[AMRadio] 75A-2 follow up

[CL in NC]

Well, my fishing expedition did not turn up anybody, so had to rejoin the CCA reflector, and did get an answer.  Turns out this 75A-2 was beautifully modified per a 1955 QST article that took all the Collins service bulletin changes and made one article out of it.  So, what I was working on was a 75A-2 that had been modified, except for V4 the 6BE6 second mixer, into a 75A-3.  Main problem turned out to be a shorted cap on V3, if I remember the tube number right, the LO for the first mixer.  The grid to plate cap short burned up the plate resistor and killed the oscillator.  Changed one other cap and resistor after checking them all in the front end, and found a shorted .1uf, one of those flat and rectangular ones in the IF chain killing the bias volts.  did not have to touch a thing tune up wise, did check it, and found it to be aligned perfectly, and the PTO still tracked perfectly.  Owner was happy to get it back after traveling though the hands of several folks.

Charlie, W4MEC in NC