[ICOM] Warning about W1GEE interface cables

[Doug Faunt N6TQS +1-510-655-8604]

   From: "Dave Bernstein" <aa6yq at ambersoft.com>
   Date: Tue, 1 Jun 2004 21:29:18 -0400

   Since the transceiver side of the interface is a simple TTL
   open-collector bus, it is indeed challenging to guess what the W1GEE
   circuit must be doing to reliably fail with two specific transceiver
   models. Anyone have a W1GEE schematic?

If the two radios require that the "low" voltage to be slightly lower
then the other ICOM radios, and the W1GEE I/F doesn't quite pull that
low, that could be the reason.

I was building some interfaces, and found that some radios required
that the pull-down be a little closer to ground then standard
opto-isolators would provide.  I found some NEC components that are
called "solid state relays" but could also be described as
opto-isolators with FET outputs, that did the trick.  The PTT circuit
in the IC706MKIIG data interface (as opposed to the ACC connector) had
the problem, to bring it back to ICOM rigs.  Look in the Mouser
catalog. 

I think people have had this problem with FSK keying on the FT1000's,
also.

73, doug