VCR as a VHF TV Transmitter
 

How strong are the modulator in the VCR's?

Any old VCR's have a Ch 2 Option on it?

200 ft is my Max

1) not very strong - a few millivolts into 75 ohms
2) never heard of a channel 2 option, but I don't know
3) do you mean you want to broadcast 200 feet to a receiver?

I read that the signal from a VCR with rabbit ears will only reach a few feet. Would be interesting to know if they could be modded to output on other channels though for a hard-wired setup. I reckon a distribution amplifier would help with a wireless setup, but that just wouldn't be feasible.

I'm just going to get a Blonder Tongue RF Modulator the one you can select your channel

Can I hook up a TV VHF Antanna to it?

The simple analog ch 3/4 units could probably be modded by changing a crystal, but you might not get full modulation depth if you go too high in frequency.

My Dish TV satellite box has an analog output that can be set to any UHF channel; obviously contains a synthesizer/modulator that can handle the high frequencies without stray leakage around the modulator element.

Too bad about those modulators that are set at the factory to a certain channel, lots of searching and waiting involved if you want to cover multiple channels with different video devices. Having a bunch of selectable units would just be an unnecessary expense.

Well I'm going to use it for my Pocket TV's like my Casio and my Sony

Besides I like the VHF Channels, Mainly Ch. 2, 3 and 4

Yes, this article describes what you are talking about: a Blonder-Tongue agile modulator using a TV rabbit ear antenna to transmit:

http://antiqueradio.org/HomeTVTransmitter.htm

Easy to hook up and it works well.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

http://antiqueradio.org/art/TVTransmitterRearWindow.jpg

I remember I seen some mods online somewhere to boost up the VCR RF modulator but got to watch those.They probably pushing over the limits and get in trouble over it.

I have a Ramsey TV6 and it only goes 60 to 100ft if I'm lucky.

I picked up a UHF unit on channel 14 for about $30 bucks ant it does the same distance as the Ramsey kit goes.

I've done it. Some VCR TV modulators get the carrier frequency from the tuner circuit's reference frequency, but the ones useful to us usually use a small SAW resonator. These look like a small flat metal rectangle. Remove it carefully (to not damage the circuit board traces). The pinout is usually 4 pins in a row, a drive pin, ground, then the last two pins are for channel 3 and 4 (I don't remember which order). I've used a 18.432MHz crystal (a small one about 1cm tall and 2/10 inch pin spacing for the leads) to replace it. It will run at 3 times that frequency, which is close to channel 2's. One lead goes to the driver, and the other one feeds one of the connections for channel 3 or 4. Then tune the TV to channel 2 and play with the ch 3/4 switch to see which way it needs to be to get a signal.

See if you can read the chip number off the modulator chip. and maybe you can find a data sheet, try http://www.digchip.com/. Googling it will likely give you dead leads, as various Chinese web sites fool the Google spiders into thinking datasheets exist at their web sites. If you luck out and find a data sheet, it should have a sample circuit that will show the video carrier and sound carrier output pins, and then you can trace out the circuit in your VCR modulator. They usually have attenuation resistors from each output feeding another resistor to ground, remove the to ground resistor, and strap resistors 1/10 the ohms across the other two, this should make the output stronger. If it's surface mount, I've salvaged resistors off junk boards (easy if you use a pair of soldering irons, one tip per end of the resistor to melt both solder joints), and in this case it's easiest to just stack the new resistor atop the old one and solder it down. This for the bigger ones, like 1/10 inch long, forget the modern micro ones...

I would give a thumbs down to the Ramsey kit. I built one years ago and it was awful, compared to a Blonder-Tongue agile modulator. If you watch on eBay, you can find a reasonably priced B-T unit (and usually some very overpriced, ones, too).

Phil Nelson

I agree.The TV6 is a piece of shieeze.I would like to get a B-T setup.

Channel 2, at LEAST 1/4 mile or nearest FCC inspector,
$35

http://www.ebay.com/itm/Audio-Video-...item4185c6ea12

Since no one watches the analogue channels anymore it would be interesting to put a 5 watt transmitter on say channel 2 or 3 and see how far you could get one night :)

I've considered trying to make as strong of a booster as I can, and doing that.
I even modified an old test pattern to use by adding the call letters WTFt, and a jab at DTV to it. I thought it could be fun on some future April fools day to crank it up and transmit some stuff that files in the face of the ever diminishing profanity standards of the FCC :finger: ....Comedies that contain the F-word, and maybe some porn. :D:smoke:

Hahahah that reminds me of the time my friend lived in the top floor of an apartment. He had a unit that plugged into the audio out of the tv and modulated the signal to FM band so you could use the stereo to simulcast the audio,,

He hooked it to the VCR and dropped in a porn and let it run, he later noticed a crowd of kids gathering around a car downstairs listening in... :D

SR

:lmao:

If either of you have an interest in truly transmitting your own live TV signals, as opposed to "seeing what you can get away with", I can give you lots of information on how to do so legitimately; I do it on a regular basis. It is a lot of fun to do things like show pictures of the sets I am restoring, or put myself on camera on an in-house Channel 1 signal into an RCA 8TS30 TV set, then transmit a camera showing THAT, live.

I can tell you that such signals are viewable all over much of the San Francisco Bay Area when I get on the air, with easy-to-obtain equipment and the NTSC TV sets you already have. This is TV over ham radio (known as "amateur television" or ATV), and you do need a license but the tests are not too hard to pass.

Let me know!

Back around 1978, someone in Syracuse did essentially that. Channel 7 was empty (Syracuse had then only 4 TV channels), and word had it that the transmitter was made from an old guitar amplifier. VCRs were a new product, and they played tapes of Star Trek, some porn, and such... Went on the air a Friday night and shut down Sunday night (the nearest FCC field office was about 150 miles away, in Buffalo, and they didn't work on weekends). Seems it was the first pirate TV station ever done. It got a short article in the New York Times.

Wow thats interesting buddy :)


You have a W callsign which means you have been a radio user FOR ALONG TIME!! (They havent issued W calls in many years)

Whats the farthest you have talked buddy??

I am a ham radio operator as well, and with a "W" call sign. Got my first amateur license in 1972 and am presently licensed (my callsign appears after my signature), so I've been fooling around with the hobby in one form or another over 40 years. Am now on 2-meter FM and Echolink (an amateur radio linking application that connects licensed amateurs to other amateur stations via their computers) because I live in an apartment building and, even though my landlord would allow it (I asked him about this some months ago), do not want to go to the trouble of erecting an antenna.

VK member ChrisW6ATV has a point as far as legitimate amateur radio operating is concerned, and a darn good one at that. Licenses are always required for any type of operating in the amateur bands, even if you use just a 100-mw (0.1 watt) transmitter. There are no exceptions. The Federal Communications Commission (FCC) has very strict rules regarding unlicensed amateur operating; the penalties range from very hefty fines to, at worst, imprisonment.

I would even be leery of using a VCR's RF modulator as a transmitter, its very short range notwithstanding. These modulators are not intended to be used as transmitters; their only purpose is to generate an NTSC TV signal on channel 3 or 4 to be sent over a coaxial cable to the TV set. The FCC's rules set very strict limits on the amount of RF leakage from any modulator, whether built in to a VCR or outboard. This is why any attempt to use a VCR, or a standalone RF modulator (as used with DVD players), as a low-power TV transmitter will yield very disappointing results if you are looking for any kind of range (read miles). That is, the dodge will work if your TV is within, for example, 200 feet or less of the antenna, but don't try to use it to broadcast your VCR's RF output to a television in the next room--it will not work, and if you try to boost the signal by any means, you will be running afoul of the FCC's rules and could be subjected to a fine or a jail sentence as well, as I said above. Best to get an amateur radio license and transmit amateur television signals legally, in the 432-MHz range.

The Amateur Radio service has a program where you can pick almost any unused call sign that fits the standard format for ham-radio call signs in the USA, so many people now have "W" call signs again. That is how I got mine, with "ATV" in it, in 1996 after having "K" and "AB" call signs before that.

From northern California, the farthest, I am not sure, maybe South Africa. That is on the shortwave/"HF" radio bands. The live TV signals are on UHF bands (above TV channel 83, or below channel 14) and they go through a repeater (relay station) on a mountaintop 3000-3500 feet in the air. By using that mountaintop repeater (there are two different ones near here for ATV), others watching (and sending their own video signals back) have been 70-100 miles away at times.

Just for "fun", this Web page has a chart that seems to say that the output of a Blonder-Tongue AM60-550 modulator at maximum (+60dBmV if I understand them right) is about 13 milliwatts connected to a 75-ohm antenna (load).

http://www.maximintegrated.com/en/ap...dex.mvp/id/808

The problem with that is that to transmit legally, you can't
transmit anything entertaining. You can't legally use a DVD
or repeat OTA, and even making actual shows yourself
is a bit iffy. Of course you could make travelogues of your
vacation with callins using ham radio, etc., and that would be 100% legal.
And at the full legal power you'd go a long way.

What are the cable channel numbers in the 432 MHz band? 69?

But for around the house on an antenna (and at full power out
a good fraction of a mile, quite illegal) you won't beat the Blonder-Tongue BAVM, which are always available on Ebay for under $40, if you
just wait for the channel you want. I have a Ch. 6 and a Ch. 10.
They are wired to all my old TVs but the leakage inside the TVs
is so bad that I can pick them up anywhere in the house
and a bit outside on my Watchman. At full power the leakage
gives excellent pictures on the Watchman. With the power way
down pictures are excellent on the wired TVs.