[aprssig] NMEA Sentence problems into SCS Tracker....from GarminEtrex

Jack Chomley radio at irock.com.au
Mon Nov 26 03:44:39 EST 2007

At 08:49 AM 25/11/2007, Stephen wrote:

>You don't need any complex regulator.  Just pull up the DATA IN line 
>of the GPS to any convenient source of DC through a 4.7K to10K resistor.
>As long as you have the current limiting of a series resistor, the 
>source voltage can be higher than the normal data-in voltage level.
>A simple fix without modifying any existing cables is to use one of 
>the male-to-female serial-cable patch blocks used to make custom 
>adapters for serial cables.  (These are typically grey plastic boxes 
>with a female DB9 or DB25 on one end, a male DB9 or DB25 on the 
>other, and a small PC board inside where you solder jumpers and 
>crossover connections between the two ends.   They are sometimes 
>referred to as "mini-patchers", and are available at almost any 
>store that sells computer or electronic supplies, even Radio 
>Shack.  Note that these are not the common gender changers with the 
>same sex connector on both ends, or "null modems" that have fixed 
>wiring inside.)
>I connect the common and DATA OUT lines (data out relative to the 
>GPS) end-to-end straight through to like-numbered terminals.   I 
>then connect the resistor and external power lead to the DATA-IN 
>terminal on the end facing the GPS but NOT to the end facing the 
>computer or TNC.   Drill a small hole in the plastic cover to pull 
>the power lead out. You can then just unplug your existing GPS cable 
>from the TNC and sandwich the adapter block between the TNC and the 
>existing cable.
>Stephen H. Smith    wa8lmf (at) aol.com
>EchoLink Node:      14400    [Think bottom of the 2M band]
>Home Page:          http://wa8lmf.com --OR--   http://wa8lmf.net

I made up the adapter cable between the Garmin OEM cable and the SCS 
Tracker and powered it off a 12v gel cell battery and it worked fine, 
drawing about 1.5mA. I think the Etrex is working better than the old 
Magellan 315, judging by the signal levels coming from the Sats.
My test today, was a success....


Thanks for the help :-)




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