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KPA 500 Attenuated Receive Signals

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Barry Simpson

KPA 500 Attenuated Receive Signals

My KPA 500, which is several years old, has just developed an issue which
so far I have been unable to resolve.

What has happened is that when I put the amplifier into OPER, the received
signal strength drops by several S units. It transmits normally and also
receives normally in STBY.

The issue occurred when I was changing rigs to use with the KPA500.
Specifically I connected a Ten Tec Omni 6 but I cannot see how that could
have caused the issue. However, the KPA500 now exhibits the same issue with
my TS990 which it never has before.

I believe that some considerable time ago, I did experience a similar
situation and after reading all the manuals etc I found a way to resolve
it. However, I have read the manual until I am blue in the face but I
cannot find an answer this time.

Of course I may have initiated a fault in the KPA500 but I would be
surprised as it has taken all the mistakes I have thrown at it over the
years and it has not so much as blinked.

Any suggestions on how to sort the issue out, or what damage I might have
caused to the switching circuitry, would be appreciated.

Thanks in advance.

Barry Simpson VK2BJ
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Don Wilhelm

Re: KPA 500 Attenuated Receive Signals

Barry,

I think you may find a problem in the KPA500 T/R switch area.
Email [hidden email] for further checks and resolution.

73,
Don W3FPR

On 9/8/2019 2:34 AM, Barry Simpson wrote:
> My KPA 500, which is several years old, has just developed an issue which
> so far I have been unable to resolve.
>
> What has happened is that when I put the amplifier into OPER, the received
> signal strength drops by several S units. It transmits normally and also
> receives normally in STBY.
>
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Barry Simpson

Re: KPA 500 Attenuated Receive Signals

Thanks Don
That's what I thought. I will email them tomorrow.

73

Barry VK2BJ

On Sun, 8 Sep 2019 at 21:36, Don Wilhelm <[hidden email]> wrote:

> Barry,
>
> I think you may find a problem in the KPA500 T/R switch area.
> Email [hidden email] for further checks and resolution.
>
> 73,
> Don W3FPR
>
> On 9/8/2019 2:34 AM, Barry Simpson wrote:
> > My KPA 500, which is several years old, has just developed an issue which
> > so far I have been unable to resolve.
> >
> > What has happened is that when I put the amplifier into OPER, the
> received
> > signal strength drops by several S units. It transmits normally and also
> > receives normally in STBY.
> >
>

Dave wo2x

Re: KPA 500 Attenuated Receive Signals

I had the issue with my 1500 several months ago and it was traced to one of
the PIN diodes. Good news is after trip to the left coast for repair and all
ECO updates applied the amp has been perfect.

Dave wo2x

-----Original Message-----
From: [hidden email] <[hidden email]> On
Behalf Of Barry Simpson
Sent: Sunday, September 8, 2019 8:22 AM
To: [hidden email]
Cc: Elecraft Mailing List <[hidden email]>
Subject: Re: [Elecraft] KPA 500 Attenuated Receive Signals

Thanks Don
That's what I thought. I will email them tomorrow.

73

Barry VK2BJ

On Sun, 8 Sep 2019 at 21:36, Don Wilhelm <[hidden email]> wrote:

> Barry,
>
> I think you may find a problem in the KPA500 T/R switch area.
> Email [hidden email] for further checks and resolution.
>
> 73,
> Don W3FPR
>
> On 9/8/2019 2:34 AM, Barry Simpson wrote:
> > My KPA 500, which is several years old, has just developed an issue
> > which so far I have been unable to resolve.
> >
> > What has happened is that when I put the amplifier into OPER, the
> received
> > signal strength drops by several S units. It transmits normally and
> > also receives normally in STBY.
> >
>

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Dr. William J. Schmidt, II

Re: KPA 500 Attenuated Receive Signals

In reply to this post by Barry Simpson

I had the exact same problem with my KPA500. I inadvertently left it
connected in a lightning storm in the Caribbean and, after some diagnosis on
my RF bench, I found that the PIN diodes on the receive side were blown.
Replacing them cured the problem. While in there be advised that there is
an upgrade kit for some components in that circuit. Contact Elecraft techs
for more info.

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

email: [hidden email]

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Barry Simpson
Sent: Sunday, September 8, 2019 1:34 AM
To: Elecraft Mailing List <[hidden email]>
Subject: [Elecraft] KPA 500 Attenuated Receive Signals

My KPA 500, which is several years old, has just developed an issue which so
far I have been unable to resolve.

What has happened is that when I put the amplifier into OPER, the received
signal strength drops by several S units. It transmits normally and also
receives normally in STBY.

The issue occurred when I was changing rigs to use with the KPA500.
Specifically I connected a Ten Tec Omni 6 but I cannot see how that could
have caused the issue. However, the KPA500 now exhibits the same issue with
my TS990 which it never has before.

I believe that some considerable time ago, I did experience a similar
situation and after reading all the manuals etc I found a way to resolve it.
However, I have read the manual until I am blue in the face but I cannot
find an answer this time.

Of course I may have initiated a fault in the KPA500 but I would be
surprised as it has taken all the mistakes I have thrown at it over the
years and it has not so much as blinked.

Any suggestions on how to sort the issue out, or what damage I might have
caused to the switching circuitry, would be appreciated.

Thanks in advance.

Barry Simpson VK2BJ
______________________________________________________________
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Help: http://mailman.qth.net/mmfaq.htm
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Help: http://mailman.qth.net/mmfaq.htm
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