[Elecraft] OT--RFI Issue

[Jim Brown]

> 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