The W5RRR IC-781 was taken out of commission during 2017 Field Day because we observed intermittant noise crackling on the receive and transmit signals.
It got on the bench for troubleshooting. Based on online owner’s knowledge sharing, areas of known weakness were:
cracked solder joints at the crystal filter in IF
Phased Lock Loop unlock
IF FET 2SK125s
We’ll I screwed something up. After removing the RF module the whole receiver chain is white noise.
It’s one of those classic headaches, “you try to fix one thing, but you induce another problem”.
At least I used this as an excuse to buy a new oscilloscope.
BTW, the IC-781 has a great reputation as a solid rig, but it’s a PITA to work on. All the modules are compartmentalized and it’s almost as heavy as a tube radio.