[Elecraft] Probable KXAT1 Problem

[Phil Wheeler]

Regarding the following, it appears I fixed it.  My first thought was to 
remove the atu pcb and look it over for unsoldered joints, etc.  All 
looked good.

Then it occured to me that I had had a similar problem with a pcb in the 
K2 which was cured by an R&R of the board.

Apparently that worked here, too.

The assembly process -- inserting the plugs in the main board and 
installing the atu pcb on the plugs may have had something to do with 
it.  Likely if I had done an R&R as part of the assy process, I would 
not have had this problem.  Who knows?

In any case, I now get non zero values of C and L after a tuneup and r 
is indicating the result of tuning, not the swr of the untuned antenna.

If only all my troubles and errors were so easy to fix :-)

73, Phil

Phil Wheeler wrote:

> When building the atu, it passed all checks.  I even went through all 
> the Troubleshooting steps on page 11 of the manual.  So all seemed 
> OK.  And I thought all was good, since it loaded the antenna I was 
> using well. BUT -- that antenna is pretty much 1.0:1 where I operate, 
> so I suspect that led to a false sense of success.
>
> Now I am trying the rig with a variety of wires and balanced antennas 
> and I am coming to suspect that the atu is not working correctly.
>
> Consider three cases (from among many):
>
> Antenna A (beam): MFJ analyzer says it is 2.0:1 on 14050
>
> Antenna B (D4 multiband dipole): MFJ says 1.2:1
>
> Dummy load:  1.0:1
>
> Scenario is as follows:
>
> 1.  I connect Antenna A and push Tune.  Relays clatter away and 
> eventually stop.  Indication is r2.2
>
> 2.  I connect either Antenna B or the dummy load: Relays do nothing. 
> Indication is r1.0
>
> 3.  I reconnect Anenna A.  More clattering and r2.2 results.
>
> Then I read the L and C using the ATU menu.  I get L.00 and C.00
>
> I would expect very different behavior and result.  r should indicate 
> the swr after tuning, not that of the untuned antenna.  And L, C of 00 
> does not look right when loading an antenna with an inherent swr of 
> 2:1 or so.
>
> It is basically as though the atu, while making the dutiful noises, is 
> not matching the antenna.  BTW -- band does not matter; I just chose 
> 20 m for this data set.
>
> Now I know why my initial attempts to load a 24 ft wire a few days ago 
> were so odd.  I think the atu is not doing what it is supposed to.
>
> Since I have done all the troubleshooting steps with the expected 
> results re C and L readings, relay switching and so on, adjusted R1 
> and R2 according to the manual, etc. -- where should I look for this 
> problem?
>