[aprssig] Garmin GPS 18 PC

Gary n6lrv at cox.net
Sat Mar 14 14:27:29 EDT 2009

I see. I'm only a technician not an engineer so I don't make such assumptions about diagram symbols.
Speaking of assumptions, if "many people" are cutting off the lighter plug of a GPS18PC and still
applying 12Vdc then they get what they deserve, a fried GPS receiver. Garmin can not be blamed for
this nor any misinterpretation of their diagrams. I feel you were incorrect when in your original
posting about Garmin claiming a 12Vdc input in their specs for the GPS18PC, it was designed for it
and works fine as designed. As with any device this spec applies to the device as it is supplied by
the maker, in this case with a voltage regulating lighter plug on the power cord. If someone chooses
to cut it off for any reason then Garmin bares no burden of responsibility for damage resulting from
this unauthorized modification. I think both our points are now well taken by the group so we should
probably move on.

From: Stephen H. Smith

The "power source" with blocky rectangular outline with big stud 
terminals on top sure looks like a car battery to me.   It was a very 
bad and careless choice of symbol.  An outline of something like an AA 
cell with a bump on one end, or just a box with + and - characters 
inside it with "5 VDC" between the two signs (i.e. suggestive of a bench 
power supply) would have been far better. 

I pointed this out in my original post.   However, many people don't 
realize that active regulator circuitry is "hidden" inside the lighter 
plug.   They assume that you can just cut the plug off and hardware 12 
VDC directly to the remaining lead.     Over the years there have been 
several "disaster stories" on various APRS-related mailing lists from 
people who have done exactly this.  

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