K3-100 #1433: K3 ATU MALFUNCTION

[Jack]

To Any Who Might Be Interested,

I received the K3ATU board and replaced the suspect K3ATU to no avail. The
problem remained.

I called Elecraft and talked to Renee. He instantly suspected problems with
the TRANSMITTER GAIN CALIBRATION.  

With Renee on the phone we did test with a dummy load (I had it set up to go
before I called!) and verified that the same symptoms on the same bands
happened with the dummy load in bypass mode!!!!!!!

When using the ATU Renee heard the clicking and the lenght of time it took
to tune and recognized the symptom.

We then did the 5 and 50 watt meter calibration.

Next was the Transmitter Gain calibration on the suspect bands.  This fixed
the problem.  Renee left it to me to do the calibrations on all the bands. I
did and the rig is working like it did after the initial assembly.

These procedures fixed the problem but I should mention that along the way
Renee had me check various values to compare them with the factory values
and those of his experience.  The values we found for the TXMT GAIN were not
those he expected.  As it turned out, his suspicions were correct.

I had done the calibrations initially and again when working on my low power
on 40 M LSB problem. The fix to that problem was to upgrade to 2.23 from
2.33.  I believe that the ATU malfunction began after that upgrade. Given
the possibility of operator error and my uncertainty about the timeline I
can not state that the upgrade caused the ATU malfunction.
 
All is well that ends well.  Elecraft did an outstanding job in helping me
resolve this problem in a very timely manner.  If you are like me and get
very frustrated with these kinds of problems please take my advice and relax
and let Elecraft help you.  You have a great radio and you'll be amply
rewarded for you patience.

 Jack, AE6GC, KX1 #1403, K3-100 Kit #1433
_______________________________
From: Jack Regan
Sent: Monday, August 18, 2008 2:42 PM
To: 'Gary Surrency'
Subject: RE: AE6GC Re: K3-100 #1433: K3 ATU MALFUNCTION
Gary,
Before I called support this morning I did use a dummy load to verify the
condition of the rig.  I talked to Scott this morning with the dummy load
still connected.
The problem is clearly with the ATU. The dummy load and the K3 in bypass
mode show the same swr. The K3 in ATU AUTO mode shows higher swr figures for
the two resonant antennnas. The funny thing is that the ATU tunes the 40 M
dipole to 30 M with a 1.0 to 1 swr.  This is inspite of a big mismatch.  On
the contray, on 20 M the ATU takes a 1.1 swr and see 2. or highe. It even
gives a high swr warning.
Anyway, Scott is sending a new ATU.  I hope this works. BTW, I sent a more
detailed update to the reflector.

Thanks,
Jack
______________________________
From: Gary Surrency
To: Jack Regan
Subject: AE6GC Re: K3-100 #1433: K3 ATU MALFUNCTION
Hi Jack,
Did you try a dummy load in place of the antenna to be sure it still finds a
1:1 SWR?
Also check L10, C10 for visible signs of damage on the KAT3.   C10 is the
big cap opposite of L10, on the back of the board, next to the right side
panel.
73, Gary AB7MY
======
Jack Regan wrote:
Support Staff,
On Saturday the 16th I noticed that the ATU gave a higher SWR than bypass
when transmitting to a resonant antenna. The difference was small so I
thought I would just note it and observe.

Today, Sunday the 17th I found that on 14.050 in bypass mode at 14.050 I get
a 1.1 to 1 reading but in ATU mode I get higher that 2 to 1 and a HI SWR
message.
On 7.050 I get 1.0 to 1 in bypass and 1.4 to 1 in ATU mode.
 This is a change from when the rig was first built. Originally if I had 1.2
in bypass I would get 1.0 in ATU mode.
 Help! I thought I was up and running after a week of problems and now a new
one! Any suggestions would be appreciated.
Jack

 

 

 

 

 

 

 

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