That was the first thing I did with the USB/RS232 cable - I set the port to Com1. I verified that the command was working by changing it to Com2, and then back again to Com1. Lady Heather displays the Com port very prominently. I also set the speed, etc. Those steps gave me some confidence that the BG7TBL and the PC were at least communicating at some minimal level with the USB/RS232 cable.
In the eBay ad it says:
4.3 Connect PC
GPSDO-DB9 PC-DB9
PIN2--------------------PIN2
PIN3--------------------PIN3
PIN5--------------------PIN5
PIN8--------------------PIN8
GPSDO-DB9 PIN2,PIN5,PIN8 is connect to PC-DB9 PIN2,PIN5,PIN8,
Baud rate is 9600BPS,Baud rate is fixed.
Normally, I would expect Pin 2 (RX) to talk to Pin 3 (TX) but I confirmed with the seller that the pins assignments are as specified in the eBay ad. The seller refers to his pin assignments (above) as "direct connect". In fact I confirmed that the cable I am using is "direct connect" by checking continuity from one connector end of the cable to the other connector.
(And I'm certain that with the PC's RS232 port the BG7TBL is working fine with Lady Heather - so I'm very confident that the software and the GPSDO play well together).
In case it helps, in the photos I posted above there is green activity on the 2 RX, 3 TX, and 8 CTS pins - as the eBay seller specified in the ad. 4 DTR and 7 RTS are permanently red. That leaves 5 GND (which the seller acknowledges is in use) plus no activity on 1 DCD, 6 DSR, and 9 RI - none of which we would expect would be used.
So I'm guessing that the USB to RS232 cable that I'm using is wired differently than as per the "direct connect." I don't quite get the USB architecture and how it maps to some or all of the pins on a DB9 - but with the USB to RS232 cable some commands (such as port, speed, etc.) are getting through - but the /rx auto receiver command isn't working and none of the other commands to set the receiver type are working (I tried them all I think).
Either I need to figure out the command to set the receiver using the USB/RS232 cable (similar to how I set the Com port and speed), or I need to get a better/different USB/RS232 cable. (The RS232 to RS232 connection is fine on the current PC but most other computers are not going to have a DB9 RS232 port and will need a USB port).
You need to tell Heather what serial port number that the OS is mapping the USB converter to (use the Windoze device manager). To set the com port number use the /# command line option where # is the com port number... also note that Linux,etc is a bit different). If you don't specify a port number Heather will use COM1.