[Elecraft] Dish/Direct TV RFI?

Jim Brown jim at audiosystemsgroup.com
Wed Mar 14 18:47:32 EDT 2018


On 3/14/2018 1:36 PM, John Huggins, kx4o wrote:
> I have personally seem a 40m signal change the channels on our Direct TV
> setup. This is, unfortunately, a common problem...
>
> https://www.google.com/search?q=direct+tv+amateur+radio+changes+channels&oq=direct+tv+amateur+radio+changes+channels

Problems like this are the result of design defects in the cable modem. 
It should be possible to solve problems of this sort by winding multiple 
turns of both the coax and the power cable #31 or #43 Fair-Rite toroids. 
See

http://k9yc.com/KillingReceiveNoise.pdf

for part numbers and guidelines for winding. While the app note 
discusses RX noise radiated from gear like this, the cures are the same 
for both.

AND -- because it's the result of a defective modem (i.e. a bad design), 
ALWAYS call the vendor and tell them to fix it.

73, Jim K9YC



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