My QO-100 system started life in 2019 not longer after QO-100 was launched, and during that year the system was built. My first QSO via the satellite taking place in the summer of that year. The system has been designed to be portable around the house since the best location for the dish has never been near to where the shack is located. Therefore the need for operation from 12V has not been an issue, being relatively physically portable, and with fast setup times has.

The core of the system has remained pretty static since that time, but a major re-engineering of the system took place in early 2022 and a number of parts were replaced, usually improving the operation of the system. Compared to approaches involving the Pluto SDR that have become possible since I built my system, my system may seem overly complex. or even outdated.

Components

The current and past components of it are:

• Ice cream cone dish feed, previously a POTY. https://nolle.engineering/en/ice-cone-feed/ and https://uhf-satcom.com/blog/patch_antenna
• Bullseye LNB, previously a GPS stabilised modified Octagon LNB. From Amazon.
• 7m of M+P low loss coax for the transmit signal. From Martin Lynch.
• RG6 for the receive signal. From eBay.
• 85cm dish and heavy block mount, previously a tripod. From eBay.
• IC-705 for the transmit IF on 432 MHz, previously an FT-817. From your favourite emporium.
• Old i7 laptop for the receive side and transmit control, previously a newer i5.
• A combined 739MHz bias-T and downconverter to 144MHz, currently unobtainium due to having come from Ukraine. This is based on the G0MRF design. https://amsat-uk.org/projects/uhf-vhf-receive-converter-for-satellite-lnb
• SG-Labs 13cms transverter, previously GPS stabilised. http://www.sg-lab.com/TR2300/tr2300.html
• SG-Labs 2.4 GHz 20W amplifier. http://www.sg-lab.com/AMP2400/amp2400.html
• A cheap SDR stick. From Amazon.
• SDR-Console running under Windows 10. https://www.sdr-radio.com/Console
• A Meanwell 12V SMPSU turned up to 13.8V, previously a heavy duty 40A SMPSU. From Mouser.
• A Meanwell 24V SMPSU turned up to 28V for the SG-Labs amplifier, previously a buck-converter. From Mouser.
• Various connectors, adapters and such like. Usually from eBay.

Apart from the power supply arrangements, the biggest changes to the system were the replacement of the dish feed from a POTY to the ice cream cone which provided a better uplink signal, but with a slightly weaker downlink signal, only by a dB or so.

The system was originally built when operation on QO-100 was still rather experimental. The idea of locking your receive side to the PSK beacon was not known about so initial systems had GPS locking of the LNB which turned out not to be essential. At the same time I GPS locked my SG-Labs transverter but this was unnecessary and was removed. Removing the locking saved on weight and the number of cables going between the transverter box and the dish feed making the system much easier and quicker to set up. The only loss has been the ability to operate from 12V for potential portable operation.

The original FT-817 transmitter wasn't controlled from SDR-Console so frequency setting was done manually. In the new system the 705 is controlled by SDR-Console allowing for seamless operation.

The general arrangement of the major components can be seen in the following block diagram.

In November 2023 I tried my new IC-905 on QO-100. Unfortunately Omni-Rig as used by SDR Console was unable to control the IC-905 so frequency setting was done manually. The IC-905 fed directly into the SG-Labs 2400 MHz amplifier and the transverter was disabled. Also for simplicity the amplifier was set to be permanently on as no PTT line was available. The results were excellent, apart from the manual frequency setting, it was a joy to use. Setting the frequency on the IC-905 to match the expected uplink frequency for the downlink frequency displayed by SDR-Console worked extremely well. The uplink was perfectly set (thanks for the GPS based frequency stabilisation on the IC-905) and no further frequency adjustment was necessary. I did not buy the IC-905 for QO-100 work, but it was good to be able to use some of its microwave capabilities without having to (re-)build a portable microwave system.

Photographs

The System as of Summer 2019

The original POTY dish feed and Octagon LNB. The connections to the LNB are for the GPS disciplined oscillator (with the white tape), one for the narrow band transponder, and one for the wide band transponder. This latter connection was never used.

The transverter box. Comparing this with the later image shows that the internal power supplies are missing, but with a Leo Bodnar dual output GPS disciplined oscillator feeding the LNB and the upconverter.

The equipment in situ at the operating position.

The System as of Spring 2023

The new ice cream cone feed and Bullseye LNB and heavy base. This system can now withstand high winds, and is lighter because of the less amount of coax in use compared to before.

The new arrangement of the transverter box. The GPS disciplined oscillator has been removed and the SMPSUs have been added.

The new operating position with the IC-705 in the background. The FT-817 in the foreground is being used as a second receiver using the 144 MHz output of the downconverter/bias-T. Operating FT8 on QO-100 as I was doing here is an interesting experience to say the least.