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[aprssig] Group Tracker Build Projects ?

Bruce Gordon bgordon at ltronics.com
Sat Sep 24 17:45:04 UTC 2005


Hi all,

Attached are some pictures of our trackers.

 P9150638 is the inside of the top case showing the antenna connector and
the internal copper shield which carries the highest antenna current around
the electronics and across the joint between upper and lower case halves.
The rectangular opening (lighter grey) in the nickel paint for the GPS
antenna can be seen.  The nickel paint alone was not enough to keep the RF
out of the tracker chip.  The white recess mount for the power switch was
made from a plastic pipe cap.

P9150642 is the pcb with the TinyTrack chip, a low dropout
regulator/transient protector for the radio and a surface mount switching
regulator for the GPS on the back side.  The wires go to the power switch,
LEDs, battery clips, power input jack and the radio battery tray, microphone
and earphone plugs. The 8 pin chip is a code translator peculiar to the
Earthmate GPS.  Battery life depends on the amount of channel traffic.  A
lot of traffic will keep the receiver from going to battery save mode and
the receiver is the biggest load.

P9300651 shows the inside of a complete unit.  Three magnets (not visible)
are glued to a steel plate and extend through the bottom of the case.  They
are covered with a mylar sheet to maintain the seal and avoid scratching.
The radio and battery are fastened to the top of the plate with double stick
foam tape.  The GPS and pcb are attached to the top of the case, also with
foam tape.

P9270647 shows 8 units in place in the com van with charging plugs in place.
Felt strips on the metal shelves allows the units to slide out while still
allowing the magnets to hold them firmly in place.  The units are numbered
so the receiving software can assign tactical call signs as needed.

I hope this gives you some ideas for your project.

Bruce Gordon N6OLT

----- Original Message -----
From: "William McKeehan" <mckeehan at mckeehan.homeip.net>
To: "TAPR APRS Mailing List" <aprssig at lists.tapr.org>
Sent: Friday, September 23, 2005 11:55 AM
Subject: Re: [aprssig] Group Tracker Build Projects ?


> This sounds like a very nice tracker package. The kind of thing that I
would
> like to build.
>
> How much time would the 2.3 AH battery operate these units?
>
> Do you happen to have any pictures of the units?
>
> On Fri, September 23, 2005 11:48 am, Bruce Gordon said:
> > hi,
> >
> > Our ARES group built 10 successful portable trackers several years ago.
> > Each used an Icom T2H 5 watt HT, a TinyTrack chip, a (now obsolete)
> > Earthmate GPS and a 12V 2.3 AH gel battery packed in an 8.75 x 5.75 x 3
inch
> > watertight plastic box (Bud PN1329)  A BNC jack on top holds a 1/4 wave
> > whip.  The inside of the box is coated with nickel conductive paint
except
> > over the GPSantenna to provide the antenna ground.  Three large,
doughnut
> > ceramic magnets and a steel back plate mounted flush with the bottom
hold
> > the unit on any car top.  No external wires to tangle or trip over.  We
did
> > get some discounts on the radios, GPS receivers, boxes and other parts
even
> > at this quantity.
> >
> > We made a custom PC board to hold the TinyTrack CPU and associated
parts, a
> > switching regulator for the GPS and some protective circuitry.  A
recessed
> > power switch, track and battery LEDs and a charging jack are brought to
the
> > outside of the box.  The battery gives 10 to 12 hours of operation which
has
> > been more than enough so far. Eight of the units are kept charged in a
rack
> > in our comm van.  The tracker batteries have the same charging
> > characteristics as the van main gel batteries so they take advantage of
the
> > van's sophisticated charger.  We also modified some switching "wall
warts"
> > for recharging  elsewhere.  They have been used on a variety of vehicles
and
> > some  helicopters and airplanes (inside).
> >
> > Bruce Gordon
> >
> >
> >
> > ----- Original Message -----
> > From: "William McKeehan" <mckeehan at mckeehan.homeip.net>
> > To: <aprssig at lists.tapr.org>
> > Sent: Thursday, September 22, 2005 1:32 PM
> > Subject: [aprssig] Group Tracker Build Projects ?
> >
> >
> >> Does anyone know of any groups that have built several trackers for the
> > group
> >> to use during events? Not the property of any one individual, but the
> > property
> >> of the group?
> >>
> >> OR any individual that has built several trackers for deployment during
an
> > event?
> >>
> >> I'm looking for recommendations on 1) configurations used; 2) bulk
> > discounts
> >> available and 3) any tips on such an effort.
> >>
> >> --
> >> William McKeehan
> >> KI4HDU
> >> Internet: mckeehan at mckeehan.homeip.net
> >> http://mckeehan.homeip.net
> >>
> >> _______________________________________________
> >> aprssig mailing list
> >> aprssig at lists.tapr.org
> >> https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig
> >>
> >>
> >
> >
> >
> > _______________________________________________
> > aprssig mailing list
> > aprssig at lists.tapr.org
> > https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig
> >
>
>
> --
> William McKeehan
> KI4HDU
> Internet: mckeehan at mckeehan.homeip.net
> http://mckeehan.homeip.net
>
> _______________________________________________
> aprssig mailing list
> aprssig at lists.tapr.org
> https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig
>
>
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