[Elecraft] Upper limits of KPA500?

[Bob McGraw K4TAX]

As long as one stays within the duty cycle times limits, no problem.

Do note that some antenna system which are lower impedance will require 
the amp to draw more current for a given amount of power. And it does 
vary from band to band.    The attached EXCEL spreadsheet should be of 
interest regarding lower power operation.

73

Bob, K4TAX


On 5/6/2020 1:03 PM, Tom Azlin W7SUA wrote:
> Hi Dave,
>
> I run around 100-150 watts out of my KPA500 using 5-7 watts from my K3 
> with the KPA500 hitting 70C using Olivia during nets. I assume could 
> go to 250 but never needed that much power. Does not seem to be a 
> problem with temps above 70c. Also run up to 500w PEP using SSB when 
> needed.
>
> I did hear Wayne say run full power RTTY with no fear.
>
> 73, tom w7sua
>
>
>
>
>
> On 5/3/2020 1:26 PM, Dave Cole wrote:
>> Hello,
>>
>> I just got the new MMSSTV software, and will be running a bit of 
>> SSTV. SSTV is 100% duty cycle.
>>
>> Initial testing here indicates no power level is safe...  At 150 
>> watts the KPA500 reaches 70C pretty fast, in under two minutes, and 
>> 70C is my upper limit for testing...  At 500 watts it reaches 70C in 
>> about the same time...
>>
>> Can I assume the amp is not the most efficient thing in the world at 
>> 200 watts?
>>
>> If the KPA500 can't deal with 100% duty cycle, for two minutes, how 
>> does the K3 deal with 100 watts for two minutes, at 100% duty cycle?
>>
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