Re: [Elecraft] KAT3 (not KAT3A) issue - older K3 take note

Alan Baker - G4GNX

There's a whole stack of mods done over the years. They were on the Elecraft website in pdf format. If you can't find them, I have all of them here and have performed most of them on an older K3.


Alan. G4GNX

------ Original Message ------
From: "Jeff Stai" <>
To:; "Elecraft Mailer" <>
Sent: 14/06/2021 22:36:08
Subject: [Elecraft] KAT3 (not KAT3A) issue - older K3 take note

TL;DR: Got a KAT3 in your K3? Next time you have your K3 open, pull out
KAT3 and preemptively remove L10 and C10, and replace with a jumper. You
don't need them and they are probably messing you up at times.

(Are there any other older K3 issues like this? Tell me!)

I have an early model K3 that still has all of its original modules. I was
having an issue where the power output was sometimes dropping to just a few

Running the TX calibration would sometimes fail completely with weird error
messages, but if I could get it to run it would get through most of the way
but always fail on 52MHz due to high SWR (over 2). With a dummy load or a
matched antenna, SWR was over 2 also in normal operation.

Of course, this low power situation would magically correct itself after
some poking around, though the 52MHz high SWR was consistent.

I finally decided that I wanted to do some 6m operating and I used the KAT3
to get matched to the load. I would just operate until something finally
decided to fail fully.

It did. After a few hours C10 on the KAT3 blew, LOUDLY and smokily.
Undoubtedly due to some crazy high voltages presented by the tuner.

After some sleuthing in the Elecraft reflector I found the C10/L10 filter
issue being well discussed. Pulling them out and jumpering solved all my
issues. With the K3, anyway. :)

This filter was not included in the KAT3A. If you have one of those, you're
good. If you want to know more about the history of this filter it's easy
enough to find in the email archives. :)

Hope this helps - jeff wk6i

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