Hi Eric --
We have an AM station about 2 miles from the W1KM site. It's small
but runs 5 kW during the day on 1420... enough to mess up antenna
analyzers hooked to the low band verticals... and enough to trash receivers.
Fortunately at night it drops to a 1 kW directional pattern and we
don't see it. But we've been thinking about a filter anyhow so that we
can chase DX near sunset/sunrise on 160m. I would be curious to learn
more about the BCI filter you are using.
73,
-- Eric
on 05 May 28 21:21 Eric Rosenberg said the following:
I've been following the thread on BCI to the Orion with both interest
and amusement.
I live in Washington, DC proper, 5.5 miles from a 50kw AM station
operating at 1500 kHz (signal measured a -10 dBm with a lab-grade
spectrum analyzer on my inverted-L), and another relatively high power
AMer at 1260 kHz.
From my roof I can see (and have photos of) all of Washington's TV
(NTSC and HD) and FM broadcast towers, not to mention the plethora of
US and foreign government, commercial and other point-to-point
transmitters and repeaters that operate into the microwave bands and
seemingly beyond.
Regardless of the number and size of cavity filters, weak signal and
amateur satellite operations are difficult (I used to operate on AO-13
and to a lesser degree the pacsats) or impossible.
And the intermod/overload on 160 is pretty amazing, regardless of the
radio I've used... be it Kenwood, Icom, Yaesu or Ten Tec.
For the past 5 years, I had an Omni-6+. For the past year, an Orion.
The solution? Well designed and built BCI filters. I spent as lot of
time researching what was available in the amateur radio
world. Neither the ICE filter (402X), W3NQN, Top 10 Devices or anyone
else's worked for me. In the end, I did find one, not (yet)
commercially available filter that worked so well for me that I had my
best score ever in the CQ 160 contest! If and when it becomes
available, I'll post information here on the reflector.
A great resource for locating the broadcast (AM, FM and TV) stations in
your neighborhood is AMSTNS and TVFMSTNS by Bob Carpenter,
W3OTC. Bob's software was invaluable to me in identifying the local
broadcasters to better understand who and where and to what degree the
offending stations might be. An overview of the software is available
at http://users.erols.com/rcarpen/INFO0227.html while the latest
versions of the software are available at
http://home.earthlink.net/~lvehorn/ For best results follow the
various links!
The bottom lines is that if you're close to a broadcaster and suffer
from intermod and overload problems, don't blame it on the
radio! External filters are the only solution.
GL!
Eric W3DQ
Washington, DC
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