[Elecraft] KXPA100 Mobile Operations -- Power Output

[Edward R Cole]

I need to correct some of my last statements on this topic (thanks to 
Dave AB9CA/4 for pointing them out).

I apparently was thinking of other battery chemistry than lead-acid 
batteries.  A check with wikipedia reveals that full charge voltage, 
open-ckt, is 2.1v per cell (12.6v for auto battery).  Fully 
discharged open-ckt voltage per cell is 1.95v (11.7v) and 1.75v 
(10.5v) when loaded.

Matt was seeing full RF output with 12.2v at the amp.

But that was with his engine running (alternator charging) which 
ought to deliver higher voltage to the amp (if cable losses are low - 
something like 0.5v drop if wiring is 8-awg).  Alternators run at 
14.2v in full charging.  They have a voltage regulator that drops 
this when battery reaches full charge (not sure what voltage that is 
but seems I've seen >13v).

I do not recall what gauge of dc wire was run to the 100w Motorola 
VHF trunk-mount radios we used to install for police and fire, but 
they held power pretty well with engine off (with fresh battery 
charge).  I am thinking the wires were 12ga awg and 17-foot long 
before cutting to length in each install.

The rest of my suggestions for testing and connections are still good.

73, Ed - KL7UW
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