Here is another simple explanation. Perhaps it is voltage drop on
your power supply. You probably have the best match and most power
output on the 40m band, Is your power supply up to it? A simple way
to test this is to turn the power out down by 30W or so. Not enough
db wise to make a difference if it is an rf interefence issue but
will considerably reduce the demand on your power supply.
Raj, N2RD
On Sep 16, 2006, at 5:20 PM, Jonathan Taylor, K1RFD wrote:
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]>;
<elecraft@mailman.qth.net>
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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