[CQ-Contest] Filters

john at kk9a.com john at kk9a.com
Mon Jun 12 14:39:36 EDT 2006

I agree that the Dunestar filters don't like to be used on the upper end of
80m phone.  I've used them that in that range and my transceiver just cut
back on output due to the high SWR from the filters.  There is tremendous
malicious QRM above 3850MHz and in my opinion it's not a good segment for

John KK9A

Subject: [CQ-Contest] Filters
From: John Laney
Date: Mon, 12 Jun 2006 10:37:35 -0400
List-post: <mailto:cq-contest at contesting.com>

While the discussion about filters is fresh in memory, let me add a word
of caution on using Dunestar filters on 75 meters SSB.  Hal, N4GG, is an
expert on this subject and advised me not to use the stock Dunestar 80
meter filter above 3890.  He said it would fry above that frequency
approximately.  Since I have a General class license, that would tend to
deny to me use of most of the General class SSB band and could be a big
factor in ARRL SSB SS and a few other contests.  I talked to N7EA at
Dunestar about it and he advised that it wasn't safe to use their
80-meter filters above 3850.  That would leave out the entire General
class band.  However, he specially altered one of their filters for me
for use on the high end of 75 meter SSB.  I ordered that in addition to
two six-packs, so I can switch to it as an alternate for 75 M SSB.

Incidentally, I also ordered Dunestar single band filters for the three
WARC bands to use on contest and DXpedition trips.  I was very impressed
with Dunestar's service and customer service.  They very quickly
repaired a couple of their filters that I had burned out components in.
  Another word to the wise, DO NOT use your ATU to tune an antenna while
the filter is in the line.  Most of them will put out too much RF at too
high a SWR and the components will blow.  If you are using an external
antenna tuner also, do your antenna tuning with the filter out of the
line and be sure the ATU is turned off when you put the filter in the line.


John, K4BAI.

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