Film-Tech Forum ARCHIVE: FM Stereo Transmitters

This is topic FM Stereo Transmitters in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Barry Floyd (Member # 385) on 04-03-2001, 01:17 PM:

Has anyone ever tried to build an AM or FM radio transmitter from one of the "kit" places like Ramsey Electronics?

When I purchased the contents from the drive-in back in May, one of the things I got was a "Ramsey FM-25" FM stereo transmitter. I know it was a kit because they (Ramsey)still list it on their web-site for $129.95.

I ordered an AM kit from them last week and I'm gonna give it a try.

What types of transmitters have any of you other "drive-in" guys used and what should I look out for when purchasing a transmitter?

------------------
Barry Floyd
Floyd Entertainment Group
Nashville, Tennessee
(Drive-In Theatre - Start-Up)

Posted by Ken Layton (Member # 133) on 04-03-2001, 06:45 PM:

The Ramsey FM-100 FM stereo transmitter is professional quality and rock steady on frequency. Also with the Tru-match antenna the coverage is good. You can program the frequency you want to transmit on by entering the test mode and using the up/down keys on the front panel to lock in the new frequency (non-volital memory).

This kit is recommended for advanced skill levels only. It's too complex for amateurs.

Posted by John T. Mellor (Member # 468) on 04-03-2001, 08:53 PM:

Barry,
At my drivein we used two different transmitters Catel and the other came from Marble I like the marble because we could change the frequncy with out removing the cove and changing the dip switches. also a good stereo preamp is nessesary to achive good sound transmition. hope that is some help to you
John

Posted by Don Anderson (Member # 397) on 04-03-2001, 09:11 PM:

I bought one many years ago to use for a pirate radio station. 1/4 watt unit, which we build a "booster" to bring it up to 75watts. I stayed on the air 24/7 for nearly 5 years before being shutdown by the Feds. The unit worked extremely well with no drifting whatsoever. As a matter of fact, the unit (1/4 watt) is still in use as a public address system for a small race track.

Posted by John Pytlak (Member # 331) on 04-04-2001, 06:40 AM:

Don:

Running five years without getting caught is amazing. Your rig must have been putting out a pretty "clean" signal that didn't cause anyone interference, and the commercial stations didn't view you as competition. Surprised the FCC didn't confiscate the transmitter.

Drive-ins need to "keep their noses clean" and not let the signal carry far outside the lot. Neighbors are likely to complain if too many young teens are watching and listening to "R" rated movies adjacent to the theatre.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

Posted by Chris Erwin (Member # 176) on 04-04-2001, 09:41 PM:

Barry,

Take a look at Decade Transmitters. www.decade.ca

I have heard their transmitter on the air. Very clean. It's a nice unit. What's what I would run.

I have seen other units but have not heard them on the air.

I haven't used it, but the Smart DIT model processor looks real good! It offers AM,FM,Field Amp,monitor,and concession outputs. Hats off to Smart for creating a product just for the drive-ins.

--Chris

Posted by Gordon McLeod (Member # 33) on 04-04-2001, 10:12 PM:

I have installed many decade units and they are excellent as is the Smart Mod2BDIT

Posted by Josh Jones (Member # 447) on 04-05-2001, 12:12 AM:

I've got a collins tube/transistor hybrid 10 watt exciter that is run into a dummy load. I use it to listen to music while mowing the lawn. good machine I got free from a radio station that threw it out. Never had time to get the stereo generator to work though. The AFC whines when there is no modulation. Dissable the AFC, and the signal swings and the whine dissapears. strange huh? Broadcast warehouse makes PLL xmtr kits. a little expensive though.

Josh

Posted by Mark Gulbrandsen (Member # 72) on 04-05-2001, 10:08 AM:

Josh,
I had a coustomer in Monroe Wi that is also using an exciter as a transmitter. A bit on the high maintainance side of things as his was all tube, but extremely high quality sound.

Gord, The Smart Mod2 drive in version is great I also add a center channel EQ card and eq the ramp speakers. They actually sound good if you do it that way.
Mark @ GTS

Posted by Joe Schmidt (Member # 822) on 04-08-2001, 02:55 AM:

Don, I was kinda sorry to read of your FM pirate station and how the Feds shut you down. One of the things most wrong with our Nation today is that we have this US Congress full of bag men who take money under the table {oops, sorry, "political contributions"] from lobbyists representing Big Bu$$$$iness and as a result of this we have laws like the horrible "Digital Millennium Copyright Act" and the Napster case which has all the kids in a tizzy and --

the Satellite Home Viewers "Improvement" Act which provides that you can legally receive tv stations only from your local "designated market area" even tho the technology makes it possible to receive everything from ALL major markets ... we can hear radio stations from all over on the Internet, why not tv???

...and then the latest tightening of the bankruptcy laws so the poor suckers can't get out of the usurious interest rates and exorbitant fees charged by American Banks who today in my opinion are Public Enemy No. 1 of the American People. Even the Mafia Board of Directors of The Godfather would be embarrassed to charge what these banks get away with!!!

"Pump Up The Volume" was a good movie about a kid running a pirate station, and at the end we saw the mighty Feds assembled with the fat pompous bureaucrat in his limousine beating up on the kid and hauling him off to prison.

We're in a bad way.

Posted by Jerry Chase (Member # 660) on 04-08-2001, 11:46 AM:

Joe, I have to disagree your comments on the Feds shutting pirate radio down. There was a recent change in law that would have opened up the airwaves a little more, unfortunately, it was shot down _not by the for profit sector_ but by National Public Radio! Do a web search and you'll find the controversy. Your other comments on bankruptcy and political graft would be better commented on in film-yak. However, since pirate radio is still on topic because of its use by drive-ins, I'll comment on that here.

The Miami area has a lot of pirate radio stations and the bandwidth is very crowded, both on AM and FM. One pirate station in particular set up shop right on top of the best station around, a public station operated by a local university.

Apparently the pirates felt more secure trying to drown out a public station than a private station, who would immediately trace them, inform the Feds, and push to aggresively prosecute. That pirate station would suddenly come on air in the middle of an interesting program on the university station and peg the needle over them, blasting Creole (C)rap. They didn't realize the public station manager was getting multiple complaints and was was mad enough to do the legwork to get them shut down.

It took a couple of months to bust the station, but when they did the bust and caught the guys, there was all sorts of stolen electronic gear found in the house. Nice guys, eh? They ended up adding to our cost of housing inmates.

Pirate radio is one thing in Montana or the wheat fields of Alberta, where a lot of the band is open, but it has no business in the cities. All AM stations in rural areas as well as cities have to be careful during nighttime because of the changes in propegation that could cause them to interfere with a station miles away.

For many years my dad was chief engineer of a high powered AM station with a directional array and three huge freestanding sticks. He prided himself in keeping signal strength as close to the designated limits as possible, which is no small trick, when rain and atmospheric changes can affect conditions.

Although pirate radio was rare in those days, he would have regarded those pirates with about the same respect as someone here would regard someone trying to open a theatre showing 8mm film. Pirate junk adds noise to the spectrum and turns off many listeners. If you run a pirate station for a drive-in, please keep the signal down and verify that you aren't interfering with a station trying to follow the rules.

Oh yeah, FWIW, Miami AM regularly gets drowned out by the jamming equipment in Cuba. During the night when the U.S. stations have to reduce power, the signal will still reach Cuba. Castro then fires up the jammers to keep his people from hearing the U.S. news. About an hour after sundown, the local all news and traffic station can't be heard ten miles away from the stick because of the jammers. Nice, huh?

Posted by Gordon McLeod (Member # 33) on 04-08-2001, 12:20 PM:

Joe without regulations anarchy would rule.
The interferance caused by radio pirates can disrupt other life saveing functions.
Over regulation is bad but the alternative is often worse

Posted by Barry Floyd (Member # 385) on 04-08-2001, 09:50 PM:

It was my understanding that as long as a drive in complied within the limits of Part 15 of the FCC regulations, it is allowable to transmit for several hours as long as it did not interfere with anyone's licensened station?

What exactly to the reg's say?

------------------
Barry Floyd
Floyd Entertainment Group
Nashville, Tennessee
(Drive-In Theatre - Start-Up)

Posted by Ken Layton (Member # 133) on 04-08-2001, 10:25 PM:

I think Ramsey's website has the regs posted on it: www.ramseyelectronics.com

Posted by John Pytlak (Member # 331) on 04-09-2001, 09:21 AM:

Here's the specific page on the Ramsey site:
http://www.ramseyelectronics.com/sitepages/fcc.htm