ZS2M/ZS6DX/V51VE
Satellite Communications

Update 27/9/2023: With some better weather I managed to get some work done on my QO-100 Satellite station today. After trying one more time to get the 120cm dish going I gave up and removed it (not fun!) and replaced it with the little 70cm dish. I used the same LNB and cabling.

My first attempt to get it aligned did not go well, same results as with the larger dish! Could not believe it! I decided to see if there was another issue. I did ask my supplier if the LNB he supplied was standard or modified but he never replied (guess the items I have in my shopping cart on his web page will stay right there!)

Anyway, I decided to give and old DSTV LNB I had lying around a go. Once it was on the dish I could actually see very weak signals! I quick trip up the ladder armed with a laptop and a spanner was all that was needed, finally decent signals from QO-100! To say I was happy would be a mayor understatement!

What a fantastic sight! Signals from QO-100!

The LNB was drifting quite a bit but fortunately the SDR Console software allows you to lock on the beacon, once I had that configured the frequency was rock solid.

Next task was to setup the transmit side. I did not expect much due to a few things. Firstly there was the dish that is a lot smaller than the one used in the original "power needed" computations. Next there was the suspect pre-amplifier and to crown it all the transmit antenna is only a small, linear polarized yagi antenna, not circular polarized as it should be for QO-100.

Test showed that I could just see my transmission on the QO-100 transponder. At least the signal was strong enough that I could calibrate the TX/RX frequency so that I can transmit on the frequency I am listening on. I might just have enough power (no idea how much but most likely around 1W) to make a CW contact, will try tomorrow if I have time.

So how to improve my signal into the bird? There are a few options. I can try the larger dish again, but I am reluctant due to it's mounting requirements especially taking the high winds we often have into consideration. Next I could (and I should) replace the TX Yagi with a decent helical antenna. I would have to build my own as there are non available locally. They are not that difficult to build if you have a 3D printer (I do have one) but my problem is that at this stage I gave no way to measure the SWR on 24GHz. If I get it wrong I could damage my (expensive) amplifier.

I think I need to acquire a VNA, it will be useful to build antennas at the higher frequencies and will also be usable on my HF antennas.

Another option would be to increase my transmitted power, firstly I could (and again I should) get a decent pre-amplifier that outputs at least 200mW, not the measly 12mW I am getting now according to the specs of the one I have now. A second option would be to run my amplifier on 24V. It can run on 12-24V but will only produce it's rated power at 24V.

I think I will take as many of the steps above as I can and see where I end up. I did listen to a few QSO's CW and SSB, reception and signal strengths are fine on the small dish.

A CW signal received on 10GHz, a first in my shack, the signal has travelled around 70 000km to get to my receiver!

Update 17/9/2023: I am making progress on the assembly of my QO-100 ground station. I have now done all the soldering and cable assembly with the exception of the final connections to the dish. I will only do that one the dish is installed and everything is where it should be, that way I can make sure the cables are exactly the right length, at these high frequencies losses are high in the cables so they should only be as long as absolutely needed. I still need to make up the power harness as well, also waiting to complete the installation first.

I do need to decide what I am going to do for the 5V power supply, the Pluto Plus 2 needs 5V, up to 3A and the little 2.4GHz pre-amplifier also needs 5V, what amperage I have no idea as it is not mentioned anywhere. Will check the current draw once it is running, should not be more than 1A I think.

All the software is setup and the Pluto is working well, I tested the receive side with 145MHz and 30MHz transmissions. I have now completed the assembly of the 2.4GHz transmit antenna that will feed the dish. I connected this antenna to the Pluto and used it to TX tones on 2.4GHz (drive set to 0 gain so no idea how much power but very little). Since the Pluto is full duplex I could monitor the signal on the RX side and it sounds good and looks clean on the scope.

I still need to test the CW TX but since I will be using a tone injected on a SSB signal I am sure it will be fine. To generate the tone I will use the CWType program. It allows you to connect a key or paddle to a serial port, works well. It can either key a transmitter through a serial port (real or virtual for a SDR) and/or sent the tones to a sound device. By using a virtual sound cable you can then use the tone output as input on the SDR software to transmit the CW. It works on the Flex so it should work the same on the Pluto.

The 1.2M dish is now also assembled and I have the mounting hardware ready and the location has been decided. All I need are 4 rawl bolts, will hopefully be able to get them tomorrow morning from the local hardware store.

Almost ready to begin the bit I am not looking forward too, aligning the dish! But it needs to be done before the fun can start.

Update 16/9/2023: I received a call early this morning from the local courier agent asking if I can please come and pick up a parcel that would not fit in his car, I was there in a flash!

The parcel was my QO-100 satellite station equipment. The component that made it so large it would not fit in his car was the 1.2m dish, fortunately it did fit in my car!

I had a quick look and everything seems to be there with no shipping damage. I am still concerned that I was supplied with the wrong pre-amplifier but the supplier insists that it is the correct one, we will soon see!

There are a few small things missing, some like 2 power supplies because the supplier did not have stock and a few other things like cables and connectors because they were forgotten. No big problem, I have power supplies, spare coax cable (for the LNB) and connectors for the LNB cable. I received 1 power injector, all he had in stock but I need two, again no problem as I can supply the pre-amplifier direct with the needed 5V as it is going to be close enough to a power supply.

I loaded the Pluto plus 2 drivers and installed the SDR Console software on my shack computer. Once I connected the Pluto plus 2, via a USB cable, the software detected the Pluto and it is receiving. I will test transmitting later when I have an antenna. The Pluto can also be connected to the computer with an Ethernet cable, will try that later but I think I will run it connected with a USB cable as the whole "station" will be mounted outside just below the dish and that is less than 2m away from my shack computer.

Computer connection, via USB or Ethernet, and power supply side of the Pluto.


The output side of the Pluto, 2 TX and 2 RX connectors for the 2 transceivers.

I have started putting everything together, first thing I did was to mount the 20W 2.4GHz linear amplifier to a heat sink. The supplier did not have heat sinks but a quick search through my "spares/junk" supply produced a heat sink of the correct size, it used to be mounted on a 28MHz to 430MHz transverters that I scrapped at least 25 years ago, see why you should never "dump" stuff?

20W 2.4GHz linear amplifier.


Inside of the amplifier, input at the bottom, output at the top.


Mounted on the heat sink, electronic components work better and last longer when kept cool! And yes, I only saw the cat hair after posting the photo here! Sometimes my "helpers" can be a problem, I think I will simply pretend the cat hair is there to give scale...


The pre-amplifier that sits between the Pluto and the linear amplifier, needed to boost the 30mW output of the Pluto to a level high enough to drive the Linear amplifier to a decent output level. This is the unit I am not so sure about, this looks like a small signal receive pre-amplifier to me and what I can find on the internet confirms that. Will try it but chances are trying to transmit through it will "let the smoke out".


Power injector, supplies 5V to the LNB via the coax cable.

Next major thing I need to do is to install the dish and line it up with QO-100, unfortunately I will have to wait till the wind storm we have at the moment, peaking 80-100km/h subsides before I can try that.

Update 12/9/2023: I have been doing a lot of reading and watched a few YouTube videos on the QO-100 satellite. I also spoke to a local supplier to see what is available. Fortunately it looks like I will be able to get most if not all the components from him.

I still need to finalize the list with him but I have decided on a full SDR station. Initially I was against that because none of the SDR solutions really offer CW as an option. Some research and a few experiments with the SDR software I plan to use has convinced me that I will be able to get a decent CW signal from the SDR using software keying, a nice challenge!

Here are the components I am going to acquire for my station.

Main radio: Pluto Plus 2 SDR, this a dual RX/TX radio that covers from 70MHz to 6GHz out of the box. This is a very versatile radio and I can see that I will use it for a few other things as well!

Antenna will be a 1.2m dish. One of the components not available is the 2.4GHz feed antenna for the dish but I will build my own, most likely a 3D printed helical antenna.

The SDR will output RF into a small pre-amplifier, the output from the pre-amplifier will then feed a 20W 2.4GHz amplifier.

On the RX side the dish will focus the 10GHz signal on a low noise, high stability LNB that will down convert the signal to around 700MHz. This signal will then be received my the Pluto Plus 2 SDR.

There are also a few small things needed like a "power injector" to provide power to the LNB via the coax cable, a 5V and a 28V power supplies, a heat-sink plus fan for the amplifier plus a bunch of coax and connectors.

I am planning on running SDR Console software as main software.

Hopefully everything is in stock so that I can start the project soon.

Late afternoon update: Unfortunately a few needed items are not in stock and it will take about 3 weeks to get them, so it does not look like I would be "on the birds" as soon as I hoped. Oh well, such is life!

Update 11/9/2023: I have been looking for a new challenge in amateur radio for a while, I love DX'ing and chatting to friends as well as restoring/fixing older equipment and I will continue doing that but what I need to stay enthusiastic and active is something different.

One possibility is to get involved with satellite communications again (I did play with satellites many years ago), it is technical and fun plus you are not so restricted by band conditions. Often I have time during the day or evening but then the bands are dead so my interest turns to other hobbies. With satellite communication you do not have that issue, your only limit is that you have to wait for a satellite to come over the horizon but even that has changed!

The Es`hail 2 (QO-100) is a geo-stationary satellite, that means that it is visible 24 hours a day plus you do not have to track it as it does not move! It uses a 2.4GHz up link and a 10GHz downlink. Since I am not equipped for either of those frequencies in the shack I would need additional equipment for the shack but that is half the fun! There are no "brand name" radios available that covers those frequencies so the way to go is normally an up-converter (usually from 144MHz or 28MHz) for transmit and a down converter or SDR receiver "dongle" that covers 10GHz. Home-brew or at least matching of different modules is normally the way to go and I love the challenge!

I would also most likely need a 2.4GHz RF amplifier (10-30W) and a pre-amplifier for 10GHz. A dish antenna would be needed as well but that I do have as it is the same as what I have been using for my long distance FPV video and RC radio links.

The challenge is to now to source the needed bits and pieces, hopefully local to reduce waiting time. I am already excited!

I do need to make a few decisions, how will I drive the up-converter? From a "satellite" ready radio like my Yaesu FT-847? But a satellite ready radio is not really needed as you do not have a fast moving satellite so there is no need to compensate for Doppler effect. Easier might will be to use a radio with a good spectrum display like the IC-7610 or Flex-5000A so that you can "see" other stations in the satellite's pass-band. Fun times ahead! I think if I stick to an up (and maybe down) converter that uses 28MHz I have many different radios to select from and to play with.

The satellite I am most interested in as it offers 24/7 contacts and a nice technical challenge


QO-100 "Footprint", lots of DX to work!

Other satellites will also be fun and I think I will start with them while I am waiting for the QO-100 equipment, see you on the "birds"!

I will report back here as I make decisions and acquire equipment.   

(c)R Venter 1996-2023