[Elecraft] K3 (not S) Antenna tuner strangeness

[brian]

Guys,

I've run into something on 80M trying to use the internal antenna tuner.
It fails to tune to a low SWR.

My recollection is that the tuner worked fine on the same antenna 
before. "Worked before" may have been with a slightly different tap 
position.

Antenna is an MFJ 1/8 Wave vertical with loading coil and 4:1 "Guanella" 
balun at the antenna base.

With the current coil tap an RF analyst antenna analyzer shows the 
following:

3.55 MHz SWR=2.0  Z=35 ohms
3.6      SWR=2.7  Z=36 ohms

The K3 in the tune position (tuner out) shows SWR's of 1.7 and 2.4 
respectively.

The antenna tuner finds a match for a 50 ohm dummy load OK.  Using those 
settings as a starting point, we attempted to match the antenna.

The best it can do is bring the 1.7 SWR down to 1.4.  The 2.0 SWR can 
brought down to 1.7 at best.

Other bands work OK.

Any thoughts?

73 de Brian/K3KO