[Premium-Rx] Follow-up: RA6790GM Remote Control Board Troubles Solved

[Guy Atkins]

Hello Group:

A few weeks ago I posted a plea for help with the A6A1 Remote Board for the
Racal RA6790GM. Despite many extremely helpful postings and personal emails
from the Prem-RX group members and careful study of the manual and searches
on the Web, I could not get responses out of the receiver.

The problem turned out to be a faulty A6A1 board I had purchased. Allen Bond
at Max-Gain Systems was very helpful and was more than happy to send me a
replacement board to try out. The original board could "talk" to the
RA6790GM just fine, but not "hear" any of the receiver's responses such as
signal level, current parameters, etc.

The new board works just great at the full 19,200 baud rate, both through
WinXP Hyperterminal and W6GER's Virtual Receiver program for the RA6790GM.
All parameters, commands and responses both to and from the receiver work as
they should. Now that I know the RA6790GM communicates correctly, I'm really
looking forward to the forthcoming Racal driver in the ERGO receiver control
software.

As a side note, I've removed the 400 Hz and 16 kHz filter modules from the
receiver, and installed a couple of crystal filters that I on hand. One is a
2.4 kHz Kenwood-labelled large crystal filter, and the other is a 1.8 kHz
crystal filter from International Radio (INRAD).  I used very short lengths
of RG-174 coax from the I/O & ground connections on the filters and
fashioned proper diameter "pins" from brass rod stock to insert into the A4
Board. The receiver's BITE test recognized the new filters immediately and
placed them in order with the existing bandwidths. I'm very pleased with the
perceived ultimate rejection of the new filters-- definitely much better
than when they were used in an AOR AR7030 I owned. The entire system's
ultimate rejection clearly contributes to the improved performance of the
2.4 and 1.8 filters. The line-up of voice filters in this Racal is now: 1.4,
1.8, 2.5, 3.3, and 8.0 kHz (measured BW's).

Thanks to all in the Prem-RX group who took the time to offer many
suggestions with the A6A1 problem, and to Allen for his willingness to swap
boards.

Guy Atkins
Puyallup, WA