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Setting up a microwave link can be quite tricky at best! After a bit of practice though, it becomes a lot easier. Forget everything you have learnt about band 2 transmitter (around the 100MHz range) this gear is in the 10GHz range and has many different (and rather weird) characteristics. The diagram below shows the basic setup for a microwave audio link (see pages microwave rx and tx)
The picture below demonstrates a full microwave link setup on the work bench:
The frequency of a gunn oscillator is mainly set by cavity size. The cavity has usually has a brass screw inserted into the side just in front of the actual gunn diode to adjust the frequency. This screw can be replaced by a PTFE (plastic) screw for easier tuning (usually if you need to retune often) otherwise my advice is set the screw then glue it good!
Ok so you have line of sight (with no obstructions!) from the gunn to the LNB? its time to tune. Set the linkbox gunn voltage to around 8Volts (for most gunn modules). You may want to experiment with different gunn voltages as it can affect the frequency response of the modulating audio. Solfans and large C&Ks such as the one demonstrated here seem to work best on 7.9-8.5 volts. I have noticed the higher the gunn voltage, the more the higher audio frequencies become attenuated resulting in more bass, bottom heavy audio.
With the gunn now running, monitor the remote satcan receiver (you should hear white noise if no link is established). Now turn (very slowly) the brass tuning screw on the gunn until you hear the dead carrier (no white noise). Feed the linkbox with some audio and see how it sounds as it might be just a spurious emission.