On 01/29/21 15:13, sjdevience@gmail.com wrote:
The technical documents and schematics in the other thread were interesting, but the still didn't answer the simple question of what the LO is. I guess we can calculate them since we know the TX and RX frequencies and that the IF is 45 MHz.
You are correct: The IF, based on the schematic, looks to be 45 MHz. There are two stages of filter/amplifier with the ECS-75SMF45A30B crystal used as a band-pass filter. Knowing the uplink is ~145MHz, one can then assume that the MQF326D oscillator is 100 MHz.
However, any good RF design would be shielded and the LO leak-through using the LT5560 double-balanced mixer will likely be too weak to hear.
I've been thinking about what this high power result might mean.
< .. >
My first guess would then be that the antennas didn't deploy.
I might also hazard a guess that either or both of the U4 or U2 power amplifier driver stages has failed.
--- Zach N0ZGO