[Elecraft] Anderson PowePole connectors

[Jim Brown]

I commented on the value of twisted pair for power and loudspeaker 
wiring. 

On Wed, 01 Aug 2007 22:15:57 +0100, David Woolley wrote:

>there might be some benefit if there was a problem 
>from a co-sited transmitter, 

We're hams, right? We have co-sited transmitters!  :)

>but one would need a common mode choke at
>the equipment end, and unless the power supply was well balanced or
>differential mode filtered, at the power supply end.  

Differential filtering is ALWAYS a good idea on power leads. 
Unfortunately, not all equipment has that, and not all filtering is 
sufficient. The primary cost of paired cable is the copper. For a 
given wire size, twisting is essentially free. I LOVE free techniques 
that make things better! 

Common mode and differential mode susceptibility are additive. Using 
twisted pair ALWAYS reduces differential mode noise (and RFI) both TO 
and FROM a given circuit. It is VERY common for RFI to be reduced by 
20 dB or more simply by replacing zip cord with twisted pair. 

>> standards worth changing. 

>Headphones might benefit, but you would need a common mode choke, or 
an
>output transformer. 

Not necessarily -- ordinary headphone and loudspeaker output stages 
are well known to be susceptible to RFI coupled on their output 
wiring, and it is also well known that replacing zip cord with 
twisted pair reduces RFI a lot. And neither a common mode choke or 
output transformer must be present for this to happen. 

> Also, I suspect that headphone lead pickup tends to 
>get injected in common mode.

All of this stuff is received common mode by antenna action, but can 
be converted to differential mode at the terminals of the equipment 
because the two conductors are not balanced with respect to the 
equipment signal reference or power supply earth AT RADIO 
FREQUENCIES. And an output transformer is NOT likely to be balanced 
at RF, thanks to the stray capacitance associated with its 
construction. 

These concepts are among those covered in my tutorial on RFI, which 
also includes a discussion of common mode chokes. 

http://audiosystemsgroup.com/RFI-Ham.pdf

73,

Jim Brown K9YC