Good to know, I don't have to buy another unit. I put the CH50 on-line as primary and unplugged the TM751, I sometimes need more than 16 units running, but they are mainly temp things. I don't remember what came with the CH50, it's been bouncing around for years.
To tell you the truth, I've been using this same TM751 with AH and the CM11A for about a decade and never had issues. I was forced to upgrade when I got a new computer running windows 7. I have more problems with the new setup, like my 'random turn on' thread.
Years ago I "upgraded" to AHP, but it was so unreliable, I sold it and went back to AH. I would switch back in a heartbeat.
The RR501/HC50 are limited to one house code only. You need an additional one for each house code you want to use with RF.
The CM15A was designed with an RF transceiver built into it, with the goal of not needing other RF transceivers (like the TM751 and the RR501/HC50). It can handle all 16 house codes (and you can pick which ones it passes along to the powerline - if you want to block RF transmissions from neighbors, etc).
In reality, however, the design was somewhat flawed. Most users don't get very good RF reception with the stock (unmodified) CM15A. There are a number of mods out there for adding external antennas, and most users who have done them have reported really great results, depending on the individual circumstances and the specific mod performed.
In my case, I did the simple "reflector" mod, which doesn't involve opening up the CM15A, or voiding the warranty (which had long expired in my case, anyway). This is the simplest mod I know of, and takes no more than a few minutes to perform.
For this mod, you simply attach an 18.5-inch length of wire alongside the CM15A's existing external antenna. No electrical connection is made between the two. The longer wire simply acts as a "reflector," to redirect the signals to the CM15A's antenna. I've done the mod twice, on two different CM15A's. Originally, I used two small pieces of masking tape to hold the wire on. I later cleaned that up with a spiral wrapping of some electrical tape. On the second unit, I slipped a length of heat-shrink tubing over the CM15A's antenna, and inserted the new wire. It was a tight enough fit that I didn't even need to shrink the tubing down.
I now have really great RF coverage in my entire house, where I barely had a few feet of range before.
You might want to try this as a first step. You might find that you can remove the RR501/HC50 units from your setup, simplifying the whole arrangement. If you feel more adventurous, you can look for the mods that replace the antenna with either a longer telescopic antenna, or a connector for you to connect to a more centrally located external antenna.
