I'm not sure if this is in the right forum. Please move if necessary.

My question is: can I use a modulator like the Cable Electronics 1001ST Stereo RF Modulator in a DTV system that has qty 4, H20 receivers? Since I expect to have my local channels soon, I will not need an OTA system and thus do not have OTA wiring throughout the house.

If so, how do I set it up?

What are you trying to do with the modulator?

Let's say I wanted to distribute an outdoor camera signal to any of my 4, H20's
via a UHF channel selected by the modulator. I would like to be able to use any unused UHF channel. Can this be done, and how would the connections(wiring)
be made? How would the UHF channel be selected by the H20's?

Sorry if this sounds like a dumb question. I know it would work if I had an OTA
wiring system throughout my house. But, I am trying to avoid all the extra wiring and just use the same coax's that feed the sat signals to the H20's.

If your outlets are homerun to a multiswitch, just connect the modulator to the terrestrial input of the multiswitch and install a diplexer at each receiver. If the outlets come straight from the dish, you could run a cable from the modulator to the dish, where you would connect it to a 4-way splitter. The 4-way splitter would then feed diplexers that you would install on each of the cables going to the outlets. You would still need a diplexer at each receiver to separate the locally modulated signal from the satellite signals.

I am presently installing a new slimline dish with a Zinwell multiswitch for the new satellites. There is no provision on the multi switch for an OTA like in the 'good old days'-----lol.

You can't use diplexers with the new dish, it overlaps the OTA range now. I don't believe the H20 has an NTSC tuner either so you couldn't feed something from a modulator into it anyway.

I believe you are gonna be stuck running additional wiring and will need to make sure your sets have NTSC tuners in them.