[Hallicrafters] s-38 Oscillation

[Roger D Johnson]

Brent Seres wrote:
> Thanks for all of your suggestions. I think I have found the problem, 
> and it's not the radio (at least as it was designed) . I live very close 
> to an LF Beacon for the air force base hear, which operates around 
> 220kHz. I suspect that this is getting into the front end, being 
> doubled, and then beating with the BCB stations. This would explain why 
> things would be worse at the lower end of the BCB, and also why I also 
> hear it on my original model S38.
> 
> The S-40 is immune because of the tuned RF stage.
> 
> I connected my old crystal set double tuned circuit up as a 
> preselector....problem solved!
> 
> Thanks again
> 
> Brent

If the beacon was getting into the front end it could cause cross
modulation. For instance, if you had a BC station on 800 kHz, you
could have intermod products on 580 and 1020 kHz. These would have
the modulation of both signals superimposed. They would not manifest
as a tuneable heterodyne.

73, Roger

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