Jim Brown jim at audiosystemsgroup.com
Fri Dec 23 17:33:07 EST 2016

Bill and Bob,

While this is certainly worth trying, I suspect that the problem is 
caused by the antenna itself being so close to the victim devices. And I 
would definitely wind serious chokes onto wiring connected to that 
garage door unit. By serious, I mean at least 12 turns around a #31 
toroid, or half as many through a clamp-on that's an inch long.

Since this antenna is inside, I suspect that you're running barefoot. If 
so, or if you're running less than about 300W, the bifilar-wound choke 
using a pair of #12 or #14 THHN on a single #31 core would handle the 
power unless the antenna is VERY badly unbalanced.

BTW -- about six months ago, I updated RFI-Ham.pdf to address power 
handling of bifilar wound chokes on #31 toroids. If you are considering 
using one, by all means download it again.

73, Jim K9YC

73, Jim K9YC

On Fri,12/23/2016 1:41 PM, Robert Nobis wrote:
> Bill,
> I had a similar problem with an electronically operated doggy door.  What I found was that I had relatively high common mode current on my antenna feed so the feed was also radiating. My antenna was not perfectly balanced as one end was close to metal siding. I added an antenna feed line choke following the recommendations from Jim Brown’s tutorial (k9yc.com/RFI-Ham.pdf <http://k9yc.com/RFI-Ham.pdf> ), and the doggy door problem disappeared.  I used 6 turns of RG8 through five 2.4” o.d. #31 toroidal cores for 80-meters.
> 73,
> Bob Nobis
> n7rjn at nobis.net
>> On Dec 23, 2016, at 10:59, Bill Price <billp7634 at sbcglobal.net> wrote:
>> I live in a HOA subdivision with restrictive covenants. As such, at this time all my antennas are in my attic. I just strung a fan dipole up for 75 and 17. When I operate on 75 I have RF issues. Two of my security lights come on, one of the garage door opener lights come and an electric soap dispenser (motion activated) comes on and dispenses a butt load of soap. I thought it may be due to one side of the 75M dipole coming close to a length of romex. So I located that romex and put two snap on ferrites around that wire with the romex wrapping twice through the ferrite. I also put a ferrite on the power wire from the wall wart after having wrapped that several times. The problem still exists. I also have a 40M dipole and a 10M beam in the attic and have no problems with running a KW at any frequency other than 75M. The ferrites I have are a 31 mix. Any ideas as to how to solve this issue?
>> Bill   W5LO
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