[Elecraft] Proper K2 power cord?

[AJSOENKE at aol.com]

The numbers look kind of  low don't they? These are for DC continuous  duty 
cycle. Many manufacturers of mobile and 100W tranceivers ship a 12 GA power  
cablke for DC operation. I consider this too small and prefer a minimum 10GA. I  
run 6 or 8 GA in my mobiles ( also using silver plated with many more strands 
 than the hardware store variety ). We just installed #8 on a 240 line in the 
 house for AC that mfg specified as a 40 amp circuit - way more than the AC  
uses.
 
I don't spec my DC operating Cables on basis of maximum current carrying  
capability, but rather for best DC resistance characteristics. Remember Ohms law  
when applying current to a DC supply, If you are running a 100 watt 
transceiver  with a nominal 20 amps at voice peak on transmit and you have as little as 
0.1  Ohm resistance in the power supply circuit, your supply voltage at 13.8 
VDC will  drop 2 VOLTS! That's at current (VOICE/CW) peaks when you need them 
the  most.
 
Also, judging wire gauge by insulation (85C for instance) will not be a  
valid measurement unless you actually plan to run currents that will generate  
heat in that cable. That would be a sure indication of IR losses that  are  way 
beyond anything you want to have i.e. for that 2 volt loss you'd be seeing  40 
watts going into heating. Also remember that the connection points  
(terminals) are most likely the highest resistance points.
Being concentrated heating points the terminals are usually where fires get  
started when they are dissipating too much heat. 40 watts is about what the  
average soldering iron provides (doing soldering jobs in ham rigs), so you 
could  conceivably desolder a poorly done terminal if it has as little as 0.1 Ohm  
resistance.
 
de AL, WA6VNN



************************************** Get a sneak peak of the all-new AOL at 
http://discover.aol.com/memed/aolcom30tour