[NA-User] 2 radios - 1 COM port

k8cc k8cc@comcast.net
Wed, 13 Mar 2002 22:56:54 -0500

If you look at the schematic for the CT-17 (at least I got one with mine) 
all four radio jacks are wired in parallel.  The CT-17 doesn't keep 
anything straight - it counts on only one device (either a radio or the 
computer) talking at a time.  This is also due to ICOM's decision to tie 
the rx data and tx data lines together.  If two devices talk at the same 
time, data collisions occur and the data gets scrambled.  This is general 
the reason why you see erroneous "RADIO OUT OF BAND" messages with ICOM radios.

Tip #1: Turn OFF the TRANSCEIVE function in your ICOM radio, either by a 
menu or by the DIP switch inside the radio.  This function has no benefit 
when used for HF contesting with either NA, CT or TR, but it causes the 
radio to spit out data continuously while the VFO is being turned.  This 
leads to data collisions.

As currently designed, NA cannot do what WX3M has described.  The reason 
for this is that the serial port functions, as configured in CONFIG.EXE, 
allow only one *serial data* function per COM port.  (Note that I said 
*serial data* - you can share serial data and CW keying on a single COM 
port).)  You can't assign RADIO1 and RADIO2 both to the same serial port.

The only guy I've ever spoken to who uses the "two radios on one COM port" 
configuration is Phil, KT3Y in VA.  He does it with CT, using (as I recall 
at the time) a IC-775 and a IC-765.  I pondered the merits of using a 
single COM port, but nobody ever asked about it.  Leave it to my friend 
(and SO2R "deep thinker" WX3M).

Don, if you want to try it, I could kludge up a special NA version to try 
with your setup.  I'm not altogether sure how satisfactory this is going to 
be, since with two radio on the CT-17 there will be more opportunities for 
data collisions.