[aprssig] Snowmobile tracking

[JGalt54 at aol.com]

Dear Brian,

Here's a post I made to the Kenwood D7 Yahoo group, that may help with your 
snowmobile tracker.  Infact a friend of mine is so impressed he is thinking 
about using it on his motorcycle:

In my quest for the perfect TH-D7 Tracker to carry with me while out 
Geocaching, many times alone, I have sucessfully tapped the Batteries America 1800mAh 
7.2V for power to run a Delou Lite GPS.
 
There is already a power jack on the back of the battery pack that accepts a 
3.4mm coaxial plug to charge this pack if desired.  But
from the factory, power is not available to this plug because of a blocking 
diode.  Note: it is unusual in the fact that the CENTER PIN
IS NEGATIVE.
 
Running a very sharp knife along the cement seams caused the pack to come 
apart fairly easily with no damage.  Once I had access to the internal wiring it 
was a simple matter to clip the existing wire from the shrink wrapped diode, 
bring it around behind the jack, and 
resolder to the positive terminal on the group of cells.  A little 
TLC was necessary on the cardboard insulator to allow the wire to feed 
freely.  I cleaned up the seams of the battery pack, popped it back together and 
cemented the seams.  Total time 1/2 hour.  I did 2 
battery pack modifications with no problems.  A plus is that I could still 
charge the pack through the existing jack.  Doing the mod this way, does not 
change any other internal wiring to the battery pack.
 
How does it work?  The Deluo Lite GPS draws 120mW and can accept 
5-9VDC while tracking satellites.  While using it last night, on a freshly 
charged battery pack, I got 15+ hours with a beacon every 3 minutes at 3W 
output.  Not too shabby.  Since I carry my TH7 in a 
Palm Pilot soft case with a solder strap (or in a pocket of my backpack), it 
is completely self contained with no wires to snag on branches and limbs.
 
The antenna I use is one of the superflexible cat’s whisker 19 inch ones so 
as I move through the brush it doesn’t snag. 
 
BTW, Deluo now has a GPS with the next generation chipset with the
same size (41x41mm) and power requirement specs.  This new generation of 
chips can track satellites indoors easily, and has a much faster aquire time (5X 
faster).
 
Keep on trackin!
John
K2QY
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