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, [email protected] wrote:
Message: 23
Date: Tue, 5 Nov 2024 08:57:54 -0500
From: David Olean<[email protected]>
To: Elecraft Reflector Reflector<[email protected]>
Subject: [Elecraft] KPA500
Message-ID:<[email protected]>
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
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