I have obtained two MICROSOURCE synthesizers some time ago. Label on that device says:
FREQ: 10.2 - 13.35 GHz
I was told by several other HAMs that this unit is practically identical to ELCOM unit and can be controlled through a device with 12F675 processor, such as described by Dave WW2R here. The only difference is supposed to be the oscillator type - ELCOM uses "DRO" while MICROSOURCE uses "YIG".
I am not a beginner with ELCOM synthesizers. In fact, I already have a 24GHz transverter based on DFS1201, so I thought that using this new MICROSOURCE unit to generate signal for 24GHz beacon would be piece of cake. Well ...
The synthesizer simply refused to cooperate. I tried to program it for various frequencies above 12GHz, but it always generated 12GHz output signal (note that my counter isn't locked to GPS yet):
I spent hours researching Internet and checking my wiring, switching synthesizers .. nothing. I even contacted Dave WW2R by email, but he didn't have "hands-on" experience with this model. After quite some time I finally remembered that Michal OK1VM published something about this synthesizer on his web site, so I have sent him an email.
OK1VM told me that he has some recent experience with this synthesizer. He also mentioned that although the label on the MICROSOURCE unit says otherwise, it ONLY responds to programmed frequencies in the 11.2 - 12.0 GHz range. So, I have modified my programming to 11.88GHz and here was the result:
OK, the synthesizer works. I can't use it for a small 24GHz beacon, but there are many other ways how to utilize these wonderful devices.
Again, no matter what the label says, both of my MICROCOM units let me set them to a frequency in the 11.2 - 12.0 GHz range ONLY, exactly as DFS1201 from ELCOM.
So, before you decide to buy such a unit (mine came from eBay), be aware that your synthesizer might have the same limitation as mine does.
Thanks to Dave WW2R and Michal OK1VM for their help with solving this mystery!