Puzzling Incident; Now Have a Problem

[Dennis Payton]

This morning I was listening to my KX1 on 80-meters on an approximately 5/8
wavelength wire I recently put up, with an L-network tuner at its end, then
coax ran into the house. Just out of curiosity, I decided to go through the
other bands and see what the KXAT1 would do, trying to get a match through
the outside L-network tuned for 80-meters, and of course SWR was high on all
bands.



Then I decided to listen to 40-meters, so I disconnected the wire antenna
and connected the coax from my R7 vertical. As soon as I hooked it up
though, the KX1 power died. I quickly disconnected the antenna, and the rig
powered back up. I suspected a power supply problem so unplugged it, going
to internal battery power, but when I started to hook up the antenna again,
it died again. I then checked to see if there was a static charge on the
line and there wasn't. I reconnected the 80-meter antenna and it seemed
fine, but when I tried to reconnect the R7 again, the rig died again. I went
back & forth several more times with the same result, then I turned on its
lamp and tried to connect it, and the lamp went out, which alarmed me.
Knowing there wasn't a charge on the R7's coax, I hooked it up to my ATS-3,
and the rig worked fine. Then I decided to see what would happen if I hooked
the rig up through my T1, but when I tried to connect the T1 to it, before
hooking up the R7, it died again. Then though, that seemed to be the end of
my problems! I couldn't do anything to get the rig to act up again, and
couldn't see anything. I verified it worked properly on 40, 30, & 20 into my
R7, so I was convinced that I no longer had a problem. I was puzzled though,
as to what had happened.



Tonight when I got home, I decided to hook it back up to the 80-meter
antenna but found it had trouble matching the already 50 ohm load. Also, it
said the power output was about half what it has been. I got out a dummy
load and transmitted into it on 80-meters, and the tuner worked hard to give
me a 1.4:1 match and the power reading was still low. The other bands were
still fine though. This led me out to my shack & the oscilloscope. I
operated the rig off of its internal batteries, which now go down to 8V. on
transmit, but output was a good clean +/- one watt on "all" bands, which
surprised me, since the rig's readout was still telling me that it was only
putting out .5 watt on 80-meters. I recalibrated the tuner which was already
fine, but have given up on it for the night. I don't yet have a clue though,
as to why the tuner won't recognize a good match on 80, or the proper power.
Does anybody have an idea that would help me trace this problem down, and
does anyone have an idea as to what happened this morning?



Thanks!



Denny    N9JXY


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[Don Wilhelm-3]

Denny,

The only thing I can think of in the KX1 is that C44 may be shorted which
would put your power supply voltage onto the antenna jack.  If I had to
guess, I would say that your R7 had an RF Choke to ground, but your other
antennas do not short the coax for DC.  You may have zapped the RF Choke on
the R7, and that would explain why it now 'works'.  There is a DC path
through the tuners (to the antenna) that you used, so yes, my scenerio is
quite possible.

The first check you should do is look for DC on the KX1 antenna jack - you
can do that without transmitting.  The second thing that you may want to do
is replace the 1N5711 diodes in the KXAT1, your lower power indication may
be a result of a diode failure - easiest way to check is just replace them
(fix any DC at the antenna jack first so you don't zap the new ones).

73,
Don W3FPR

> -----Original Message-----
>
> This morning I was listening to my KX1 on 80-meters on an
> approximately 5/8
> wavelength wire I recently put up, with an L-network tuner at its
> end, then
> coax ran into the house. Just out of curiosity, I decided to go
> through the
> other bands and see what the KXAT1 would do, trying to get a
> match through
> the outside L-network tuned for 80-meters, and of course SWR was
> high on all
> bands.
>
>
>
> Then I decided to listen to 40-meters, so I disconnected the wire antenna
> and connected the coax from my R7 vertical. As soon as I hooked it up
> though, the KX1 power died. I quickly disconnected the antenna,
> and the rig
> powered back up. I suspected a power supply problem so unplugged
> it, going
> to internal battery power, but when I started to hook up the
> antenna again,
> it died again. I then checked to see if there was a static charge on the
> line and there wasn't. I reconnected the 80-meter antenna and it seemed
> fine, but when I tried to reconnect the R7 again, the rig died
> again. I went
> back & forth several more times with the same result, then I
> turned on its
> lamp and tried to connect it, and the lamp went out, which alarmed me.
> Knowing there wasn't a charge on the R7's coax, I hooked it up to
> my ATS-3,
> and the rig worked fine. Then I decided to see what would happen
> if I hooked
> the rig up through my T1, but when I tried to connect the T1 to
> it, before
> hooking up the R7, it died again. Then though, that seemed to be
> the end of
> my problems! I couldn't do anything to get the rig to act up again, and
> couldn't see anything. I verified it worked properly on 40, 30, &
> 20 into my
> R7, so I was convinced that I no longer had a problem. I was
> puzzled though,
> as to what had happened.
>
>
>
> Tonight when I got home, I decided to hook it back up to the 80-meter
> antenna but found it had trouble matching the already 50 ohm
> load. Also, it
> said the power output was about half what it has been. I got out a dummy
> load and transmitted into it on 80-meters, and the tuner worked
> hard to give
> me a 1.4:1 match and the power reading was still low. The other
> bands were
> still fine though. This led me out to my shack & the oscilloscope. I
> operated the rig off of its internal batteries, which now go down
> to 8V. on
> transmit, but output was a good clean +/- one watt on "all" bands, which
> surprised me, since the rig's readout was still telling me that
> it was only
> putting out .5 watt on 80-meters. I recalibrated the tuner which
> was already
> fine, but have given up on it for the night. I don't yet have a
> clue though,
> as to why the tuner won't recognize a good match on 80, or the
> proper power.
> Does anybody have an idea that would help me trace this problem down, and
> does anyone have an idea as to what happened this morning?
>
>

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