Comments on: Recycle those old RF modulators

By: Elk M1 review

Elk M1 review — Tue, 08 Dec 2009 02:50:55 +0000

This is a pretty creative use of these modulators actually – I had a bunch I was going to toss so I googled it and this came up, now I’m not going to sleep tonight while I rewire my house, lol.

By: Michael

Michael — Wed, 04 Feb 2009 07:50:05 +0000

I have done this with my Tivo for years. I ran a second coax cable to each device in addition to the antenna and have A/B switches so we can watch Tivo or regular tv (regardless of what tivo is recording) anywhere in the house.

By: Shadow

Shadow — Tue, 03 Feb 2009 17:40:59 +0000

Its been awhile… Anywho for anyone not affliated with the FCC, I have been using a (newer) modulator , hooked into a battery powered amp and a custom diretional antenna as a means of displaying A/V from my laptop, as many of the bars & pubs in my area still use the old loop antenna’s on their tv boxes. Its a matter of finding a close seat and tuning though. Though naturally I don’t recommend trying this, but it brings hours of enjoyment, much like tvbgone.

By: Randy Wallace

Randy Wallace — Wed, 21 May 2008 02:59:24 +0000

This would be great to use for a baby monitor. You could have the babycam feed on all the tv’s in the house. I’m trying to figure out how to do this and not upset the wife by screwing up the cable feed. Can’t interrupt American Idol. Anyone have a link to someone setting this up?

By: Schnulli

Schnulli — Thu, 27 Mar 2008 00:36:21 +0000

Just a short comment about your warnings regarding the fcc:
I live in Germany in an area where TV con no longer be received via an analog antenna. They have stopped analog transmission about half a year ago. You must now use DVB-T, cable or sat. So it should not be a problem feeding the signal into the antenna cable. But I’ll test with my TV and a normal antenna if you can receive the signal over the air or just through one of the connectors, before I make the system permanent.

By: Larry Sanchez

Larry Sanchez — Sun, 23 Mar 2008 10:16:46 +0000

I seem to recall that when I was 15 I read that the modulators (specifically the type used in spectrums with rf output) can be simply modified to use as a transmitter by removing a few components. They only had a range of say 20m or so, with the right aerial but it would cut out the cable going from the modulator to the tv’s. Since it is such a low power I doubt the FCC would ever pick up on it.

I now work in a sportsbar and all of their distro for the tv’s at the tables (16 in total) is done using 10 rf modulators all hooked up on the one coax line feeding each tv – one for each source, and it works pefectly. I believe the signal is split using a 16 way rf amp.

By: chr0n1c

chr0n1c — Sat, 22 Mar 2008 04:26:46 +0000

i did this way back in the day with my apex dvd player and a sega genesis rf adapter and a tv with no composite inputs. you had to have the genesis ON to play dvds. (or i guess a 9 volt battery woulda workked) i just installed a switch to swap the vid signals out for dvd/sega. i ran all the audio through a component amp anyways so that was no biggie. HA! how many people actually bought one of those convertor boxes to do this?

By: Doug

Doug — Sat, 22 Mar 2008 01:20:21 +0000

I guess I haven't been keeping up with the times, don't VCR's and the outboard modulators for DVD players still use VHF? I was unaware any of the modulators for TV used double sideband as apposed to vestigial sideband. I have noted while they and be received on an adjacent channel, I have never seen them occupy 3-4 channels. Not that I'm saying the consumer goods are CATV quality. Nor that are they good enough to use 2 to feed 3 & 4 to the same system
atrain; I wouldn't have a clue what your device is. In that it has a UHF output, I doubt it is UHF to VHF converter. In the event it's an active (powered) device, perhaps a RF amp that splits the output? Otherwise a simple signal splitter.

Orv; In areas where their is Amateur TV activity those uses the ntsc standard cable ready television can be used to receive it.

Shadow; While it took 2 looks at the block diagram, I understood the antenna wasn't for transmitting.

By: Bullwinkle Jones

Bullwinkle Jones — Sat, 22 Mar 2008 00:43:44 +0000

This is completely unrelated, but I’ve attached an antenna to my cable-tv feed so that the FM radio also in the line is broadcast around my house… Works great.. wonder what the cable guys think about it!

I’m surprised that it doesn’t interfere with my cable internet somehow, allowing interference in the line and all..

By: Jake

Jake — Fri, 21 Mar 2008 23:51:53 +0000

@Schnulli: you can just stick in a few diodes and you’re sure not to mess with anybody next to you. Some catv spliters even do that for you … if not you can get a one way filter/

By: WeblionX

WeblionX — Fri, 21 Mar 2008 23:39:09 +0000

I've been thinking about doing things like this for a while, but I've never figured out what would be required to do this. The problem is we have a bunch of cable boxes with mostly encrypted digital channels, so I'd have to set up a filter on one of the analog channels that no one watches.

Anyone planning on making cheap device like this that can transmit digital TV signals?

By: fermicirrus

fermicirrus — Fri, 21 Mar 2008 22:29:32 +0000

This would work if you dont have cable tv. Otherwise, just get a UHF modulator and switch between antenna and cable within the TV menu

By: kdeal

kdeal — Fri, 21 Mar 2008 22:28:17 +0000

I've been sending video and stereo audio from a Tivo, an MP3 media player and a DVD player over cable for many months using this:
http://www.homecontrols.com/cgi-bin/main/co_disp/displ/prrfnbr/1302/sesent/00/Netmedia-3-Channel-Digital-Micro-Modulator

Even though this digital modulator can transmit on UHF frequencies unused by my cable company, mixing the cable signal and the modulator output has not proven successful. (I've yet to aquire a band-reject filter to try.)

Using various amplifiers and splitter/combiners never produced the desired quality.

I had an extra cable run back to my wiring closet so ultimately I added this A-B switch: http://www.radioshack.com/sm-remote-control-a-b-switch--pi-2049643.html in the wiring closet to choose between the cable feed or the locally modulated signal.

I use a combination of IR-to-RF and IR-over-cable to control both the A-B switch in the wiring closet and the other devices from the entertainment center, all with a Harmony remote. The remote control is even smart enough to negotiate triggering the A-B switch in the right direction depending upon the chosen input.

By: Matthew Wiebe

Matthew Wiebe — Fri, 21 Mar 2008 22:22:32 +0000

I’d say use the distro-amp and feed it into an antenna.. Less wires!

By: MrChilly

MrChilly — Fri, 21 Mar 2008 21:06:26 +0000

I wouldn’t worry about the signal leakage too much. Just keep your fittings tight. The modulators do drift some, so you will screw up ch2 or ch4… depending on where you live, hit up a passing cable man and ask if he has an old filter on his truck. A lot of cable companies used to have ch3 filters for movie channels. 4tv’s…I would get any higher than a 15db amp or you’ll risk overdriving the pic..