Clark and all,
With regard to losing gain with the 250 Hz narrow filter and having to
set the passband tuning to 750 Hz, it just ain't so. You set the offset
to be whatever you want it to be. Mine is set for 450 Hz. There is a
gain compensation jumper near the filter so you don't have to lose
anything when using it. It's documented in the manual.
73,
Dave Heil OH2/K8MN
Clark Savage Turner WA3JPG wrote:
>
> > I always use the 250 Hz 282 filter and I think I want to add a 250Hz
> > 9 MHz 219 filter to give me more selectivity.
>
> I have used this combination and it works well within its
> limits. The PBT becomes very sensitive and you need to be very
> close to the 750 Hz offset in order to hear anything. The other
> limit is that the losses from the 219 are about 10 db and the
> amp in the front end are not nearly enough to make up for that
> (I don't know why, it seems simple to get enough gain in that
> stage....) so that when you kick in the NAR filter from 9 MHz,
> the signals go way down, and weak ones may be lost. The QRM
> does go away though.
>
> I have used an outboard preamp, simple Palomar P-310X to cure
> the problem. It interferes with the QSK in a way, but you
> can use the preamp with a separate antenna into the other jack in
> the back and cure that problem too. I suspect the right way to
> handle this is to modify the 9 MHz IF so that you get a little
> more gain from the NAR filter there.
>
> Good luck.
>
> Clark
> WA3JPG
>
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