Howard wrote:

Brian,
You may be better served by using a bandpass filter - or in your case
a "band no-pass" filter. Something that attenuates signals below 2
MHz may be useful; just browsed the HRO and AES catalogs and did not
see one for that range though. Dale Parfitt, of PAR Electronics, pops
up on this ng from time to time; his company markets bandpass filters
for VHF/UHF that are highly regarded and perhaps he could help point
you in the right direction. PAR Electronics can be found at
http://www.parelectronics.com/index.htm , Dale is also now offering a
nice end-fed wire antenna you may wish to consider. You may also wish
to go to the library and see if they have the ARRL Antenna Book or
Amateur's Handbook - you might find something in there.

FWIW, I have a 7600G that when hooked to an inverted L also picked up
the local AM stations, the problem did not duplicate itself when I
attached the Alpha Delta sloper. The inverted L was grounded at the
feedpoint whereas the AD sloper has a 30' wire downlead to act as a
counterpoise - but is also attached to a ground rod (manufacturer
indicates you can either let the wire dangle or connect to ground).
Never did figure out why the problem existed but when I rewired the
balun on the inverted L with no DC continuity between input/outut the
problem went away. Perhaps this info will help you resolve your
issue.

Good luck,
Howard

Par makes a BCB filter for SW - it's just under $50

http://www.rffun.com/catalog/filters/4426.html

The Par BCST-HPF is designed to help shortwave listeners cope with interference from stations under 1700 kHz ... especially nearby AM stations. Strong AM stations may cause the front-end of a receiver to overload. This may cause an AM (medium wave) station
to appear on the shortwave band.

The Par BCST-HPF is a 7 pole elliptic filter designed to eliminate AM broadcast station problems on shortwave. The housing has an SO-239 jack for input and one for output (accepts standard PL259 plugs). A bypass toggle switch is featured to take the filter
out of line.

The bandpass is 1.8 to 200 MHz.
The minimum attenuation for below 1700 kHz is 41 dB.
The notch band is 0 kHz to 1700 kHz.