This is topic What AM tower is this (Paul G. Thompson or anyone?) in forum Film-Yak at Film-Tech Forum ARCHIVE.


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Posted by Matthew Bailey (Member # 601) on 10-01-2003, 06:19 PM:
 
Just took som photos of a brand new AM tower in my city not far from where I live. It recently replaced the original tower which they had until this year, both guy supported. It is used by a local AM station KOLE 1340 for their remote auxilary transmitter. The station is actually locater in the neighboring city of Beaumont(?). It uses a Harris Allied or Harris Gates transmitter,dont know how many kilowatts-up to ten or more. At the base of the tower,there are four grounding straps leading to a horizontal buried grid,copper I believe,plus there are six vertical wires adjacent to the tower running up most of the full height of it.
Will load more pics of the tower at a later time.
 

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Posted by Randy Stankey (Member # 64) on 10-01-2003, 07:26 PM:
 
You stood right UNDER that antenna when it was transmitting?! You're supposed to wait until the power is turned off, Ya' Know! You're probably sterile now!


 

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Posted by Jack Ondracek (Member # 1466) on 10-01-2003, 08:42 PM:
 
For a brand new tower, there's sure a lot of vegetation around it!

That copper strap jumpering the base insulator is grounding the tower itself. Those vertical lines you noticed are actually the radiating elements of the antenna. It's a folded unipole design.

It's interesting that there isn't any tuning equipment in the picture (is there a "doghouse" nearby?). Otherwise, this doesn't look unusual at all. There are a LOT of these installations across the country.

At 10kW or so, AM frequencies probably won't sterilize you anytime soon. I used to have to do daily tower current readings where the meter was mounted ON the tower. I had to climb a wooden (read: insulated) ladder to the "hot" part of the tower, where the shunt switch was. This thing ran 10kW, and I have 4 daughters to prove it didn't do anything to me!
 

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Posted by Joe Redifer (Member # 3) on 10-01-2003, 09:14 PM:
 
That'll make you sterile? COOOOOOL!!!!!! I don't want any kids and I don't want anyone nipping and cutting down there. Sounds like the perfect plan... plus it's free!
 

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Posted by Matthew Bailey (Member # 601) on 10-01-2003, 09:15 PM:
 
There's not a doghouse nearby, just the building that the lines to the tower come out of. The bulding was used as a remote station,I don't know if it's still in there ,but the bathroom had the spark gap in it! The back of the transmitter protrudes through one wall of the bathroom & yes, all covers are on it.

 

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Posted by Mark Gulbrandsen (Member # 72) on 10-01-2003, 09:37 PM:
 
The high power stuff can indeed sterilize you. When I was at WCFC TV in Chicago which had a true 100kw input to the bays the tower engineer always called us to lower our power to 1/3 normal (1.2 Million watts ERP with both visual and the single aural Klystrons functioning)so he could safely pass our radiators. He said at 1/3 power he could still feel his testicles get warm so he always went by quickly. This transmitter used 8" hard transmission line pressurized with nitrogen.

I would say that you photos represent a pretty small transmitter site judging by the insulator at the base and the size of the heliax running into it. Its also a light weight tower as again the insulator is quite small in diameter and the load of the tower sits on it. Probably not more than 2500 watts. If it were larger than that there would be at least 3 inch transmission line instead of the Heliax. Generally, the larger the transmitter power the larger the insulator, and transmission line. Not necessarily a larger tower though.

All new commercial AM, and FM transmitters are solid state all the way through and including the final amplifier stage. Most are modular so if a module or two fail all that happens is that the output power lowers a bit. You still stay on the air though. The best part of the solid state xmitters is the low power consumption. Some are so efficient as to not soak up any more power than the old AM modulator section of the transmitter it replaced. A good example was the MONTHLY power bill for the TTU-110 transmitter at WCFC. It usually topped 20,000 dollars.
Mark

P.S. Here is a large transmitter and tower. The tower at this station weighs 900,000 lbs!! The base inslator supports the entire weight of the tower.....
http://hawkins.pair.com/wlw.shtml
 

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Posted by Paul G. Thompson (Member # 655) on 10-01-2003, 10:56 PM:
 
Mark, BAH! Sure, his testicles got warm. So do the wrenches, coins, and other metal objects they have in their pockets do when they climb "hot towers."

Most of the radio station engineers I know that have died was due to leukemia or some other form of cancer. There was a sailor that thought high-power energy blasted at the balls would sterilize him. He did that on a many occassions. Unfortunately, he was still capable of "doing it" and his faithful wife and him still had children.

It takes more RF energy to sterilize a person than it does to kill them.

I have been around many towers for years, working inside the fence areas. I still don't have any problems with that.
 

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Posted by Daryl C. W. O'Shea (Member # 1303) on 10-01-2003, 10:57 PM:
 

quote:

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This thing ran 10kW, and I have 4 daughters to prove it didn't do anything to me!

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No sons though, eh?
 

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Posted by Paul G. Thompson (Member # 655) on 10-01-2003, 11:02 PM:
 
Mathew, I don't have enough to go on by looking at the picture.

What is the tower registration number? I'll look it up. However, if the tower is not exceeding "X" number of feet and they are not in a flight path or hazard to a local "White Knuckle Airlines" airport, they may not need a registration number.
 

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Posted by William Hooper (Member # 71) on 10-02-2003, 01:00 AM:
 

quote:

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For a brand new tower, there's sure a lot of vegetation around it!

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Don't things grow at ALL in Washington? That picture looks like the guys mowed it just last week, for the US coast on the Gulf of Mexico.
 

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Posted by Jeff Stricker (Member # 224) on 10-02-2003, 07:32 AM:
 
Can't tell for sure from the pictures, but think its a "folded unipole". This type of tower has skirt wires around it. The wires are connected to the tower at the top and are insulated at the bottom. The tower is actually grounded at the base and the RF is fed (through appropriate matching network) near the base across the skirt wires and ground. The ground system more than likely contains 120 radials of buried copper wire extending 1/4 wavelength out from the base.
 

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Posted by Mark Gulbrandsen (Member # 72) on 10-02-2003, 08:33 AM:
 
Yea, but I doubt that you guys would still "function" very long after having passed a 100kw bay running at full power
Mark
 

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Posted by Jack Ondracek (Member # 1466) on 10-02-2003, 08:36 AM:
 

quote:

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No sons though, eh?

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Yah... I thought one of you clowns would catch that!

quote:

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Yea, but I doubt that you guys would still "function" very long after having passed a 100kw bay running at full power

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Mark, you may have a point. I used to get headaches working around the 100kW FM plants that had their studios at the transmitter, But I also spent a lot of years with AM, and that never bothered me. In that time, most engineers I knew weren't that concerned about the lower frequencies, either.

Now... you'd probably be nuts to go anywhere near that WLW transmitter when it was at power... but that was probably more a practical matter...
 

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Posted by Matthew Bailey (Member # 601) on 10-02-2003, 03:04 PM:
 
I'll obtain the tower registration number later today. It's on the fence & resembles a license plate.I have photos of the top of the tower & the bottom where the six wires are attached.


 

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Posted by Matthew Bailey (Member # 601) on 10-02-2003, 06:24 PM:
 
OK,here's the tower registration number. It's 1232099.
 

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Posted by Jack Ondracek (Member # 1466) on 10-02-2003, 07:13 PM:
 
Folded Unipole. Those 6 wires are hot.
STL antenna on top (easy to do, since the tower's grounded).
What?... humongous Marti yagi up there???
 

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Posted by Paul G. Thompson (Member # 655) on 10-02-2003, 08:34 PM:
 
Matthew, the registration number does not reflect what kind of tower it is. However, it is 60.4 meters high (198.16 feet). It is located at 29-54-18.0 N and 093-56-24.0 W (Intersection of Florida and 27th. The owner is CityGate Media, Inc. If you are nice, they may tell you all about it if you email manager@teamradio.com. I think that is 1340 or 1380 AM KRCM in Port Arthur, Texas.

According to the FCC Website, daytime power is 1KW, night power is 127 watts. (non-directional) FCC has it as Voice Broadcasting, Inc. I would presume that is who owns it now. There home base is Beaumont, Texas.

Mark, I still say, "BAH!"

Seems to me that when I was about 22 years old, I was working with a 125kw radar at Naval Air Testicle Twisting Center in Memphis, Tenn. I didn't know it, but the demonstrator radar set was blasting me with full power from the other side of the wall.

We didn't have a dummy load on the demonstrator radar set since it was used to track aircraft during classroom "playtime."

Anyway, the antenna was about 6 feet from me. In about an hour, I noticed my eyes felt like sandpaper. That is a danger sign so I left the area. I found the radar on the other side of the wall was running full power unattended. Naturally, I shut it down.

Well, I am almost 63 now, and I am still "functional"

I had fun with that 125KW radar, too. At night I would wait for the post watch to come around the building. I had a big shitcan full of flourescant lights sitting in the field. When that poor kid who was on watch come diddy-bopping around the corner, I fired the transmitter up and beamed the antenna at the shit can.
BLINK!!!!! They all lit up. It would scare the shit out of that kid on watch. One took off running the other way once.

And then, the 'ole APS-20 2-megawatt radar....Someone had a armful of flourescent tubes. The radar tech working on the radar fired the transmitter at him, and all the tubes lit up like a Christmas Tree. The person who was carrying the tubes went into a panic, through all the tubes up in the air and took off running like an ape. All that was left was a pile of glass. I would presume the person who was running away went back to the barracks to change his underwear.

(Ah, those were the days....)
 

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Posted by Mark Gulbrandsen (Member # 72) on 10-02-2003, 10:13 PM:
 
Yea, from the photos it looked like low power stuff to me.
Mark
 

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Posted by Luciano Brigite (Member # 1104) on 10-02-2003, 11:54 PM:
 
My knowledge of antenna towers and big transmiters is about none..
the only thing I know is that they looks nice and why not amazing..
Specially the old time ones, spent more than 2 hours looking at picturees of them, starting at the link Mark posted in one of his replies. Those big tube transmiters ,in special some of the RCA's and a few others I saw in the pictures are,to me, hmm.. something beyond beautiful. Makes me wish to see some of them in person and on the other side wonder where to find something like that where I live and how to make to see it
 

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Posted by Paul G. Thompson (Member # 655) on 10-03-2003, 01:10 AM:
 
Luciano, I had to keep an RCA 50KW Ampliphase BTA-50H1 transmitter running or a while before it was replaced with a Harris. They operated on 460 volts 3 phase and would draw 130KW off the AC line at 100% modulation. Really made the power meter spin..

They were about 16 feet long, about 8 feet high and 4 feet deep. The power supply cabinet was so big you could walk into it and take a look around. (with the power off, of course...) In addition to that, they were built like a brick shithouse. Definately "Industrial Strength."

The forced air blowers to keep the damn thing cool were powered by 2.5 horse-power motors if memory serves me correctly. The blowers were so noisy that ear protectors were needed. The plate transformers were huge....about 4 feet high and two feet in diameter. They were located outside. The place where the transformers were looked like an electrical power substation.

Getting that thing "on the road" was tricky.

Here is the start-up procedure:

1. Close the external incoming line switch.
2. Close the distribution breaker.
3. Close the control breaker.
4. Close the Transmitter Start Switch.
5. Close the filament switch.
6. Close the plate switch.
7. Close the ACB Closing Coil Breaker.
8. Supposedly, you are then "On The Air". (maybe if you are lucky)
There are also time delays during the start-up. If the start-up procedure is violated, damage to the transmitter could result.

I didn't like that transmitter. When it dies, the challenge of getting it back on it's feet becomes personal. It was an extremely complicated transmitter.
 

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Posted by Chris Greenwell (Member # 1660) on 10-03-2003, 03:28 AM:
 
Hey Mark, what station was it you were telling me about that had a huge transmitter??? And I use to think the Harris Shortwave SW100B transmitter here at KTBN was big...its a baby compared to some of these older transmitters
 

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Posted by Paul Konen (Member # 41) on 10-03-2003, 11:47 AM:
 
Paul, Very funny about the flourescent lights.
 

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Posted by Floyd Justin Newton (Member # 1316) on 10-04-2003, 08:05 AM:
 
In 1961-2 I was working at KYND-AM 1580 (MOR). We operated a
Collins 10KW. Well, one day we got the go-ahead to increase
power, and double the height of the stick to 300 feet. Our new
transmitter was a GE 50KW. There was no need to turn the lights
on as they were on all the time anyway (50KW of power makes
things do 'strange' things as anyone who has work with RF can
attest to).
 

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Posted by Edward Jurich (Member # 1787) on 10-04-2003, 10:59 AM:
 
There is no doghouse, the matching network is in that little gray box next to the tower. The insulator at the base of the tower is grounded (ground strap across it) so it is indeed a folded unipole tower. The RF is fed up the wires running outside the tower. This type of tower puts out less skywave and more ground wave improving local reception somewhat. The fence around the tower is to keep you out of the danger zone, you'd have to be standing next to the tower to be in danger. However, it's not a good idea to spend a lot of time (hours-days) near an AM tower while it's on.

PS, I was a broadcast engineer for almost 30 years
 

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Posted by Luciano Brigite (Member # 1104) on 10-04-2003, 12:22 PM:
 
Thought it was easy to have a transmitter like that turned on..
but then, there's all that switchs spread on the panels and they're not htat just to cover a hole made by mistake
Compared to all the switchs,controls,variable capacitors and coils that need to be adjusted during the setup of one.. it seems nothing (tried to build a simple AM transmitter once,tube based and did get mad with the matching coils in the output stage,ended tossing them far away and connecting the antena cable with a ceramic capacitor .. ended with a frying machine )
 

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Posted by Mark Gulbrandsen (Member # 72) on 10-04-2003, 04:46 PM:
 
Chris,
That was WCFC in Chicago. Its now a PAX station with different call letters. Far as I know they are still running that TTU 110 though. It had a huge 3 phase feed, probably 460 volts, definately a 1200 amp feed as I had to reset that mother of a breaker once by myself. The 6 high voltage cubicles paralleled put out 18kv at close to 20 amps for the three Klystrons! And a huge power bill monthly of at least 15 grand. Those cubicles were not oil cooled but air cooled and had to be cleaned out monthly of dust to prevent really nasty things from happenning.

Interestingly, enough those Varian Klystrons were manufactured here in SLC, but donno if they still are. We had a specially made case we called "Grandpas Coffin" that we shipped the Klystrons back to Varian in to be rebuilt. This transmitter filled half the 94th floor of the Hancock Building in downtown Chicago. The actual transmitter cabinets were along one wall of a large room with everything else behind those. There were also three school bus sized heat exchangers right above the ceiling of the 94th on the parapit. We put in deionized distilled water(which we produced ourselves)and got steam back out of the Klystrons. The distilled water we produced kept the level constant as there was always a little loss. There were also MANY cooling problems with the plumbing in those TTU-110's and we were forever re-doing water pipe joints. WBBM, Channel 2's TV transmitter was in a small closet right next door. It was all contained in one tall cabinet. It was only 5kw. There werea total of three TU-110's in Chicago with the two others being installed and still are running over in the Sears Tower. Just about everything else was Continetal Electronics or Harris.
I have photos of the studios and Master control, but unfortunately not of the transmitter site .
Mark
 

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Posted by Edward Jurich (Member # 1787) on 10-05-2003, 09:39 AM:
 
Mark Gulbrandsen....I'm from Chicago originally and started in radio at WBBM (CBS) in 1970. I was at WBBM-TV's transmitter on the Hancock for a visit once, can't remember why. Then they had an engineering staff that had shifts watching the transmitter.
Back in 1970, WBBM-AM radio was still using the original studio equipment, all tubes (octal at that). The FM had just built new studios and had new soild state Harris consoles.
 

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Posted by William Hooper (Member # 71) on 10-06-2003, 02:15 AM:
 
Edward Jurich wrote:

quote:

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PS, I was a broadcast engineer for almost 30 years

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a GENIUS of broadcast engineers.
 

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Posted by Jeff Stricker (Member # 224) on 10-06-2003, 11:42 AM:
 
I remember taking a tour of the Purdential Building in Chicago in 1968. At that time WGN (ch 9) had their transmitter there. Visitors to the observation deck could watch the transmitter techs through a glass window. They wore white lab coats like doctors!
 

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Posted by Paul G. Thompson (Member # 655) on 10-06-2003, 12:00 PM:
 
Well, NUTS! The 10KW Collins blew its brains out. Time to pussy-foot up to the station and find out why. One of these days something is going to burn up and there is not going to be parts available to repair it. The transmitter is about 30 years old.
 

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Posted by Edward Jurich (Member # 1787) on 10-06-2003, 05:56 PM:
 
Collins made great transmitters. With a little care they just keep running. I've had installations where the "state of the art" main transmitter was more of a problem than the 30 year old Collins back-up transmitter.
 

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Posted by Paul G. Thompson (Member # 655) on 10-06-2003, 08:42 PM:
 
Edward, I was in error about the transmitter being 30 years old. It is closer to 36.

I got it back on line, a couple of 4-400's went flat. I agree it is a nice transmitter....but many things have passed on. Things like choke coils (can't get them anymore) the plate transformer is about ready to fly south for a vacation, and the choke coil in the HVPS took a dump and burned up some wiring. Good thing I was able to repair that. Some of the high voltage capacitors have sprung leaks and had to be replaced.

Anyway, it is running...but due to its age, it is about ready for the pasture.
 

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Posted by Phil Hill (Member # 371) on 10-06-2003, 11:14 PM:
 
I agree Edward...

As with all older equipment, things do fail. That is NO reason to slam them for being "old" and useless. There are many "work-arounds" for those that have the inspiration and knowledge to not be negative and take the bull by the horns, so to speak. I get tired of hearing the whining from those that complain about every time someone sneezes.

Me thinks some here need to respect the heritage and stop complaining about old equipment just cuz they are themselves "OLD"...

>>> Phil
 

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Posted by Paul G. Thompson (Member # 655) on 10-07-2003, 01:04 PM:
 
Yes Phil...I agree. I love the old junk because of the quality engineering and pride that went into it when this stuff was designed and manufactured.

However, there comes a time where it has to be retired. Just recently we spent close to $2200 on bottles to keep it running. In about 3 more months we will have to spend another untold amount on a 3CX-10000 final for that thing. Power consumption? HAH! What a joke! 35 years ago electrical power was about 2 cents per KWH. Today? About 10 cents if not more....

A new solid state transmitter will pay for itself in a several years in power savings.

That transmitter makes our paychecks possible. Obvoiusly, if the machine starts to become excessively troublesome and expensive to maintain, it has to be removed. We cannot spend the time to use ingenious repairs. Examples are when the plate transformer finally goes, a replacement is not possible. We are off the air. When the choke burned up in the power supply, I was able to repair it. But the battle scar still remains. When the plate load inductor burned up because of a shorted 4-400, I had one that was broken. I had to use it. In fact, a picture of the one that burned up has been posted somewhere on a FT thread.

The broken coil I had - I had to remove one coil from it because it was totaled. The form was broken so I had to devise a method of mounting it. Luckly, I was still able to "tune it" to keep the system balanced.

The high voltage capacitors that had to be replaced can be had, but the mechanical mounting is, in some cases, completely incompatible.

The transmitter at KBRC is a AMFET 5 built by Nautel. It has been in service since 1983. Sure - we had some problems with it. When it was installed, it was set up for enough current for 5,000 watts on No. 1 tower. However, the common point for that setting was 10.6 amps into a 56-Ohm load. That represents 6,292 watts. The transmitter was designed for a maximum of 5,500 watts. For 15 years it was making 6,292 watts which just happens to be 792 watts above what it should have been making. No wonder it was having "issues"...

I went to work for that place in 1985. I questioned why the common point was so high at that time but I was assured I didn't know what I was talking about. We have had fuse failures, inductor failures, RF Driver failures - you name it. For 15 years, that transmitter was basically running outside of design parameters. When I throttled the common point to 9.45 amps, all the problems went away. I have had to do NOTHING to that transmitter since then other than to make sure the power ratio, phase angle, modulation, etc. stayed within our license requirements.

I have helped in the installations of several solid state Harris 1KW transmitters and one 50KW transmitter. They are running flawlessly.
 

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Posted by Jeff Stricker (Member # 224) on 10-07-2003, 04:55 PM:
 
I worked at a station that had a 1KW GE AM transmitter (c 1948) that developed several ailments that required "Rube Goldberg" solutions to keep it running. Luckily it had been relegated to standby status and only needed once in a while when the main rig needed servicing.
 

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Posted by Luciano Brigite (Member # 1104) on 10-08-2003, 09:28 AM:
 
Some of the tubes used in these transmiters can give a nice ,and interesting,lamp shade ( ok.. had to look for the word in the dictionary ),Don't remember how the 4-400's Paul mentioned in his posts looks like but I think they're all glass, the 3CX 's FWIK are ceramic/metal ( I had a 3CX2500A3 until it rolled over the bench and turned into pieces on the floor ) The lamp shade I have in my room was made with a TB4-1250 and the plastic core from a 1" videotape reel .also have an Eimac 4E27 for decoration purposes, have no idea what's it's use or if it is in working condition.Ifind these big tubes interesting and nice to look at.gotta find ound when a radio or tv station will put the junk out and see if I can find some of them to restart a collection
 

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Posted by Mark Gulbrandsen (Member # 72) on 10-08-2003, 10:34 AM:
 
Normally in a large commercial market that xmitter would be relegated to just backup service but Pauls not in a large market up there. If the station is doing marginal as many small ones are then complete rebuilding of that transmitter properly may very well pay off in the long haul. With all the paperwork, engineering studies, and attorneys fees involved just in applying for a construction permit to replace the aliing xmitter one may come out ahead even taking power costs into consideration. This is also in the state of Washington where you need to get a permit just to get a permit!!

There are quite a few "transmitter salvage" places that could sell you used parts, or you can have custom parts made to completely re-condition it, including the transformers. Also changing/upgrading to a different final could save even more money in vacuum tube costs. Shopping E-bay can also pay off for vacuum tube purchases as I have seen both those tubes(new and used) for sale on E-bay from time to time. There are also less expensive Russian vacuum tubes available on the market that are quite good.

While at WCFC we had to completely rebuild the HV diode stacks in the six HV cubicles that made up the entire HV power supply for the TTU-110. The original RCA stacks were epoxy encapsulated and if a diode in an individual stack failed that bad stack literally exploded and usually started on fire because RCA failed to use fireproof epoxy....burning epoxy also conducts pretty well and this would usually take you off the air. To solve this our transmitter engineer designed a new stack to replace individual stacks in each cubicle. Each cubicle contained over 100 stacks and each stack had 8 diodes with resistors paralleled across them, fortunately the HV capacitors were seperate from the stacks. It took quite a long time and we built up enough stacks for one cubicle over about a months time and replaced them over two six hour down periods over another month. All in all it took about a year and alot of work to get them all done but the failure rate of the originals was so high we had no choice. The new stacks never failed once during the remaining 2 years I spent at the station. During that 2 years we upgraded the TTU-110 with a pulser kit to lower the power bill. It was the first pulser ever installed in the field
on that transmitter but persistance paid off and eventually it worked well lowering the power costs almost 20% every month.
These are but a couple of examples of what can be done to old ailing equipment....
Mark @ CLACO
Mark
 

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Posted by Paul G. Thompson (Member # 655) on 10-08-2003, 01:07 PM:
 
Mark said:

quote:

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This is also in the state of Washington where you need to get a permit just to get a permit!!

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Ain't THAT the truth!!!!!

Luciano, the 4-400 tubes are glass bottles, but they are kinda cute. The 4-1000's are bigger glass bottles that are just as cute. The 3CX10000 tubes look like a cookie jar with handles and all.

Do a FT search in Film Yak using the keywords 4-400. There is a picture of the 4-400's glowing nice and red. They would make good night lights if one could afford to run them.
 

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Posted by John Pytlak (Member # 331) on 10-08-2003, 01:28 PM:
 
A link to Paul's photo:

Photo of 4-400A Tetrode XMTR Output Tubes Glowing
 

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Posted by Jeff Stricker (Member # 224) on 10-08-2003, 02:31 PM:
 
You can light the filaments on a 4-440 (that has seen its usable life) with a 5 Volt 15 Amp transformer. Makes a great conversation piece.

I've been using Russian 6L6GC's in one of my MACS for several years with great results.
 

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Posted by Luciano Brigite (Member # 1104) on 10-08-2003, 09:41 PM:
 
Thanks Paul and John for pointing the picture of them
I find them cute too.. in fact, the 4-400 in the picture looks like the Tb4-1250 I used to make a lampshade, except for the plate that has a diferent shape ( the tube isn't being turned on, just used as the body for the lamp, the filament is broken and has tinny pieces of it at the bottom of the tube)I'll try to have the webcam working again and try a picture of it just for curiosity
Jeff, I have some tube amps that uses the 6L6GC and I'm using russian 6L6's on them, but don't know why the plates on all of them glow dark cherry red, checked the voltages and they're within the specs in the manual. mine are branded National. wanted the Svetlana ones but couldn't find them at the time and now they seem to have disapeared.
 

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Posted by Paul G. Thompson (Member # 655) on 10-08-2003, 09:58 PM:
 
Sorry you live in Timbucktoo, Luciano. I now have 4 each 4-400A duds! I would send you some, but it would cost too much to send them, and by time you got there they would probably be smashed anyway.

Red plates on the 6L6? Check your bias. It might be too low. In a Class "A" Biasing condition, it should be about -18 volts with a Plate Voltage 350 volts and screen voltage about 250.

Or, -14, 250 and 250 parameter or a -12.5, 300 and 200.

Push-Pull application: -17.5, 270 and 270 will do a nice job with Class "A" Bias.
 

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Posted by Josh Jones (Member # 447) on 10-08-2003, 10:44 PM:
 
Allright boys, its my turn

I work for Triad broadcasting up here in Fargo. I help maintaine 7 radio stations, 5 FM's and 2 AM's. KQWB-FM, aka Solid Rock Q98 has a 1968 CCE 26KW transmitter using a 4CX 15000A7 final tube, and an 8 bay ERI antenna mounted roughly 500' above ground. KVOX-FM, aka Froggy 99.9, a country station, uses a late 60's RCA BTE-20E running at 16.5 KW, feeding and isocoupled 8 bay RCA antenna. The preceeding two sites are independant of each other, the next three all share a site.
KLTA-FM, aka Lite Rock 105, has a 1983 Continental transmitter, cant remeber the number off hand, has a legal power of 17.5 KW, diplexed into a 12 bay ERI antenna at roughly 500'. KPFX-FM aka 107.9 the fox, is running a Harris 20-H3 running about 17KW. The two stations, KPFX and KLTA are diplexed into the same antenna, having a total ERP of around 200KW, or 35KW of antenna input power. The last FM we maintaine is KEGK or The Eagle 106.9. This is a brand new transmitter running 16KW into an 8 bay ERI antenna, for a total of 50KW of ERP. At thjis site we also have and old 60's Collins 10KW FM for backup, and have a 5KW version at the Froggy site.

Now onto AM's

KWQB-AM 1660, which recently switched formats from Adult Standard to talk, has a 3 year old Harris DX-10 transmitter feeding a 355' stick onmidirectional. The transmitter has never had a module failure, and is so efficient, we now have to heat the building during the winter. The site previously had a 5 tower directional system and ran two HT 5's in tandem for 10 KW. The null on this station was so tight you could drive 2-5 miles and loose the signal. The other AM I work on is 1450 KBMW, in wahpeton ND which is a nondirectional 1KW station running a 80's Harris MW-1A. This transmitter was neglected for sewveral years and we are in the process of getting it back together again, shot-gunning modules, and the like.

Thats my current day job

Josh
 

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Posted by Jack Ondracek (Member # 1466) on 10-08-2003, 10:54 PM:
 
Sounds like you've got plenty to keep you busy, Josh. I once had a pair of those RCA BTE-20s, running combined at about 38kW tpo. They were good, solid, stable boxes... as long as you kept a good supply of ipa tubes onhand. For some reason, we seemed to go through them like popcorn. Hopefully, they got that resolved in later models.

Don't recognize the model... what's an HT5?

One of the first MW-1 transmitters (pre "A") is still running strong at KGY, Olympia, WA. I think it was around 1978 or 9 that they retired their old RCA box (which is still there as a standby). At the same time, they replaced their console, which was a Western Electric. It was a beautiful board, stone cold quiet, so much headroom you'd have a hard time finding the ceiling, underpowered tubes (I don't recall ever replacing one), and weighed 2.315 tons... it wouldn't have surprised me to learn they had to put extra supports in the floor under that anchor!
 

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Posted by Luciano Brigite (Member # 1104) on 10-08-2003, 11:44 PM:
 
Ooohh.. hmm.. if I didn't have to send some $$ to a friend in germany that happened to find something I've been looking for a very long time, we could make some kind of arrangement for the 4-400's. I received several tubes from an US store once (8 4B4G and 4 47) they all arrived here intact. all that was inside the box was a lot of styrofoam pieces and shreded paper. Shipping from the US to here, depending on the weight and size gets darn expensive unfortunately.

About my glowing 6l6's.. they're set up on a push-pull ultra linear config. , +B is about 360V and the bias is now running at -32V. there are 2 amplifiers, they're alike and the same problem happens on both amps .
 

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Posted by Josh Jones (Member # 447) on 10-09-2003, 12:19 AM:
 
I have noticed that some brands of tubes glow easier than others.

Of the bunch, the only real problem transmitter has been the 20KW continental. That CCE transmitter we are using in Q98 is very good to finals. The bottle thats in there is pushing 3 years, and she still is making power

HT 5's may be incorrect, I'm not sure before my time.

The BTE-20 had a cavity and coax fire a few years back, but after the rebuild has been running flawlessly, no driver problems either, I'm happy to report.
 

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Posted by Paul G. Thompson (Member # 655) on 10-09-2003, 12:50 AM:
 
Luciano, what's the cathode current running on your 6L6's? Are you using self bias or fixed bias?

If you are drawing up to about 66 mils with a zero-signal condition, I would bet they are glowing. For a zero signal condition, 54 mils for a plate voltage of about 350 volts or so would be about right.

I'll bet you are using self-bias. Sounds like the plate currents you are running are sufficient to draw the butthole through a skunk.

I'll rathole some of the 4-400's for you. Pay the postage - they are yours.
 

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Posted by Luciano Brigite (Member # 1104) on 10-09-2003, 03:51 PM:
 
Paul,
the 6L6's are running on self bias ,having a wirewound resistor of 510 Ohm connected to the cathode of both tubes ( 1 resistor for the 2 tubes + the bypass cap)I'm thinking about putting one resistor for each tube and see what happens.I didn't take current readings on them yet, will do it this weekend.
with zero signal they're running hot but hardly show any glowing spot.with any signal they start to go blood red.

Thanks for the 4-400, I'll email you soon to arrange the shipping
 

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Posted by Paul G. Thompson (Member # 655) on 10-09-2003, 05:33 PM:
 
Hmmm....510 ohm resistor common to both cathodes is about 63 mils total. Or, roughly 31.5 mils per tube.

That does not sound too unreasonable. However, not taking screen current into consideration, the plate dissapation is about 11.5 watts per tube. I'll have to insult the tube manual and see what the maximum allowable is. When I get home, I'll plot a loadline and see where it falls in the EcIb curve. Been 40 years since I done that, but I'll try...

By the way....what is the screen voltage?
 

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Posted by Luciano Brigite (Member # 1104) on 10-09-2003, 10:34 PM:
 
Being a pushpull UL stage, the screen voltage is the same of the plates. according to the specs. taken from the RCA manual, when the screen of each tube is connected to a tap on the output transformer, is permissible for the voltage to be as high as 500 volts. on the amp, the screens are conected to taps on the output transformer and have a 220 Ohm resistor in series with them . also according to the manual, the no signal current for them in self bias,Class ab1 is 44mA , with signal 100mA .the recomended cathode resistor on the manual is 248 Ohm .

going back to transmitter tubes , what's the use in a transmitter for a 828 and a 4E27A / 5-125B ? I have one of each but have no idea about it's use ( here they're being used as decoration )
 

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Posted by Mark Gulbrandsen (Member # 72) on 10-09-2003, 10:36 PM:
 
My favorite audio tube is the 6C33 triode which is used as a voltage regulator tube in Russian MIG fighters. It works really well for building OTL type tube amps as well as output transformer type. It has a very low plate impedance to begin with. Running 6 each of these on two mono block amps will cause the generators at Hoover Dam to stall!
There is another incredible audio tube that is also Russian and thats the 6H30....similar in looks to the 6C33 but capable of higher power dissipation and was used in Russian nuclear bombs. Both these tubes are now easily available on the normal vacuum tube market and commercially produced amps are also available for big bucks.

Mark
 

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Posted by Paul G. Thompson (Member # 655) on 10-09-2003, 10:45 PM:
 
Well, with the parameters you are using and the tube still glows, maybe the next set of bottles should be the JAN 5881. (Military version of the 6L6GC.) Definately industrial strength...
 

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Posted by Luciano Brigite (Member # 1104) on 10-10-2003, 12:15 AM:
 
JAN tubes! (I have about 6 JAN-Type 5R4WGA and have no use for them except display and they're NOS. and the JAN equivalent for the 12AU7)
Well.. before I start hunting for them, I'll redo the circuit all again, even if I did that before, but wwhat's one more try?
these amps were a restoration project, a friend gave them to me and I rebuilt the entire thing ( new tubes, sockets capacitors and some resistors, before everything was de-assembled I drew the schematic for it and made sure it was right. the transformers and filter choque seemed ok, I replaced the connection wires on them ( they have solder points inside the casing for the wires) stripped everything off the base, repainted and reassembled the circuit. the original tubes on them where the ST16 shaped 6L6G for output, 6N7 for phase split 6SF5 for pre/input and 5Z3G for rectifier.
Josh is right when he said that some tubes glows easier than others,when I saw the glowing tubes, I shut everything down, a while after I put a set of old 6L6 I have for testing purposes and powered up again, they took a little more time to go red than the new ones. they doesn't have the brand on them anymore and doesn't looks like a Russian tube but doesn't look like a decent 6L6 too and did get reddish plates.

Now 2 pictures of the afterlife of a TB4-1250 tube :
(sorry about the quality of these pics.. took them with a webcam)




 

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Posted by Jack Ondracek (Member # 1466) on 10-10-2003, 12:39 AM:
 
Paul... speaking of industrial quality.

I have some old JAN 807s at the Port Townsend drive-in... found them somewhere around 35 years ago.

They're still on the shelf. There aren't enough of them to match up a full set, but have been used as spares from time to time over the years and are still perfectly fine.
 

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Posted by Paul G. Thompson (Member # 655) on 10-10-2003, 12:41 AM:
 
Jack, the 807 is what I am using to drive the 4-400A's in the RF line with the Collins. Very seldom do they turn sour. I use JAN's if I can find them. For every 3 sets of 4-400's I lose, I lose only one 807 because of low transconductance.

Luciano, the JAN 5R4 was crap.

The 5881's, 6146's and a bunch of others could stand up to the jar imposed on them when a 38,000 pound aircraft experiencing an arrested landing (basically, a controlled crash) on navy-issue aircraft carriers. Cat shots, too! The Radar power supplies used the 5881's and 6146's as regulators in the days of vacuum tubes. They hardly ever failed.

Yes, Josh is right. Some do and some do not glow. I am aware of this, and after I discovered you were running Class AB1 Push-Pull with the low plate current you were using, I made the posts for you to read. Had the idle current been in tha area of 65 mils or better, I am sure they would definately glow.

I think the glow Josh has on his 6L6s' is because of roughly 500 volts on the plates and a little lower bias he has on those things (I forgot what it was) is causing excessively high idle plate current. Under continual usage, I don't think he will get very good mileage out of them. I never did find out what the plate current was in the applications he was using them for.
 

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Posted by Phil Hill (Member # 371) on 10-10-2003, 01:55 AM:
 
Luciano: GREAT pic of your lamps! Luv 'em! I am inspired to do the same thing! (But would light the Filaments for a "night-light")
Also, I wouldn't give anyone a plugged nickel for 5881's...they are a POS...much rather use 6L6GC which are rated the same or in some cases better and will out-perform the 5881's for "grounded" people. The 5881's "small" bottle was sooo prone to overheat that it wasn't even worth using. 6L6GC were/are a MUCH better choice.

Also, the 5V4 (in ALL versions)is a great rectifier for the applications they are intended for. Much rather have a 5U4 though...

Most of the vacuum tube regulators I came across in the military used 6550s.

As with all electronic devices, they will perform VERY well if used within their specs. AND!!! even better if conservatively used.

I have junked more 5881's than I can say and happy I did so! A true POS!

>>> Phil
 

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Posted by Paul G. Thompson (Member # 655) on 10-10-2003, 02:43 AM:
 
Luciano, those are nice looking lamps. One of those tubes (the bigger one) looks like a 4-1000. The only information I have on the TB4-1250 like you have is a power triode that is about 7.8 inches high.

Here is a 4-1000. This would make a nice lamp. The filament wants 21 amps at 7.5 volts. It is 9.63 inches high and 5.25 inches in diameter. It weighs about 1.5 lbs. The one in the picture was given to Josh.



Here is a cute little devil:



Phil, If you junk the 5881's, send them this way. The 5881 was rated at 11.3 watts with a 4200 ohm load where the 6L6GC was 10.8. There is only one milliamp difference in zero signal plate current, probably since the tube is physically smaller and the Rp was significantly higher in the 5881. The 5881 is not a direct replacement to the 6L6GC, but it will work. It is, as the RCA Tube Manual says, "similar" By the way, what were was the color of the octal base of the 5881's you had so much trouble with? The ones I had good luck with were built to the orginal military specification. Most had the brown octal base.

I will be happy to take them off your hands. I'll even pay the shipping. I have had very good luck with them in the '50's and 60's. Maybe the newer ones were garbage, but the old ones I thought were great!

As far as the 6550 is concerned, that is possible. However, I am more familiar with the 6080. The old "G-51" used them as regulators in the +300, +150 and -250 power supplies.

[ 10-10-2003, 02:31 PM: Message edited by: Paul G. Thompson ]
 

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Posted by Luciano Brigite (Member # 1104) on 10-10-2003, 05:03 PM:
 
Thanks for the comments on the lamp
Phil, making one isn't hard,all I needed to put things toguether on that one was some epoxy adhesive and hot glue (quite a bit of them) It's base is a plastic core taken from a 1" videotape reel. I'd not use the tube itself as a night lamp because it'd spend a lot more power than the bulb I use on top of it , also the filament in that tube is broken in many tinny pieces.

Paul, the big tube is the TB4-1250 the small one is a 4E27A.
The 4-1000 surely will give a nice lamp, it's a little bigger than the TB . Nice looking plate on that tube too.

The other tube is interesting, I wonder why you called it cute little devil,judging by the specs in the base, I guess it's a kind of trigger tube or something close to that (a thyratron (sp?)maybe?)

tech data for the TB4-1250
 

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Posted by Edward Jurich (Member # 1787) on 10-10-2003, 05:22 PM:
 
--------------------------------------------
With all the paperwork, engineering studies, and attorneys fees involved just in applying for a construction permit to replace the aliing xmitter
--------------------------------------------

With deregulation, there is no paperwork involved with replacing a transmitter with another of the same power rating. You don't even have to notify the FCC.
Before I got out of radio (about 4 years ago), I found that transmitter sites were becoming poorly maintained at many stations thanks to deregulation. Without the requirement for a FCC licensed tech, any Joe Blow could work on a transmiiter (and a lot of sites I saw looked like it). Inspections of transmitter sites by the FCC are pretty much a thing of the past so many older transmitter fell into disrepair. One FM Collins I saw had every interlock, including the air-flow interlock, disabled. I commented that some day it would burn up, and it did. No doubt the station got insurance to buy them a new transmitter.
 

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Posted by Phil Hill (Member # 371) on 10-10-2003, 08:04 PM:
 
Paul, chill out...it's just a tube.

As far as sending you those tubes... sorry. I just this last week gave my last 20 5881 red-bases to the LAPD for target practice. Great tax write-off considering what the dumb-asses are paying for tubes on eBay.

Ed Said:

quote:

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Without the requirement for a FCC licensed tech, any Joe Blow could work on a transmiiter

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You are 100% right! Now, any self-appoined "expert" can f*ck-up anything they wish. It was really a shame that the FCC stopped the testing and the various classes of radio-telephone licenses as a qualification to work on transmitters. At least that had ensured one had read the "License Manual".

>>> Phil
 

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Posted by Paul G. Thompson (Member # 655) on 10-14-2003, 11:46 PM:
 
Just for Luciano...

You can make a lamp out of this one. Busch cans, Budweiser cans, or any beer can can serve as a base.



This thing has some balls.
DC Plate Voltage: 3000 volts.
Maximum signal DC plate current: 500MA
Plate Pissadation: 350 watts
Maximum Signal Plate Input power: 1300 watts

Run a set of these hummers push-pull in an audio application can give you 1900 watts if they are used as audio power amplifier. Of course, you need 20 watts of power to do that. The peak AF grid to grid voltage swing is 450 volts.

This bottle is 8-3/4 inches tall and 4-1/2 inches in diameter.

For you guys who want to build a powerful stereo to blast the rappers out of there Hondas, here is the plate characteristics. And, the filament only sucks 10 amps at 10 volts.




 

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Posted by Jack Ondracek (Member # 1466) on 10-15-2003, 12:40 AM:
 

quote:

---

Before I got out of radio (about 4 years ago), I found that transmitter sites were becoming poorly maintained at many stations thanks to deregulation. Without the requirement for a FCC licensed tech, any Joe Blow could work on a transmiiter (and a lot of sites I saw looked like it).

---

quote:

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OMG Paul! My FAVORITE bottle! Built a few xmtrs with those puppies! I loved to watch them thar plates glow cherry-red!

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Unless Paul can contradict this... I don't think there ever was a pre-solid state, tube-type 1kW transmitter with 4-400 tubes that could come close to holding a candle in any way... modulation, distortion specs, positive peaking... ANYTHING... to a transmitter with 833A tubes in it. As far as I've known... it just couldn't be done. That 833 tube was magnificent! The 4-400 based boxes just didn't have any headroom at all. Even the ones with the 4-500 tubes (were there any besides McMartins? (yech)... they weren't any better, though the tubes were more expensive. Until Collins came out with the "rock" series of transmitter (5-500 based... and much heavier iron), the 833s were the best.
 

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Posted by Phil Hill (Member # 371) on 10-15-2003, 01:15 AM:
 
You know Jack, what is really sad about the Eimac rip-offs like that Mullard is the lack of quality control. Notice the "leaning" of the plate and the lousy balance of supports between the left and right of the "elements". I have seen that more times than I can say...

Give me Eimac ANYDAY!

>>> Phil
 

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Posted by Paul G. Thompson (Member # 655) on 10-15-2003, 01:58 AM:
 
Yeah, by looking at the leaning of the plate, I would think the quality control inspector was smoking "the good stuff"...

If memory serves me correctly, I got that thing out of an RCA 1KW AM transmitter in Moses Lake. That was the transmitter that so full of rat shit that Lonnie and I just tipped it over on the side and dragged it out of the transmitter shack with a chain attacted to Lonnie's truck. Jeeze, that thing stunk. We had to wear face masks to keep from breating in the rat shit. It was enough to make a maggot puke.
 

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Posted by Josh Jones (Member # 447) on 10-15-2003, 03:30 AM:
 
Just call me the tube man


4CX15,000 out of our Continental 816-2R (the beige cabinet)

Josh
 

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Posted by Daniel Fuentz (Member # 1684) on 10-15-2003, 03:46 AM:
 
My only trip to a transmitter site was a few years ago, oddly enough I saw the transmitters of the station I work for now. At the time, they had an NEC unit that was quite large, and a vintage RCA backup unit that was even bigger! Now all that is gone and we have a small (compared to those things) Harris, which I've not seen, and a low-power backup. Even though I'm not very technically inclined seeing stuff like that is very interesting to me. I doubt many people today even think about what's involved in getting the signal to their TV or radio...
 

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Posted by Luciano Brigite (Member # 1104) on 10-15-2003, 01:02 PM:
 
833! I did see a few of them several years ago at the same place I got the TB I used to make the lamp..I almost got it instead of the TB but because the way it has the pins at the bottom I left them there, It's plate looked very different, with large ceramic suports inside and were made by Philips. it must be a triode and triodes are the fine thing for audio amps .Seeing the data for them makes me wonder the size of the output transformer for a pair of them If wasn't the cost of such parts, I'd give a try at one

Josh, is that tube you're holding a tetrode? ( I know that the coding on them tells what they are but I don't remember then anymore) and goldish cooling fins and anode cap? that I never see. umm lemme try.. 4CX15.000 .. tetrode, ceramic envelope 15.000watts output ? wish I had kept the lousy photocopy of a Eimac catalog someone gave me along with a 3CX2500A3, unfortunately the tube fell from the bench and the rest is well know

I'm trying to remember what tube was one of the few xmiter tubes I had that has the grid connection on the side , anode on top and filment on a 4 pin round socket at the bottom ,the tube being about the size of a beer bottle. it's 8?? ( not sure if 813, 811 I think the 813 is a tetrode or pentode)
 

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Posted by Phil Hill (Member # 371) on 10-15-2003, 02:13 PM:
 
Luciano, While the external-fin radiators look good as a doorstop, the glass bottles look way more cool for lamps.

The last digits refer to the max plate dissipation.

Eimac has a website with all sorts of stuff's data sheets just for us tube guys! Here

>>> Phil
 

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Posted by Paul G. Thompson (Member # 655) on 10-15-2003, 02:46 PM:
 
Josh, the 4CX15000 you have in your paws look like the 3CX-10000 I use in the Collins. It does look a little like a mushroom with cookie jar handles.

Remember we were talking about the 6697 Power Amps in the RCA BTH-50H1 transmitter looking like someone sitting on a toilet? Well, here is a picture from the manual.



That transmitter has balls!



When they fire and it is the first time you ever heard them fire, you'll want to go home and change your underwar.

Of course, I just gotta post a picture of that big pig.



For the test of you engineers out there, here is a little write up on the RCA Ampliphase transmitter:

The principle of Ampliphase is to take a single frequency source, split it into two feeds, phase modulate each feed, then add the two signals in a combining network. Amplitude modulation is achieved by the degree of addition or subtraction due to the phase difference between the the two signals. All (?) Ampliphase transmitters are arranged so that under zero modulation conditions, the quiescent phase difference is 135 degrees. The two signals are modulated in equal but opposite directions by a total of +/- 45 degrees, giving maximum and minimum differences of 180 and 90 degrees. At 180 degrees, the two waves cancel out in the combining network, hence this is the 100% peak negative modulation condition. At 90 degrees, the two waves add to give close to 100% positive modulation.

Ampliphase transmitters quickly acquired the nickname of "Amplifuzz" due to the quirky nature of setting them up and maintaining consistant performance, and became the transmitters engineers loved to hate. (That was definately said correctly. I hated them.)

Although the technique became obsolete for broadcast use in the 1970's, outphasing has undergone a bit of a renaissance in recent years in the microwave spectrum. It is used as an efficient and accurate means of producing phase/amplitude (QUAM) modulated wideband carriers, necessitated by todays digital communications systems.

I just found this out: The 6697 PA is basically no longer available. Not too many companies rebuild them anymore. The tube crosses to nothing. One company I found does rebuild them at about 2800 bucks a pop with a dud. Without a dud, it is 3500 bucks.

I guess the old RCA Ampliphase transmitters that use that tube are going to soon wind up in the scrap yard or serve as anchors for the navy-issue aircraft carriers. EXCELLENT!! The sooner the better.
 

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Posted by Phil Hill (Member # 371) on 10-15-2003, 04:04 PM:
 
Deleted...

Wrong post...sorry.

>>> Phil
 

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Posted by Jeff Stricker (Member # 224) on 10-15-2003, 04:09 PM:
 
The one time chief operator (now deceased) of WOWO in Ft. Wayne, Indiana told me they used to run a 50 KW RCA Ampliphase rig. In those days they were 50 KW ND in the daytime and 50 KW (three tower) directional at night with once heck of a signal up and down the east coast. I used to conduct strong signal overload tests on car radio designs at their antenna site.

Several years ago they scaled back their night power to 9.8 KW and tweaked the pattern to allow a station in NYC on same frequency (1190) to operate at night. A big nighttime voice is now just part of the co-channel clutter!
 

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Posted by Luciano Brigite (Member # 1104) on 10-15-2003, 07:45 PM:
 
Phill, all glass tubes does looks better than the glass/metal or ceramic metal tubes and looks even better when running but I remember of one, but not it's code, that was a glass/metal tube about the same size in heigh and 1 1/2 the diameter of a beer can, it had external fins for air cooling that I did like, the curious thing on them.. all the ones I saw, about 20 of them, had the glass part popped off of the metal and you could pull the entire filament /grid assembly out of it.

After staring at the picture of the 833 and reading Paul's post, I started thinking about building a more serious tube amp, i've seen from time to time one or another schematic floating on the net of amplifiers using transmitter tubes in the output stage but never got interested enough to pick one and see what happens.
last one I saw had a ceramic/metal tube as single end class A amplifier. the tube looks cute , if I reall (part of ) it right, it was a 3CX tube made by Svetlana , the most expense on that amp I believe that was the tube itself and the socket .
Now I have one question..
suposing I get to build a more serious amp, using transmitter tubes for output stage ,wich ones I'd give a try?
things to take into account: tube prices, easy to find, sockets and that they're triodes ( to keep some of it simple)
what do you guys says?
 

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Posted by Phil Hill (Member # 371) on 10-15-2003, 09:01 PM:
 
I say, get yourself on hellava speaker system!

>>> Phil
 

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Posted by Matthew Bailey (Member # 601) on 10-15-2003, 09:43 PM:
 
From the color of the picture,I think you ought to paint that RCA transmitter Christie blue & green.
 

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Posted by Luciano Brigite (Member # 1104) on 10-15-2003, 11:22 PM:
 
Phil, I already have some , from the days I was out of a booth and did some DJ work at small parties to get some $$ most of the gear is long gone but still have a set of big speakers (biamping required tho)taking space.
and I just finished the weird math to find out core, wire sizes and coil turns for output transformers for a class AB1 amp using 4-65A's and another using 3CX*ahem* tubes , I think something is wrong on them, because I ended with a xformer that's 6"x 2" in size.. it seems just.. too small. (the impedance, voltage and turns ratio came out ok for them tho..)and yes.. I know the 4-65A is a tetrode and I mentioned I'm looking for something with transmitter triodes.but heh.. it was part of the fun

Matthew,if you folow that link Mark posted some pages ago here in this topic and keep following the links on those pages you'll find a transmitter with the colors you mentioned
I remember seeing a green transmitter in one of those pages and it was either an RCA or a GE.
 

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Posted by Phil Hill (Member # 371) on 10-16-2003, 01:37 AM:
 
If your planning on using those 65kw PP tubes... you will not only need a lot bigger speaker system, but also different neighbors...

>>> Phil
 

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Posted by William Hooper (Member # 71) on 10-16-2003, 02:19 AM:
 
I think you should pull the front plastic panel off a Coke machine, glue it on the cabinet door, cut a slot in it, & mount the external organs of a bill acceptor over that.
 

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Posted by Paul G. Thompson (Member # 655) on 10-16-2003, 02:43 AM:
 




(I know it is childish, but I just could not resist.)
 

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Posted by Phil Hill (Member # 371) on 10-16-2003, 06:31 AM:
 
???? Me thinks someone has been smokin' some of that I-30 stuff...

>>> Phil
 

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Posted by Luciano Brigite (Member # 1104) on 10-16-2003, 11:29 AM:
 
Phil ,the 3CX ***** I'm thinking about isn't one of the big tubes
it's a wee compared to most of the 3CX's you have seen , actual code is 3CX300A1, a triode designed for audio and was made by Svetlana only ( buh...)Already called the places I know that still deals with tubes and none of them have the tube or head about it. and Svetlana seems to be gone then find a quad of them will be difficult ( and pricey).
The 4-65A only one place deals with it but they didn't have the price for it but told me that it's not cheap, ah well.
My speakers are all rotting away and I won't mind if they blown away with the amp..my neigbors are noisy at tiems and we all have out share along the week to bring the house down
 

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Posted by Paul G. Thompson (Member # 655) on 10-16-2003, 02:43 PM:
 
Phil, I had a reasonable suspicion my last post would blow some minds.

I wonder what Josh will reply with?

Luciano, I don't think the 833A tubes would sound all that great in a class "B" bias situation. The transition from one tube to the outer would not be that great. Class AB1 might be better or just plain class A. But I doubt you could get the balls out of it under those circumstances.

However, it'll probably do a great job of shaking the neighbor's windows....and running up your power bill.

Between the power transformer, filament transformer, fixed bias transformer and output transformer, you might have something that weighs about 500 lbs.
 

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Posted by Phil Hill (Member # 371) on 10-16-2003, 03:47 PM:
 
Paul, it wasn't "other" minds that I thought was blown....

While the xmfr iron would certainly be impressive, think about the size of the speaker magnet! Whoo Wee!

Luciano, I looked up the 3CX300A1...very interesting tube.

Cool audio amp here

Some more app notes here

>>> Phil
 

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Posted by Luciano Brigite (Member # 1104) on 10-16-2003, 06:53 PM:
 
Paul, class A (SE or PP) and AB are my kind of thing.class B has it's problems and advantages, there are people that likes class B amps, but I'm more into the A (ouch! hot hot hot! )but the manuals doesn't say anything about the 833 or any other xmiter tube running in class A. most of them I've seen has the AB1/AB2 or B .
Having in mind the current draw from the tubes I think the filament transformer is the one that'll break someone's back when it comes the time to move it.. or.. one single transformer with all the windings in there .

Phil, the 3CX300A1 is indeed interesting and.. expensive as I found out while looking at the pages on the second link you posted.they want $110.00/each.. for a tube that I can't see the insides glowing ,it's not all fun.
The PP schematic I already know, saw it when I read about the tube for the first time. there is another one,but single ended that has about nothing in it only 2 tubes some other components and the transformers. The PP amp in the link uses 2 6BM8 to drive the 3CX's.. the 6BM8 alone gives a simple and reasonably good tube amp , I built two of them on a piece of wood , using transformers I had laying around here and cheapo output transformers. I have to stop being lazy and go buy some iron and copper and wind the transformer that gave me a few grey hairs while doing the maths , add the "black magic" to it and see what happens.
Speaking of transformers.. the math for the 3CX300A1 gave me the following results: ( sorry but the measures are in milimeter)
primary winding: 1674.1 turns of 0.1mm wire (section)
secondary winding 105.86 turns of 1.58mm (closest is 1.65mm)wire (section)
lamination: center "leg" of 44.4mm ,stack of the same size in height (44.4 x 44.4)
gap: 0,31mm for std iron ; 0,2mm for hq iron

the "black magic" : not telling

it's for a 2000 ohm PP to 8ohm transformer

Who'll dare to give it a try?
 

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Posted by Phil Hill (Member # 371) on 10-16-2003, 06:59 PM:
 
$110 for a tube ain't that bad...especially for that type of tube. You outta see what the jerks on eBay are paying for tubes...

I agree 100%, ya gotta see 'em glow! That's part of the "experience"...

Grey hairs...at your age? Yikes!

Having designed and wound tons of ac & audio xmfrs... I ALWAYS use the HQ close-gain stuff...

>>> Phil
 

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Posted by Paul G. Thompson (Member # 655) on 10-16-2003, 09:54 PM:
 
Phil, that's why one of my away messages on some of my IM programs say, "Out of my mind...I'll be back in a few minutes."

Luciano, you are correct. I found nothing about running them class A, either. I am not even sure at this point if they would be suited for audio work because most of the characteristic curves show a positive bias on the grid with respect to the cathode. Grid current in audio applications = distortion.

Unless DC was used on the filaments, one would have to use some kind of hum balancing circuit also. Then again, maybe not...if the thermal inertia of the filaments is high enough.
 

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Posted by Josh Jones (Member # 447) on 10-17-2003, 01:15 AM:
 
Paul, sit and spin


 

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Posted by Paul G. Thompson (Member # 655) on 10-17-2003, 01:34 AM:
 
Oh, well...
 

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Posted by Luciano Brigite (Member # 1104) on 10-17-2003, 01:19 PM:
 
Yup! grey hairs and some white ones too, I need only one year and some months to get the 30's. Guessing my age by that picture of me in the booth with the red dragon shirt will be a bit off. the picture is about 3 years old by now (btw.. I'm thinking about a new pic)

While trying to get asleep in front of the computer last night I found this I think Paul G. will be interested in it the power supply for it is here
Class A2 .. hrrmmm....
 

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Posted by Phil Hill (Member # 371) on 10-17-2003, 04:54 PM:
 
The 833A & 833C also make one hell of an oscillator for a tesla coil... YIKES!

>>> Phil
 

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Posted by Jack Ondracek (Member # 1466) on 10-18-2003, 01:20 AM:
 
Paul...
ITA built a good-looking 5kW transmitter that used a pair of 4-1000 tubes to modulate a 3CX2500F3 final. It had it's hv iron in a separate box. Do you know of this transmitter... and is it anywhere around the same vintage as your 1kW???
 

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Posted by Paul G. Thompson (Member # 655) on 10-18-2003, 01:06 PM:
 
Jack, I never saw the ITA 5KW rig. Ours is an AM500/1000 box. It dates back to 1962.

Here is a picture of the ITA:



Here is a book picture picture of what I have for the 10KW transmitter.



This is what I actually have in the transmitter room.



Timeline for Collins:

The Collins Radio Company was founded in 1932 by Arthur A. Collins* at Cedar Rapids, IA. It was famous for producing high quality transmitters for amateurs, the military and the broadcast industry. Under the Collins label also came some of the most popular consoles and cart machines used by radio stations.

Dave Hultsman recalls that "Collins first sold FM transmitters from 1947-1958, but found little demand. They then sold ITA transmitters with a Collins logo for a few years, before building the 830 series in the early 1960s. The ITA tetrode transmitters were very unstable in the PA stage. Neutralization was a major problem. That is probably why Bernie [Wise] went to Juan Chibrando's grounded grid triode design at CCA."

Collins reduced the neutralization problem by grounding the screen in the 830 and 831 series.

In 1964, Collins moved the Broadcast Division from Cedar Rapids to Dallas, TX. Among the first products was the 820 series of AM transmitters, designed to meet new FCC regulations regarding the need to contain harmonics and spurious emissions inside the transmitter.

In the mid 1970s, the 831 series was produced, the first model being a 2 kW, 831-D, to take advantage of adding vertical polarization.

In 1977, Collins Radio Co. was bought by Rockwell and moved to Dallas, TX, as Rockwell-Collins. On October 1, 1980, Rockwell spun the Collins Broadcast line off to Continental Electronics.

[ 10-18-2003, 07:20 PM: Message edited by: Paul G. Thompson ]
 

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Posted by Jack Ondracek (Member # 1466) on 10-19-2003, 12:42 PM:
 
Paul...
Same series. The 5kW also had that metal door handle with the control buttons in it. Iron was in a box separate box about 1/3 the size.

Aside from the cost of the 4/1000 mods, which couldn't be rebuilt , the transmitter was a decent box. I put a CRL processing package on one, and it handled it fine... plenty of headroom for aggressive processing.

Oh... talk about your 4-400s glowing... those 4-1000s.... wow!
 

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Posted by Phil Hill (Member # 371) on 10-19-2003, 02:58 PM:
 
Paul, that ITA looks really cool.
Jack, I agree it's ALL about the glow!





>>> Phil
 

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Posted by Luciano Brigite (Member # 1104) on 10-19-2003, 03:01 PM:
 
That ITA transmitter looks like my fridge ( too bad the fridge doesn't have the glowing things inside)
The Collins looks neat.
 

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Posted by Paul G. Thompson (Member # 655) on 10-19-2003, 07:47 PM:
 
Yeah, Luciano. I might come up with an old 1KW AM Transmitter and give it to Josh. He was mumbling something about making a refrigerator out of one, using the meters as temperature gauges. I thought the idea was funny as hell, but it does have some merits.

It would be unique, that's for sure.

It is just an issue on how his mom and dad would take to a 1,000 lb box sittin' in the garage. But his parents are great people, so they would probably go along with it...maybe.

Hey, Josh...let's build a Tesla coil like Phil posted. I can get another 833. I have another one sitting at the station.

Phil, do you have the specs on those things?
 

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Posted by Phil Hill (Member # 371) on 10-19-2003, 08:32 PM:
 
Paul, I'll email you the schematic and parts list...give me a few days to pull it all together...

While the "spark-gap" ones sound really cool and are "scary", the 833/811 ones run quiet.

I like the spark-gap ones better!

Also, I have a 0.5kW FM xmtr here in my house that I run...on and off for a show that I do. I want to carry KVXL to all of Hollywood...but...

>>> Phil

Corrected typo...

[ 10-20-2003, 07:16 AM: Message edited by: Phil Hill ]
 

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Posted by Luciano Brigite (Member # 1104) on 10-20-2003, 02:30 PM:
 
Aren't the Xenon ignitors suposed to be a smal lversion of a tesla coil? the ones I make seems just like that..
That's the first time I see a tesla running on tubes.
Speaking of tubes ... *sigh* I'll have to go back to the beginning of everything.. I just got my hands on a copy of the RCA RC25 tube manual and while reading some of the stuff in there I realized that at least half the stuff I laid down on the paper isn't very right.. and later while looking for more info about output transformers I found out that all the darn math I use to find out core size, winding's turns and all that is only for SE transformers, and about all the (now wrong)schematics I did are for PP ( and a strange one for PP-P) .. ah

Anyway... I don't know everything.. I'll never know everything..
 

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Posted by Jason Burroughs (Member # 68) on 10-20-2003, 02:48 PM:
 
The Dallas Collins facility was acutally in Richardson part of what is now called Telecom Corridor, just north of Dallas. The buildings were later sold to Alcatel in the early 90's. Alcatel has since moved out and the buildings sit mostly vacant. They had one interresting building that had two "pods" on each side, with equipment to connect to trucks that had transmission eqipment on them, for testing purposes. The building was pretty well insulated for RF. Radios inside got VERY poor reception.
 

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Posted by Matthew Bailey (Member # 601) on 10-20-2003, 03:51 PM:
 
I'll see if I can find photos of the transmitter that Art Bell has installed in his station KNYE FM.
 

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Posted by Jack Ondracek (Member # 1466) on 10-20-2003, 07:38 PM:
 

quote:

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...from Phil..
I have a 0.5kW FM xmtr here in my house that I run...on and off for a show that I do.

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Ahhh.... then you'd be a pira....er.... experimental broadcaster then, eh?
 

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Posted by Matthew Bailey (Member # 601) on 10-20-2003, 10:00 PM:
 
Not really. I have a photo of a Raytheon/Penta Labs PL-254w transmitter tube.. It has four pins on the bottom, one connection at one side, & another at the top.
 

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Posted by William Hooper (Member # 71) on 10-21-2003, 12:35 AM:
 
Is that the tube the judge said that they could pull out of that lady in Florida?
 

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Posted by Sam Hunter (Member # 1119) on 10-21-2003, 12:36 PM:
 
What was that am radio station somewhere right across the border in Mexico that had was so big they had to clean the carbon off the pa tubes or something. Damn its been a long time ago since I heard about that and don't recall all of the story. It was 100000 watts if I remember right. I just don't remember.
 

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Posted by John Pytlak (Member # 331) on 10-21-2003, 01:21 PM:
 
Other "monster" transmitters:

quote:

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The purpose of the Voice of America, of which the Bethany Relay Station was a part, was to transmit news and information across America and around the world.
The Bethany site directed signals to Central and South America and included ten transmitters and twenty-two antennas. The total power required to operate all the equipment was 3.5 Million Watts

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quote:

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If you can't afford to build your own AM Radio Station to broadcast your programs across Central America, here is the next best thing:
The Voice of America (VOA) Relay Station in Belize, Central America (a U.S. Government broadcasting facility) has recently signed an agreement with the Government of Belize which allows us to provide "Third-Party" program transmission RELAY services on our two, 100,000 watt AM band radio transmitters .

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quote:

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Behind the scenes, WLW and founder Powel Crosley worked tirelessly during the 1920s and 1930s to advance the state of radio engineering, including several years as the only U.S. station ever to operate with 500 kilowatts of power and many years as one of the few U.S. stations to operate an international shortwave plant in addition to domestic AM broadcasting....On May 2, 1934, WLW's 500 kilowatt signal, which had been operating experimentally under the callsign W8XO, made its first official appearance, activated by President Roosevelt by remote circuit from the White House at 9:30 PM.

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quote:

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Originally developed for Voice of America long range high frequency broadcast service, the Model HC-114 transmitter delivers 250,000 watts of R.F. carrier power at any frequency between 3.95 and 26.5 mc. Plate modulated, the transmitter is capable of 100% amplitude modulation on a continuous basis.

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http://www.transmitter.be/gat-hc114.html

100,000 Watt Output tube:

http://www.tube.be/4cv100000c.html

500,000 Watt Output tube:

http://www.tube.be/4cm500000g.html

Hints on tube life:

http://www.burle.com/cgi-bin/byteserver.pl/pdf/tp202.pdf
 

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Posted by Phil Hill (Member # 371) on 10-21-2003, 04:42 PM:
 
More, really cool pics from here of VOA at Bethany Ohio:

One of three 250kW AM transmitters:



Control/Meter Panel:



Power Supply and High-Level Modulation Transformers:


The whole room is interlocked to kill the power and short the caps if anyone enters.

I want the power and I want it ALL NOW!

>>> Phil
 

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Posted by Paul G. Thompson (Member # 655) on 10-22-2003, 11:06 PM:
 
Geeze, Phil....those are some real beauties....Very nice pictures.
 

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Posted by Phil Hill (Member # 371) on 10-22-2003, 11:35 PM:
 
Yeah Paul, that, and many other sites, have some really cool pics.

Another one of my many many vices is: I love radio (don't like TV). Have spent waaay too much time over the years surfin' those radio sites...

>>> Phil
 

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Posted by Paul G. Thompson (Member # 655) on 10-23-2003, 01:16 AM:
 
Smellivision? IKK! I hate TV. Hardly ever watch it unless my favorite baseball team is playing or there is some really hot news such as 911, etc. that may be airing. Other than that, TV sucks.

When I was a kid, I had an old Stewart-Warner floor radio. Back in those days, they had RF amplifiers in the front end instead of just dumping the radio station signal almost directly into the injector grid of the pentigrid converter. Those type radios had selectivity that was fine if you had the radio sitting on top the transmitter.

But those old radios that had the RF amplifiers that fed the converter....those receivers were "hot" in sensitivity. I tuned that old SW radio I had to 1000KC and connected a low-power RF signal generator to the antenna. I then tuned around on the RF generator knob and the frequency would beat with a short wave station that produced a difference frequency of 1000khz...and presto! Russia, China, VOA, WWV, you name it! I could tune it in on good "skip distance" nights better than I could get them on the short wave band.

When I go and visit Josh this Christmas, I am going to bring my RF generator with me, get his old Zenith running, and see what kind of crap we can tune in like I did when I was a kid.
 

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Posted by Phil Hill (Member # 371) on 10-23-2003, 01:26 AM:
 
Paul, are you coming to my place for xmas? Josh told me he was spending those holidays here this year at my place...

>>> Phil
 

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