[HBR] Birdies

[Bill Cromwell]

Thanks,

You keep reminding me why I like regens <evil grin>




On 01/12/2015 12:04 PM, Brian Burns wrote:
> Hello Ian,
>
> ~ Sometimes it can be very difficult to tell which signals are causing the
> interference. High harmonics of the BFO can mix with lower harmonics of some
> other oscillator, for example. You can sometimes get a clue by observing how
> fast a birdie moves relative to the tuning control - a fast-moving birdie
> indicates a multiple of your variable oscillator is involved.
>
> ~ There are programs that will calculate mixing terms that fall within a
> given window, but in a typical superhet there are too many such windows, and
> the number of potential interferers is just too large to manage (in my
> limited and frustrated experience, anyway!).
>
> Right, the little buggers multiply like rabbits! I figure that a combination
> of shielding and by-passing would be the place to start. For the BFO and
> second LO, that will hold still at least, might it be possible to use a
> simple band-pass filter to at least quiet down their harmonics?
>
> Pity the poor HB-XX guys with 4 oscillators running at the same time!
>
> Cheers,
>
> Brian
>
>
>
>
> ---
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