The ANC4 can be effective
> on
> > some bands with stable local sources, but can be a PITA to keep tuned
with
> > different/multiple sources. And I think that fundamental overload would
> severely limit
> > its usefullness on FD. I would like to find a better solution. Maybe the
> MFJ is better?
> >
> You may have a point, Jim, but remember the ANC4 and
> likewise the MFJ unit (I think) have all the active gain in the
> noise leg. This is the controlled path which you would
> hardwire to the offending transmitter (station A) with a
> directional coupler to siphon off a sample of the
> broadband noise. The key is whether or not the noise
> cancellor would have enough dynamic range to pass
> the offending transmitters fundamental (fm station A) without blocking and
> still
> deliver a large enough sample of the co-channel
> broadband noise to its internal combiner such that you
> could cancel the co-channel noise coming from the
> receive antenna.
>
If all you're depending on the canceller for is the far out sideband noise,
you could notch the Tx fundamental before sampling for the canceller. You'd
depend on a notch in the main Rx line to keep the Tx carrier from
overloading the front end.
As far as PITA keeping it adjusted, this is an obvious application for
computer control. It would be much too complex to keep track of, especially
in a multiband environment with Tx and Rx both QSYing. However, such
tedious things are ideal applications for computers. Run the calibration
once when you've got stuff set up, and that might be good enough. Or, you
could put an adaptive loop in, but that is quite a bit more complex.
Again, this is why manufacturers like LDG need to be thinking about generic
interfaces to their products, because that tunable LC network has a lot of
applications other than matching antennas to transmitters.
_______________________________________________
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Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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