[Elecraft] KAT500 apparent loss of control

[Dick Dievendorff]

The ATU goes into bypass if too much RF power is applied into a high SWR
antenna (as measured by the "bypass VSWR".  The tuner is rated for an
antenna load (as measured by the Bypass VSWR) of 10:1 SWR at 600 watts and
3:1 SWR at 1500 watts. If you exceed these limits, the tuner will go into
bypass and signal a fault.  The KAT500 Utility display of the fault log may
be of interest.

Did your antenna change?  Still using the right antenna connectors for the
antennas you do have?

Try tuning with relatively low power, under 200 watts, to see if it goes
into bypass at low power. If it doesn't, and does go into bypass as you
increase power, and the bypass VSWR is higher than 3:1, then that may be the
issue.

73 de Dick, K6KR


-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Robert G Strickland
Sent: Thursday, September 05, 2013 19:50 PM
To: Elecraft
Subject: [Elecraft] KAT500 apparent loss of control

My KAT500 is running the latest firmware, 1.32, which I loaded a few weeks
ago. For the past year or so of operation it has worked flawlessly. Now, not
sure why, I am encountering various anomalies. 
Using the tuner utility (v 1.13.5.12):

- I cannot manually adjust the tuning (for better or worse); the utility
keeps reverting to "BYPASSED," and the VSWR and Bypass VSWR are the same;
there are no checked boxes for L/C.

- In Auto mode, much the same. Key the K3 and initiate tune; KAT500 tunes to
a not-so-low VSWR; the utility operate window reverts to "BYPASSED," no L/C
boxes checked, and bypassed and tuned VSWR are the same (high).

- Loaded factory defaults and tried as above with no change.

- I notice with K3 off and watching the config utility, the "bypass" box
always reverts to BYPASSED; I can un-check it, and in about 2sec it reverts
to BYPASSED.

Note, I have adjusted the VSWR thresholds to Autotune at 1.5 and Bypass at
1.2. However, the autotune function always reverts to BYPASS with the high
VSWR (on a resonant antenna as indicated on a MFJ259B). Also, the TUNE STATE
indicates 0 6 199 (?). Thus, I have limited to no control over operation,
the unit keeps reverting to bypassed, and the resultant VSWR is higher than
without the tuner. Any help on how to work with this or what may be
happening is appreciated. Thanks ...robert
--
Robert G Strickland, PhD ABPH - KE2WY
rcrgs at verizon.net.usa
Syracuse, New York, USA
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