On Fri, 29 Jul 2005 12:36:59 -0400, Jon Gauthier
wrote:

Another question - and I know this has been hashed before but a search
didn't turn up the answer:

In a network with NMEA equipment from different manufacturers in which
some equipment has a real, separate NMEA (-) lead and other equipment
that takes the cheap route and uses DC ground for the signal return, is
it best to just leave the NMEA (-) leads floating, or run them to DC ground?

I do have a DC ground bus bar for all my nav equipment (including VHF
but no SSB) that ties back to the main DC ground bus using a #6AWG
cable. According to my stereo's AM band, the system seems electrically
quiet

For a differential talker going to a single-ended listener, I'd leave
the talker's (-) lead unconnected.

For a single-ended talker going to a differential listener, the
listener's (-) lead _must_ be grounded. Theoretically, it should be
grounded at the talker's ground terminal, but for practical purposes,
any point on the vessel's DC ground should work.



--
Peter Bennett VE7CEI
email: peterbb4 (at) interchange.ubc.ca
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