[aprssig] RE: [Kenwood_TH-D7] TH-D7 Power up problem

Herb Gerhardt hgerhardt at wavecable.com
Tue Nov 21 19:01:11 CST 2006

Our county recently tried to use their TH-D7 SAR tracker I set up for them
several years ago and they could not make it work.  I did my darnedest to
try to talk them through all the possible problems.  I did not succeed.  So,
I now have the entire tracker here at my house for troubleshooting.

Here is what I discovered so far:

1.    Even with a good fully charged battery attached, it will not power up.
I bent the radio contacts out some more but that did not help.

2.    With 12+ V attached to the external plug, I can read voltage (11.6 V,
which is normal since a diode is involved) on the normal battery connection

3.    The external battery pack cable that I made for them years ago, causes
intermittent connection to the radio.  It does the same when connected to my
radio.  I built a new cable using the power connectors I bought from Mouser
and those are also too loose and work intermittently.  This
looseness/intermittent connection was experienced on both the county's SAR
TH-D7 and my personal TH-D7 radio.

4.    I supplied external power to the normal radio battery terminals on the
SAR TH-D7 and it will NOT power up.  Applying the same power to the battery
terminals on my radio makes mine work just fine.

So, it appears that there is a problem between the normal battery terminals
on the back of the DEM radio to the circuit board inside the radio.  Joy,
joy......  I have never seen or heard of such a problem.  Is there anyone
that has seen this problem before?  If so, what did you do to fix it?

My late elk hunting season starts tomorrow, so this radio problem will have
to wait till after my hunting season.  Any inputs in the mean time would be

The unfortunate part of this problem is that this is the first time that
they really tried to use this TH-D7 tracker during an actual search.  Sure
would have been nice if it had worked.  I have been trying for years to get
them to use this tracker during an actual search and now when they finally
tried it, it would not work.  It worked just fine about a year ago when I
checked it out.  As far as I know, no one has used it since then.

Herb, KB7UVC
Mason County ARES/RACES ex-President & APRS Coordinator

Mason County ComVan:  http://map.findu.com/KB7UVC-1
Mason County Relay Truck:  http://map.findu.com/KB7UVC-2
Mason County EOC:  http://map.findu.com/KB7UVC-3
Mason County Foot Tracker:  http://map.findu.com/KB7UVC-6

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