Fault Finding in an Old 10GHz Transverter.

In the autumn I made a first test of a home-made 10GHz transverter I got my hands on, and started testing.

The initial test was a simple connection to an older FT-290 transceiver, and going out to spme place a bit higher than where my house is located.

I was listening for the beacon OZ7IGY at a distance of about 25km. Nothing in the garden. If I placed an satellite TV LNB about 4m above ground I could hear the beacon, very weak, because it is behind some hills about 30m higher than where I am.

I tried to go to a place somewhat higher with the FT-290/transverter setup on a tripod, and tested. Absolutely nothing heard. tuning about 30kHz to either side of the beacon frequency.

So now I got started fault finding.

The first suspicion after talking to a local ham was the 2556MHz local oscillator module. Testing on a spectrum analyzer showed a nice signal with an offset of less than 600Hz. Not bad, this would give an offset of less than 3kHz. The output (to the Qualcomm up/down conversion module) is close to 5dBm, so that looks quite good. I can safely say that the LO module works nicely.

Now more tests are necessary.

 I do need a small 10GHz signal source, and I have thought of using one of the following:

- a low power (0.5W) 70cm FM transceiver with an attenuator and a single diode as multiplier

- a synthesizer PCB with a AD 4350 or 4351 chip, just using the 3rd harmonic. 

At least I can test those with the spectrum analyzer, so I know if there is a strong enough 10GHz signal.

I think the simplest of the two is the attenuator/diode multiplier, so I think I should start there.