[TowerTalk] Common Mode Choke Question

marsh at ka5m.net marsh at ka5m.net
Wed Sep 27 15:11:17 EDT 2017


I'd recommend referring to RFI-Ham.pdf by K9YC.

http://www.audiosystemsgroup.com/RFI-Ham.pdf

Good info and a great reference resource.

For 160M and / or 80M I'd go with the recommended 7 turns through five type 31 cores.

See Page 35 of RFI-Ham.pdf

"160 and 80 Meters: With RG8 or RG11, use 7 turns through five 2.4" o.d. #31 toroidal cores."

One CM choke at the antenna feedpoint, and one CM choke at the station.

73,
Marsh, KA5M

-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Carol Richards
Sent: Wednesday, September 27, 2017 1:43 PM
To: towertalk at contesting.com
Subject: [TowerTalk] Common Mode Choke Question

Hello,

At present I have an inverted "L", 100+ feet vertical with 4 elevated radials, about 130 feet long at 10 feet in height. I am about to construct a CM choke. On hand, I have 4,  Amidon 2.4 inch cores. From the reading, it seems that I should have 5 cores and about 5 turns of
RG8 coax. I can I get away with 4 cores?


Carol

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