Experiments with 47ghz and 78ghz with 12ghz diodes.....

I decided to do some further experiments at 47GHz and try out 78GHz.  I had obtained a DB6NT transverter at Central States VHF conference a couple years ago and have built a CW transmitter/downconverter for 47ghz (power out < 10 dBM) but I wanted to try a simple spare 47GHz system using the BAT-15 or similar diode assemblies soldered onto an SMA flange or .141 hardline.  I have enough odds and ends for testing/detecting a signal.  No way to tell power output though outside of building a down converter to hook up to my HP 141 spectrum analyzer but without a calibrated source, its all guesstimates.  My thought is - build it, take it out and see how far I can be heard....

First thing to resolve was the IF frequency for the transverter which will drive the local oscillator requirements.  Working the math assuming operating frequency of 78.192 GHz and 47.088 GHz, and assuming 432 MHz for an IF.

For 78.192GHz, the LO would be 12.960GHz and for a beacon, the LO would be 13.032 GHz.
For 47088, the LO would be 11.664 GHz (432 MHz IF)

I picked up an Elcom phase locked DRO from the auction site for the 11.664 GHz - but for the 78GHz LO, I lucked into some frequency agile bricks from CTi and also MA/COM - and even better - the CTi bricks run on +15 Volts!  The MA/COM one runs on +20v but its nice to be able to have LO source voltages that are not positive ground like the ones built for telecom plant.

I used my trusty HP synthesized oscillator to find the magic frequency to lock the brick at both 12.960GHz and 13.032GHz - so the first step was to build up a LO and include varactor tune to lock the LO.   I built a test source LO to get things started and then add in the varactor/PLL when I get that built.

Then, build up a couple test assemblies with diodes on SMA bulkheads and an IF diplexer.  The plan is to have the diode assembly to be more flexible with dish/feed mounting.