I published two narrowband filter designs. The 40M filter is
29kHz wide two resonator filter with 6 dB loss. The coils are wound
on 2.4" PVC pipe and enclosed in custom aluminum boxes. I'd say this
would be a difficult construction project for the average ham, but no
big deal to a skilled machinist.
The 80M filter is 59 kHz wide two resonator filter with 2.3 dB
of loss. A much simpler design using inductors wound on T130-6 toroidal
cores.
73--Zack Lau W1VT
Nov 1998 QEX 58 A Narrow-Bandwidth 40 Meter Band-pass Filter
(RF) Lau, Zack, W1VT
Sep 1998 QEX 57 A Narrow 80 Meter Band-Pass Filter
(RF) Lau, Zack, W1VT
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See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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