KPA-500 Switch from STBY to OPER

I am looking for thoughts and suggestions to diagnosis what I am seeing.
When the amp is changed from STBY to OPER the receive signal drops by
multiple db and the general background seems to increase significantly. The
tuner seems to work the same with or without the amp. When I transmit it
appears I am getting full power output. I am driving the KPA-500 with a K3.

 

Thanks in advance

 

Allan

WA7BKD

 

 

 

 

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[Bob McGraw - K4TAX]

Sounds as though the TR switching has failed.  Contact Elecraft support.

Bob, K4TAX


Sent from my iPhone

> On Feb 10, 2020, at 5:05 PM, [hidden email] wrote:
>
> I am looking for thoughts and suggestions to diagnosis what I am seeing.
> When the amp is changed from STBY to OPER the receive signal drops by
> multiple db and the general background seems to increase significantly. The
> tuner seems to work the same with or without the amp. When I transmit it
> appears I am getting full power output. I am driving the KPA-500 with a K3.
>
>
>
> Thanks in advance
>
>
>
> Allan
>
> WA7BKD
>
>
>
>
>
>
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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If there is a relay in the rx signal path, check the contacts. I had that happen with my Alpha recently. Of all the possibilities that was the easiest thing to fix. Thankfully that was the problem :-).
73,
Bill WE5P

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On Feb 10, 2020, 17:52, at 17:52, [hidden email] wrote:

>I am looking for thoughts and suggestions to diagnosis what I am
>seeing.
>When the amp is changed from STBY to OPER the receive signal drops by
>multiple db and the general background seems to increase significantly.
>The
>tuner seems to work the same with or without the amp. When I transmit
>it
>appears I am getting full power output. I am driving the KPA-500 with a
>K3.
>
>
>
>Thanks in advance
>
>
>
>Allan
>
>WA7BKD
>
>
>
>
>
>
>
>
>
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:[hidden email]
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html
>Message delivered to [hidden email]

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[Don Wilhelm]

Bill,

No relays in the T/R switching path for the KPA500 - all solid state
switching.

73,
Don W3FPR

On 2/10/2020 6:39 PM, Bill Weaver wrote:
> If there is a relay in the rx signal path, check the contacts. I had that happen with my Alpha recently. Of all the possibilities that was the easiest thing to fix. Thankfully that was the problem :-).
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[Dr. William J. Schmidt, II]

If you notice a drop in signal strength when simply switching the amplifier
from "Standby" to "Operate", it means that the T/R diodes are biased for
transmit (not receive).  Check R7 the 51 ohm SMD resistor on the daughter
board as the most likely failure.  It has happened to me and several others
on the reflector.


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

Moderator – North American QRO Group at Groups.IO.

email:  [hidden email]



-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Don Wilhelm
Sent: Monday, February 10, 2020 6:00 PM
To: Bill Weaver <[hidden email]>; [hidden email]
Cc: [hidden email]
Subject: Re: [Elecraft] KPA-500 Switch from STBY to OPER

Bill,

No relays in the T/R switching path for the KPA500 - all solid state
switching.

73,
Don W3FPR

On 2/10/2020 6:39 PM, Bill Weaver wrote:
> If there is a relay in the rx signal path, check the contacts. I had that
happen with my Alpha recently. Of all the possibilities that was the easiest
thing to fix. Thankfully that was the problem :-).
______________________________________________________________
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