[Elecraft] K3 Auto ATU Problem

[Rick Bates, NK7I]

The KAT3, KAT500, KPA1500 tuners, all have the same feature.  I have all 
three.

If you want a finer (lower SWR) value, within a few seconds of the first 
tuning cycle stopping, start the sequence a second time and the tuner 
will cycle through ALL possible settings to attempt a lower match.  It 
may/not make a difference.

I would also, at this point, seek out an antenna analyzer to see what 
data could be gleaned from that; perhaps a cable, connector or other 
antenna system element (anything beyond the tuner, even IN the radio) is 
no longer valid.  Tuning into a KNOWN 50 ohm dummy load may show 
something interesting as well.

Again, setting CONFIG | TUN to 10 (watts), should help resolve your 
issue, 5 watts is a touch low.  If it does not, you may have a failed 
component (or relay) in the tuner.

If you can, try to eliminate the possibilities (antenna, feed, 
connectors) to find out what failed/changed; narrow the search.  (Does 
another radio tune the antenna easily, EVERY time?)

73,
Rick NK7I

On 12/7/2021 3:13 PM, Fred Jensen wrote:
> The KAT500 will enter a fine-tune mode if you re-initiate a tune cycle 
> right after the first one has finished.  I don't know if the KAT3 will 
> do that, and I can't test it because mine always finds the primary 
> match the first time, but Elecraft would have a lot of incentive to 
> reuse KAT3 algorithms and code in the KAT500.  I believe the Elecraft 
> tuners use some variant of the steepest descent algorithm which can 
> hang up on a less than optimal solution
>
> 73,
>
> Fred ["Skip"] K6DGW
> Sparks NV DM09dn
> Washoe County