[Elecraft] K2 ATU

[Dave Gingrich]

At 12:03 4/25/2002 -0700, Art Horne wrote:
>Just getting my feet wet with the K2 and it's ATU.  I ran into a problem
>(for me) that I'm curious about.  I have been loading up my antenna ok in a
>temprary location with good SWR.  I then put it in the attic and when I
>tried to tune it (looking at power out) I couldn't get anything but a 100%
>reflection on all bands.  Of course, I assumed I had shorted or opened the
>coax when I shortened my cables.  As it turned out the rig didn't cause the
>ATU to re-tune when I hit the tune button because the ATU had been selected
>to read Power Out.  When I switched it back to Auto it retuned ok on each
>band and then when I went to Power Out everything was fine.  I had assumed
>when you select "TUNE" that it woud do just that.  Apparently I was wrong.
>Should it have?  Where was my thinking wrong?

It's all detailed in the manual for the KAT2, but here is a summary.

There are basically three operating modes of the KAT2 and "Tune".

1. CALp and CALs - Tuner is bypassed direct 50 ohm out. Tune button 
provides full output set by Power control. Use this if you have a 50 ohm 
antenna or external tuner.  CALp reads power out, CALs reads SWR

2. Auto and Alt - Auto tune mode, tune button provides reduced power and 
the KAT2 will attempt to match the feedline impedance. Use this to match a 
directly attached wire or any coax fed antenna that needs to be matched.

3. Pout and x.x-1 - The tune button provides full power (subject to power 
control) with the tuner in-line, settings remembered for each band/antenna, 
but it will not re-tune the tuner.

I usually run with two antennas attached to the K2. One is a long inverted 
L with an SGC SG-230 automatic coupler at the feedpoint. Second is an 80 
meter horizontal loop fed directly with coax.  I need the KAT2 for the 
loop, but not for the Inverted L (external tuner).  So I run through a tune 
routine on Antenna 1 (the inverted L) on each band to auto-setup a 50 ohm 
passthrough. I then switch over to Ant 2 (the loop) and tune it for each 
band.  I then switch the tuner to the POUT position so it won't 
retune.  The KAT2 remembers the settings for each band for the Loop on 
Ant2, and remembers the 50 ohm settings for the SGC tuner on Ant 1, so all 
I have to do hit Tune on Ant 1 to get the SGC to retune if I change bands.

Since the KAT2 remembers the settings for each band, for Ant1 and Ant2 
separately, this works very nicely.

================================================
Dave Gingrich, K9DC - Indianapolis, Indiana  USA
K2 #2211, K1 #931, QRP-L #2376, ARS #1109,
FPQRP #389, IRLP #473, k9dc.ampr.org, CCIE #6748
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