HR-10 thread...

[Gerald C. Lemay]

You can indeed narrow the "nose" of the filter but you can't really
improve "skirt" selectivity due to the fact there are only 2 crystals
comprising the filter. Some years ago I got a junker HR-10, took out the
filter transformer and crystals and put it in another HR-10. Other than the
fact insertion loss was greater than a stock HR-10, selectivity was then
pretty decent for most CW operation and some SSB.

> Regarding the lack of selectivity, couldn't the xtal filter be
> "narrowed" a bit to correct this, i.e., by changing one of the xtal's
> to something closer, like 1.8khz instead of the 3khz that it's designed
> at?  Wasn't the 3khz bandwidth chosen as a comprimise --barely wide
> enough for AM, yet barely narrow enough for CW?
>
> ggg
>
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