[Premium-Rx] Racal A6A1 Board Setup Help Needed

[Guy Atkins]

I have a newly-installed A6A1 remote board in my Racal RA6790GM, and the
setup has me stumped. I'm attempting to verify that it's communicating in
RS232 protocol by following the instructions at
http://vradio.home.att.net/Racal_6790.htm

I've followed everything exactly and checked connections, but I cannot get
any response when using Windows Hyperterminal. One thing that puzzles me--
the instructions at the web site mention settings of "8 bits, no parity N
and 1 stop bit", while the RA6790GM manual on page 3-21 says "The data
format used for remote control of the receiver via the serial asynchronous
interface is the standard ASCII asynchronous format which consists of a
start bit, seven data bits (one ASCII character), a parity bit, and two stop
bits." This sounds like conflicting information to me, but I'm not
knowledgeable enough on serial communications to say for sure.

I've tried settings both ways, but still get no response through the
terminal program. Just to see if the PC and receiver are communicating, I'm
sending a "S2" command to put the Racal in REMOTE mode, but no luck yet.
Like the web page indicates, I've set up the rig for an address of 37, and
send the full command of "$37S2".

What is the receiver's default address if connector pins K through T are
left open? Perhaps it results in no address at all. (I don't understand the
receiver parameters in Table I on schematic page 7-31.) After I got no
results with various serial port settings and the receiver wired for address
37, I returned pins K through T to their open state and tried using
addresses of $00, $01, and $99, thinking that maybe one end or the other of
the address range would be the default with K through T "open" (ungrounded).

I also tried various combinations with pin U grounded for parity, based on
the info from manual page 3-21, without success.

Any tips to get this board up and running would be appreciated. BTW, all my
efforts have been with the baud rate at 19200, and with connector pins W
through Z left "open".

Guy Atkins
Puyallup, WA USA