Ref: [Amps] AL-1200 Pop

[Will Matney]

Well,

I'd say it was the tube arced internally first thought. I wouldn't 
discount parasitics causing this either. There's not too many things 
that cause a loud pop in an amp. If it were an electrolytic capacitor, 
you'd smelled a real sour smell coming from the amp and foil with paper would be everywhere it "once" was. If the coupling cap shorted, it should have blown a fuse. If the tube did arc, it would have blown a grid resistor if that amp has them. Some uses a choke and some none at all. Let's put it this way about parasitics, MFJ the manufacturer of your amp threatened a law suit over someone even mentioning parasitics causing tube and band switch arcing! Now that should tell you something about it.

Will




"Subject: [Amps] AL-1200 Pop

I just finished replacing the open frame relay in my old AL-1200 with the Ameritron relay PCB mod.  Put it all back together, seemed to work fine,tuning on 40m.  Moved to 160m, had the Amp in Standby while I set the output power on the exciter.  Heard a loud Pop - exciter power only.I turned the Amp off for awhile, then tried it again.  It still works fine.I opened it up looking for a visibly bad component, none found. Any ideas what this might have caused a Pop in Standby?  Should I worry?"

Dana