Something is quite fishy about this amplifier section after the 3rd mixer. With the -20dBm test signal feeding the analyzer input 1, I followed the signal through the output of the first mixer up to the input of this amp. I see about -14.6dBm on the input to Q19, the first transistor in this amplifier with my high impedance RF millivoltmeter probe. This works out pretty much inline with the gain/loss up to this point. According to the manual, I should see 14dB gain after this amp, which appears to be a frequency compensation amplifier as well as being a broadband amp. At least that's what I'm assuming the manual means by, "30MHz f. Gain collection Amp.". Regardless of what exactly it is, I see very little gain, if any, between the input of this amplifier and point M on the schematic, the input to either of the two RBW BPFs. I don't know if my gain issue is due to the output being loaded by a faulty component in the BPF switching network or due to a bad transistor. I do know that Q20 runs warmer than Q19, but looking at the voltages on the transistors, it appears that at least at DC, neither Q19 nor Q20 are bad. I will mock up the circuit in Multisim today to see what I get at DC levels.
Making progress...
