Mike,
It sounds to me like the manufacturer of the switcher wall wart bothered to put
RFI suppression on only 1 side of the line, rather than both sides. I'll also
guess that there is no line-to-line cap in it, either, on the wall plug end.
If that is true, I guess that is only half as bad as omitting all RFI
suppression components, as some makers are prone to do.
73, Dale
WA9ENA
-----Original Message-----
>From: "W5JR.Mike" <w5jr.mike@gmail.com>
>Sent: Aug 26, 2013 2:43 PM
>To: "jim@audiosystemsgroup.com" <jim@audiosystemsgroup.com>
>Cc: "rfi@contesting.com" <rfi@contesting.com>
>Subject: Re: [RFI] Recent RFI status - Direct TV and Dish?
>
>I agree with Jim to watch out for the switcher power supplies. My own
>experience with a Comcast unit replaced over the summer was noticed to be
>quite ugly on 160m later in the fall when my focus turned back to TopBand. I
>could easily trace the electrical wiring in our walls with my AM radio looking
>for the source. Unplugged the very tiny wall wart and all was quiet. I plugged
>it back in after the contest and found flipping it 180* was quiet, but as
>originally plugged in was noisy. My outlet indicated proper wiring from one of
>the usual plug-in checkers. I left it plugged in the "quiet" way.
>
>tnx
>Mike / W5JR
>
>On Aug 26, 2013, at 3:23 PM, Jim Brown <jim@audiosystemsgroup.com> wrote:
>
>> On 8/26/2013 11:33 AM, Tim Duffy wrote:
>>> Also, how about RFI problems associated with nearby transmitting antennas
>>> that might cause RFI overload problems to the Dish or Direct TV systems -
>>> as in TVI?
>>
>> I would expect any issues to be the result of 1) noisy switching power
>> supplies, 2) noise from the downlink electronics, and 3) common mode
>> coupling on the coax (both TX and RX). and I would expect them to be easily
>> solved by winding turns around ferrite cores. I had DirecTV in Chicago, and
>> never had any issues, with antennas and DirecTV downlead in close proximity
>> (5-25 ft). I don't remember if I did anything with chokes.
>>
>> 73, Jim K9YC
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