Here's the equipment rundown:

TV: Mitsubishi WL-82913, Mitsubishi LT-2240, Sony 23" LCD
Satellite: DirecTV - HR20, D12, and D10

The issue is the both Mitsubishi sets respond to each other's IR commands (power, channel, etc.). Neither have menu options to adjust remote settings. I can use the RF-IR wireless extender that comes with the 890 to control the WL-82, but from what I can tell, the IR receiver is behind the screen, leaving me no place to mount the IR emitter.

I have the DirecTV boxes all set up with the IR emitters coming from different ports on the Harmony Wireless Extender, but they still respond to each other's commands (i.e. Channel up on any box - which is going RF-IR - changes channel on all the boxes). The HR20 has a RF mode for the remote, but the "RF" 890 only can send RF commands to the extender box (at least as far as I can tell).

Just wondering if anyone has advice on where to go from here and if there is a better remote solution to control this equipment than the Harmony, without going down the professional-installed route (been there).

Thanks in advance.

In the Harmony software did you assign your DirecTV boxes to the correct port or did you leave it set to ALL? Using one of the four ports for each box and assigning it to that port shouldn't cause your problem. To troubleshoot your issue I would completely unplug the cable from the RF extender port and send a command to that DirecTV box. If the other box still responds to that command then you know you've got the software setup incorrectly.

Each of the 4 devices coming off the wireless extender is using it's own port. I'll do the test you recommended here a little later today.

I'm beginning to the think that I may just have to use the Harmony to control the main TV, main DirecTV box, and have the side TVs controlled by the individual DirecTV remotes. IIRC, the DirecTV boxes only have 2 different remote settings though, correct? Which means, I may still have problems. The other issue is that I can't have the smaller Mitsubishi plugged in at all otherwise it turns on with the larger one.

How do you get your TVs to work now with the original remotes? I'm not sure how you would get around your issue with two TVs using the same codes in the same rooms no matter what remote you choose.

One solution, once you get your port addressing sorted out, would be to run an emitter to one of your TVs and put black tape over the emitter and the rest of the receiving sensor. This would keep signals from the other TV from bleeding into this one. Set up the software to control only this TV from that port and the other TV from the remote itself.

To make them operate independently, you need to go into the remote setup in each of the directv boxes and assign them different codes in "Receiver" mode (follow the onscreen instructions), i.e., box 1 is 00001, 2 is 00002, etc. (the HR has 2 possible codes, and the D's have 4 possible codes, IIRC, so there are plenty to do what you want to do). Then do the same on the harmony side. I have no idea how to do this on a harmony, but it is easily done on an RF JP1 remote like the URC-9910. Using directv native RF is only possible with the OEM remote, and it disables IR, so that's not an option. Do you really need RF anyway? Not using it may solve your TV problem since you'd have to aim the remote straight at the TV you want to control, hence not affecting the other (assuming they're not right next to each other. If they are, that just doesn't make any sense). You could at least remove the repeater from one of your TV's. And keep in mind that the emitter doesn't have to be right in front of the device. It only needs a good line of sight, but could be a few feet away.

Each directv receiver knows only two IR codes, no matter what it says in the on-screen menu. For the D10 & D12 the codes are 00001 & 00002. For the HR20 they're 00001 & 00003. So with D10 set to 00001, D12-00002, and H20-00003, you should have no more trouble with conflicts.

Thanks.