On Mon,9/22/2014 6:50 AM, Ed Stallman wrote:
Has anyone used this High Pass Filter ?
http://www.dunestar.com/store/160-Meter-Highpass-Filter-pid-8.html
The spec for this filter is ambiguous. Is the -40dB at all frequencies
below 1.6 MHz, or at 1 MHz? BIG difference. OTOH, the Dunestar filters
are decent for the price.
I found I have a 25KW AM 1520 Khz BC transmitter 12 miles from me ,
is that close enough to interfere with me receiving weak signal DX on
the top Band ? I do hear some wide band hash 1837 to 1840 !
That may be because they are transmitting digital radio. No filter will
remove that -- it's part of their sidebands.
Thought I would asking before placing an order, not sure how what to
look for with BCB interference ?
A year or so ago, I reviewed a bunch of bandpass filter sets designed
for contesters. I also measured an ICE BCB filter (160M highpass).
k9yc.com/BandpassFilterSurvey.pdf The pdf includes a link to pdfs of
the VNWA data. I measured the filters that I either owned or could
borrow from local NCCC members. Sorry -- the ICE BCB was the only one I
had access to.
I didn't put a marker at 1.5 MHz (I would have, but I was out of
markers), but eyeballing it without a marker, I'd say that all of these
filters (except the ICE419Bs) would be down by at least 15 dB at 1.5
MHz. The ICE BCB was about -16 dB at 1.5 MHz. 15 dB would reduce that
25kW station to 800W. Maybe enough, maybe not. For more rejection,
you'll need one of the W3NQN designs that Array Solutions sells. And
remember that NO filter will touch any sideband trash that the station
puts on 160M.
73, Jim K9YC
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