# Unusual Connectors in and Around our Auditorium



## Lambda (Aug 22, 2011)

I've been wondering about these things for a long time. They are made by RCA and have both a coaxial connector (like for a TV) and an RF connector (like for a CB radio) in an outlet the same shape as a power outlet. There's at least 6 of these in the auditorium, and a couple of others elsewhere in the school: One in the gym, and a couple in each lunchroom. 
My attempts to trace the wires have failed, because the conduits that carry them are built into the walls. They must be original to the 1965 building. 
I think that they must be a part of some sort of multimedia system, because of the labels "camera" and "TV rec". Under the faceplate, they're stamped with "939" and "502". 
I find these especially odd because in 1965, recording video wasn't simply done with videocassettes. It involved reel-to-reel machines and 1" tape. As far as I know, none of those machines are still floating around in AV storage, which is odd because they keep EVERYTHING, even movie projectors and shelves of records. 

I talk too much, here are pictures:


----------



## DrPinto (Aug 22, 2011)

Back in the old days, the schools didn't use portable recording and playback equipment. It was too bulky and expensive. Instead, they wired the school with coax that hooked up to a main distribution panel and amplifier in the AV room. If a teacher wanted to see a video tape, he or she would make a request to the AV department. The AV guy would wheel a TV to the room and hook the coax to the wall outlet. At the appropriate time, the video would be played from the AV room. It would be patched into the amplifier and sent throughout the school's coax.

If something was to be recorded (maybe an event in the auditorium or gym), the camera would be plugged into the coax and the signal would be sent to the AV room, where the recording equipment was.

This way the school only needed one expensive tape deck.

If you want to find out where the connections terminate, look for a large silver box on the wall (if it's still there) in the AV room. If you don't have an AV room, try the library.


----------



## derekleffew (Aug 22, 2011)

Yep, your school was quite advanced for 1965. "TV in the classroom? That will never catch on." Part of a CCTV system, top is an F connector, bottom is a PL jack.


----------



## Lambda (Aug 22, 2011)

Thanks for the names of those jacks. That's an excellent theory, but the thing is that there aren't plugs in the classrooms. Only the gym, lunchrooms, and the auditorium. Maybe the students went to the lunchrooms to watch videos. Plus, none of the recording/playback equipment remains. It's very odd of them to throw anything away, no matter how outdated. 
Interestingly enough, there IS installed today pretty much exactly what you're describing. It was put in in the early 80's, very unprofessionally (there's coax cable hung from all the ceiling beams). It does pretty much the same thing, except there's TVs in all the classrooms. They use it in the morning to broadcast some bull-excrement news program to all the students and sell advertising time. (We don't see it in our tech homeroom, yay)
But the media system certainly seems the most probable. It's too bad I don't know anybody that went to the school back then. When I get back to school I'll explore the AV room a bit more and see if I can find any panel, or some of that old equipment (I love that kind of stuff). The new system is controlled from the library, but the room that it's in isn't on the original blueprints, so it's likely that it wasn't there when this system was installed. Maybe if I find the panel I can re-purpose the system somehow, for something or other.


----------



## DrPinto (Aug 22, 2011)

I love discovering the answers to mini mysteries too!

If the classrooms did have outlets, they may have been removed during renovations (look for a blank outlet cover in the front of the classrooms. Usually everything was painted over after years of no use.

Back then, they called the systems MATV for Master Antenna TV. The amp was also hooked into one big antenna on the school's roof. That way each TV didn't need an antenna. When they plugged the coax in, they could receive all the local stations (usually 4: CBS, NBC, ABC, and PBS). I think the AV room had a modulator on an unused channel in the area to broadcast content from the AV room.

Also, I thought you might find this interesting. Notice the RF output connector on this 1966 era camera:

CONAR Model 800 TV Camera


----------



## cpf (Aug 22, 2011)

Lambda said:


> Interestingly enough, there IS installed today pretty much exactly what you're describing. It was put in in the early 80's, very unprofessionally (there's coax cable hung from all the ceiling beams). It does pretty much the same thing, except there's TVs in all the classrooms. They use it in the morning to broadcast some bull-excrement news program to all the students and sell advertising time. (We don't see it in our tech homeroom, yay)


Sounds like a serious case of Channel One News, or a spin/ripoff...


----------



## Lambda (Aug 22, 2011)

DrPinto said:


> I love discovering the answers to mini mysteries too!
> ...snip...
> Also, I thought you might find this interesting. Notice the RF output connector on this 1966 era camera:
> 
> CONAR Model 800 TV Camera


I know, I love solving these little mysteries. 

Unbelievable! It's CONAR! I used to have an oscilloscope made by them. I went crazy trying to figure out who they actually were, where I could find documentation on the thing. In the end I replaced it with a newer one a few years ago. Interesting that they made TV cameras too. 
If the school has something like one of these, I definitely want to see it. 
I have seen a MATV system before, in a 1960's era hotel. They had a bank of amplifiers up on the rooftop machine room, all decommissioned. Some of them even used vacuum tubes. 


As far as I know, there's no bank of amplifiers in the school. But it's a small school, they probably only needed one amplifier.


CPF said:


> Sounds like a serious case of Channel One News, or a spin/ripoff...


So you've heard of it? Yes, it's channel one, alright. I only had to put up with it freshman year, in my sophomore year, my homeroom teacher didn't like it and disconnected her TV, and after that I was on the tech crew. But it really was just awful.


----------



## DrPinto (Aug 23, 2011)

Lambda said:


> Unbelievable! It's CONAR! I used to have an oscilloscope made by them.


 
You had one of these?

CONAR INSTRUMENTS 250 NATIONAL RADIO SCOPE OSCILLOSCOPE | eBay


----------



## museav (Aug 24, 2011)

derekleffew said:


> Yep, your school was quite advanced for 1965. "TV in the classroom? That will never catch on." Part of a CCTV system, top is an F connector, bottom is a PL jack.


I don't think the top jack is an F connector, it looks more like an HN or SC connector. There were times when SC, TNC, N, triax and similar connectors were fairly common in video applications.

"Back in the old days" I designed a number of central media retrieval systems for universities and schools with both RF and baseband distribution as well as several RF distribution systems that used backfeeds where you would have a portable modulator that could be connected to the cable connection and you designed the RF distribution system to allow the signal to go back to the headend as well as being received from it, a more difficult design task than looking at the signal flow in just one direction.

I'm curious about the comment regarding the cable being hung from the ceiling beams being unprofessional. It definitely could be an unprofessional install but code does typically require that cabling be supported from structure and not off other building systems such ductwork, piping and ceiling hangers or laid directly on the ceiling, so being hung from the ceiling beams could also reflect good practice.


----------



## derekleffew (Aug 24, 2011)

museav said:


> I don't think the top jack is an F connector, it looks more like an HN or SC connector. ...


You're right; I didn't look at it closely enough.

Amphenol RF- HN Connector Series
Amphenol RF - SC Connector Series


----------



## Lambda (Aug 24, 2011)

DrPinto said:


> You had one of these?
> 
> CONAR INSTRUMENTS 250 NATIONAL RADIO SCOPE OSCILLOSCOPE | eBay


 
Nope, I had a 251. A much different style, and I estimate it was from the late 70's. It was low quality and never triggered right, but you get what you pay for. I upgraded to a BK 1474.



museav said:


> I'm curious about the comment regarding the cable being hung from the ceiling beams being unprofessional. It definitely could be an unprofessional install but code does typically require that cabling be supported from structure and not off other building systems such ductwork, piping and ceiling hangers or laid directly on the ceiling, so being hung from the ceiling beams could also reflect good practice.



Well, I mean it looks rather unprofessional having bundles of cable everywhere rather than in conduits. I am surprised that they didn't just run them through the utility tunnels, after all, that's what they're for. All the other wiring (internet, power, intercom, and some of our snakes) goes through there. In the majority of the building, there aren't drop ceilings.


----------



## dramatech (Aug 25, 2011)

derekleffew said:


> Yep, your school was quite advanced for 1965. "TV in the classroom? That will never catch on." Part of a CCTV system, top is an F connector, bottom is a PL jack.



Derek, I wouldn't dispute your identification of connectors, but The bottom connector in the pic was known as a UHF connector. Now this may be a regional thing, but my education and experience in the 60s through the 90s was in Television more than theatre. I built several TV studios and remote trucks and all of our video was sent over RG59 coaxial cable, and early on used the UHF connector. Later, most manufacures switched to the BNC. This is what we called it in Vietnam at AFVN, at the University of Utah, Brigham Young University and Brooklyn College, where I worked or studied. We also used that term at the TV studio that built at the CIA training base and for the equipment that I worked on in "bugging" foreign embassies.
"PL", in those same days was a term used for Party Line, or headset communication as we know it today. It is altogether Possible that where you have worked, The UHF connector was used in some way for communications and thus received that termanology. I know that it many of the places that I worked, a long time ago, The older Western union version of the 1/4" phone plug was know as a "PL jack", because it was used for headset systems, especially on the old RCA cameras used in early broadcasting.
Because of regional differences so many years ago, I have come to the conclusion that what we call something is of little importance, as long as all of the participants understand it. Even that said, there are times that I have seen people move to a new area and insist that the term used in their old venue was the only correct term. 
I turned 70 this year and have been involved in theatre since 12 and television since 16, so I have had to adapt as you young guys keep changing the vocabulary. When did "Teasers and Tormenters" become legs and borders? When did "Beams" become Front of House (FOH)? When did "Xray" become first electric ? or do I have that one wrong. Why do we use the term Boomerang for two different things ?

Isn't it lovely how with forums on the internet, that we are able to finally use one set of terms and understand what the old, the young, West coast and East coast are saying, or do we yet ?
Yes I know too much thinking muddies the waters.

Tom Johnson


----------



## derekleffew (Aug 25, 2011)

Thanks Tom.

UHF? That's that hoopy ring thingy, right?

My great-grandfather told me that in the olden days, TV signals used to come through the air, and were free!

From Differences between PL-259, SO-239 and UHF Connector » Please Name My Blog :

> Both PL-259 connector and SO-239 fits together and is collectivly called the UHF type connection.
> 
> So hope that would clear up confusion associated with SO-239, PL-259 connector. Both of them are known as UHF connector but with different names for male/female jack. That’s all for today folks!


----------



## DrPinto (Aug 25, 2011)

dramatech said:


> Derek, I wouldn't dispute your identification of connectors, but The bottom connector in the pic was known as a UHF connector.


 
I guess it is a regional thing. I always called that bottom connector a SO-239.

And we still call the lighting positions "Beams" and "Booms" and use the terms "Teaser" and "Torms". At least in my theater.

It's great to see someone with your experience here on CB. That's what makes this place so great. You could be 13 or 90. It doesn't matter. We learn, we teach, we vent. We all have theater in common. That's why I hang out here instead of eBay. Plus, it's a lot cheaper!


----------



## Nelson (Aug 25, 2011)

As Derek quoted, my understanding is that the outlet is an SO-239 and the mating plug (not shown) would be a PL-259. Generically, they are UHF connectors. This term comes from the "old days" of radio when anything above the AM broadcast band was called the "ultra highs". UHF connectors actually are inadequate for UHF signals as we now know them. They are OK at HF and VHF frequencies.

I've never seen a wall plate like the one shown by the OP, that is neat!


----------

