[Elecraft] KPA500 High Reflected Power Fault

[Wayne Burdick]

Nels,

The K3 and your other rigs may be happy with it at 100 W, but at 500 W  
it may be more critical. The present SWR level (actually, the  
reflected power) could be just barely faulting the amp. Did you try  
reducing the drive a bit?

Also: Is there any reason why the LDG tuner can't find a little better  
match?

I've forwarded this to our amp design team to see if they can give you  
any additional advice.

73,
Wayne
N6KR


On May 15, 2011, at 8:00 AM, Nels Anderson wrote:

> Been enjoying KPA500 #32 for a couple of days now. Haven't yet made a
> lot of QSOs with it, but the extra power on RTTY and to bust a couple
> SSB pile-ups has been welcome.
>
> However, the amp does not like my 40m setup. As soon as I transmit it
> instantly goes into high reflected power fault and shuts down. My
> antenna is a 120 foot center fed wire using 1 inch ladder line and an
> LDG 1 kw auto tuner. SWR on 40m is under 2:1 and the K3 and other rigs
> I've used it with have always been happy with the antenna arrangement.
>
> In experimenting I used the K3 tune function and reduced the power in
> steps to see if I could reach a low enough power level that it would
> operate, but even at 1 watt of drive the amp still instantly went into
> fault.
>
> On 80m it did the same thing the first time I tried it, but then I
> manually tweaked the antenna tuner, got a lower SWR reading and then  
> the
> amp worked. On the higher bands that I've tried there has been no  
> problem.
>
> So, any idea what is causing this?
>
> 73 Nels K1UR
>
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