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Old January 25th 07, 01:50 AM posted to rec.radio.amateur.antenna
RST Engineering RST Engineering is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 49
Default Local station bad harmonics on 80 meters

Because he's got a SINGLE frequency interfering with his station. To hell
with covering the entire band. A single parallel resonant network will do
something in the order of 80 dB of rejection if the L and C are at LEAST
something reasonable for Q.

Care to calculate the order of filter that will do 80 dB as a low pass
filter? And the Q of the components necessary to make the insertion loss
negligible at 160 meters?


Jim


"Richard Clark" wrote in message
...
On Wed, 24 Jan 2007 08:49:21 -0800, "RST Engineering"
wrote:

Why all this stuff about "high pass filters" and such. You are dealing
with
a spot frequency, not a band of frequencies. A simple parallel resonant
notch filter should do the job quite nicely and still pass everything from
DC to daylight except that spot frequency.


Hi Jim

There's not much more effort in completely covering a band of problems
with a band reject (high pass) filter. The original poster could
discover the NEXT broadcaster creating problems when he limited his
suppression to the first one. Who needs a chain of notch filters when
one would work as well for the entire band?

73's
Richard Clark, KB7QHC