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From: notes@ucf-cs.UUCP
Newsgroups: net.ham-radio
Subject: TR-2400 explodes
Message-ID: <2181@ucf-cs.UUCP>
Date: Sat, 7-Dec-85 05:29:15 EST
Article-I.D.: ucf-cs.2181
Posted: Sat Dec  7 05:29:15 1985
Date-Received: Sun, 8-Dec-85 03:27:56 EST
Sender: notes@ucf-cs.UUCP
Organization: Univ. of Central Florida, Orlando
Lines: 36
Nf-ID: #N:ucf-cs:54600001:000:1710
Nf-From: ucf-cs!hawkins    Nov 25 22:16:00 1985

Subject: Kenwood TR-2400 Blown UP!

When I got my TR-2400 (used) I received a few "Weak Modulation"
signal reports and so I proceded to turn up the mike gain pot
that was clearly marked on the schematic and was easily found
on the circuit board. I figured that such a slight change could
not possibly get me in to trouble. I was wrong. Upon putting
the radio back together I asked for a signal report to see if
my modulation was up. It was. 

I thought I had it licked until a few days later I tried to access
the local autopatch. It completely ignored me. Hmmm, I thought,
let me turn this little pot over here that increases the voltage
from the touch-tone chip. That didn't work. I had better look at 
this on the scope, I thought. I probed around with the comparatively
large scope probe and blew out a coil.

The coil is made of a fine wire wound on a resistor. Its purpose is
to act like a fuse. The only problem is that the resistor still conducts.
Not aware of this at this time, I pluged it in to a 10 amp 12vdc supply.
The radio worked. Unplugged it, and it didn't. Figured the battery was 
shot.

I tested the battery and found that it was good and figured that
there may be something wrong with something between it and the 
circuit. So as an experiment I wired the battery in through the
external voltage connector to see if it would work. It didn't,
it blew up instead. I had connected it backwards. Several of the
transistors literally exploded, and some didn't.  I still haven't
figured out where all the non-exploded bad transistors are.

Has anybody faced such a problem with this rig, or is it just me.
If anyone has any contructive comments I would appreciate them.

Dennis Hawkins / N4MWD