Quote:
Originally Posted by IsquaredR
I've discovered an oddity with the B+ voltage being fed to the 455 kc Gate (V17 6BA6) and the 1st Converter (V3 6BE6). While the plate voltage on these two tubes is supposed to be 250 volts DC, it is only 140 volts DC. The voltage coming from the OA2 is good (around 270 volts DC) and the plate voltages on all the other tubes are correct. My problem seems to be in the circuit vicinity of I.F. transformer T3.
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So far as I can make out the anode voltages for V3 and V17 given in the manuals (the one in the link at Post#5) valve voltage table for the HQ180A are wrong, according to the schematic for the HQ180A the anodes of those two valves derive their supply from the OA2 stabilizer valve which stabilizes at 150 volts, that might account for your voltage measurement difference.
Lawrence.