What is this Triplexer for? The installer left it in the 722 empty box.

66137

It is used for "backfeeding" signal for tv2 If your rec is just hooked up to 1 tv our tv2 is hardwired it is not needed.. Go get a couple bucks for it off of EBAY...LOL

What is the purpose of the third output, UHF/VHF?

That is for TV2. You need another diplexer at another point for it to work..

Thanks, I found this on line which shows all the connections.
I guess you would use it if you don't have regular access to TV2 from the receiver location.

66140

Correct. You get a better picture if it is hardwired in.. Rather then using the triplexers and diplexers.. Before that triplexer came out.. We had to put another diplexer there.. It just saved us installers a little bit of time..

If I have some separators in my van. And the triplexer is not needed I usually put in the separator also. It just removes one thing out of the system that can go bad..

I think you can also use it for your OTA antenna.

I think you can also use it for your OTA antenna.

Yes you can. To put it simply its just a way of allowing you to use a single cable into the house vs two or three for one box.