RF Modulator

DMT · 03-01-2004 10:34pm #1

Can anyone recommend a good quality RF modulator (and where to buy it) with adjustable output channel?
Having to run my DVD player through the VCR to get to all the TVs in the house is driving me nuts.

My need to play videos and DVDs simulataneously is a necessity.....

robbie1876 · 04-01-2004 3:18pm

Do you have a budget in mind? Maplins have some good modulators for less than €100. The best one I know of that I have used previously is by Channel Plus and costs around €250 I think. DVD images throught this modulator are superb, you would hardly notice the difference. Of course the rest of your RF system has to up to spec to notice. If you are just using basic RF splitters and stuff then just get a basic cheap modulator.

DMT · 04-01-2004 7:07pm

The other thing that sprung to mind is that the modulator would have to be able to cope with NTSC signals.

As it is, when I play a NTSC encoded DVD, the picture becomes balck and white once it's passed through the VCR.

byte · 04-01-2004 7:37pm

Hmm, would that not be a problem wiht the Televisions not being able to decode NTSC RF signals? Most TV's I'm aware of only can decode NTSC to colour via Scart. Maybe things are different now.

How old is your VCR? Nearly all new VCR's are NTSC compatible and cost less than a modulator?

DMT · 04-01-2004 10:15pm

Originally posted by byte
Hmm, would that not be a problem wiht the Televisions not being able to decode NTSC RF signals? Most TV's I'm aware of only can decode NTSC to colour via Scart. Maybe things are different now.

How old is your VCR? Nearly all new VCR's are NTSC compatible and cost less than a modulator?

All my TVs can decode NTSC RF signals - I know because I've play an NTSC video tape with no problems.

Both the the DVD and VCR are brand new.

Capt'n Midnight · 04-01-2004 10:36pm

Why not get a second cheap video - prob cost less than a good RF modulator - maybe someone you know has a VCR that eats tapes or has a dead head ??

DMT · 06-01-2004 7:54pm

Originally posted by Capt'n Midnight
Why not get a second cheap video - prob cost less than a good RF modulator - maybe someone you know has a VCR that eats tapes or has a dead head ??

How would a cheap VCR modulate the NTSC signal any better than the brand new VCR I'm using at the moment?

Capt'n Midnight · 07-01-2004 10:35am

Ah the DVD is outputting in NTSC..
Get a cheap DVD - €59 in Dunnes !

The main difference between NTSC and PAL is about 5 frames per second and the colour is done a different way ...

You said you wanted to play both DVD's and Video's at the same time - hence a SECOND video... Many VCR's will playback NTSC videos to SCART or to PAL - but it's not NTSC that gets sent to the TV. (While the composite on SCART might be NTSC the RGB ain't)

DMT · 08-01-2004 1:35am

Originally posted by Capt'n Midnight
Ah the DVD is outputting in NTSC..
Get a cheap DVD - €59 in Dunnes !

I don't think you quite understand, probably because I thought I had added more information in my original post than I actually had. The DVD player is a Sony RDR-GX3, it video output is going via a scart lead to the VCR (Sony SLV-SE730).

My problem is two-fold:
1. I want the DVD player to have its own RF channel to avoid having to go through the VCR,.
2. When the DVD player plays an NTSC encoded DVD, the picture comes out black and white after passing through the VCR.

So I want an RF modulator that will be able to cope with the NTSC picture from the DVD.

ZENER · 08-01-2004 3:34pm

In theory any UHF modulator - even one from a defunct Commodore 64 - should be capable of doing what you require.

The RF Mod does not deal with Colour subcarriers or Video IF matters it merely modulates whatever is inserted onto a carrier and sends it out as a UHF TV Signal with the audio 6MHz away from the video IF which should be compatible with any Irish TV. Once demodulated from the carrier the TV will then have to be compatible with whatever Video standard the original signal was created in.

You may have to settle for Mono audio though on all formats as nicam encoder are expensive !!!!

Capt'n Midnight · 08-01-2004 4:36pm

Yeah modulators don't insert field or line pulses - so it would depend on whether the composite I/P was PAL or NTSC to begin with.

Years ago had an italian TV game - of course it's modulator put the audio channel (0.5MHz?) away from where UK/IRE PAL would have it... Had to take the audio out separately

Not sure how DVD handles films but IIRC Movies are shot at 24 fps and when played on PAL they just speed it up a few % to 25fps. For NTSC they duplicate one frame in 6...

1 - put the DVD through the second VCR (eg: 2nd SCART OUT goes to primary VCR)
2 - if you connect the TV directly to the DVD and play NTSC do you get colour ??
if not then check the DVD is set to output RGB to the scart lead.

DMT · 08-01-2004 9:08pm

Originally posted by Capt'n Midnight
2 - if you connect the TV directly to the DVD and play NTSC do you get colour ??
if not then check the DVD is set to output RGB to the scart lead.

DVD + NTSC connected directly to Tv = colour.
Just an older VCR in place of the new one and it too turns the picture B&W.
I also changed the DVD SCART output from video to RGB, but the NTSC picture remains B&W.

(Incidently, the DVD in question is "Brendan Grace: Live At the Gaiety" (I bought it for the mother... no, really...) and for some reason they encoded it as NTSC instead of PAL, presumably so people can send to their enemies (or relatives) in america).

Want ot get this NTSc problem licked in case I ever get the region free hack for the DVD recorder....

ST · 10-01-2004 1:46am

Maplin Electronics have a universal modulator. I got one before christmas for €50, but I think they have them on special offer for €40 at present. You can select whatever channel you want by means of DIP switches. I don't know how it will work with NTSC signals.

http://www.maplin.co.uk/Products/Module.asp?CartID=040110003926914&ModuleNo=33050&MR=N

Does the Macrovision Copy protection not cause problems when the DVD signal is routed through the VCR?

DMT · 10-01-2004 1:57am

Originally posted by ST
Does the Macrovision Copy protection not cause problems when the DVD signal is routed through the VCR?

Haven't really noticed it except that when I have one of the menus onscreen (even with a DVD-/+RW or no DVD at all) the brightness of the picture gets slightly darker then brighter again.

ZENER · 10-01-2004 2:08am

Originally posted by ST
I don't know how it will work with NTSC signals.

Shouldn't really be a problem as all it does is modulate the video and audio signal onto an RF carrier.

It's then down to the receiving TV to decide wheather it likes the NTSC component. I know many TV sets claim NTSC support through the SCART input but I'm not so sure about the RF input.

The audio subcarrier on an NTSC Signal is in a different place compared to PAL plus it's AM instead of FM. I doubt if the TV will have an NTSC tuner/IF module so perhaps it will just act on the NTSC video system !

When playing the NTSC DVD through a SART socket what effect has it on the picture on the PAL/NTSC TV set. Does picture size change etc? I've never actually tried this so would be interested in finding out from someone with first-hand experience !

Tinky

ST · 11-01-2004 11:45pm

Haven't really noticed it except that when I have one of the menus onscreen (even with a DVD-/+RW or no DVD at all) the brightness of the picture gets slightly darker then brighter again.

Does this happen when the DVD is connected directly to the TV or when it is connected through the VCR, or both?

Does the DVD player have different outputs (Scart, Composite Video, etc.)? If so you could see if a different method of connecting the DVD and TV would solve the problem.

DMT · 11-01-2004 11:53pm

Just when connected through the VCR, even switched the scart output from composite to RGB, but no difference.

ST · 12-01-2004 10:34pm

Could you try it with a different VCR? It may be that the video level from the DVD is too strong for the VCR. How is the VCR connected to the TV when the DVD is connected through the VCR?

DMT · 14-01-2004 2:41am

Originally posted by ST
Could you try it with a different VCR? It may be that the video level from the DVD is too strong for the VCR.

Tried that, same result.

How is the VCR connected to the TV when the DVD is connected through the VCR?

VCR is connected to TVs through RF output.

John R · 14-01-2004 6:40pm

I tried this with my DVD and several vcrs and other equipment with rf modulators. None of them would produce a colour picture through rf with ntsc DVDs although all produced a colour picture through av inputs. Colour through rf was not a problem with pal dvd's either. All of the vcrs were effected by macrovision but the other equipment wasn't and they still did not output colour through rf.

RF Modulator

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