[Elecraft] KPA1500 reduces power as it gets warmer?

[Kevin Robertson]

FT8 is a weak signal mode, designed for low power. Given its high duty cycle, you are asking for trouble if you operate your power amplifier in FT8 mode using your KPA1500 at anywhere near high power. I burned out my final on my K2 at 15 watts on FT8. 

73,
Kevin Robertson KD2WCY


> On Jun 4, 2022, at 12:42 AM, Rick NK7I <rick.nk7i at gmail.com> wrote:
> 
> Yes, the KPA1500 will drop 10% of the output, as it warms up. 1500 drops to 1350, so you have to compensate with the drive.
> 
> I'm told this is typical of all solid state finals (my KPA500 did likewise).
> 
> If you're running the station remotely; bump up the fan speed to slow the drop (or wear cans).
> 
> 73,
> Rick NK7I
> 
>> On 6/3/2022 9:22 PM, David F. Reed wrote:
>> I note my KPA1500 drops power at its temperature rises...
>> 
>> Using FT8, so a relatively high duty cycle.
>> 
>> Say I start at a heat sink temperature of 27 C, and 1,000 watts out; by the time the temperature is at 65 C, the power has dropped to 893 watts out.
>> 
>> I have a couple of questions about this (not a complaint by the way):
>> 
>> 1. Does anyone else experience this?
>> 2. Is it normal?
>> 
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