Diplexer Dilemma

[Gatormanpaul]

Have 2 different scenarios I need to address that require using diplexers. I have bought Radio Shack Diplexers that are DC Pass on both sides. Both of my scenarios involve using the diplexer to send the directv signal from the dish to my living room HD and Tivo units. On the HD unit, I need to send a signal from a over the air antenna that I'm installing on my roof. It currently does not have a preamp, but I'm pretty sure I'll need one. I'm behind a hill and have not been able to get a signal in my front yard. Will this dual dc pass diplexer work for this application...with and without a preamp?

The other scenario has to do with using the same dc pass diplexer to send a modulated signal out of my VCR to get it up to an amplifier in my attic. I would assume I must diplex it back out before I amplify that signal. Will these work for this application also? Thanks so much for any advice!!!

[boba]

I'm not totally clear on whatyou are doing but you need to use diplexers in pairs. One combines the signals and another divides the signals back out. Of the two diplexers the one going to the antenna with a pre amp can be voltage passing the one in the house going to the TV should be voltage blocking on the TV ant side or you will be sending DC voltage to the TV tuner. A diplexer is used to combine a satellite signal and a cable frequency or OTA frequency signal. If you are just sending the output of a VCR back it dosen't need a diplexer unless you are combining it with a satellite signal.

[jdspencer]

You need to use diplexers that DC pass only on the Sat leg so that the LNB or integrated multiswitch gets the switching voltage. If you add a preamp to the OTA side, the power inserter needs to be on the OTA side of the upstream diplexer. Otherwise the preamp power can interfere with the LNB switching.

I currently use one sat line to diplex my OTA to the HD receiver and a different line to diplex the RF output of the HD receiver back down to a modulator for distribution to other TVs in the house.

[Gatormanpaul]

Thats good to hear you are doing this!! Just so I'm clear, that means that the dc pass aspect of the diplexer should not be a problem for me? So I can use it with or without an amp on the OTA leg and can also use another set of diplexers for use with my vcr out to the house? I read something on a post about the dc pass causing damage to some components.... Thanks for the help!!!

Here is what I need to work:
Coax 1: Dish to HD sat receiver and OTA Antenna to HD sat receiver sharing a coax. (diplexer on each end breaking signals out)

Coax 2: Dish to Tivo and VCR up to amplifier in attic. (diplexer on each end breaking signals out)

OK to use the DC Pass diplexers for both these?