Netnews Marty aa4rm wrote:


PS... now that I've got ur attn, anyone know a 'filter' that hunts
out a hetrodyne freq. and nulls it automatically?


Hi, Marty

I'm the happy owner of a "Magic Notch" filter, which goes
between the receiver audio output and speaker. It has a
built-in 2 Watt audio amplifier, and requires a 12 VDC wall wart.

Per the manual -
"It has a switched-capacitor active filter which is scanned through
the audio frequencies, and stops scanning when the output drops.
The filter then phase-locks to the interfering signal and tracks
any varitions in its frequency until it disappears."

One nice feature is a green LED indicating power on, which turns
to steady red when the filter is ready to notch out a heterodyne.

The filter is a small grey box, with a bypass switch and a phone jack.
It was a product of "j-Com", but I bought mine from Ramsey
Electronics, Victor NY, who I think took over the j-Com line.

They also made the much more complicated "W9GR DSP II" audio
filter, which includes an automatic notching filter,
and was featured in Sept 1992 QST.

73,
Ed Knobloch