A Few QRP QSOs with CW on the QO100 Satellite.

 Yesterday I got my SDR connected to the converter again (after a long pause), after re-arranging the shack corner.

When I saw some signals in the CW portion of the transponder I found PY2PIM and tried to call him, he was gone.

In stead of just giving up, I moved up a few kHz and made a CQ call, and voilá! There he was. 

After the QSO I was called by several stations, activating the LEILA (overload) system, so I could not hear them immediately. I made 6 QSOs all in all. 2x PY, 2x SP, 1x E70, 1x G)

Not bad for a single CQ call.

Since my output to the antenna is less than 3W, I will consider those QSOs as a part of my personal QRP challenge. We shall see how many satellite QSOs I can make this year with this set-up.

On HF the QRP QSO count is up to 80 this year, so I should be quite capable of reaching my challenge goal of min 365 this year.

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.

Small Update on the QO-100 Uplink.

 The uplink signal using the single patch antenna resulted in quite a weak signal on the satellite, There were even instances where a station simply continued calling CQ while I called them, I could easily hear my signal on the downlink, but it was not strong enough to get any attention.

While I am planning on improving the set-up with a bigger dish and with a helical feed antenna, I was browsing for QO-100 feed antennas, and came across this 4-patch feed which has circular polarization. I realized that I have a small WiFi antenna, a so-called 14dBi panel that I estimated having 4 patches phased together, a bit like the feed in the link, albeit this just with linear polarization.

I taped the panel to the dish, got it aligned, and sure enough, the signal is a few dB stronger than before.

Further, I had removed a 10dB attenuator between the 432MHz TX and the up-converter, and when I received a report on a spurious signal on the CW signal I tested with reduced power, and sure enough the distortion disappeared and the tone was clean again. The S/N was even better, now close to 10dB in SSB bandwidth, a quite comfortable level for receiving a CW signal.

Further, after some email exchanges with PA1GSJ, and some of my previous thoughts, I will be testing some more improvements on the uplink.

- a circular polarized feed antenna, such as a helical.

- replacing the low cost satellite cable with RG-6 may provide a sufficiently low loss to eliminate the "driver" Edup amplifier and the extra filter in the outdoor unit.

- a larger dish for the uplink is contemplated, such as a 100cm one.

- I do have a 80cm dish, and I might replace the 60cm receive dish with this one.

- a better reference oscillator (set) 10/25MHz is on the way, so I know better which frequencies I work on

- a second receive converter , so I can use my dual band 2m/70cm TRX in satellite mode (70cm for the uplink and 2m for the downlink), and having the TX and RX tracking.

This is quite a list, so I will take my time and slowly improve/optimize the satellite system.

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

QO100 Frequency Stability.

Today I picked up the RFzero 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.

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.

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.

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.

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.

New Satellite With Amateur Radio Transponder Launched

The Es'hail 2 satellite has been launched and is going into 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. 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.

For reception a 1m (3ft) dish with a PLL controlled LNB, as well as a receiver around 700MHz should be sufficient to hear the transponder on 10GHz, even if the frequency stability is probably not very good.

That would be my first step in amateur geostationary satellite communication.

Now I have to find a PLL-LNB.