[Elecraft] KAT500 and VARA

[Hank]

Gentlemen...
I've had the same issue in the past on 2 configurations: K3S+KAT500/KPA500 and with the KX3+KXPA100 (w/built in tuner).

I'm assuming barefoot through the KAT500?  I solved the issue with the KX3 and KXPA100 by introducing a choke (LDG 1:1) between the KX3 and the amp/tuner (ant coax) - don't know why it works, but it does.  In this scenario I am using the KXPA100 amp outputting approximately 45 watts to the antenna system.  However it is the same antennas, same linear power supplies, external soundcards, etc.

As for the K3S+KAT500/KPA500, I can eliminate the random tuning when using VARA by using an external sound card (PK-232SC+ or Navigator) that is galvanic(ally?) isolated (transformers) between the audio lines and PC except on 80 meters. Still happens on 80 meters!  If using the internal K3S soundcard - I get "retunes" on every band with the KAT500.  None of it happens with the amp on standby.  I added a choke between the K3S and amp (ant. coax) but no joy.  Why it works for the KX3 setup - I have no clue.

I have always assumed that one of the VARA tones (with the rig running at lower power for digital) makes the tuner think I am forcing a "retune".  Oddly enough, I have a remote MFJ legal limit tuner (installed near the base of my dipoles) that I use with the K3S and a legal limit tube amp, and it does not "retune" doing HF VARA - 100 or 1500 watts.  I guess I should use it for everything, but the point and shoot of the KAT500 and KXPA100 is hard to beat.  

I have tried chokes, snap on chokes, cables wrapped through toroid chokes, rerouting cables, even temporarily relocated my station to be farther away from my antennas, but to no avail. So basically if I am using Winlink/HF VARA on 80 meters, I'm using 45 watts on my KX3/KXPA setup so it will work.

I thought all of this time it was just me!

Hank, K4HYJ
ARRL SM Georgia
EC Whitfield County
----- Original Message -----
From: George Moss via Elecraft (elecraft at mailman.qth.net)
Date: 06/02/25 12:35
To: elecraft at mailman.qth.net
Subject: [Elecraft] KAT500 and VARA

I use Winlink/VARA for ARES email.  However, VARA sends the KAT500 off searching for a match on a frequency that has already been matched.  It will run along just fine and all of a sudden start trying to rematch.  Any thoughts/ideas are appreciated.

George Moss, KC4GM
31 Hopewell Road
Irvington, VA  22480
(703) 608-7894
georgemoss at yahoo.com

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