[Premium-Rx] Racal A6A1 Board Setup Help Needed

[Guy Atkins]

Hi Larry,

Thanks for taking the time to comment.

I've check the receive & transmit lines, and I have those correct. My CPU
board & software are the same as you describe.

Since you mentioned that removing LK1 on the CPU board is definitely
required per your manual, I tried it again. Unfortunately the results were
the same-- all zeros across the frequency & BFO display, and only "00"
showing on the mode LCD. It acted totally locked, would not accept keyboard
entry and wouldn't go into BITE. I installed the LK1 link once again, and
the receiver returned to manual operation.

I'm pretty sure the A6A1 board must be good, as I got it from Allen Bond of
Max Gain Systems. The board is also marked "OK" on the bottom in marker pen.

I've verified receiver address of 99, and have tried both 9600 and 19200
baud. I've set flow control to NONE to disable the rx handshake issue. I've
also tried two PC's serial ports, each with Hyperterminal running under
WinXP and Win98. BTW, I've had no problems with controlling other receivers
through the serial port on the WinXP computer, so I know it works well.

I think at this point I'll button the rig back up and get it installed in my
rackmount case, as I've not really had a chance to use the RA6790GM for any
serious DXing yet. Manual rx control is better than no control at all <g>

Thanks again for your and everyone's help. If anyone else can shed some
light on the LK1 link issue for the CPU board, I'd appreciate it. I'm
puzzled why the radio goes brain-dead when I remove it.

Guy



-----Original Message-----
From: Wm. L. Townsend [mailto:wlt at tesnet.com]
Sent: Saturday, February 21, 2004 10:30 AM
To: Guy Atkins
Subject: Re: [Premium-Rx] Racal A6A1 Board Setup Help Needed


Guy,

Some comments on your questions & problem:

1. If you haven't determined that the transmit & receive lines are on
the right pins to the pc that could certainly be why it isn't working.
Looking into the 9 pin connector on the cable from my rx that plugs into
the pc, pin 3 is about +2.6v with respect to pin 5 (ground). That seems
low for rs-232, but the driver is an AMD29LS30 running from +/-5v, so I
guess that's about what should be expected. Pin 2 is about 0v.

2. The 6790 won't do much if it doesn't like the commands you send it.
There's no error response, so it will just lay there like a rock if it
isn't happy with what it sees on the serial input.

3. Commands for the rx are all upper case. Lower case stuff is ignored.

4. The rx has no provision for handshake on the serial interface. Be
sure you disable xon/xoff and RTS/CTS on your terminal program.

5. The configuration inputs on the rx serial connector have internal
pullups, so if a pin is open, it's high as far as the rx is concerned.

6. From the documentation I have, the receiver serial interface uses 7
data bits, optional parity, and 2 stop bits. It will work fine with a
terminal program set to either 7 or 8 bits as long as parity is turned
off (no connection to pin U). My rx is running right now and it doesn't
care whether I set the terminal program for 7 or 8 bits. The 8th bit
just looks like an extra 'stop' bit to the rx which won't hurt anything.
The pc side also seems happy enough when set for 8 bits, probably
because the packets from the rx are fairly short. I'm running it at
19200 baud.

7. The rx address is BCD, so it can be anything from 0-99. Leaving all
the address bits open will result in a bogus value so the rx will
probably not work, although I've not tried this. You need to configure
the connector so that the rx sees an address in the correct range. (I'm
using 37, as shown on the Visualradio stuff.)

8. I've never seen the CPU and serial boards you describe. All the
documentation I have is for the CPU with 3 proms. There are at least a
couple of software versions for the 6790s. Mine claims to be '9666' from
the labels on the proms. This rx has the signal level data in serial
responses, tune rates are 1, 30, and 1000Hz, and it will accept any
frequency (down to 0.0000000) from the keyboard. It works down to about
20-25kHz, but the sensitivity is not very good below 500kHz.

9. From the description in my manual, LK1 on the CPU board (not the
serial board) definitely needs to be removed if you connect the serial
board.

Hope maybe this helps,

larry/wa8ulo
--
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Wm. L. Townsend
TES, Inc.
Cincinnati, OH    USA
(513)661-3200 fax:(513)661-3732
www.tesnet.com
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