[Elecraft] KPA500

[Bob McGraw]

Seems to indicate the T/R switching has gone kaput.

Search the KPA500 Files on Groups.IO for discussion on the topic and 
solutions of which parts to replace.    Schematics are available on the 
Elecraft website.

FET idle current is 0.6 to 0.8 amps, somewhat depending on 
temperature.    I would not dare mess with the PA bias.

73

Bob, K4TAX


On 11/5/2024 7:58 AM, elecraft-request at mailman.qth.net wrote:
> Message: 23
> Date: Tue, 5 Nov 2024 08:57:54 -0500
> From: David Olean<k1whs at metrocast.net>
> To: Elecraft Reflector Reflector<elecraft at mailman.qth.net>
> Subject: [Elecraft] KPA500
> Message-ID:<80757635-66b4-4101-a103-b7bca60a2b35 at metrocast.net>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> I have a KPA 500 that is hardly ever used. I think I made less than ten
> contacts with it. As a result, I am not that familiar with it except
> that it worked great. I loaned it out to a friend and it came back
> broken. I am trying to figure out what happened. When I key the radio I
> see about 0.6 amps of idle current. TX Signals will pass thru OK on
> standby, but if I try transmitting into the amp, I see a high input
> VSWR? and the idle current stays constant at 0.6 amps. There is no
> output power.? It seems that maybe the input TR switch may be at fault.
> Question: What is the proper idle current for the FETS as displayed on
> the screen? If I had a schematic, I could dig into it, but not having
> that, I figured that I would ask a few questions to get me pointed in
> the right direction.? Can anyone help out?
>
> Dave K1WHS