TV transmitter Kits? - Videokarma.org TV - Video

#1 11-01-2004, 12:08 AM

Well I hope this is ok to post here as I am not sure what other category on this web site it might go better in so here goes:

Has anyone built any TV transmitter kits?

I've tried the TV transmitter kit from vectronics and it works ok but the signal strength is pretty poor... I practically have to have my tv's antenna sitting right next to the transmitter in order to get a static and interference free signal on my TV...

and the Vectronics TV transmitter kit uses a loop antenna and I have heard that loop antennas are pretty poor for transmitting signals, they seem to work good for receiving but are no good for transmitting...

in the mid 1990's in my high school electronics class I tried the Ramsey electronics TV transmitter kit and so did another classmate as well as the electronics teacher and none of us could ever get the thing to work at all... and the teacher was no slouch either as he had worked for many years as an electronics teacher at an electronics institute... though now it looks like Ramsey has changed the design of their TV transmitter kit I am kind of gun shy about possibly throwing away my money again if it should turn out as poorly as the first TV xmitter kit I tried from them...

So does anyone possibly know of any better TV transmitter kits? I'd love to find a TV transmitter kit that is on par with the SStran broadcast band AM transmitter... That kit is incredable and if I could find a good quality TV transmitter kit I'd be willing to pay about the same price as the SStran kit for it...

I would like to find a good kit as I hate to have my VCR sitting on top of my antique TV's when I want to watch leave it to beaver or I love lucy on them as a VCR on top of a 1954 TV just does not look right

any help would be greatly appreciated.
thanks,
Antonio
MN, USA

#2 11-01-2004, 12:37 AM

I betcha one of the main problems with getting a TV transmitter with any kind of decent power is due to FCC regulations that prohibit any sort of real power lest you cause interference within your area.

Seeing as how you'd need to have your TV on whatever channel you're broadcasting on why not just use a VCR and hide it and the cable somewhere? Use a 75ohm to 300ohm adapter to connect the coaxial cable to the screw terminals on the TV. Cheap and easy, just like my dates!

Anthony

outlawmws · #3 11-01-2004, 12:38 AM

Unless things have changed in the past 22 years ,unlicenced TV Xmitters are limited to 100mw. I was working for a company that dabbled in the things as temporary security units. I belive other companies sell them today as complete units.

We used short rubber whip antennas with decent results. These were B&W Xmitters and cctv cameras.

Not much to go on but thats all I have.

Carmine · #4 11-01-2004, 07:59 AM

Let's just say you lived in the middle of Montana, so interference is not an issue

... Couldn't you just build some kind of amplifier for your VCR and "broadcast" over channel 3?

Carmine · #5 11-01-2004, 08:14 AM

Let's just say you lived in the middle of Montana, so interference is not an issue

... Couldn't you just build some kind of amplifier for your VCR and "broadcast" over channel 3?

outlawmws · #6 11-01-2004, 08:36 AM

The UK seems to have lots of this stuff. Try THIS

Or google.

tv beta guy · #7 11-01-2004, 08:05 PM

I have one of the new Ramsey kits. The thing is still terrible. It does transmit a good distance, but converting the audio and video from the VCR to RF frequency it terrible. The only channel I could get to work is channel 5. That's the only channel I could (barely) get A/V sync on the TVs. Very poor gain too. And only my B&W TVs would work with it. Forget about color and modern TVs.

What I am going to do is design and build my own TV transmitter one of these days. Try to build it as powerful as possible within FCC regulations.

AgentWinchester · #8 11-01-2004, 08:20 PM

If you're in an area where other people picking up your signal is a slim chance, and you can brodcast on a channel that nobody will ever tune to (i have an old B&W set that can tune up to CH82 on UHF, don't know if that's possible today) could you not build a small amp? (Linear Amplifiers in the CB world, AKA "snowshoes", which are also illegal) that would step up the signal to max FCC ratings, or a smidgen above?

Is that even possible on TV Transmitters? If it can be done on a CB Radio, why not?

I know nothing about this, and i've never tried anything of the sort, but this just brought up the idea. just my $0.02

Sandy G · #9 11-01-2004, 08:28 PM

Unca Charlie-the FCC-takes a mighty dim view of running w/snowshoes, but folks do it all the time. Ever hear of pirate radio? Those guys make no pretense at being legal-and when they invariably get caught, they usually klose their gear, & pay VERY hefty fines.But as far as making a "leen-yar" for a TV transmitter, I don't see why it couldn't be done.-Sandy G.

Carmine · #10 11-01-2004, 08:30 PM

Quote:

If you're in an area where other people picking up your signal is a slim chance, and you can brodcast on a channel that nobody will ever tune to........

That's kind what I was driving at. As Howard Stern would say, F the FCC.

AgentWinchester · #11 11-01-2004, 08:41 PM

Well just a stupid idea. I agree with Heathkit TV, though, that's what i'd do at least. Of course the thrill of broadcasting is lost, but the picture is better.

#12 11-01-2004, 10:17 PM

Quote:

Originally Posted by Carmine

That's kind what I was driving at. As Howard Stern would say, F the FCC.

Howie put the "F" in FCC.

What a guy. Love him or hate him, at least he has the balls to say what's on his mind unlike all the PC goody 2 shoes out there.

Anthony

wa2ise · #13 11-01-2004, 10:54 PM

TV modulators are somewhat similar to AM modulators, but the video signal is "single ended" instead of "dual ended", like audio. The video signal has to get modulated such that the TV channel carrier is at peak amplitude on sync tips, and around 5% carrier level on peak white. The input video should be "clamped", aka DC restored right at the modulator tube/transistor. You don't really have to do anything extra for color. As for the sound, run an FM modulator at 4.5MHz and add that to the video just before the TV modulator. The video signal may need a 4.5MHz notch filter to avoid video energy at 4.5Mhz from interfering with the sound carrier. Though FM can take a fair amount of interference and not be bothered.

If you have an old notch filter color TV, and a DVD player with an S video output jack, you can get better picture quality by passing the luma video thru a 3.58 band stop notch filter, and the chroma signal thru a 3.58 band pass filter, and then adding them together to make a compsite signal. Then feed that to a TV channel modulator.

gonzothegreat · #14 11-02-2004, 04:03 AM

A decade ago I wasted $50 on the Ramsey kit to broadcast a VCR to my room upstairs. Just how miserably did it perform?

My bedroom is directly above the frontroom and the total distance was not more than TEN FEET. It could not produce a satisfactory picture! I even tried screwing around with a bigger antenna on the xmitter and rcvr to no avail.

While the various FM xmitter kits generally do a respectable job, I think part 15 (iirc) prevents TV transmitters from doing much more than what comes out of your average RF modulator.

Forget about the transmitter. Would be nice but the cash you blow for this project could be better spent elsewhere. Get a 300->75 ohm impedance transformer and enjoy some Soupy Sales reruns...

asynchronousman · #15 11-02-2004, 02:25 PM

Quote:

Originally Posted by gonzothegreat

A decade ago I wasted $50 on the Ramsey kit to broadcast a VCR to my room upstairs.

Yes you did. Now go find an old VCR Rabbit. End of story.