Re: KPA-1500 Efficiency As A Function of Input Power

Posted by Bob McGraw - K4TAX on Aug 17, 2018; 2:43pm
URL: http://elecraft.85.s1.nabble.com/KPA-1500-Efficiency-As-A-Function-of-Input-Power-tp7644440p7644449.html

I've said this and measured this for years with tube type amps, where as
I hear hams say they are running reduced power to "save the tubes".  
That's HOGWASH.  Determine the efficiency at reduced power vs. rated
power.    The excessive heat at reduced power has to go somewhere.

I view running an amp, tube or solid state types, at reduced power is
much like driving with your right foot on the accelerator and the left
foot on the brake  {US style} and wondering why your gas mileage suffers
and your brakes wear out.

Tune it up, load it up, and run that sucker at full power.  After all,
........that's why you have an amp.

73

Bob, K4TAX



On 8/17/2018 8:11 AM, ANDY DURBIN wrote:

> "There was a similar post about the KPA500 in the last year or so. Elecraft responded that the amp was designed for 500 Watts running less was less efficient and running amp at low power was doing it no favors."
>
> Here is an example of measured PA dissipation for a KPA500:
>
> https://www.dropbox.com/s/bq0v2740t3iztnj/KPA500%20PA%20DISS%20for%2040%20meters.pdf?dl=0
>
> 73,
> Andy k3wyc
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