# RF Modulator



## 8dalejr.fan (Nov 20, 2005)

I got a DVD-VCR for Christmas, and an RF modulator to go along with it so I could hook it up to my older TV. 

My setup is as follows

Outside cable TV source --> RF In on VCR 
RF Out on VCR --> Ant In on RF Modulator
To TV on RF Modulator --> TV

It might just be me, but some channels seem granier when I'm watching regular TV, but when I'm watching TV through the VCR, they seem clearer.

Here's the problem though...

Every time I shut off the VCR, my TV screen flashes two or three times with white/black "noise" bands before going back to the regular channel. 

I have an even older TV with a similar setup, and it doesn't flicker twice with noise when the VCR is shut off.

Why is it doing this when I shut off the VCR? Is there a problem with the RF Modulator?


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## kiwiguy (Aug 17, 2003)

Probably nothing wrong, it is more likely just the older TV AGC reacting to the signal level change when the VCR is shut off, as it will see a momentary loss of signal as the VCR internal modulator goes into "straight bypass mode".

You probably will see some graininess though as there will be a quality loss with recereating the frequency in the modulator. 

You are introducing several modulation/demodulation stages in your setup so some quality loss will be evident.


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## 8dalejr.fan (Nov 20, 2005)

It's not gonna damage the TV is it? You know, when it goes all black and white with the noise and changes back?

My mom has a TV that's at least twice as old as mine and it has a VCR and a DVD player (2 separate ones) going through a RF modulator and it doesn't do it on hers.


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## johnpost (Dec 18, 2005)

8dalejr.fan said:


> I got a DVD-VCR for Christmas, and an RF modulator to go along with it so I could hook it up to my older TV.
> 
> My setup is as follows
> 
> ...


 i think you are misstating a device or a jack.

rf out of a vcr can go directly into a cable/antenna input of a tv set.

you may mean video/audio out on dvd/vcr into rf modulator.

i don't know your unit but all vcr i've seen have an rf out and
except for the earliest ones a video/audio out. if it's a 
dvd/vcr then the couple i've seen all have rf out.

the rf modulator would be needed for dvd player which only
have video/audio out to go into older tv which didn't
have video/audio input.

whenever you put stuff/devices in together you will deteriorate
the signal by both decreasing it and adding noise/interference.
every device, piece of cable, adapter, splitter causes deterioation
of the signal.

if you use the tuner in the tv to select channels then the signal
may be weak and give a grainy picture. if you use the vcr to
select channels (and in your case, with no video/audio inputs
on tv just antenna/cable input, so tv is tuned to channels 3
or 4 (in USA)) then you may get better picture for two reasons;
the vcr amplifies the signal and usually vcr tuners are much
better than tv tuners (especially older sets).

like others have said the flicker you see when swithching off
vcr is not a problem.


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## 8dalejr.fan (Nov 20, 2005)

Must be a problem with the modulator though... I swapped it with another one and it shuts off perfectly normal and the picture looks better.


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