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[aprssig] Re: Placer 450 GPS

Al Wolfe awolfe at Route24.net
Wed Jul 27 04:33:08 UTC 2005

    As someone mentioned the Placer 450 GPS was an early Trimble 8 channel 
unit. They came in several configurations. They may have 1, 2, or 3 DE-9 
connectors on them. Looking at the back of the unit, the left most DE-9 is 
the RS232 I/O data port. The other connectors supported an MDT or other 
options or RTCM.
    They want 10 to 32 VDC, nominal 250 ma. The lithium battery is good for 
5 years. There is usually +5 vdc on the antenna jack for an amplified 
antenna. Seems like there may be couple of pads on the bottom of the PC 
board to get you the 5 volts if it isn't there.
    The info on Trimble's web site is probably enough to get one working. I 
never got around to using one for APRS, but did determine that they worked 
and could put out NMEA data. They should work OK for APRS. Look for a file 
"450-455.pdf" on the Trimble web site for info. Also, I found a file there 
called "pla450CDPD-Firmware250.exe" that I think is the software to 
configure a 450.
    It's been a couple of years since I played around with a Placer 450 so 
hope this info is correct.

Good luck,
Al, K9SI 

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