OK, here's what I've learned so far:
>>I would try reconnecting the +5 volts to both the receiver and transmitter boards. Then try the none choice for the transceived house codes.
Remember if both the TM751 and the CM15A receive the signal from the HR12A Palm Pad. Both may show in the Activity Screen.<<
I did this except that I removed the transmitter daughter board completely -- no use for it and conceivable RF interference -- left the single transceived house code on for the moment, and also unplugged the TM751. In this configuration I had essentially the same problems as before except that commands executed directly from the CM15A were now listed as "Macro" in the log instead of "Transmit" -- a small improvement. In particular, although remote RF commands (if the remote was very close to the CM15A, but that's another issue) were executed, they either didn't show up in the log at all or produced bursts of meaningless garbage in the activity log. Similar results were obtained with remote (wired) commands. (Note that this last problem, at least, cannot be avoided by improving RF reception by.CM15A and elimnating the TM751! The CM15A just is not detecting remotely executed commands correctly.) In fact either kind of remote command often seemed to permanently lock up the log.
Setting tranceived house codes to "NONE" was no help at all except, of course, that the RF commands were not executed.
Added back the TM751 solved the latter problem, of course, but also produced bursts of garbage and/or lock-ups in the activity log.
>>If that doesn't do what you need.
You can tie pin 9 of the RX3310 chip on the receiver daughter card to +5 volts. I used a 100K 1/8 watt in my preliminary tests and a 10K 1/8 watt in my modification.<<
Electrically disabling the RF receiver in this way appears to be the best configuration for me, as RF reception by the CM15A is blocked, producing no garbage or lock-ups in the log. But all of the other problems continue, including garbage and lock-ups due to RF commands executed by the TM751. It's as though the internal (macro and ActiveHome-issued) commands work OK until a few external commands are detected, an then problems begin. (As discussed in thread,
http://forums.x10.com/index.php?topic=27918.0, I also tried an earlier version of ActiveHome Pro that was advertised to help with this, but his did not solve the most annoying log problems.)
The main problem for me remains that it's difficult to determine what a "program" actually does (especially with dawn/dusk and/or "security" options) without being able to rely on a recorded log during the testing phase... -- jclarkw