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Author Topic: What AM tower is this (Paul G. Thompson or anyone?) Edward Jurich Master Film Handler Posts: 305 From: Las Vegas USA Registered: Jul 2003 posted 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.  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 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.  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 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  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 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.  |  IP: Logged Jeff Stricker Master Film Handler Posts: 481 From: Calumet, Mi USA Registered: Nov 1999 posted 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.  |  IP: Logged Luciano Brigite Master Film Handler Posts: 277 From: Sao Paulo, SP, Brazil Registered: Jan 2002 posted 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  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 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  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 10-08-2003 01:07 PM                     Mark said: quote: This is also in the state of Washington where you need to get a permit just to get a permit!! 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.  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 10-08-2003 01:28 PM                        A link to Paul's photo: Photo of 4-400A Tetrode XMTR Output Tubes Glowing  |  IP: Logged Jeff Stricker Master Film Handler Posts: 481 From: Calumet, Mi USA Registered: Nov 1999 posted 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.  |  IP: Logged Luciano Brigite Master Film Handler Posts: 277 From: Sao Paulo, SP, Brazil Registered: Jan 2002 posted 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.  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 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.  |  IP: Logged Josh Jones Redhat Posts: 1207 From: Plano, TX Registered: Apr 2000 posted 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  |  IP: Logged Jack Ondracek Film God Posts: 2348 From: Port Orchard, WA, USA Registered: Oct 2002 posted 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!  |  IP: Logged Luciano Brigite Master Film Handler Posts: 277 From: Sao Paulo, SP, Brazil Registered: Jan 2002 posted 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 .  |  IP: Logged

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