[Elecraft] KPA500 no power out

[iain macdonnell - N6ML]

On Tue, Oct 15, 2019 at 7:04 AM w5zzt <w5zzt1 at outlook.com> wrote:
>
> Well my T/R circuit just failed yesterday.  Mine is a 2016 model that was a
> kit.  serial number 3032.
>
> It's out of warranty so waiting for Elecraft to call me so I can send it in
> to be fixed.  No smoke just quit and disconnected it before it blew the
> finals of my radio.

What does "just quit and disconnected" mean?

My KPA500's T/R also died recently, and also damaged my K3. The
initial symptom was that the KPA500 would throw a fault 09 (high
reflected power) immediately on attempt to transmit on any band. While
attempting to diagnose this remotely, at one point I turned the K3's
output level below 12W (so just using the LPA, not the KPA3). After
that, the K3's TX was dead - "long story short", the final FETs in the
LPA were fried. Seems like something in the KPA500's T/R allowed big
RF to get fed back to the K3 - apparently the KPA3 finals could take
it, but the LPA ones couldn't. I've since replaced the two FETs, and
my K3 is back to life. When I brought the KPA500 home, the symptom
changed. On attempting to transmit, if I provided any RF drive, the
asterisk on the display would disappear - so it seemed to be unkeying
itself. It seemed like RF may be leaking into the keying circuit. In
an email exchange with support, some voltage readings suggested a
diode problem. I replaced the D7 thru D10. That made the voltages look
better, but the symptom of the amp unkeying itself persisted. Support
said that no one has heard of that happening before. Since I don't
have a supply of parts at hand, and have limited diagnostic skill, I
sent it to Watsonville Hospital. It's now waiting in the queue
(supposedly 10-15 days).

> Anyone had this repair done lately?  I just wondered what the cost is to
> repair if anyone knows.

Minimum $95 (one hour), plus parts and any additional labour. Waiting
to find out....

73/GL,

    ~iain / N6ML