To take this thread a step further, in my "junkbox" are two Delorme
Earthmate GPS receivers formerly used with laptop computers. For some
reason, the output from these units does not convey location information
to my radio. (I have not yet tried it with the autotiller.) My guess
is that there's a baud rate problem. I'm not aware of adjustable
settings on the units, which are said to be NMEA compliant, but it seems
that there MUST be a way to switch from RS-232 to RS-422 in order to
utilize the NMEA output feature. I've found Delomre tech support to be
of absolutely no help with off-the-wall questions like this.

padeen wrote:
Thanks for the explanation, Meindert. You've allayed my suspicions 1/2 way.
Padeen

"Meindert Sprang" wrote in message
...

"padeen" wrote in message
...

That's $250 US for a box with some connectors all wirenutted together
inside. "Optically isolated" means you can't see the wirenuts! There

must

be a less expensive way...

Well, an expander is bit more complicated than just a 'junction box'. It
contains an opto-coupler wich takes care of the optical- or galvanical
isolation. Next, there are a few buffers to give each output enough power

to

drive the required four listeners per output. And then the power supply,
this might vary from a simple three-terminal regulator to a more expensice
DC/DC converter (also isolated). Put this on a PCB, stuff it in a box, add
the usual markups and there you are at a pricelevel of around $150. So
indeed, $250 is a bit over the top.

Meindert