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[aprssig] Pocket Tracker???

Robert Bruninga bruninga at usna.edu
Sat Nov 19 02:21:58 UTC 2005


Scott says:
>This might interest you [for an APRS TX kit]
> http://www.sarl.org.za/forum/topic.asp?TOPIC_ID=249 

Please tell him to keep it at 12 watts and don't
cut it back to 5W!

The duty cycle of an APRS transmitter even at
30 second rate is less than 3%.  Thus the
12 watt device (probably takes 25W DC
input power) but at 3% dutycycle this is only
an average device dissipation of 750 mW
and can easily be dissipated by just the
PCB.

Yet the difference in reliability between
a 5W and a 12W tracker is very significant.
Also, he can assure no burn-out abuse by
making sure there is a 1 second RC time
constant on the PTT line, so that it can
never be in TX more than a second at a time.

I cannot email him because I am not on the
reflector.  But if the thing can do 12W then
we want it to do 12W!

Thanks, WB4APR

>>> scott at opentrac.org 11/18/05 8:53 PM >>>
> I noticed this too. I went to their website and saw that they 
> are no longer around. Does anyone know of another similar 
> platform that is small and would fit this niche? I wanted to 
> get one but it looks like I was a little slow on the trigger.

This might interest you:

http://www.sarl.org.za/forum/topic.asp?TOPIC_ID=249 

I have one of the prototypes on my desk, and if time allows I'll be
integrating an OpenTracker processor with it this weekend, removing the PIC
and having the OT take over PLL control.  However, I can't promise anything
on when or if this combination might be available in production.  It seems
to be a nice transmitter for tracker use, but you wouldn't want to use it
for connected mode packet or anything - it's meant for low duty cycle use
and gets hot fast.  On the other hand, it puts out 20 times more power than
the Pocket Tracker.

I know of one other foreign (non-US) project working independently to
integrate the OT with a synthesized transmitter.  I've also heard about two
projects to produce small low-power transmitters that might be suitable,
though I'm not directly involved in either effort.  In any case, multiple
people are working on this sort of thing and I expect SOMEONE will have a
superior replacement for the Pocket Tracker available next year.  So have
patience.  =]

Scott
N1VG




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