[TowerTalk] Rotor Cable size

[Jim Brown]

On Wed, 08 Sep 2010 12:21:21 -0400, cqtestk4xs at aol.com wrote:

>My guess is the 2-14 would be sufficient.

It depends on the operating voltage and current of the motor. Although 
it's a simple Ohm's law problem, sometimes it's not easy to find what 
values to plug into the equation, because the mfr sometimes doesn't tell 
you in a form that you can use. 

When  I did that last year for a 350 ft run to a Yaesu rotor, I spent  
time with the manual (and with the rotor, measuring its DCR), so that I 
could translate the mfr recommendations for wire size into IR drop. I 
translated Yaesu's wire size requirements for a given cable length into 
Ohms, then used Ohm's law and the wire tables to figure out what wire 
size I needed. For my 350 ft run, the result was that I needed #14-2 for 
the motor, but could live with a much smaller size for the sensing 
circuit.  

73, Jim K9YC