[Elecraft] Mea culpa (KPA-500)

[Fred Jensen]

ynkedragon at aol.com wrote:
> Thanks Wes, N7WS, for sending me back to my calculator.
> 
> 500 watt output is indeed 7dB greater than 100 watts, not the > 5 dB
> I previously stated.
> 
> Even better.

7 dB is 1.1667 International Standard S-units.  10 dB [1KW vs 100W] is
1.6667 ISS-u.  1.1667 ISS-u can make a fair difference in a pile-up,
0.4999 ISS-u more -- mabye not so much.

Capital Costs:  The KPA500 is alleged to cost around $700. A good 1-1.5
KW solid state amp generally runs something over $2,000 and up.

Operating Costs:  @ 50% efficiency, 2KW averaged over the 48-hr CQ WPX
CW [30% duty cycle, our hypothetical contester calls CQ continuously] @
$0.16/KWh will run him $28.80 and presumably other 48-hr marathons would
do likewise [CW WPX SSB, CQ WW CW, CQ WW SSB, ARRL DX CW, ARRL DX SSB,
ARRL SS CW, ARRL SS SSB] $230.40 for electricity.  Snack food, aspirin,
coffee to keep you awake through all these contests, and all the chores
you have to do before/after the contest to "make it up" to you-know-who,
are fixed costs -- equal for both amps.

KAP500 looks like a good deal to me.  Of course, there's the opportunity
loss during NAQP's where you don't use the KPA500, but the six of them
each year only last 10 hours each.

This does not factor in replacement costs, which could be substantial in
the case of the "big" amps.  How much do 500 2N2222's cost?  You can do
the math.

[Andrea is *very* happy our income when I was employed did not depend on 
my cost-benefit analysis skills :-)]

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2010 Cal QSO Party 2-3 Oct 2010
- www.cqp.org