Topband: Common mode current and QRN on 160m

[Arthur Delibert]

Yes, a pennant antenna with a pre-amp could be a tremendous help.  I live in a densely populated suburb where everyone (including us) has all the latest digital noisemakers.  Without that set-up, the lower bands would be completely useless to me.  Also, add common mode chokes to  both ends of the lead from your receiving antenna.  Otherwise, it can pick up a lot of noise on the way into the shack, some of which finds its way into the received signal.  Fair-Rite makes a large snap-on choke that’s ideal for the purpose (Fair-Rite 0431177081).  Wrap 7 turns of your coax through it, and spread the turns out over the full circumference of the choke so they’re as far from one another as possible.  (See “A Ham's Guide to RFI, Ferrites, Baluns, and Audio Interfacing” by Jim Brown, K9YC, which is available on the internet.)

Hope this helps.

Art Delibert, KB3FJO

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From: John Randall via Topband<mailto:topband at contesting.com>
Sent: Saturday, October 28, 2017 9:14 AM
To: topband at contesting.com<mailto:topband at contesting.com>
Subject: Topband: Common mode current and QRN on 160m

I have built up a simple switch box to use on 160m which reduces the QRN a bit on the band so that I can see the weaker stations out there. My noise level is usually s9 and am going to try a 1:1 current balun at the antenna feed point which is a 45mm dia 6m high pole bottom fed. I have about 15 - 20 radials in to fit my garden 30ft x 30ft, but neeed to improve my reception and the QRN. Any suggestions on how to cut the local "smog" other than what I am trying. The pole is mounted abot 3ft away from the garden corner ( not ideal ), but it has to be there. I was thinking about another antenna for receive such as a pendant or such like mounted above the roof and use a small rotator with preamp, that should reduce the QRN even further

73John - M0ELS
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