KAT3 (not KAT3A) issue - older K3 take note From: jeff stai wk6i Date: Mon, 14 Jun 2021 14:36:20 PDT 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 watts. 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 -- Jeff Stai ~ WK6I ~ wk6i.jeff@g*** RTTY op at W7RN Twisted Oak Winery ~ http://www.twistedoak.com/ -- View This Message: https://groups.io/g/Elecraft-K3/message/35398 Reply To This Message: https://groups.io/g/Elecraft-K3/message/35398?reply=1 Mute This Topic: https://groups.io/mt/83542299/818764