[Elecraft] OT--RFI Issue

[Walter Underwood]

https://www.google.com/search?q=14+gauge+twisted+speaker+wire

wunder
K6WRU

On Mar 20, 2013, at 4:19 PM, ab2tc wrote:

> Hi,
> 
> Please indicate a source of twisted pair wire suitable for speaker feeds.
> #16 or #14 is fine for me. I am still having trouble keeping my 15m signals
> out of my family room system. Currently that room's speaker wire is of the
> parallel kind.
> 
> AB2TC - Knut
> 
> 
> Jim Brown-10 wrote
>>> Your position should be to offer to assist a qualified technician in
>>>> isolating and correcting any deficiencies by providing periods of
>>>> operating to test the results of any repairs.
>> 
>> I'd say it depends entirely on the attitude of the RFI victiim, and the 
>> ham's relationship with that party.  The vast majority of RFI complaints 
>> today are the result of Pin One Problems in the victim equipment.  These 
>> are a manufacturing defect that is the result of poor design, and any 
>> wiring connected to the equipment will act as a receiving antenna for 
>> our signals, where they will be rectified and amplified.
>> 
>> In today's world, "qualified technician" for consumer electronics is an 
>> oxymoron.
>> 
>> Several years ago, I helped ND2T diagnose and cure strong RFI to his 
>> next door neighbor's "exotic high futility" system, in a living room 
>> only 20 ft from Tom's antennas, which were driven by a big ACOM legal 
>> limit amp. Tom introduced me as an audio expert and RFI expert (which I 
>> am) then returned to his shack and transmitted on all the bands. I stuck 
>> chokes on cables until the RFI went away, and by the time Tom arrived 
>> after our work was done, had the guy ready to open his wallet to buy 
>> them at my cost.  Tom, however, insisted on paying for the cores 
>> himself. Problem solved.
>> 
>> It is NEVER a good idea to modify the equipment, but it IS good to 
>> disable the antennas (that wiring) by adding ferrite chokes tuned to the 
>> transmitter frequency(ies). Tuning is accomplished simply by using the 
>> "right" ferrite mix and adjusting the number of turns through the core.
>> 
>> Speaker cables are a very common antenna. Another excellent move is to 
>> replace parallel wire loudspeaker cables (zip cord, no matter how 
>> exotic) by twisted pair. #12 copper makes excellent speaker cable 
>> (there's a classic AES Paper by Prof. R. A Greiner, Dept of EE at U Wis 
>> about this), and  twisting strongly rejects RF coupling. I have solved 
>> MANY cases of RFI by doing this.
>> 
>> RFI causes and solutions are covered in considerable detail in
>> 
>> http://audiosystemsgroup.com/RFI-Ham.pdf
>> 
>> 73, Jim K9YC
>> <snip>
> 
> 
> 
> 
> 
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/OT-RFI-Issue-tp7571483p7571594.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

--
Walter Underwood
wunder at wunderwood.org