[Elecraft] KPA500 270V Failure

[Dr. William J. Schmidt]

YEP

 

 

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

 

Moderator – North American QRO Group at Groups.IO.

 

email:   <mailto:bill at wjschmidt.com> bill at wjschmidt.com

 

 

From: Bruce Forsberg <bruce.forsberg at gmail.com> 
Sent: Saturday, July 24, 2021 11:10 PM
To: bill at wjschmidt.com
Cc: elecraft at mailman.qth.net
Subject: Re: [Elecraft] KPA500 270V Failure

 

OK, I see what you're saying now. I might have 2 problems. 1 or more diodes in the PS board and the TR switching diodes. I will make the check you stated.

Thanks for the tip.

 

Bruce, WB6IZG

 

On Sat, Jul 24, 2021 at 9:03 PM Dr. William J. Schmidt <bill at wjschmidt.com <mailto:bill at wjschmidt.com> > wrote:

Well my experience is that the supply doesn’t just die for no reason… 

 

 

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

  

Moderator – North American QRO Group at Groups.IO.

 

email:   <mailto:bill at wjschmidt.com> bill at wjschmidt.com

 

 

From: Bruce Forsberg <bruce.forsberg at gmail.com <mailto:bruce.forsberg at gmail.com> > 
Sent: Sunday, July 25, 2021 5:55 AM
To: bill at wjschmidt.com <mailto:bill at wjschmidt.com> 
Cc: elecraft at mailman.qth.net <mailto:elecraft at mailman.qth.net> 
Subject: Re: [Elecraft] KPA500 270V Failure

 

Thanks for the reply but in my case the problem is the voltage multiplier circuit on the power supply PCB. I just disconnected the HV (~70V) and 270V lines so they did not go anywhere and the 270V line still only measures 85V.

 

Thanks

Bruce, WB6IZG

 

On Sat, Jul 24, 2021 at 8:36 PM Dr. William J. Schmidt <bill at wjschmidt.com <mailto:bill at wjschmidt.com> > wrote:

Here it is.  From Elecraft technical support:  

Nominally:

TP2= RX 13.1 TX 0.8
TP4= RX 3.9 TX 13

>From Rene Morris at Elecraft (great guy!).



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

Moderator – North American QRO Group at Groups.IO.

email:  bill at wjschmidt.com <mailto:bill at wjschmidt.com> 


-----Original Message-----
From: Dr. William J. Schmidt <bill at wjschmidt.com <mailto:bill at wjschmidt.com> > 
Sent: Saturday, July 24, 2021 10:35 PM
To: 'Bruce Forsberg' <bruce.forsberg at gmail.com <mailto:bruce.forsberg at gmail.com> >; 'elecraft at mailman.qth.net <mailto:elecraft at mailman.qth.net> '
<elecraft at mailman.qth.net <mailto:elecraft at mailman.qth.net> >
Subject: RE: [Elecraft] KPA500 270V Failure

This happens a lot... search the forum for past msgs.  It's not the HV power
supply that is the problem.  That power supply powers the PIN diodes for TR
and RX... and it is more likely that the PIN diodes shot craps and shorted
the power supply.  There are two voltage Test Points "TP" on the board under
with the diodes and  you need to check the voltages on those test points.
That will tell you everything you need to know.  Will post the voltages when
I find them.


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

Moderator – North American QRO Group at Groups.IO.

email:  bill at wjschmidt.com <mailto:bill at wjschmidt.com> 



 


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