[Elecraft] KPA-500 Running hot on 20m

[Fred Jensen]

It also is fairly sensitive to how tightly enclosed your KPA500 is in 
your station equipment configuration. Mine came on high-fan often when 
on RTTY, or [fruitlessly] calling CQ in SS CW on Sun.  I finally moved 
it out of it's "cubbyhole" under the shelf assembly, and it stayed on 
low fan all the time, which I couldn't hear with the cans on.

For my K2/100, the heat sink got very hot with repeated [unanswered] 
CQ's and on RTTY.  I mounted a computer fan on top of the heatsink with 
a tab of velcro, blowing down.  Heat sink stayed cool to the touch with 
80-90 W on RTTY.  I am repeatedly amazed by thermodynamics. [:-)

Fred K6DGW
Sparks NV DM09dn
Washoe County

--Northern California Contest Club
--CU in the Cal QSO Party
--7-8 Oct 2017


On 1/8/2017 5:10 PM, Don Wilhelm wrote:
> Mike,
>
> The efficiency will very from band to band, and is also somewhat 
> dependent on the SWR it is working into.
> I would not think it is a problem - that is what the high speed fan is 
> supposed to do, cool it with faster air, even if that is disconcerting.
>
> A lot depends on your transmit vs. receive time intervals may be. 
> There are a whole lot of dependencies.
>
> 73,
> Don W3FPR
>
> On 1/8/2017 7:44 PM, W0MU Mike Fatchett wrote:
>> I was running the RTTY contest this weekend and expected to see higher
>> than normal temps but on 20m and maybe 15 the amp was running 65c and up
>> where the highest speed fan would come on. Generally in RTTY I would up
>> the normal fan a couple of notches and it would be fine.   I was not
>> pushing it for full output either as I was not serious in the test.
>>
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