I have two paper instruction manuals Vol-1 and -2. There are no schematics in these manuals. A while ago I found a PDF with VOL-1 and 2 including schematics but the IF1 schematic is missing. If you google “KO4BB TR4172” you will find the pdf but I assume that you already have it.
I have mounted the IF1 module back in the analyser but unfortunately I’m still missing 12.5 dB? Jeremy what do measure if you do the following:
- Master reset
- Cal -20 dBm 50 MHz at input 1 (level checked with power meter)
- CENT 50 MHz and SPAN 10 MHz
- ATT 0 dB
- ZERO SPAN (Shift, Arrow Up)
At the CRT I see -32.5 dBm. At the IF output at the back I measure -38.6 dBm at 3.33 MHz, see picture. It is wiggling a bit. The calibration screw at the front is at max.
Jeremy, nice that you can make plots via the GPIB interface by accessing the memory. This is also on my wish list. Maybe you can tell me more at a later moment if I have solved the old gain loss issue
.
Best regards, Lex