In this case the antenna is a simple coax-fed 40M dipole with a balun at the
feedpoint. Without the KAT100 in line the SWR is approx 1.2 to 1 at 7100
where the problem occurs.
A quick check shows that yes, the problem seems to occur only on 40m. I
also noticed that other accessories on the same power supply re-set
themselves when it happens, supporting the foldback limiting theory and the
work-around that Tom posted and Mark pointed out. However, it happens only
when the KAT100 is in line; I cannot reproduce it at any frequency or power
level when the KAT100 is disabled.
----- Original Message -----
From: "Don Wilhelm" <[EMAIL PROTECTED]>
To: "Jonathan Taylor, K1RFD" <[EMAIL PROTECTED]>; <[email protected]>
Sent: Saturday, September 16, 2006 4:47 PM
Subject: RE: [Elecraft] KAT100: Strange K2/100 Behavior During Tune
If it is RF feedback, the proper way to deal with it is at the source - in
your antenna system.
An easy way to check it is to cut a quarterwave wire for each band that is
troublesome - attach one end of the wires to the ground terminal on your
tuner and the other end just stretches out and attaches to nothing excpet
an
insulator. There will be high RF Voltage on the open end of the wires, so
keep them clear of human and pet contact and keep them far enough away
from
objects to prevent arc-overs (treat the far ends sort-of-like the end af
an
antenna).
If these wires correct the problem, then you do have work to do on the
antenna system. If they do not help, then you can look further for a
K2/100
or KAT100 problem.
From your description, I would think something is causing a very high
current draw (even for a very short time) - your power supply may be going
into foldback limiting and the K2 powers off momentarily. The other
possibility is that the resettable fuse in th ebase K2 is tripping and
causing the power off condition (yes - it is powering off since you see
the
ELECrAFt on the display).
Is this by any chance happening most frequently on 40 meters?
73,
Don W3FPR
-----Original Message-----
I have a K2/100 with a KAT100. For the most part, all works well as
expected.
Intermittently, though, when I press the TUNE button, the KAT100 will
chatter briefly as if finding a match, and then it suddenly stops
and the K2
acts as if its CPU has been re-set; the bargraph and the LCD go blank
briefly, then the ELECrAFt sign-on message appears briefly and
finally the
frequency is re-displayed. During this time, however, the power supply
indications are normal and the LCD backlight remains on.
This problem seems to be frequency-dependent and seems to happen
more often
at high power, which leads me to think it is an RF feedback issue.
However, I've noticed that turning the power down to bottom end of the
high-power range (approx 12 W) usually doesn't help, yet turning
it slightly
lower than that, to get into the low-power range (approx 10 W), does.
Any advice on how to solve it?
Thanks
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