Film-Tech Forum ARCHIVE: The 1KW Transmitter Self-Distructed.

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Posted by Paul G. Thompson (Member # 655) on 04-06-2004, 11:15 PM:

No more do I have to worry about glowing plates of the 4-400's.

One morning at 0300 hours, the transmitter caught fire. I described that in another thread.

The insurance inspectors came today and gave us clearance to remove the transmitter, which I did. We have a new 1KW BE coming in on Thursday morning, so I should be back on the air Thursday night at power change time. We also have a DX-10 coming in about a month to replace the old 10KW Collins. Since the DX-10 will easily operate at 10KW Day Power and 1KW night power, we will use our new 1KW Broadcast Electronics transmitter as a backup if for some reason we have to take the DX-10 off the air.

Anyway, here are some pictures of the 1KW ITA after it self-distructed. Here is what is left of the HVPS choke coil and modulation transformer.

This is what remains of the constant voltage filament regulator and the wiring loom that feeds the controller and oscillator/modulator driver panel.

And, the center of the fire.

What caused it, I really don't know. But the plate transformer escaped damage. The rest was toast.

Tomorrow I will finish stripping the old transmitter and haul it off to the dump. We almost lost the building on this one....

Posted by Paul Mayer (Member # 355) on 04-07-2004, 01:26 AM:

Geez! I guess you were lucky. Our local NBC affiliate (back when it was KORK-TV channel 3) burned to the ground after a transmitter fire. The cause? Rats! The station always had a rat problem. Used to be fairly common for the station to get knocked off the air momentarily due to rats getting into the transmitter (this was the old station on Boulder Highway when everything was in the same building). Finally one of them chewed through some high-voltage cables... ZOT! A friend of mine was in master control when the fire started. He made one phone call to the chief engineer, "The station's on fire, I have everybody's licenses, bye."

The only thing they saved were the head ends of the station's two TK-43 cameras, which they pushed on their airpeds out into the parking lot. Those cameras sat on the floor in the studio at my station (KLVX-TV channel 10) for several weeks after that, useless since the CCUs burned (actually I think most video people would say the TK-43 was useless anyway, with its goofy mixing of IO and vidicon tubes [Smile]

). Even though the place was a total loss, they commandeered another transmitter (destined at the time for a new Don Rey Media station in another state) and had a test pattern on the air one week after the fire. The transmitter arrived in pieces on a flat bed truck. All of the engineers in town at the time, regardless of affiliation, came over and pitched in to help get channel 3 back on the air. It was like working on the world's biggest Heathkit.

In the mean time, channel 3 used the studio in the basement of the Flora Duncan Humanities Building at UNLV. They moved back into the Boulder Highway building several months later.

BTW, anyone going to NAB this month? I got my free badge this week. It's always fun to go look and play with a convention center full of other people's expensive toys.

Posted by John Pytlak (Member # 331) on 04-07-2004, 08:57 AM:

Kodak will be exhibiting at NAB, but I am not one of the lucky ones who get to attend.

Posted by Luciano Brigite (Member # 1104) on 04-07-2004, 01:55 PM:

Hmm. judging from those pics, the damage was smaller than what I thought when I read your first post about it .Depending on how and what was used to put the fire down, and to what degree you do the stripping on it, a lot of things can be saved from there .Don't have any idea about what's inside that box right above the burned transformer,but from the look of it what's in the upper section of it may have escaped.. or not.
I'd go for all the tube sockets, even the smaller ones,wirewound resistors,switchs,panel metters relays/contactors,fans or blowers,coils,tubes hv caps,oil or not(if not messed up) and leave only the burned stuff ,wiring and cheapo parts.Then sell the rest by weight to junk [Smile]

Posted by Jack Ondracek (Member # 1466) on 04-07-2004, 07:14 PM:

At least Paul will be working with far lower voltages now. [evil]

Of course, he'll have to keep his screwdrivers away from the power bus!!

Posted by Mark Gulbrandsen (Member # 72) on 04-07-2004, 07:50 PM:

Looks repairable to me..... The xformers are no problem, I know a guy in Vegas that can wind new ones for it.

Paul M.,
Thats a pretty cool story indeed. The TTU110 I worked on typically had water leaks so it would go into safe mode and you had 30 min to get from the studio to the 94th floor of the Hancock building...and past the Hancock Security of course.... sometimes you made it sometimes not depending on the traffic in downtown Chicago. Then get it on local control and either defeat the safe mode if the leak wasn't too bad or shut it down until the transmitter engineer arrived if it was a gusher.

We also lost a couple of visual Klystrons to lightning hits and another one that was improperly assembled at Varian....man 150K for one Klystron in 1980 dollars! the funny thing was that the aural Klystron was the original Varian tube made in 1964. It probably lasted so long because it only ran at 1/3 rated power all its life. Lightning never took that one out for what ever reason.

The TK43's musta been dogs. Our station program manager worked at a station in southern Missouri that had them and he mentioned 1000fc minimum light level for the news set.... Thats alot of light and tons of heat. I maintained five TK45's and they were a pain some days because they got moved around alot between three different studios in the facility. But man those Plumbs really looked great and had gobs of resolution! Awsome coloremitry. If the 45's were left alone they were actually pretty stable .....

Mark

Posted by Paul G. Thompson (Member # 655) on 04-07-2004, 11:02 PM:

It was just too far gone. When I can buy a used 1979 1KW 820D-2 for 200 bucks that is in 1,000,000 times better shape than the old early '60's vintage ITA. The transformer Luciano was wondering about is a constant voltage filament regulator. It iwas all melted inside, and was complete junk. The Choke was really toasted. There is no way that thing could have been salvaged. The modulation transformer got hit hard, too. The bias transformer (another 50 pounder) that does not show in the picture leaked all its tar out and made one big mess. The 4-400's were toast, and 1/3 of the wiring harness on the left side was rendered useless. The remaining parts of the transmitter were heavily smoke damaged. Some of the capacitors blew up, too.

When I stripped it down, the only things that were salvageable was the tube sockets, all the brass nuts and bolts, insulator standoffs, some capacitors, some 200 watt dog bones, and the tank coils. I was able to salvage the four 4-400 filament transformers.

The rest went to the scrap yard - as one smokey mess.

Posted by Daniel Fuentz (Member # 1684) on 04-10-2004, 10:12 PM:

Ah... Reminds me of what happened about 3 years ago when I was working at KMPH-TV 26. We ran MC for the Bakersfield Fox affilliate (KBFX) in our facility through a microwave link that was localted at our back-up transmitter site. One night, programming on KBFX disappeared. We called down there and were told they weren't getting a signal fron us. We check our link and get nothing. The engineer that went up there to see what the problem was found nothing... The whole building, transmitters, towers, everything had burned to the ground! The station management had to rent a sat truck and book sat time to get the signal down to Bakersfield until a fiber feed could be established. It took them about a year to get the backup transmitter site rebuilt, mainly due to the snow up in the mountains.

Posted by Jack Ondracek (Member # 1466) on 04-11-2004, 04:01 PM:

They ever figure out what caused the fire?

Posted by Steve Kraus (Member # 476) on 04-11-2004, 06:13 PM:

Where do you suppose the tradition started that when speaking of tv transmitters and related items one says aural and visual instead of audio and video? Funny too is the old school/business definition of A-V as audio-visual that mixes both styles.