KPA500 REFL HI fault

[K5SM]

I put my KPA500 on 80 meters for the first time this morning, and it
faults after several characters. SWR as shown on both the K3 and the
KPA500 is 1.3:1. I reduced drive to 11w (250w out), and it still does
it. The first few cw characters, swr looks fine, but if I pause a bit
and hit the key again, swr jumps above 5:1 and the amp shuts down with a
"refl hi" fault. If I run the K3 barefoot at 100w, the swr is steady at
1.3:1 no matter what I do. Anybody know what is going on?

Bob K5SM
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[Don Wilhelm-4]

Bob,

I suspect a fault in your antenna system that is OK at 100 watts, but
does something "funny" (like perhaps arc over) when 500 (or 250) watts
is applied.

Does the same thing happen into a dummy load?  If so, then it is a
KPA500 problem, but if OK on a dummy load, take a good look at your
antenna system.

73,
Don W3FPR

On 9/29/2011 8:43 PM, Robert Redmon wrote:
> I put my KPA500 on 80 meters for the first time this morning, and it
> faults after several characters. SWR as shown on both the K3 and the
> KPA500 is 1.3:1. I reduced drive to 11w (250w out), and it still does
> it. The first few cw characters, swr looks fine, but if I pause a bit
> and hit the key again, swr jumps above 5:1 and the amp shuts down with a
> "refl hi" fault. If I run the K3 barefoot at 100w, the swr is steady at
> 1.3:1 no matter what I do. Anybody know what is going on?
>
>
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[Johnny Siu]

Hi Bob,
 
I experienced the same with my former ICPW1.  The problem was from loose connection / poor contact of the coaxial connectors.  Check also the ground connectors as well.
 
Please check with a good quality dummy load first as suggested by Don W3FPF.

TNX & 73,


Johnny VR2XMC


________________________________
從︰ Don Wilhelm <[hidden email]>
收件人︰ Robert Redmon <[hidden email]>
副本(CC)︰ "[hidden email]" <[hidden email]>
傳送日期︰ 2011年09月30日 (週五) 8:50 AM
主題︰ Re: [Elecraft] KPA500 REFL HI fault

Bob,

I suspect a fault in your antenna system that is OK at 100 watts, but
does something "funny" (like perhaps arc over) when 500 (or 250) watts
is applied.

Does the same thing happen into a dummy load?  If so, then it is a
KPA500 problem, but if OK on a dummy load, take a good look at your
antenna system.

73,
Don W3FPR

On 9/29/2011 8:43 PM, Robert Redmon wrote:
> I put my KPA500 on 80 meters for the first time this morning, and it
> faults after several characters. SWR as shown on both the K3 and the
> KPA500 is 1.3:1. I reduced drive to 11w (250w out), and it still does
> it. The first few cw characters, swr looks fine, but if I pause a bit
> and hit the key again, swr jumps above 5:1 and the amp shuts down with a
> "refl hi" fault. If I run the K3 barefoot at 100w, the swr is steady at
> 1.3:1 no matter what I do. Anybody know what is going on?
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[K5SM]

Thanks to Don, Rick, and Johnny for the suggestions. I had the
opportunity to closely inspect the 80 meter antenna today after running
a dummy load at the antenna switch and found a carbon trace on an
insulator at the feed point.  Mystery solved.

73, Bob K5SM

On 9/29/2011 7:50 PM, Don Wilhelm wrote:

> Bob,
>
> I suspect a fault in your antenna system that is OK at 100 watts, but
> does something "funny" (like perhaps arc over) when 500 (or 250) watts
> is applied.
>
> Does the same thing happen into a dummy load?  If so, then it is a
> KPA500 problem, but if OK on a dummy load, take a good look at your
> antenna system.
>
> 73,
> Don W3FPR
>
> On 9/29/2011 8:43 PM, Robert Redmon wrote:
>> I put my KPA500 on 80 meters for the first time this morning, and it
>> faults after several characters. SWR as shown on both the K3 and the
>> KPA500 is 1.3:1. I reduced drive to 11w (250w out), and it still does
>> it. The first few cw characters, swr looks fine, but if I pause a bit
>> and hit the key again, swr jumps above 5:1 and the amp shuts down with a
>> "refl hi" fault. If I run the K3 barefoot at 100w, the swr is steady at
>> 1.3:1 no matter what I do. Anybody know what is going on?
>>
>>
>

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