Quote:
Originally Posted by maxhifi
I'm thinking it could be contacts for those push button tuning switches. Have they been cleaned and verified good? Check osc. coil for continuity too, and antenna.
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I checked and cleaned the push buttons , I tightened the tube socket pins and Deoxit , not it does not crackle when I move it around, not as intermittent.
I used my alarm clock radio and set it beside the radio,and turned the tuning dial which was aprox at 455 it does produce static on 1000kh .
I brought out my Heathkit RF signal generator SG-8 and set to 455 KC and soldered a .02 uF cap on the end of my home made test cable, the 12SA7 is very active, just 4 inches away, I can hear the signal tone from the generator, and later applied that signal to the grid of the 12SA7 and aligned the trimmers in the 2nd and first stage making that as loud and clear as I could get it. That worked very well and was very clear, so everything from the rectifier and audio to 12SA7 seems to work well, the IF alignment was done according to the procedure for the L-660.
I set the frequency generator to 1500KC, and turned the variable tuning cap all the way open, and with the loop antenna hooked back up again, tried to set C2B and C2A adjustments on the variable cap,but no signal.
I checked the signal generator with my clock radio at that frequency and it does work very well, so the problem lies by the RF amp and antenna and switches.
I don't think that the former owner had the loop antenna wired right, it was connected to RF, 12SK7, pin 3 and 4, I will follow the schematic and check that all out, as connecting the loop antenna does nothing, not even pulling in the strong signal from the frequency generator.