[Elecraft] KPA500 Question

[marvwheeler at nwlink.com]

What happens if you reduce the rf output on the k3 to some value below 12
watts. I have the same symptoms and thought it was the KPA500 but after
disconnecting the K3S from the rest of the station I accidently determined
that if I decreased the RF output to less that 12 watts the receiver is no
longer attenuated. I am waiting until Elecraft is on a more normal footing
before sending it back for repair.

Marv
KG7V

-----Original Message-----
From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> On
Behalf Of Mark Goldberg
Sent: Sunday, April 18, 2021 3:20 PM
To: ws6x.ars at gmail.com
Cc: Elecraft Mailing List <elecraft at mailman.qth.net>
Subject: Re: [Elecraft] KPA500 Question

Is the key line indication on all the time? This may be indicative of a
stuck key line. There was an unsoldered resistor on mine causing the issue.

73,

Mark
W7MLG

On Sun, Apr 18, 2021, 2:38 PM <ws6x.ars at gmail.com> wrote:

> I just purchased a used KPA500 (SN 0456) from a close friend. The amp 
> was just back to the factory for several repairs and was thoroughly 
> tested. The report reads, "KPA500 #0456 meets or exceeds all factory
specifications."
> My
> friend unboxed the amp and made several QSOs to be sure all issues 
> were fixed. He then personally delivered the amp to my QTH.
> Over the weekend I got the amp added to my operating position and was 
> quite surprised to find that input signals are attenuated 
> significantly when the amp is switched from STBY to OPER. No, this is 
> NOT the issue with having the aux cable and the PA key line connected 
> at the same time. This is with NO PA key, and NO aux cable connected. 
> The amp has no connection but RF input and output. It is independent 
> of band. This is with a matched antenna, band switched manually with 
> the front panel buttons. When I engage OPER the input signal is 
> attenuated by ~20 dB.
> On the TX side, the amp is fine. On most bands I get full rated output 
> into a dummy load with approx. 20 Watts of drive from the K3.
> I noticed on the service report, one of the tests was, "Tested receive 
> attenuation and IMD." I'm curious about "receive attenuation." This 
> would seem to be related to my problem. Looking at the block diagram, 
> I surmise something in the TR switch is malfunctioning.
> Before I bug an already-overloaded Elecraft support, I am open to 
> suggestions. Am I missing something obvious?
> TIA es 73,
> Jim - WS6X
> P.S. Yes, I have read the manual, and scoured the archives. The only 
> thing I can find regarding input attenuation in the OPER mode involves 
> incorrect cabling.
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net Please help support this email 
> list: http://www.qsl.net/donate.html Message delivered to 
> marklgoldberg at gmail.com
>
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html Message
delivered to marvwheeler at nwlink.com