Re: KPA500 PA current

Posted by Elecraft mailing list on Aug 04, 2019; 6:06pm
URL: http://elecraft.85.s1.nabble.com/KPA500-PA-current-tp7654248p7654259.html

Andy;

This is the effect of not being able to obtain perfect components. It is easy to forget that the toroid cores used for the inductors vary, as do the windings and capacitors. There will be variances because of this which will be different from KPA to KPA. They are set up for best case operation, but then as components age things will change. As it is, the design is outstanding. With efficiencies greater than 50%, the designers did a super job!

73!
Jack, W6FB

> On Aug 4, 2019, at 10:34 AM, Andy Durbin <[hidden email]> wrote:
>
> "Note that I don’t discount that the 20m LPF is noticeably less efficient than those on the other bands. Each KPA is unique in this sense - we tune the LPFs for best efficiency for each band. I suspect your KPA is just fine, but the more info we get from you, the more we can tell what is going on."
>
> In the time I have owned and used my KPA500 I have noticed that 20 m band requires a higher drive level than other bands.  This thread prompted me to do some more analysis of data I had recorded last year.  
>
> Data here - https://tinyurl.com/y5oygtlp
>
> The data show that my KPA500 is significantly less efficient on 20 m than on the other bands tested.  Is this a characteristic of all KPA500 and, if so, why would that be the case?  Note that my dummy load shows variation of characteristics with frequency and heating.  I have the load complex values for every data point but I used a test run average R and X to name each test plot.  
>
> 73,
> Andy, k3wyc
>
>
>
>
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