[Elecraft] K2's ATU "vagaries"

[Don Wilhelm]

Jim,

I am not certain how you would set the KAT2 to OFF.  That is not an 
option in the menu.
Setting the ATU menu to CALP or CALS will electrically bypass the L/C 
elements in the tuner, but there will be some residual reactance in the 
tuner.

The best method to "bypass" the tuner is to do as stated in the manual - 
tune (on each band) using AUTO mode into a dummy load and then set the 
ATU menu to POUT.  The L/C combination last used for the TUNE on each 
band will be set when you return to that band.

Note for KAT100 users - POUT is not an available menu option - you can 
use CAL which bypasses the L/C elements completely.

73,
Don W3FPR

On 4/30/2015 8:21 AM, James Rodenkirch wrote:
> While altering my existing antenna system which includes an LDG Z11ProII auto-tuner at the base, I had to do quite a bit of "testing" from the shack; e.g., add a un-un, go to shack, hit the tune switch, watch power out and SWR.....switch to another un-un with a different ratio, follow same procedure. All of this with the K2' internal auto-tuner turned of.
>   
> The antenna "alteration" I was trying wasn't providing the LDG auto-tuner with Zo values it liked so I was switching the K2's auto-tuner in and trying it across the various bands to see how it "played" with the altered antenna. After an afternoon of this I surrendered and restored the antenna to its original configuration, one the LDG auto-tuner tuned effortlessly.
>   
> Note: the original system is a 36' vertical with 12 elevated radials an the auto-tuner at the base of the vertical. The LDG has always tuned that configuration effortlessly on 40 through 12.
>   
> After restoring it back to its original configuration I went through the tuning cycle - K2's ATU off, hit the tune switch....yadda, yadda; that's the configuration I use - ATU off, K2 set to watch pwr out and reflected- the POUT mode. What I found was: the LDG tuned 40 through 12 effortlessly BUT, on 40 meters I observed 5 watts out and 2 watts reflected (prior to all of this, it was zero watts reflected). Given the vertical is back to its 36' configuration one would expect zero watts......so, I retuned several times but, same result. I could tell the LDG was tuning correctly and with 30 through 12 showing no reflected power I kept wondering of the K2 was "acting up."
>   
> I found the internal ATU manual and start reading up on the "Using the ATU." I found this:
>   
>     As an alternative to CALS or CALP, you can tune up the ATU into a 50 ohm dummy load on each band using AUTO mode. This will
>     cancel out most or all of the stray inductance and capacitance so that you can connect your external tuner or resonant antenna.
>     After tuning up on all bands, put the ATU in to POUT or SWR mode> The matching network settings will not change.
>   
> I ran through that sequence and...poof....no reflected power on 40 meters!
>   
>