Hi again folks:
Looking further, I checked the band 1-3 amplifier, and it doesn't look good: the output must be +26 dBm and I only read +14.x, which is the output I measured in the the A16 modulator/splitter (whose outputs look fine). I tried to feed it with an external signal (2.3 to 2.56 gig from my 8663A) and has no gain, instead, it has a 1 db of loss. So the high band amplifier is a thru.
Also, as I said, I am pretty sure that the band 0 amp is dead, I feed it with -10 and +20 (and ground) and looks shorted: drawn almost 1 amp and getting hot quickly. And has 23 dB of loss, instead of 40 dB of gain. Maybe the resistor divider made with discrete component has a shorted one, but no one looks darker or suspicious...
The diagnostic for now is the two amps are failing, allowing me to see some activity on the output of the unit at high bands, but weaked as hell because of insertion loss of the SYTM and other microcircuits at the very end of the signal path. Spare parts are present on eBay but in the States, so shipment and customs multiplies by two the price.
The A8 3.7 GHz phase-locked oscillator reads arround 0 dBm, so looking good.
Best regards,
R.
RubenRubio