I have Comcast with a digital package and I would like to make my own channel through the house. Will this RF Modulator and a channel combiner do the trick and keep the Comcast signals plus On Demand working? ONETWO
It's getting very difficult to find a "free" space available to modulate your own channel on CATV systems these days. Especially if your systems has eliminated most or all of the 'analog tier'. There just isn't any space left. That said, either of those devices should work, if you can find a big enough hole to insert the channel. Note that these products need at least 3 free 'channels' to work - one in the middle for the in-house channel, and one on either side for interference (it'll trash both adjacent channels, at least).
Between 64 and 70 are free channels. I have a fully digital service with On Demand too! Will it effect the digital services?
That totally depends on the system. Channels that are open in one system may not be open in another system. Let alone, a year down the road. The biggest problem with eliminating digitally modulated channels is that an NTSC channel contains, typically, 10-12 SD digital channels. While eliminating one channel may cause you to lose a dozen digital channels, as jautor wrote, you would need three clear channels for one analog channel. That's 30-36 digital channels that would go away. Odds are that they wouldn't be adjacent channels, either. There's no way of knowing if digital channel 634, for example, is in the same NTSC channel as 635. Or even an adjacent channel.
The majority of the cable systems in the U.S. are 750MHz systems, which is channel 117. If you had a modulator that went above, say, channel 120, you might be okay.