchase modules or better components. The main problem will be mechanical construction and weather proofing.

2019-06-14

One 10m Antenna With Multiple Receivers.

Some time ago I made a modification to my IC-703. It was a RX antenna adapter, originally made for the IC-7300.
It was possible to fit it into the IC-703, albeit with a bit of extra work: I had to file a bit of the adapter's plates an a bit in the radio casing, but it looks acceptable to me.
For a while I only had it connected to loop back the receiver signal, but this week I connected a signal splitter, so it is possible to connect more receivers in a way that does not destroy the receivers when I transmit with the radio.
Yes, when I transmit, I cannot receive anything on the 10m antenna, but I consider that an acceptable compromise. Further, it is possible to use a more complex system, so a transverter could be connected to the transceiver, too.
A TX power amplifier I have, I can connect it to the RX part/common connector, so I can transmit up to 200-250W with that combination

This is how the system looks right now:

10m vertical --- IC-703 ---                               !--- IC-703 RX input
                                         !                             !
                                         !                             !--- RX monitoring 28.074 (FT8)
                                         --- Signal Splitter --
                                                                       !
                                                                       !--- RX monitoring the international beacon project
                                                                             on 28.200

The splitter has more outputs
At the moment the signal splitter is just hanging next to the TRX, but it is the intention to build a casing for the system, so a preamplifier (attenuation in the splitter is too high for some of my receivers) and a switch for transverter or separate RX antenna can be added. For now, the system just has to work as it is, as well as possible. Improvements can come later, after other projects have been done, at least in part.

I would like to have a similar system for the higher bands (6-4-2m and 70cm), but that will have to wait.

2019-06-12

High precision TCXOs


While I was away, I received 2 TCXOs for 25MHz, with a claimed accuracy of 0.1 ppm. For 10GHz this would mean less than 1kHz drift/offset in the temperature range 0-40 at least when the oscillator is adjusted properly.

If the oscillator is put in an insulated (e.g. foam) casing, the drift should be slow enough for the LNB (converter) or TX up-converter LO, to be quite useable for SSB/CW activities. On top of this, it should be possible to find stations, knowing the frequency within 1kHz.

It has to be tested if the oscillator has a low enough phase noise, because some people have reported high phase noise, but there are also claims that it can be improved with a better DC regulator, or just a larger electrolytic capacitor at the output of the regulator.  Investigation will follow given the time. I am working on a report of the travel I had, too.



Pipe Caps Received. Filters for 2.4 and 10 GHz.

I am just back from some non ham radio related travels.
I have received some copper pipe caps, suitable for making simple filters for the 2.4GHz and 10GHz bands, and a length of semi-rigid coax cable.
On the way: 2009MHz LO modules, can be modified for 1968MHz (2400MHz TVTR LO for 432MHz IF) or possibly 1960MHz  (for 439MHz IF) with an added PLL or DDS in place of the internal XO.

I have been reading up on articles about those filters, and it looks possible, even with my not too good skills in mechanical construction, to make a few filters.

Finally, I also found a filter with a centre frequency of 2375MHz and bandwidth of close to 300MHz. This could be suitable for a transverter with 432/439MHz etc IF. I knew I had it, but could not find it before, due to the mess of moving.

The equipment necessary to test the filters for 2,4GHz filters I have. It is the MiniVNA vector network analyzers, covering all bands from a few 10s of kHz to 3GHz.

For the 10GHz filters I will have to rely on a simple signal generator like the HB100 radar module, possibly modified, and a microwave uW/mW meter.
A friend had made one with about 60-70dB range, and I intend to use that. It only provides a simple tuning aid, but I think I can get access to some better test equipment at a local ham with an extensive set of test equipment, for better alignment of filters.

Things are slowly starting moving.


2019-05-31

Vaguely 10GHz Related: Leaking Alkaline Batteries.

How is leaking alkaline batteries in any way related to 10GHz?, you may ask.

Here goes :

For my wideband 10GHz experiments I need a portable receiver. For the initial experiments I plan to use a portable scanner capable of receiving the IF from a LNB, and it needs to be wideband FM capable.
My old AOR AR-8200 is such a beast, and it has been lying with old batteries for a while, so the battery casing was full of leaked potassium hydroxide - nasty stuff. What to do? Of course, googling a bit does help, and I found that using vinegar should neutralize and make the residue removable, so I tried. Indeed, that helped, but vinegar is somewhat acidic, so in order to avoid further corrosion it has to be washed. The idea is to start with isopropyl-alcohol, then demineralized water, and then let it dry.

I did test that the radio worked with an external power supply, and it is alive, indeed. The best thing about the AR-8200 is that it also receives SSB, so tests can be made with narrow band reception in the field, too.

Next:
I have an old ICOM R3, only AM-FM-WFM capable with a totally dead battery pack. That one has a different power connector to the other radios I have - and runs on 6V only, so I have not yet tested if it is alive.
I hope so, because then I can set up two receivers on 10GHz, and make a WBFM transmitter or two, testing the range of the HB100 module, and possibly make a two-way QSO on 10GHz with those.

You may say that I could "just" use a standard FM receiver, but that requires a second converter after the LNB, and I want to start the simplest possible way. The other way would be using the HB100 module as down converter, but then the sensitivity will suffer in a significant way, probably about 20 dB worse, maybe more, than the LNB system, thereby reducing the possible range, by a lot.

Well, in any case, with a set-up of a single modulated HB100 transmitter and the LNB receive system, I can, at least, test the range of the HB100 module as it is.

Well here is to getting the AR-8200 cleaned and ready for action, and getting a modulator made for the HB100.

2019-05-28

Idea Box: 24 GHz Spectrum Viewing ?

A few weeks ago I tried the use of a TV LNB for seeing 10GHz signals, see this post.

Now, if I want to see something on 24GHz, what do I do?

I have ordered some 24GHz Doppler radar modules, and they are a bit like the HB100 (10GHz) modules. They have a simple resonator, so very unstable, so probably not very useable, also because they operate too close to (or in the) the 24GHz band.

There may be the possibility of using a frequency doubled 11-12GHz signal source which would be more stable, and then use the 24GHz module as a down converter mixer circuit, followed by a wideband amplifier.
It *should* be possible to take the output of a modified HB100 module, maybe grinding the dielectric resonator a bit for frequency adjustment. This will have to be tested, but it is probably worth trying.

The main purpose is getting an indication of how the spectrum looks like, not a detailed measurement, just like when I was using the TV satellite LNB as down converter.

How to make a frequency doubler for these frequencies - in the most simple way, I will have to look into that.

The 24GHz modules have been ordered from China, so it will take a while to get here. (I am still waiting for some 2.4GHz filters to arrive, they were ordered several weeks ago.

So many ideas, so little time.

2019-05-12

QO100 Frequency Stability.

Today I picked up the RF-Zero GPSDO. I also went to another meeting, so tomorrow I will have to re-program the frequency output to 25MHz, as the reference frequency for the LNB, and later for the synthesized local oscillator for the TX up converter.

I looked up the procedure at their website, and it looks simple enough, using a simple text terminal program with the USB port, and entering a few configuration commands.

Additionally a multi-output splitter needs to be made as several devices I intend to use, use a 25MHz reference frequency.

Moreover, other frequencies need to be synthesized in a simple way, e.g. 10MHz, 30MHz and 40MHz. The other frequencies should probably also have multi-output splitters added.

For reception the drift by the 739MHz RX is now all that is left. Certainly not as much as the drift of the modified LNB, even with the 25MHz reference crystal oscillator mounted indoors.

The 25MHz reference could also be used for an up/down converter from 739MHz to the satellite RX and to a Ham band receiver, e.g. a 144MHz receiver.

2019-05-05

Uses for the HB100 Doppler Radar Module 10GHz Experiments.

The HB100 module is intended for use as a Doppler radar motion sensor, e.g. for door openers. Could be used as a primitive speed meter, like the speeding detectors used by the traffic police.

The price of the module itself is somewhere around $3

After testing that the modules with the tuning screw could be tuned down to about 10300MHz without serious degradation of the signal, I can now see several uses of the module, some already described by others.

Here is preliminary list (other uses may be added):

1) simple 10GHz signal generator, using the module as it is, with its PCB patch antenna, tuned to a specific frequency. See also the previous post on this blog where I tested the usefulness myself.
A signal generator for 10GHz for $3.

2) Simple 10GHz WBFM (wideband FM) or FM-ATV TX, using the module as it is, but modulating the power supply. A relatively simple modulator/power supply on PCB (or experimental board) is needed. Some people have already tried this, and a Google search will reveal several ways to generate the modulation.
The modulator could probably be made for $5-10.

3) Simple RX down converter for WBFM and FM-ATV, using the module as it is, and adding a receiver at the IF port. Poor sensitivity, so very short range as the module is.
If used as receive converter only, the TX signal should be terminated in 50 ohm or similar in place of being connected to the TX patch antennas.
$3 and a bit of work.

4) Simple down converter for spectrum analyzer/frequency counter. Using the module as in (3), with the IF port connected to Analyzer/Counter.
$3

5) Very simple WBFM transceiver for *very short range* communication, using the module as is, with a modulator and an inexpensive 80-108MHz FM receiver, Chinese module, can be purchased as a simple kit for around $3, and a cheap audio amplifier, also an inexpensive Chinese module.
I estimate that the complete transceiver could be made for about $25, depending on the  external circuits used

5a) The very simple transceiver can, most likely, be enhanced by a low gain "preamplifier" between the IF output of the module and the FM receiver.

5b) Some experimentation with mounting the HB100 inside a "horn antenna", using the module's patch antennas as "illuminators".

5c) The simple TRX can, of course, be mounted in or near the focal plane of a dish antenna.

6) I have a defective HB100 (No oscillation, and high power consumption, most probably due to reversed polarity of the power supply). Experimentation should be done to see, if it can be used as an up converter with a local oscillator suited for narrow band transverters.
A simple test would be trying to insert a low level RF signal at the IF port of a functioning HB100, and check the resulting spectrum radiated from the RX patch.

6a) The mixer could also be used as an RX down converter mixer, in the receive chain of a NB transverter

It should be noted that  the very simple WBFM TRX, or the module used as a simple down converter, has poor RX sensitivity, due to the loss in the passive mixer.
However, some people have made QSOs up to 200km LOS (line of sight) when using parabolic dish antennas, interesting what can be done with just a few mW. True QRP with extremely simple and inexpensive equipment.
Some experimentation with a TV-LNB followed by a WBFM RX, would probably result in enhancing the sensitivity by 10dB or more.

I can see that the is room for experimentation, and I need to try out some of the above ideas.

If you can think of other uses for the HB100, feel free to comment.

2019-05-04

10GHz Testing, HB100 and LNB.

Today I got my first test gear for 10GHz up and running.

I have a spectrum analyzer (SA) covering up to 1.5 or 1.7GHz. Not much to see on 10GHz with that one. So, as a test I fed the SA with the down converted signal from a PLL LNB.
I chose the cheapest one I have, a Goobay that I discarded for use with OSCAR 100, because it has more local oscillator phase noise/jitter than I like. For this purpose, and for experiments with wide band FM (WBFN) it was expected to work nicely. It certainly does for the test equipment.

So how to test the system. I have a pile of HB100, cheap ($5 or so) Doppler radar modules. Some with a tuning screw, some without. 5V to the HB100, and a nice signal appears on the screen with the LNB about a meter or two away. The system clearly works. Increasing gain of the spectrum analyzer (well, reducing attenuation) shows the noise floor of the LNB, and some spurious outputs of the DRO, some 40 - 50dB under the main carrier.
A thought: This spurious response could be due to the PLL local oscillator of the LNB, and probably not from the DRO of the HB100 module. I consider this the most likely explanation. Maybe I should try with another PLL LNB, or maybe with an older DRO controlled LNB. More to try out.

Next step was creating some signal sources. What to use? HB100 modules, of course. I tested the tuning range of the modules, and found that some of them went down to 10275MHz without any problems. So, now I have some wideband signal generators covering 10275MHz - 10500MHz in 25MHz steps. Further i tuned one for 10368 (narrow band segment) and one for 10489MHz (The transponder downlink for QO-100.

What are the limitations of this, you may ask. The stability of the DRO and the rather critical setting of the tuning screw makes it difficult to adjust within less than +/- 2MHz of the wanted frequency. This makes the test system more suited to wideband system tests,  but a crude spectrum analysis of narrow band equipment is feasible.
All this with some low cost accessories for the existing test equipment that I have.
The LNB should also be useable as a converter for a frequency counter, this will have to be tested later

This does not mean that I do not want a bit more 10GHz test equipment. I am thinking of making a narrow band signal generator for somewhere around 10368MHz, either with a 24MHz crystal oscillator and a series of multipliers, or with a ADF4350/4351 synthesizer and a tripler. This will have to be later.

I think that the next step in test equipment should be a MMDS down converter with the bandpass filter removed, so I can see signals around 2400MHz. Using the LNB for 10GHz provided me with a proof of concept for the idea.

2019-04-30

Idea Box: 10GHZ TX Mixer from the cheap HB100 Module ?

I may have mentioned it before, but I intend to use this blog, not just for telling you about ideas etc, but also for me to be able to find old ideas I have had.

Looked through 10GHz websites. Found a teardown of the HB100 Doppler radar module. It turns out that, apart from the expected DRO (oscillator) is a passive balanced diode mixer, much like seen in older LNBs. It looks like a simple modification of the HB100 module - removing the DRO (or maybe just the power for it) - and entering another LO signal, the mixer could be used the other way, too, i.e. a TX mixer.
The modification should involve adding a few SMA connectors (two for RF/LO and another one (maybe SMA, too) for the IF port, and likely cutting a PCB line from the original oscillator.

The idea could be tested by using the module as it is, just entering a low frequency (IF) drive signal and see what comes out on the RX port.

The HB100 module is an interesting device, even for modification or salvaging the very few microwave components it has, the price of the module off eBay is less than $5.

2019-04-29

Microwave Day in Horsens, Denmark.

In the past week end I went to the Microwave Day in Horsens, Denmark, a one-day event of talk and testing of microwave gear.
I did not bring any gear myself, as I decided rather late to go there, and I am just beginning doing something in the microwaves, mostly due to the QO-100 satellite.
About 30 people attended, and most were experienced microwavers, so I took the opportunity to draw a bit on their experience, and see if I could get some new ideas.

There was test equipment to measure small feed horn antennas for dish antennas, and the possibility of measuring power and noise figure on microwave bands up to 10 GHz.

If they repeat this event (next year?) I may have some equipment to have tested.

In the afternoon some groups went out to nearby hills and tested their equipment in the field.

It was good to get to meetings like this, meeting other people who have already made the first (or many more) steps in the field.

Time to start getting some stuff, more than the simple modified satellite LNB for QO-100. I will need some for the home, and some for portable use, going to nearby (or not so nearby) hills ... and the small simple equipment for local tests.

Aditionally there was a show of a - not too expensive - GPSDO which has been used at the oldest, still running VHF/UHF/microwave beacon, OZ7IGY. It can be programmed from very low frequencies, up to 200MHz, and the price is half of what I have seen for comparable devices.


2019-04-25

The Last Ingredient Necessary for a 2.4GHz Transverter Has Arrived.

Today I received some Polyimide tape from China. This should make it possible to lower the resonant frequency of Microstrip and Stripline filters, applying the tape to the resonators.
This should increase the dielectric constant of the surroundings of the resonator strips, thereby lowering the velocity factor , effectively electrically lengthening the resonators.

I have seen this tape used in a TV satellite LNB for lowering the band pass filter frequency. My question is how much loss, (i.e. lower Q) this adds to the filter.

I was promised some PTFE (Teflon) tape from a friend (I suspect with lower losses), but we have not yet had time to get it to me. He has some stuff that I can measure, so he wants to come here, and bring the tape.

The coming week end will be quite busy, but after that I should be able to test the tape for losses, and frequency change of the filters I already have.

The Beginning of the "Summer" Sporadic E Season.

10m and 6m have been buzzing with European activity today, and some yesterday, too.
Also, I saw someone reporting Es on 4m.
The season has started.
This does not, of course, mean that we will have Es every day for the next monts, but it is a nice beginning.
My 10m map for the last 24 hours show (I think) Es-linked F2 propagation to South america and probably to the Middle East. At least 2 stations from the Arabian peninsula were reported here. Hundreds of reports from European stations and places like EA8, etc.
I am now changing my FT8 listening frequencies to 10m and up. Right now it will be 10m, 6m and 2m, even if I only expect tropo signals on 2m the next few weeks.

Busy times ahead, this time with operation on VHF bands and up, plus, of course, my favourite HF band: 10m.

2019-04-22

Idea Box: Simple Microwave Transverters.

For transmission to the QO 100 satellite OZ2OE proposes a simple transverter 144 (or 432)MHz to 2400MHz using cheap Chinese amplifier, synthesizer and mixer modules.
I will most probably do it mostly this way, although, while I lack a sufficiently good filter I might ise the RF amplifier/filter part of a MMDS converter as a filter/amplifier, removing the power (and maybe the components from the LO/Mixer part.

Having transmitter capability for 2400MHz, I think that a receive possibility should be added, too. either by using a modified MMDS converter (I still need to change the filter frequency of that one) or some more Chinese modules.

Lately I saw a Croatian microwave website proposing a "poor man's 5.7GHz transverter", also using the cheap Chinese modules. After getting on the satellite, getting fully on 2.4HGZ and 10GHz, I may look into that.

It looks like I will have to learn the mechanical skill of making pipe cap filters before I proceed much further.

2019-04-07

Idea Box: Second Experiment

The most local beacon for me is OZ7IGY, about 30km away.
Now I am curious how little effort it takes to receive it.
The idea is starting to use a PLL LNB without a dish, just the built-in feed horn.
Because the beacon is beyond line-of-sight, the propagation will be tropospheric scatter, so the signals may be too weak to hear, but the experiment should be done. Next step would be a 15-20dBi horn antenna, then a small dish, 30cm or so.

It would be fun, however, if the beacon is audible with just the LNB, even if it is not constantly audible. This may be an opportunity to try the PI4 mode for beacon detection.

2019-04-06

IC-703 Modification.

For the first time in almost 2 years I have been traveling (more than about 100km from my home) for a bit less than 2 weeks, and I am back now. This was a non-radio-related round trip From my home near Copenhagen through Northern Germany, The Netherlands and Belgium, then to Paris. On the way back via Köln (Cologne). Last year I spent getting rid of a colon cancer, and I am now free of it, just going to control visits every few months.

Today I modified my old IC-703 for receive output/input. Will likely use that TRX for 10m with aux RXs for 10/11/12m propagation monitoring, using the TRX with the 10m PA running about 200 - 250W CW or about 150W FT8. Should work nicely.

Why do a modification like that ?
Well I wanted to be able to add some kind of spectrum/waterfall display, and possibly use the same antenna with several monitor receivers, e.g. beacon watch, FT8 watch etc.

I was using a kit purchased for doing the trick on a IC-7300, but decided to try it with this one first.
The mod took a bit of filing off the outward side of the new adapter and filing a bit of the bottom cover, and removing the connector for the external ATU control. The external control is not necessary as long as the built-in tuner works (or is not needed at all).
It now fits nicely into the casing.
System check of the RX shows that it is working nicely in through-mode.

It is likely that the modulation circuit will need an equalizer, because the reports on the modulation are not good enough. Initially, I will check the adjustment of BFO and SSB filters.

Second use for this low power TRX could be driving a transverter to 4m, including RX output for AUX RXs, such as spectrum waterfall.

2019-03-19

Outdoor LNB for QO 100 Mounted, and Quick TX Up-Converter Ideas.

The LNB for the OSCAR 100 downlink receiver was sealed after the modification, and has replaced the temporary one mounted at the 60cm dish.
I still need to complete the indoor buffer circuit, but some preparations for other stuff had to be done first.

Next comes the transmitter up-converter to 2.4GHz. I am still waiting for a passive mixer module specified up to at least 2.5GHz, and they are on the way.

The configuration will likely be as follows:
432/439MHz transceiver frequency -->
attenuator and the LO *) signal -->
Passive Mixer -->
amplifier, probably made with the RF amplifier of a modified (filters) MMDS converter (when using 432/439MHz as IF, these filters should provide sufficient image rejection) -->
20 - 50mW amplifier -->
1W amplifier -->
cable to feed antenna system -->
"8W" amplifier, likely providing 4-5W at the feed -->
feed antenna --> dish antenna **)

*) LO signal provided by a ADF4350 synthesizer board controlled by an Arduino Uno board -->
about 20mW amplifier at 1962/1968MHz.

**) experiments with other antennas will be done. I already have a panel antenna for RHCP and a 1m long yagi, as well as a cheap, probably not very good, 17elm yagi about 40cm long, as well as a PCB LPDA antenna for test as a feed antenna.

This should provide a decent up-link signal to OSCAR 100, useable for SSB, and certainly for CW or digital modes.

The building activities will be halted for a few weeks, but mid april they should resume.
More than enough experimentation before the refinement of the system starts.

The buffer for the RX reference LO should be ready and tested soon, though.

2019-03-15

Idea Box: 10GHz Experiment.

Since I am building equipment for the OSCAR 100 satellite with receive capability for 10GHz and transmit capability for 2.4GHz, it got me thinking. Why not make some transmit/receive experiments on both bands ?

The 10GHz receiver part is easy, of course, just use a PLL LNB and a scanner receiver or SDR. I already have a few of those to play with.
Now how to get a signal transmitted ?
For that I could make a wideband FM signal by multiplying a 430-440MHz signal by 24. 432.000MHz will end up on 10368, i.e. in the narrow band segment. Not ideal. Second point is that the sensitivity/gain of the LNB decreases below 10.7GHz.
The LNB appears to have sufficient gain and sensitivity on the OSCAR 100 downlink frequency of about 10.489GHz Why not use that, and create a wideband signal on 10.488GHz. It is well outside the transponder bandwidth and should not interfere with reception of the transponder, at least not with my amateur radio "neighbours".
10.488GHz divided by 24 is 437.000MHz. This frequency with the necessary power can easily be generated by a small (hand held) 70cm FM transceiver.
Now, how to multiply this, without destroying the TX ? The intention is attenuating the output, so the TX sees a decent load, and follow this by a pair of anti-parallel diodes. Instant harmonics. A filter extracting the 6th harmonic just over 2.6GHz could be made with the input circuit of one of the MMDS converters I already have. This will probably have an output of 10 - 30mW, sufficient to drive a quadrupler.
How to make the quadrupler ? I was thinking of using an old LNB (the preamplifier and band pass filter circuit). This is likely to produce 10 - 30mW on 10GHz. Some work with (SMA) connectors for the input/output is necessary.
Finally, the signal need to be radiated. A small horn antenna is intended for the initial experiments.

Now, where should this be tested ?
I have a local radio amateur at a distance of 2km. With the antennas just above the tree top of my garden, and at rooftop at his place I estimate that we have a direct optical path.

Now, the TX equipment for this test will have to be made after I get operational on OSCAR 100, so it will have to wait a bit, but I think it will be an interesting local experiment. It might even be possible to do the experiment this year, but in the spring and summer there is quite a bit of antenna construction and maintenance, so they do not fall down in the next hurricane.

Narrow band experiments will be quite a bit later, though the PLL LNB makes for some interesting receive experiments, and this can be done quite soon, while the antenna construction/maintenance goes on.

If we succeed in making a QSO I can, at least, claim to be QRV on 10GHz ;)


2019-03-12

OSCAR 100 External Reference, update.

The external reference oscillator works fine in quiet weather.
See previous post for more info.

With rain and gusts of wind the simple solution showed its weakness.
The oscillator is not buffered, so any change of load will change the frequency enough to create chirping sounds on the OSCAR 100 beacon.

In short, a buffer stage is needed, and the outdoor part of the installation needs to be made a bit more rigid.
The outdoor part is relatively easily done, and some more outdoor work was necessary, anyway.
For the addition of the buffer stage a bit more work is needed, with some down time for the receiver.

So, when there is time, I will need to get to work on that.
... More solder smoke needed.

Receiving OSCAR 100, Stage 2: External Reference.

A few days ago I made the simplest possible modification for external reference of a LNB. The LNB was a Twin type with two independent outputs. It was purchased with a local low cost dealer, and turned out to be a PLL type, suitable for modification. They also have a single PLL LNB, of which I purchased a few, just for experimentation (I said they were cheap).
The 2 port LNB modification is done by sacrificing one of the outputs for use as a reference frequency input. This eliminates some SMD soldering. Here is the process:
1) The crystal was removed after looking with an oscilloscope which side was the reference input for the PLL IC.
2) The port nearest the input was disconnected from the output circuits by cutting the PCB tracks
3) The input of the PLL IC had a connection to ground with a capacitor. PCB track to that one was cut, too.
4) A relatively large (1006) SMD capacitor of 220pF or so was soldered directly from the (now) input terminal to the soldering pad for the crystal. Not very pretty, but it works nicely.

That's it ! (pictures will follow.)

Testing this with a signal generator from a transceiver test set failed miserably. I could not find the signal in SSB mode, so initially I thought I had destroyed the LNB.
Testing the signal generator with a SSB receiver on 25MHZ revealed the problem: The 25MHz signal had audible small frequency variations, sounding like something between a warble and a rumble. Multiplied by about 400 this made the SSB signal extremely hard to find, but with the receiver in wideband FM mode, I found it. The LNB was OK.

Now for building, in the simplest possible way, a 25MHz oscillator stable enough to receive signals. I found in my drawers a canned crystal oscillator marked 25.000 00 MHz, and soldered the circuit, including a 7805 voltage regulator and some decoupling capacitors (ceramic and electrolytic), all mouned in an old (used) die cast box with BNC connector and a feed-through capacitor, used for reference frequency output and supply voltage, respectively.
Everything connected, and voila! Test signal received.
Getting the LNB out to the dish, and - here we go. After settling in for a few hours, the OSCAR 100 beacon was about 15 kHz high on my receiver, corresponding to the 25MHz oscillator being about 40Hz too low, but with a clear tone, if drifting a bit. It settled quite nicely in the evening. What a relief having a more stable reception. Stable SSB signals were readable without re-tuning for longer than 5 minutes.

The result is quite satisfying, and should be quite useable for normal SSB/CW contacts via the satellite.
Opening the window next morning got the reference drifting down 5-10Hz, moving the LNB output signals a few kHz upwards.
I decided that it was foam insulation time. I found a piece with a cut-out almost fitting the die cast box I use. I had to make a small cut-out of a 1cm wall and for the cables (power ans 25MHz out), and a piece of flat foam to make contact. Simply taped them together with - yes, you probably guessed - duct tape. The frequency slowly settling, interesting to see where it ends up. 
The oscillator frequency was slowly drifting upwards, even with the window open, bringing the reference closer to the wanted frequency of 25 000.000kHz.
There seems to be just a bit of heat generated in the box, and I hope it would stabilize.
I will wait a few hours to see how it settles.
The LO seemed to settle around 8 - 9kHz too low on 10GHz.
This morning the offset had increased a bit, to just above 9kHz. Opening the window appears to increase that to about 10kHz. Much better than without the insulation.

I think I will try with some resistive heating inside the box, to see if I can bring the frequency closer to the wanted one. A bit of experimentation is probably necessary.
Very usable, but I will probably try to mount a, say 220ohm, heating resistor to see if I can get closer to the wanted LO.
Could be fun to get within 1 - 2kHz of the wanted frequency most of the time.

Long term I will have to make a better reference frequency generator (probably GPS disciplined or a Rubidium standard), but this will have to do for now.

Time to think about up-link transmit capability. Probably from 432/439MHz, because it is easier to filter out the image frequency. I have some of the stuff, and more is on the way from China.

2019-02-26

Receiving Es'hail QO 100 With Own Equipment, Stage One.

The Octagon PLL LNB has arrived and the set-up is beginning.
Today I got my initial setup for receiving OSCAR 100 up and running :
This is how I did it:

Assembling 60cm dish
Mounting dish on the"main" mast
Cable from shack to LNB
Feeding DC from the sat receiver through a two "output" signal splitter, so the next RX can be safely connected.
Trial and error alignment to maximize signal from Hotbird at 13deg E
Setting azimuth for Astra1 at 19deg E
Optimizing elevation for Astra, and adjust the elevation a tiny bit down.
IC-R7100 would not start up, so got the older AOR8200 down from the upper "shack".
S meter showed full, so inserted an attenuator.
LO deviation from standard frequency was unknown, so initially tried to tune RX +/- 50kHz. It turned out to need 200kHz, meaning that the reference XO was about  500Hz too low.
Optimized azimuth for OSCAR 100, the transponder noise is audible and the beacon (and other signals) quite strong. Maybe more attenuation needed.
Frequency stability is sufficient to be able to make a QSO, but too much for comfortable operation. Frequency was seen to vary about 20kHz with the current, relatively stable weather.
Not bad for a day's work.

Better frequency stabilization is needed. For the moment I will not modify the only LNB of mine that I know is a PLL type. Two new low cost ones are on the way from a "low cost" shop, known to be PLL types.

One day later :

I went to the shop, anyway, could not wait for the cheap LNBs to arrive :
Purchased cheap LNBs at Harald Nyborg, a low price shopping chain nearby.
The price for a single LNB was DKK 58, a TwinLNB was 139, and the Quad was 199.
Tested those and others I have purchased lately.
All single LNBs were PLL types Octagon OSLO and the locally purchased - branded Maximum ST-11, as expected, because others have tested them. All were relatively stable and with a clean tone reception from Es'hail, albeit at different down converted frequencies.
A cheap Twin LNB branded "Goobay" was stable, but the tone of the received/down converted signal was not clean. Phase jitter, maybe.

The other Twin LNB, Maximum ST-12 sounded clean.

The quad LNB from Maximum turned out to be a DRO controlled model, though not extremely unstable, and not suitable for narrow band operation.
Same is the case (as expected) for an octo LNB from Octagon.

The quad LNB from Maximum and the Twin LNB from Goobay are hereby relegated to use for satellite TV only.
Two more Maximum single LNBs and one Twin LNB are on the way, still, so I decided to start taking the Twin version apart. The sealing of the shielded box turned out to require  quite a bit of work, so not finished yet.

Finally finished disassembly of the Twin LNB, and things look good for a simple modification.
This simple modifications sacrifices one of the IF outputs for use to connect the external reference in the simplest possible way, and requires two cables to be connected to the LNB for just one down conversion. The "reference input" will be completely disconnected from the IF output/DC input, cutting the PCB tracks to the F connector. Ole, OZ2OE mentioned that the DC input circuitry may be the source of attenuation of the reference signal in the single LNB versions, where it is connected to the DC regulator through a low pass filter with a cut-off frequency suitable for the IF, and not to the reference frequency.

For the experimentation I needed a sufficiently stable signal source for approximately 10GHz. The initially useable solution turned out to be a cheap Baofeng transceiver transmitting on 432.000MHz. This provides a decent, if drifting, drifting signal, enough to check if the LNB is locked to the reference.

A better 10GHz signal source is planned, and probably involves a relatively stable crystal oscillator, or possibly a stabilized DDS generator with a simple multiplier made with a Schottky diode. The housing and antenna could be a now discarded LNB - it had lost its protective sealed cover for the horn, and is useless anyway, and the horn antenna has not rusted or anything, so after a bit of cleaning the feed horn should work nicely, at least for indoor work.

Stage 2 will involve doing the modification for using an external reference, and making that reference source. I still have to decide how to proceed, exactly. When it is done I should make a description of the modification I use.

2019-02-20

Old Post About MMDS Converters, From When I Received Them.

A few words from the old blog post, describing the MMDS converters I purchased several years ago :

About two weeks ago I decided that my setup for S-band reception needed to be upgraded seriously.


So I looked into possibilities for improvements. I found the filters necessary for the AR8200 receiver to work, and looked around to see if I could find some converters that were (relatively) easily modifiable.

I think I found it . MMDS converters cover the bands around 2150 MHz and around 2600 MHz, and it should be possible to modify the filters

TranSystem Inc makes some MMDS converters, I found some on ebay, TranSystem Model EIDC 3033 Down Converter, apparently with the following spec :

RF bands :
2150 - 2162 MHz and
2500 - 2682 MHz,
Intermediate frequencies :
116 - 128 MHz and
222 - 408 MHz

This is possible with a LO frequency of 2278 MHz. Since I want to use the converter for the 2200 - 2300 MHz band, some modifications are necessary :

RF filters - one pair at the input and one pair between the RF amplifier and the mixer - must be modified to cover 2200 - 2300 MHz

The Local Oscillator (LO) needs to be moved away from the wanted passband, preferably for a low side LO.

I took a look at the inner workings of the converter, and the RF frequency filters are stripline filters made of copper with air insulation (not microstrip etched on the PCB), so they are expected to be fairly high Q filters. For satellite S-band I think the best strategy will be to shorten the 2150 MHz strips (careful - we do not want to get too high in frequency), then disconnect the higher frequency filter (hmmm - that may not even be necessary).

The other modification concerns moving the LO down. The LO is a PLL with a frequency divider (256x) 2278MHz down to 8.898438 MHz. (Xtal in the reference oscillator).

It would be nice to have the oscillator running on a "rounded" frequency like 2000 or 2100 MHz, but that would require new Xtals to be made. Since I would like to be able to lock the LO frequency to a stable source that complicates things.

The other option will be to use a 8 MHz crystal oscillator, then lock that to a 10MHz TCXO or other standard. This will provide the converter with a LO frequency of 2048MHz. not exactly very "rounded", but still with a full MHZ, so the readout of the converted frequency should not be all too confusing (that remains to be seen). After all, a computer can do wonders in calculating the correct frequencies and control the receiver(s).

Time is a bit tight this week end, but I hope to be looking into it after all.

Local Oscillator for the 2.4 GHz transmit(/receive) Converter. And small update.

It appears that I already have a ADF4350 PLL board. The chip on the board can produce 137MHz to 4.4GHz signals, so 2256MHz (for 144MHz IF) or 1968MHz (for 432MHz IF) is within the range.
I also have an Arduino board, so now it is a matter of software.
I found that someone had made a piece of software for programming the (later ?) 4351 chip (same, except the lower frequency possible is about 37MHz). I will have to find out if the software will program the 4350 chip as well.

Update :
I have some 2500-2700MHz and 2150-2162MHz MMDS down converter units lying around, and may order a version that has only 2500-2700 MHz range.
If the  RX mixer in those units are passive devices it might be possible to modify the unit for use as a very low power transmitter converter.

Unfinished business ;)

Yes, I know.
I have a ton of project ideas. Not many of them will come to fruition. However, I intend to use this blog as a notebook to myself about ideas for building amateur radio projects.
Maybe someone else can use some of the ideas.

Today's project ideas are all about using low cost TV LNBs and older MMDS (yes, I have a few of those, too) converters for different ham projects. For example :
-LNBs for narrow band reception. Yes, the satellite downlink is one of those, but with a relatively stabilized LNB I should try to receive a terrestrial beacon located about 30 - 40km from my location.
First test should be with the LNB on its own, i.e. without a dish. I do not expect to be able to hear it, but it is worth a try.
-Simple 2400MHz converter with the MMDS converter. I should probably "adjust" the filter and the local oscillator in the converter, i.e. shorten the resonators in one of the internal filters.
-Using the filter and the amplifier in the MMDS converter as part of the 2400 MHz transmit converter. Same applies with respect to the "adjustment" of the filter.
-Using the MMDS close to its intended receive ranges, monitoring solar noise around 2700 - 2800 MHz. Since solar noise is broadband, there is no need to adjust the PLL in the converter

More than enough to try, just in this frequency range, and that is just a few ideas. The above ideas could take quite some time, anyway. As I said above, too many ideas, not enough time...

Update : The MMDS converters have "disappeared" in the mess of a large removal, it may be a while before I find them.

2019-02-18

Tropo and a Bit of PA Trouble

Last Friday there was a bit of tropo propagation on 2m. With FT8 I worked stations at up to about 800km distance.

Further, there is a report of someone not too far from me in Denmark (I did not get the call) heard the 10GHz beacon from the Faroe Islands (OY6BEC), at about 1200km. This is, as far as I know the first time this has happened. The beacon uses a horn antenna directed to Denmark, but this was still a surprise.

One of the fans in my Gemini PA seems to have developed a fault, making a rattling sound. It sounds as if a piece of wire, or a cable strip is too close to the fan. Time to contact the dealer, to see if he has problems with me looking into it. It is still under warranty.

Oh, yes - the ups and downs of amateur radio.

Loop antennas.

Quick update on the loop antennas:

Since the excitement about the Es'hail satellite has resulted in spending some time preparing equipment, and some research on the internet, there has been only a little activity.

The shielded loops have been painted in green and brown colours, for blending in with trees and bushes. Also an unshielded single turn loop has been created. Some experiments with the single loop will be underway.

Es'hail 2 Sattellite, aka Qatar OSCAR 100

The Es'hail 2 satellite has been launched and has entered geostationary orbit. This satellite has TV transponders, and something new for radio amateurs : a 2400MHz to 10GHz transponder in geostationary orbit.
The coverage should be all of Europe and Africa, to the East into India, and to the West a tiny bit of Brazil. Even Antarctica should be within range, if some of the research stations are within the footprint of the satellite I assume that some testing will be going on before the transponders go online, but this is an exciting time for radio amateurs interested in satellite communication.

First update:
The sat is in orbit and the amateur radio transponders are now operational.
They work very well. An SSB uplink with 60cm dish antenna and linear polarization produces a readable signal, a around 10-20 dB above the noise, as I have heard on the WebSDR.
On the spectrum of the WebSDR it is even possible to see the effect of running too much uplink power. This creates dark bands on the waterfall spectrum, and sometimes audible attenuation of received signals.
Frequency stability is the main problem with the uplink and downlink, for obvious reasons.
As a first attempt at working through the satellite I was thinking of purchasing a relatively low cost up converter from SG-Labs in Bulgaria for the uplink. This has about 500mW output, and with a 1W power amplifier at the feed point it should be possible to be heard via the transponder with SSB, and certainly with CW.
A fun experiment would be trying FT8 or JT65 with a much lower ERP.
Receiver side will be with a low noise satellite PLL LNB, possibly with a later modification of the reference oscillator.
I have decided to take time to attempt a simple up converter made of Chinese modules available on eBay.

Second update :
10GHz reception converter (arriving shortly) for downlink:
LNB suitable for OSCAR 100 reception has arrived. Octagon OSLO (PLL controlled Local oscillator.
Initial test will be done with the unmodified LNB.
It will need a modification for better suitability: External reference oscillator, preferably a TCXO, at a stable temperature, fed through the cable (disconnect the internal XO, info on the Internet).
Alternatively, for even better stability, a GPS locked oscillator could be used.

2.4GHz uplink:
Modules from China have been ordered :
1) Synthesizer : ADF4350, covers 137MHz - 4.4GHz Needs to be programmed. There seems to be a library for the Arduino microcontroller. Price per unit about 10 GBP
It turns out, looking through my stock that I have a single AD4350 and an Arduino UNO, so it is possible to start the process of building the local oscillator for the transmit converter. Now for learning some Arduino (variant of C) coding.I ordered a few mor ADF4350s as spares in case I have an accident of destroying the one I have.
Learning the coding could easily take the time needed for the stuff from China to arrive, unless I find a suitable program that just needs a simple modification. No need to invent everything all over again.
2) Passive up (and down) converter modules (also to have some spares). Price per unit about 8 GBP
3) 1W amplifier modules. Price about 10 GBP
I ordered a few, because I have a long run of cable, and would like to have one as output for the indoor unit, and one at the antenna feed point.
The official uplink power for the satellite is regarded to be about 10W into a 60 - 90cm dish. However, an output of 1W appears to be sufficient to make SSB contacts via the satellite, as I have heard several stations with similar set-ups via the WebSDR.
4) Double balanced RF mixer (down conversion) Price about 5 GBP.
Why a down converter ? Well, it is a simple addition adding receive functionality, creating not just a satellite uplink transmit converter, but getting a 2400MHz transverter, making simple two-way contacts possible on that band, albeit with low power. It will most likely be possible to make some local contacts, and possibly a bit more during tropo conditions.

I already have some amplifiers capable of an output of about 100mW on the band, more than sufficient drive for the 1W amplifier mentioned above. Those were priced about 5 GBP.
One more thing is needed for this to work without making interference. A band pass filter.
I need to look into the best solution for that.

If (when) I succeed in getting a signal through the satellite, the adventure begins. Optimization of all aspects of reception and transmission, and experiments with very low power. I was told by OZ2OE that he had heard a Dutch station running a 75mW CW signal into a 1m dish, and it was audible at 539.
Also, running 1W into a much smaller antenna is an idea I want to play with. I have a tiny Wifi yagi, 40cm boom length and 17 elements. That will be an interesting comparison with the 80cm dish I have, and a good comparison. Constant gain from the yagi, and seeing the different improvements to the dish and feed.

I see quite a bit of experiments and lots of optimization in my future.

2019-01-19

Winter VHF Day in Ringsted, Denmark.

Today, for the second year, I went o an annual VHF (etc) Day.
The gathering of (mostly) VHF-UHF and microwave amateurs is held about 45 minutes drive from my home.
There are a few presentations, but I mostly stayed in the hall and had chats with some old friends.
There is a small flea market, but not much was found there this year. Last year was pretty good, so maybe next year there will be more interesting stuff.
All in all a good day spent with ham radio friends from all over the country.

2019-01-07

Short Wave (Active) Hula Hoop Antenna.

The radio construction activities have been halted in the Christmas/New Year period, other activities have taken over. This week the ham radio activities are slowly beginning again.

The 1MHz - 2GHz 32dB gain Chinese LNA has arrived. Still waiting for LNAs for 10/100kHz - 2GHz, so the first loop tested will be for short wave.

Tried the electric connector box for the single turn loop RX antenna.
The hula hoop fits perfectly into the opening poked put of the box. Looks good.
Next step : Test transformer and 1M - 2G 32dB gain LNA.

Copper tape on small loop, with smaller box, and 1.5sqmm wire through the loop was tested. Not much space for transformer and amp in the box. Amp should just fit inside the box with connector, but not with connected connectors.
Using the copper tape for shielding is tricky to wind around the hula hoop, it gets uneven, and has to be done in short pieces with the simple "snail repellant" tape I am using.

I have an even smaller box. The smallest box only holds the 1M-2G amp if the SMA connectors are removed. This box should probably only be used with a soft wire/coax - (wire unshielded). Could probably be good with a loop circumference of 7.5 - 9m, usable up to about 10MHz.