[Hallicrafters] RE: Hallicrafter SX-122 Helppppppp

[Ray Poularas]

Hi Guys,
Something that may be of help to you.
I have had similar problems after following the service instructions and 
alignment procedure for a few radio's.
Although I have come across most of the problems that our Halli 
community has previously mentioned one of my experiences involved 
de-tuning of one IF stage on ever so slightly.
My experience was that after rebuilding one of my Hallicrafters 
Receivers I went through the alignment and decided that I would replace 
a few of the tubes that I was not entirely happy with..
The unit had been working for some hours with no problems and once I 
went through my collection of tubes and selected the best tubes I had, I 
replaced them and went back through the alignment to make sure 
everything was spot on..
A motor boating or overload was now occurring and it caused me must 
irritation as the radio had been working ok with the older set of tubes..
I found that very slightly de- tuning one of the stages fixed the problem.
The tubes I had selected had more gain than the older ones and it was 
just enough to cause a problem..
As I suspect that when these receivers were made the Resistor and 
capacitor tolerances were not a precise art and the fact that I had gone 
through the receiver and selected components that were all right on 
specification could also have contributed to the problem..
If you have a scope run through the IF section removing tubes between 
stages until you find the offending stage and then try giving it a 
little tweak..
Best of luck
Regards
Ray.
www.tuberadio.com