QO-100 Amateur Geostationary Satellite

We really need this thread as QO-100 is so close to what we are doing.
Also Othernet happens to be behind a favorite(Bullseye) Ku band LNB accurized for narrow stability.

I am curious what hardware people like for the S-band uplink generating or upconverting the signal, amplifying and antennas.
I prefer inexpensive and DIY as much as possible, no need for a commercial TV BUC; just something which will reach the satellite and can be used to send CW, maybe SSB, or a narrow data signal.

QO-100 is really easy to receive.
Sending is a bit more complicated but not hard as well.

I currently working on my TX / Uplink Setup for QO100, it already works for half a year, but i havent found time putting it into a nice box and putting it onto the Dish. It consist of the following:

  • 2.4ghz Patch Antenna
  • WIFI Amp
  • LNA (for driving the AMP)
  • Pluto SDR

Even with a 60cm Dish i was able to make CW Contacts and even some basic SSB, with ym 1.2m Dish SSB should be no Problem at all.

73 Manuel DO5TY

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I have been thinking to make a transverter fed from 2m(or HF) IC706 until I decide on what SDR to build my ultimate all-in-one radio. I think 2.4ghz isn’t so bad for short runs of trace or dead-bug wire as far as watching for accidental capacitance and impedance in the traces. I dont know if I should make the final linear amp a separate thing and put it in a heatsink Al box right at the antenna and just feed it with a bias-T on the 50ohm antenna line. Elegant would be to run everything over one line and multiplex the power and RF with bandpasses. I think I want to make a POTY to add a S band tx antenna to the Ku LNB. As fro RX I guess for now an RTL-SDR<–bias-t<–Bullseye LNB.

Since there is not already a really integrated unit I hate just buying someone else’s project off the shelf and would rather make a few crappy prototypes myself.

How did you make your bias-T for your Ku side? I have been mulling how to wipe out the oscillator noise from whatever boost I use to get the 12v to 14/17v for polarization.

How many dB to say a POTY antenna and a ~1m offset dish is needed to send up a CW or tight digital signal?
Are wifi amps really enough to show up on the transponder? What are those, something like 30dBm or less?


I just bought a Bias-T Injector from Ebay or so for a few euro and added a Buck Converter to up The voltage from 12V to the 14V i need for the LNB.

The WIFI Amp i got is 8W, well it realy does 2-3W but it is more then enought even with a little Patch Antenna on a 60cm Dish Indoors.

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Wow, it is amazing that the input of the transponder is grabbing qrp signals like that, I just imagine terrestrial noise would wash a 33-35db signal away especially with such a small antenna/reflector.

I am using a stabilized LNB with injector from DJ4ZZ in a 60cm standard tv-dish and a RPI with openwebrx as you can watch online here. The injector is fed directly from a 12 Volt solar-system.
Did not try transmitting until now.
Wolfgang, DH2WS

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You don’t need a stablized LNB, i use a normal one from Amazon and it works great, especially with simple Software Compensation with SDR Console :slight_smile:

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I love that everyone has to go back to DIY for this satellite.
I would like to get better at RF circuit design for microwave,
I used to know one of the emeritus chief scientists of Tektronix,
his name is all over tech like bluetooth.
I had a copy of the At&t manual gifted from him, now a search for that book
an amazing resource for microwave tech returns a forever list of old At&t wireless phones.

I was boning up on some microwave design and saw this as the intro in a book talking about a hoped for near future of apparently a different 1985 timeline branch than the one we passed through. They probably have a USSR and fragmented Internet though.

Hi there, i’m using the very stable bullseye. It change my setup , now I only have the LNB and a sdr receiver or the downconverter to 144 mhz for my aged ssb radio receiver. No need any gps control on the oscillator or the software compensations in SDR Console . The TX side is made by an SDR ( pluto sdr direct 2,4ghz + rf amp) or ( analogic) up converter BU500 on 432 MHz+ rf amp.
The bullseye make the difference in a simple configuration LNB + downconverter+ssb radio.
Well done othernet , thanks for this piece of hardware.

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