On Wed, 24 Jan 2007 17:50:56 -0800, "RST Engineering"
wrote:

Because he's got a SINGLE frequency interfering with his station.

He reported a single frequency, that does not limit the problem to a
single frequency. I already explained that.

Care to calculate the order of filter that will do 80 dB as a low pass
filter?

That is not particularly difficult, quite common in fact. Standard
engineering syllabus teaches us that you enjoy a 6dB/Octave or
10dB/Decade roll-off for each reactive element in a filter. I already
suggested a 6 or 8 pole filter which brings us up to your 80dB for an
entire band, much less a single frequency. Slam dunk simple.

I am quite sure that many here that are experienced in actual bench
work would nod in agreement that the better part of a project is
building the things around the electronics - like an enclosure,
connectors and such - than with the electronics. 8 off the shelf
items (actually 4 pairs) vs. 2 with one of the two needing to be
variable AND tuned? Is that such a major demand on the bench skills
of an amateur radio operator?

And the Q of the components necessary to make the insertion loss
negligible at 160 meters?

For receive? C'mon now. And 160M instead of the band he is
interested in, 80M? Anyone can contrive to fail, that's plug simple.
The next set of restrictions will have us going down the garden path
to build a crystal lattice filter for the sake of unneeded
astronomical Q and to achieve spectacularly low insertion loss - turn
up the RF gain.

The issue is moot with the probability the issue revolves around spurs
from corroded, weather beat connections. I have a buddy who suffered
identical issues from an AM station 1 mile away. He wire brushed poor
joints and solved the problem that filters couldn't solve.

73's
Richard Clark, KB7QHC