[Elecraft] KPA500 Power Output

[Vic K2VCO]

Of course! It's rated in MFJ WATTS. One regular watt = about 10 MFJ watts. Elecraft is one 
of the few companies making products rated in real watts.

On 1/27/2012 10:21 AM, Bill Gerth wrote:
> Bert,
>
> In addition to the other suggestions you received, I'd suggest that
> you make sure your dummy load is capable of this kind of key-down
> power for that amount of time.  I have an MFJ Dummy Load that is
> called a 1.5KW Dummy Load but the chart on the back panel shows it is
> only capable of around 120 watts for 60 seconds.  It can only handle
> 1.5 KW for less than 10 SECONDS.  Some fan-cooled or oil-cooled dummy
> loads might be OK for 500 watts of key-down for 1 minute, but my air-
> cooled 1.5 KW Dummy Load is NOT.  The non-inductive resistor gets very
> hot and begins to smell even after relatively short key-down periods.
> Your power change might be due to the dummy load changing its
> effective resistance due to heating.
>
> Just a thought.
>
> 73,
>
> W4RK - Bill Gerth
> Jefferson City, MO
> billgerth at embarqmail.com
>
>
>
>
> On Jan 27, 2012, at 10:57 AM, N4CW at aol.com wrote:
>
>> Sorry if this has been covered before, but I can't recall that it
>> has. Is
>> there any reason why power output
>> falls off over time? Here's what I did: using MMTTY, I "diddled"
>> into a
>> 50-Ohm dummy load for one minute.
>> I initially had a power output of 525 Watts which went to 500 W
>> shortly and
>> went down to about 465 W
>> when MMTTY "diddling" timed out. I repeated that process later,
>> monitoring
>> current and noted that it also
>> went down over time...makes sense!
>> But my question is WHY? I was under the impression that I needed to
>> run the
>> amp at 500 W on RTTY for
>> optimum efficiency because in an earlier posting I noted that at 150W
>> output (in BPSK31), the amp was very inefficient and the fan was
>> pretty loud. If
>> I can't derate the output and I can't run full output, what do I do
>> with
>> the  KPA500 in the digital modes?
>>
>> Bert, N4CW
>>
>>

-- 
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/