[NA-User] IC-746 Works!

[dap14@daimlerchrysler.com]

Randy Farmer wrote:

"I do seem to get quite a few spurious "Radio is out of contest band"
indications, so maybe 9600 is a bit fast."

This is not a problem of baud rate, but more a symptom of ICOM's poor radio
interface design.  ICOM ties the transmit data (TXD) and receive data (RXD)
lines together between the CT-17 RS-232 interface and the radio.  If NA
tries to talk to the radio while the radio is already broadcasting
frequency data, the transmissions collide and the messages get corrupted.
Depending on the timing, NA may try to interpret the corrupted data and a
"Radio is out of contest band" results.  Kenwood and Yaesu radios don't
have this problem with NA.

There is way to minimize this problem.  ICOM radios have a feature called
"transceive" associated the radio control interface.  If transceive is
turned on, the radio continuously broadcasts its frequency and mode
whenever the VFO knob is turned, transmit-receive transitions occur, etc.
The intent of this feature is to allow two ICOM radios to be synchronized
where turning the VFO on one radio causes the other radio to follow.  I
can't conceive of any situation where this would be useful to a contester.

By turning transceive OFF, the radio only reports frequency and mode when
asked by the logging program.  Since this reporting will now only occur
when NA "expects" it (once every three seconds for Yaesu radios, once every
one second for all other radio types), there are fewer collisions and
hence, fewer "out of band" indications.

On most newer ICOM radios, turning transceive on/off is a menu item.  On
older ICOMs like KC-765, IC781, etc. transceive on/off is controlled by a
dip switch inside the radio.

Dave/K8CC





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