EEVblog #569 - Tour of an Analog TV Transmission Facility - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: January 17, 2014, 12:05:36 am
content: David Kilpatrick from TXAustralia takes us on a detailed tour of the old decommissioned 10kW analog TV transmission system at the Artarmon facility in Sydney. How it all works from the broadcaster video input to final transmission output up the 180m broadcast antenna. Plus some teardowns of the old equipment that's been used to transmit the Channel 7 TV signal in Sydney since 1981.Copper rigid coaxial lines, waveguides, filters, splitters, combiners, converters, transmission valve, power supplies and all the equipment necessary to transmit a 10kW analog TV signal in a major city like Sydney.

author: IO390
author_rank: Regular Contributor
timestamp: January 17, 2014, 01:02:15 am
content: Oh, well thanks.Looks like I'm not getting much sleep again tonight (although for a better reason this time).

author: CRCasey
author_rank: Newbie
timestamp: January 17, 2014, 01:11:40 am
content: Yes this is one I have been waiting for!Woot!-C

author: Alexei.Polkhanov
author_rank: Frequent Contributor
timestamp: January 17, 2014, 01:26:16 am
content: Wow, rigid coax heaven!

author: rolandpenplotter
author_rank: Regular Contributor
timestamp: January 17, 2014, 01:31:01 am
content: Here's the actual news story referenced in Dave's tour, where you see them turning it off:

author: nitro2k01
author_rank: Frequent Contributor
timestamp: January 17, 2014, 02:05:52 am
content: I'm hearing a high pitched whine from about 48 and 53 minutes. (If you're over 30 you'll likely not hear it.) I wonder what exactly would produce such a sound. Especially when it's all digital. Maybe it's not related to the broadcast as well, but some other equipment?

author: nathanpc
author_rank: Unknown
timestamp: January 17, 2014, 02:06:30 am
content: I can't stop drooling. Thanks very much for sharing this awesome tour Dave!

author: rolandpenplotter
author_rank: Regular Contributor
timestamp: January 17, 2014, 02:19:18 am
content: Grab a few hacksaws and I'll start the truck; we're off to strip out all that ally and copper - worth a few thousand quid

author: orion242
author_rank: Unknown
timestamp: January 17, 2014, 02:22:32 am
content: Sweet video!Thanks Dave.

author: rolandpenplotter
author_rank: Regular Contributor
timestamp: January 17, 2014, 02:37:26 am
content: Dave, in the video you mentioned you were going to stand at the base of the tower and show us it, but didn't... was that an editing error?BRILLIANT video; thanks

author: pickle9000
author_rank: Super Contributor
timestamp: January 17, 2014, 02:46:05 am
content: David Kilpatrick did a great tour, easy to listen to and informative. Two thumbs up as they say.An overall excellent excellent video in so many ways.

author: EEVblog
author_rank: Unknown
timestamp: January 17, 2014, 02:51:07 am
content: Quote from: rolandpenplotter on January 17, 2014, 02:37:26 amThe shot I got is in the previous video. Sorry, nothing else.

author: BravoV
author_rank: Super Contributor
timestamp: January 17, 2014, 03:03:19 am
content: Great video and love the scenes of tons of RF voodoo at huge scale there !Meanwhile, <sarcasm:ON> ...I guess those audiophools or those pcb trace right angle nay sayers are shouting ...LOOK !!! Those engineers must be a noob there, they're using sharp turn right angle almost everywhere !

author: rolandpenplotter
author_rank: Regular Contributor
timestamp: January 17, 2014, 03:18:59 am
content: Quote from: pickle9000 on January 17, 2014, 02:46:05 amHe was a good guide, but I can't help feeling he was holding back a bit; he didn't exactly seem enthused and very driven about it (mind you, it's his daily job - he's seen it a thousand times); it may just be the bloke's character though. I loved the video, but I'm more looking forward to being back in the lab, with Dave's infectious excitement and passionate enthusiasm - I'm one for details - EXCESSIVE details, and David seemed to only skim over the basics, although I can appreciate HOW much there is to talk about for a limited amount of time in a place like this... maybe I'm wrong, who knows

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 17, 2014, 03:26:09 am
content: The amateur radio community would probably be very interested in those solid state amplifier modules. Small but a decent amount of power. The big tube stuff not so much - overkill and too big.

author: lilshawn
author_rank: Regular Contributor
timestamp: January 17, 2014, 04:12:52 am
content: Absolute beauty. More rigid coax than you can shake a length of rigid coax at. A crapload of thought and planning and engineering went into it, that's for sure.Good job!

author: dave_k
author_rank: Frequent Contributor
timestamp: January 17, 2014, 04:34:47 am
content: Quote from: rolandpenplotter on January 17, 2014, 03:18:59 amThe day that was filmed was my first day back on site after 2 weeks of Christmas holiday, plus I kept forgetting to 'hype up' my presentation to match Dave's style. In that regard I suppose I seem a bit laid back in comparison to Mr JonesThe video was not meant to be too in-depth, and there was a lot to cover with limited filming time. If there's anything you want covered in more detail, feel free to ask here on the forum.

author: Co6aka
author_rank: Unknown
timestamp: January 17, 2014, 05:50:36 am
content: Quote from: BravoV on January 17, 2014, 03:03:19 amLMRFAO!!!Anyway..."Ahhh... RF p0rn!!!"Brings back fond memories of building my (now OOB) UHF trunked system; four-window RX preselector out of a pile of cans, TX combiners from 6-cavity duplexers... the smell of a rackfull of toasty 200W amps... (Oh man, I'm getting a woodie!)Yeah, yeah, yeah.... I know... Y'all are(Yes, this is what overexposure to powerful electromagnetic fields looks like...)

author: johnh
author_rank: Regular Contributor
timestamp: January 17, 2014, 07:04:02 am
content: When I was trainee Technical Officer with Telecom Australia , ( Telstra now). Back then they maintained the transmitters for the ABC.They took us on tour of 3AR/3LO AM transmitter out at Sydenham and the ABC TV transmitter on Mt Dandenong.They had two radio transmitter that were fed to combiner that was in a hut at the base of antenna. The feeds were open air, and the birds used to land on the feeds. All you could see of the bird, were their feet.

author: bktemp
author_rank: Super Contributor
timestamp: January 17, 2014, 08:40:44 am
content: The display on the door of the channel ten transmitter is actually an Electroluminescent display made by Sharp which runs at a few 100V therefore the high voltage warning.They look nice, but the image burns in quite fast when it displays a constant image for a long time.

author: digital
author_rank: Contributor
timestamp: January 17, 2014, 09:02:00 am
content: A fascinating video, somethings I have never seen before the size of that coax brilliant video and good interview. Thanks Dave

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 17, 2014, 09:31:07 am
content: How long do those big-ass transmitter valves last?

author: jeremy
author_rank: Super Contributor
timestamp: January 17, 2014, 09:40:29 am
content: thanks both daves. Top notch video and Dave K I think you were more than enthusiastic enough, just some are not used to aussies I think

author: ve7xen
author_rank: Super Contributor
timestamp: January 17, 2014, 09:41:37 am
content: I've watched all the broadcast station tours I've been able to find, and this is far and away the best one yet. Thanks Dave and Dave! Too bad we couldn't see the new shiny.Maybe this is a naive question, but if they're combining 5 ~10kW transmitters toward the antenna, why is the total output power so low (looked like under 10kW)?

author: fcb
author_rank: Super Contributor
timestamp: January 17, 2014, 09:42:03 am
content: Quote from: dave_k on January 17, 2014, 04:34:47 amThanks Dave K & Company and Dave J for the video tour - best thing I've seen for ages, really very interesting.Nice to see where the 1V goes in (there's an old joke about BBC Television Centre efficiency in the UK: 1 megawatt in - 1v out)

author: EEVblog
author_rank: Unknown
timestamp: January 17, 2014, 10:13:53 am
content: Quote from: mikeselectricstuff on January 17, 2014, 09:31:07 amA long time I believe. I think Dave mentioned they are circa $30K each too.

author: Icarus
author_rank: Regular Contributor
timestamp: January 17, 2014, 10:17:00 am
content: That's great blog episode man.

author: Derick Freese
author_rank: Contributor
timestamp: January 17, 2014, 10:28:02 am
content: Thanks for taking to time to drive up and make this video. I've been inside a few transmitter bunkers, but never an active one. This helps me put together what used to be inside, so I can understand what those musty buildings used to look like inside.

author: Rasz
author_rank: Super Contributor
timestamp: January 17, 2014, 10:33:05 am
content: Big thanks to David Kilpatrick for making this tour possible, donating his time and knowledge.

author: dave_k
author_rank: Frequent Contributor
timestamp: January 17, 2014, 10:36:58 am
content: Quote from: EEVblog on January 17, 2014, 10:13:53 amI can check the log book when I am in the office next, and will tell you exactly how long they last!Yes, they are not cheap but when you consider the hundreds of staff and thousands of hours worth of effort and millions of dollars in revenue these valves were responsible for putting to air, $30k to $40k is not much by comparison.

author: Http 418
author_rank: Newbie
timestamp: January 17, 2014, 10:51:29 am
content: Was hoping to see some more dumpster diving, allthough this wasnt at the EEVblog corporate towerGreat video, sooo much shiny copperLove to see stuff not build down to a priceThanks to David and TXAustralia to allow us to see the inner sanctums-Http 418

author: JackOfVA
author_rank: Unknown
timestamp: January 17, 2014, 11:10:19 am
content: Many ceramic high power tubes can be rebuilt - in the absence of a major disaster, the normal failure mode is related to cathode emission and there are (or at least used to be) services that would disassemble the tube and replace the cathode, evacuate and reseal and it's good for another 20 or 30K hours. A rebuild would cost 20 or 25% of the price of a new tube, so the cost savings was worth it.We used to see 20-30K hours in the large AM transmitter tubes.Perhaps Dave can arrange for an AM broadcast facility tour as well. Parts are much larger there - we had a walk-in phasing network, for example, the size of a large walk-in closet.Also, it would be interesting to see the other half of the chain - the TV studio where programming is originated. Lots of goodness there as well, but not as high power impressive as the transmitter plant.

author: Ketturi
author_rank: Regular Contributor
timestamp: January 17, 2014, 11:27:22 am
content: One of the most pornographic and interesting EEVblogs so far, you don't see that everyday and most of us would never have access to transmission facilities. The EEVblog -Dave should have taken all abandoned hardware that are going to be disposed. Teardowns for next decade

author: atw60444
author_rank: Contributor
timestamp: January 17, 2014, 12:10:36 pm
content: Many thanks Dave & Dave_K great stuffI wonder why the reluctance to show the Digital Kit? I can't really think of a reason other than paranoid managementMind you, having conducted tours of Telephone Exchanges, the old equipment rattling and moving about is much more interesting to watch than the blank sole-less digital kit with just the whine of cooling fans. Why are the feeders so shiny? Copper usually goes dull brown left open to the air. It's it the atmosphere in the station, does Dave_K spent his spare time with a can of Brasso and a rag? LOL

author: hikariuk
author_rank: Unknown
timestamp: January 17, 2014, 12:18:33 pm
content: That was awesome. And well worth the hour of work I didn't do so I could watch itAlso Houston Fearless appear to still exist but they've branched out into other areas.

author: wilheldp
author_rank: Regular Contributor
timestamp: January 17, 2014, 12:25:57 pm
content: Quote from: EEVblog on January 17, 2014, 10:13:53 amDid you snag one of the spent ones?

author: vindoline
author_rank: Unknown
timestamp: January 17, 2014, 01:09:49 pm
content: Thanks Dave and Dave. This is one of my favorites. I was surprised at how clean and dust free everything was. Did you guys dust the cabinets before filming, or is the equipment always kept like that?!

author: dave_k
author_rank: Frequent Contributor
timestamp: January 17, 2014, 01:41:47 pm
content: It is always like that.

author: Co6aka
author_rank: Unknown
timestamp: January 17, 2014, 02:23:06 pm
content: Quote from: ve7xen on January 17, 2014, 09:41:37 amI think Dave said they meter and reference by average power; the HDTV transmitters are QAM. (Think "SSB" -- PEP vs. average power.) Also, combining is lossy, with loss dependent upon the type of combiner, channel/frequency separation, and channel bandwidth. Separation and bandwidth also typically dictate the type of combiner.(A milliwatt is a terrible thing to waste...)

author: VK3DRB
author_rank: Super Contributor
timestamp: January 17, 2014, 02:25:27 pm
content: Thanks Dave and Dave for a great blog. Beautiful engineering throughout. I noticed the SWR meters for the upper half and lower half.A small goof...The transmitters hour meter = 100000 + 80275.9 hours. Assuming 167 hours use per week (one hour off per week). That equates to 20.75 years of "continuous" operation. From when the transmitter closed, that would mean the transmitter began its working life in 1982, not 1981 as was stated.That sort of engineering is what we would find in IBM mainframes of the day. Someone should check out the Thermal Conduction Modules used in the IBM 3090 mainframes. Almost orgasmic in design.Thanks for the excellent presentation Daves.cheers,Yet another Dave

author: rolandpenplotter
author_rank: Regular Contributor
timestamp: January 17, 2014, 02:35:36 pm
content: Quote from: atw60444 on January 17, 2014, 12:10:36 pmI agree with your thoughts on moving mechanisms; I've been on a tour of three BT exchanges (one was a UAX13 [or UAX10?] - in my little village where I still live; it's now AXE10, then on a tour of a large TXE4 locally and also a System X about 5 miles away). Of all the exchanges, the Strowger was the most mesmerising and entertaining - I even used to walk up to it at night sometimes, and stand next to the air vent outside, so I could hear the"Clu-clu-clu-clu-clu-clu-clu-clu-CLONK"of the selectors!I remember, back in the 1990s, our village was upgraded to System Y (Ericcson), and there was a skip outside the exchange FULL of Strowger switches, cable harnesses, power supplies... and a ringing generator which I was given (why did I throw it away... nuts!).If you've never heard a Strowger exchange, it's high time you did:The little blue compresser underneath the wall-mounted black telephone, is using the same principle as on the Radio Tx; they blow compressed air into the cable trunks to prevent water ingress & corrosion. The whine you can hear in the background is the ringing generator, which generates all the tones (engaged, equipment engaged, NU tone... etc)Attached: Ringing generator (cream), cable compressor (blue)Yes, this was a superb tour, but moving things entertain much more, and that is noone's "fault"As for the copper being shiny, it's probably lacquered or coated, to prevent corrosion.

author: atw60444
author_rank: Contributor
timestamp: January 17, 2014, 02:48:04 pm
content: @Roland. Yeah, I guess the feeders are lacquered, but it seems a bit like unnecessary effort.At risk of getting into trouble for being off topic. I used to maintain Strowger and TXE4 exchanges. And I have a selection of UAX13 racks in the shed, the same as the video.I'm not weird, honest!

author: rolandpenplotter
author_rank: Regular Contributor
timestamp: January 17, 2014, 02:51:21 pm
content: Quote from: atw60444 on January 17, 2014, 02:48:04 pmAhhh, so you're the guy who used to walk around sweeping up all the metal dust from the switches, hmm?Oooh! Wanna sell some? (unlikely)

author: GreyWoolfe
author_rank: Unknown
timestamp: January 17, 2014, 03:24:47 pm
content: Talk about RV valve pornAnd who says size doesn't matter!

author: Frantone
author_rank: Regular Contributor
timestamp: January 17, 2014, 04:27:21 pm
content: Quote from: EEVblog on January 17, 2014, 12:05:36 amBeautiful one Dave! I spent some time in my younger days at high power valve AM broadcast radio transmitter sites, and they are (well, WERE) true marvels. Thanks for the great vid....

author: electronics man
author_rank: Frequent Contributor
timestamp: January 17, 2014, 05:10:19 pm
content: Great one dave and dave I'm now looking fowerd to the teardowns

author: bxs
author_rank: Regular Contributor
timestamp: January 17, 2014, 05:47:28 pm
content: @dave_k & @Dave,Thank you very muchloved it

author: calzap
author_rank: Frequent Contributor
timestamp: January 17, 2014, 06:55:55 pm
content: Quote from: JackOfVA on January 17, 2014, 11:10:19 amTube rebuilding services still exist and are doing a good business. The Econco division of CPI (www.cpii.com) is located near in Woodland, Calif, near me and is going strong. It's unlikely TX Australia will hand over the old tubes to Dave unless they can't be rebuilt.Mike in California

author: ZeroAviation
author_rank: Contributor
timestamp: January 17, 2014, 07:02:33 pm
content: @dave_k & @DaveEpic video guys! Love the old analog stuff!

author: ve7xen
author_rank: Super Contributor
timestamp: January 17, 2014, 07:57:48 pm
content: Quote from: Co6aka on January 17, 2014, 02:23:06 pmHmm yeah, that just seems like a heck of a lot of loss. As far as measuring the power for digital, most digital modulation I'm aware of (no experience with digital TV of course) is designed to have a flat power envelope, so I'd expect the power output stays fairly constant, thus not needing differentiation between 'peak' and 'average' power output. Average or peak, I was still expecting to see at least a couple 10s of kW heading to the antenna with 50kW of transmitters.However because of the whole flat power envelope thing, it wouldn't surprise me at all if the average power of the digital broadcasts is much, much lower than the 10kW peak of the old AM stuff, which would explain the 'low' output.

author: jzoeller
author_rank: Newbie
timestamp: January 17, 2014, 08:37:01 pm
content: Really enjoyed this.Thanks Dave!

author: Dave Turner
author_rank: Frequent Contributor
timestamp: January 17, 2014, 08:53:15 pm
content: A point to consider is that some high power transmission valves (albeit between from long to short wave frequencies) have lasted longer in service than any of the latest silicon based technology. Whether that remains to be true is yet to be seen.

author: Dr. Frank
author_rank: Super Contributor
timestamp: January 17, 2014, 09:38:33 pm
content: Brute Force Electronics!Very impressive. Very interesting.Simply beautiful.Thank you, Dave and David!

author: DrGeoff
author_rank: Frequent Contributor
timestamp: January 17, 2014, 10:10:07 pm
content: Great video Dave, I haven't been at this facility since the mid-80's, where a friend was installing a lot of the equipment. I think he was doing the 20kW systems for the 2MMM and 2DAY FM radio stations at that time.

author: johnh
author_rank: Regular Contributor
timestamp: January 17, 2014, 10:46:01 pm
content: how long do the valves last?.Forgotten. I was told that when i was trainee that these transmitter value could be refurbished. Especially the big power valves that were steam cooled.

author: VK3DRB
author_rank: Super Contributor
timestamp: January 17, 2014, 11:13:43 pm
content: The ERP will be much, much more than 10kW.Check out Melbourne's channel 10 transmitter...More modern, but has NEC stuff in there, too.

author: EEVblog
author_rank: Unknown
timestamp: January 17, 2014, 11:36:19 pm
content: Quote from: VK3DRB on January 17, 2014, 11:13:43 pmNice find.That does show some stuff that shouldn't have been shown :->

author: Polossatik
author_rank: Frequent Contributor
timestamp: January 18, 2014, 12:19:50 am
content: Quote from: EEVblog on January 17, 2014, 11:36:19 pmcare to explain a bit? it's not common stuff to see, but I don't see what can be "secret stuff" in this place.Or what someone can do "wrong" with knowing what's inside.Just watched that video and not saw something really weird or labeled "secret service"

author: EvilGeniusSkis
author_rank: Regular Contributor
timestamp: January 18, 2014, 12:44:29 am
content: @ 56:26 why is there a chip missing from a socket?

author: rolandpenplotter
author_rank: Regular Contributor
timestamp: January 18, 2014, 12:58:52 am
content: Quote from: EEVblog on January 17, 2014, 11:36:19 pmThat'swhat we like to see; a bit of corporate paranoia being proved as pointless

author: BillyD
author_rank: Regular Contributor
timestamp: January 18, 2014, 01:15:18 am
content: Quote from: rolandpenplotter on January 17, 2014, 03:18:59 amDon't know what you're on about there. He explained everything we saw, didn't interrupt, volunteered extra info wherever it was relevant, you really couldn't ask for a better person to give a tour of the place.

author: rolandpenplotter
author_rank: Regular Contributor
timestamp: January 18, 2014, 01:21:48 am
content: Quote from: BillyD on January 18, 2014, 01:15:18 amHe's a good guide, no doubt. So long as I know my own mind, it doesn't really matter that much. That's the good thing about points of view - we can all have different ones

author: atw60444
author_rank: Contributor
timestamp: January 18, 2014, 01:29:35 am
content: The guy in Melbourne seemed to have free reign with the camera. It's a pity they showed the Microwave link antennas but not the terminal equipment. Looked similar to 12GHz links I've worked on with a pair of diversity receive dishes and single transmit dish.

author: rolandpenplotter
author_rank: Regular Contributor
timestamp: January 18, 2014, 01:36:24 am
content: Quote from: atw60444 on January 18, 2014, 01:29:35 amI particularly liked the "kinetic energy store" flywheel; did he sayfourtons? I couldn't make it out. That's a really clever idea, which makes perfect sense in every way. Love this

author: atw60444
author_rank: Contributor
timestamp: January 18, 2014, 01:46:14 am
content: The flywheel was neat! Yeah he said 4 tonnes (metric). I noticed it was called a "continuity set". Traditionally that would have been a DC motor running on batteries driving an alternator.

author: rolandpenplotter
author_rank: Regular Contributor
timestamp: January 18, 2014, 01:50:35 am
content: Nothing like a pretty face to make the transmitter switch off more enjoyable:Sandy Heath, UK, switching off:More Sandy Heath:Funny how we have all this "better" digital technology, and yet they still don't seem to be able to improve on the age-old vacuum tube valve

author: atw60444
author_rank: Contributor
timestamp: January 18, 2014, 01:58:08 am
content: Makes a nice change to see a young lady technician. I taught my daughter how to solder, but she's now at college designing & making dresses

author: rolandpenplotter
author_rank: Regular Contributor
timestamp: January 18, 2014, 02:01:20 am
content: Quote from: atw60444 on January 18, 2014, 01:58:08 amAh you made a classic mistake. Now you see, if you'd taught her how to "sodder", she'd be able to get a job in America; she probably wanted to travel

author: RetroSwim
author_rank: Contributor
timestamp: January 18, 2014, 03:21:40 am
content: Is that just plain old, garden variety composite video that goes in at the front end there?If so, is that a raw feed of what you got over microwave from the broadcaster? Or did they perhaps send you something like YC/RGBs/Y-Pb-Pr which got combined in a different rack there at the facility?

author: Rasz
author_rank: Super Contributor
timestamp: January 18, 2014, 05:42:47 am
content: Quote from: rolandpenplotter on January 17, 2014, 02:35:36 pmand another one, this is from a Polish comedy:Quote from: Polossatik on January 18, 2014, 12:19:50 amscadaOld tech used to be remotely managed over the phone by a meatbag flipping big switches. Modern one can be hijacked if you know what is on the other side. Not to mention tons of NDAs.

author: SeanB
author_rank: Super Contributor
timestamp: January 18, 2014, 06:37:32 am
content: Quote from: atw60444 on January 18, 2014, 01:46:14 amThe alternative is a diesel genset with a multipack clutch that is normally freewheeling, and is force started when the power fails for more than 5 seconds. AFAIKR the alternator section was fed an AC excitation via a rotary transformer so that the AC output could have a constant frequency as the rotor speed varied from either mains variations or the diesel set running. The diesel was pretty much guaranteed to start as it was always fed with pressurised oil from a pump on the output side as well, which also fed the bearings of the alternator and the synchronous motor that drove both. 4 ton flywheel is pretty common, there are some that use a flywheel of around 10 tons that run at around 30-100k RPM in a sealed helium fill that are used as a storage medium for large data centres. Those have an armoured housing with kevlar bands that can contain the pieces if the flywheel fails. They generally are not fixed after failure as there is pretty much nothing left after the 100kWh or so of power is dumped.I remember using mobile power plants with a 6 cylinder Diesel and the alternator acting as a flywheel for the engine. Bit difficult to drive a vehicle where the flywheel is a 4 ton rotating mass that takes around 4 seconds to change speed. Generally I drove around in second gear and slowly. That genset supplied 28VDC and 115VAC 400z at 8kA and 100A respectively. Second use was as an aircraft tractor, seeing as the engine was plenty powerful enough to both tow and start a fully laden 747.

author: robbak
author_rank: Contributor
timestamp: January 18, 2014, 06:47:45 am
content: It really must have felt weird - after decades of doing everything humanly possible to keep those machines transmitting, to stand by and watch them just get turned off. And over the next few months, seeing all that equipment unceremoniously loaded into recycling bins. Knowing that you could let Dave just reef out a few boxes and load them into his car must have felt strange enough!I must admit I was surprised - I expected that the signals would be combined at signal level and amplified together - I guess that amplifiers of this size just can't be made to be wide bandwidth!I noticed from the Melbourne video that those $30K tubes may well be disposed of - there are just too many analogue sites being turned off that there won't be a market for used tubes, no matter what they cost to make.

author: firewalker
author_rank: Super Contributor
timestamp: January 18, 2014, 12:29:51 pm
content: How do they keep the dust out?Alexander.

author: VK3DRB
author_rank: Super Contributor
timestamp: January 18, 2014, 12:32:05 pm
content: Quote from: atw60444 on January 18, 2014, 01:58:08 amWhat a shame. Percentage wise, there are very, very few hands-on electronics enthusiast women in Australia. Since before women's lib and equal opportunity until now, the tiny percentage of Australian born women studying electronics engineering has dropped to almost zero. It is pathetic. About 10 years ago I emailed 30 women's rights organisations around the world kindly asking for their opinion why there are so few female electronics technicians, electronics engineers or ham radio operators compared to men and none of them could (or would) answer the question. I would dare say the reason has nothing to do with men.Australian born female electronics engineers who do still do analogue or digital work in their 50's are, to my knowledge, non-existent. Australian women have always been very rare sight in real electronics component stores, except if they have been asked to run an errand.What was the reason your daughter went from electronics to dress making?

author: Salas
author_rank: Frequent Contributor
timestamp: January 18, 2014, 01:31:09 pm
content: Mr. David Kilpatrick gave an excellent tour of the decommissioned installation with every Dave's question succinctly answered. I enjoyed his expert calm style. A very good idea to arrange for such a vid Dave, congrats.

author: noisebox
author_rank: Contributor
timestamp: January 18, 2014, 01:50:24 pm
content: Awesome video, two fair dinkum guys, it's great when you've got some company in your videos, especially like the videos with Doug Ford aswell. Is everyone in Oz so nice and friendly?The other Dave really seems to know his stuff here, shame to be losing this part of the job!

author: hikariuk
author_rank: Unknown
timestamp: January 18, 2014, 02:06:39 pm
content: Quote from: VK3DRB on January 17, 2014, 11:13:43 pmQuiet, isn't it? You can kind-of see why they've gone over to water cooling.

author: SeanB
author_rank: Super Contributor
timestamp: January 18, 2014, 02:55:08 pm
content: Easy to keep the dust out. You start with a great big inlet air filter that __WILL__ trap all dust and particles larger than 0.2 microns, then use an electrostatic precipitator and another filter to get the fine stuff stuck together and dumped into the second filter. Then you chill it or heat as appropriate to get the right temperature and humidity and feed it into the facility so as always to maintain positive pressure in the area. A controlled vent to manage the air flow and pressure and there you have an area that remains dust free. You can recirculate the air to reduce the need for conditioning, but you still basically change the inside air x times per hour while keeping it clean, dry and dust free. Visitors have a big sign to keep the doors closed and a big set of mats on the way in to get dirt off shoes.

author: rolandpenplotter
author_rank: Regular Contributor
timestamp: January 18, 2014, 03:02:12 pm
content: Don't forget your spanner...

author: kg4arn
author_rank: Unknown
timestamp: January 18, 2014, 03:19:49 pm
content: Quote from: rolandpenplotter on January 18, 2014, 03:02:12 pmLook out below if he drops that crescent wrench....

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 18, 2014, 04:46:31 pm
content: ..and don't forget this buttock-clenching classic :

author: mixt
author_rank: Contributor
timestamp: January 18, 2014, 05:21:20 pm
content: I've freeclimbed tall powerlines before which was a rush for more reasons than just height.. but that video above makes me unbelievably uneasy. I think there is one factor in play though - the helmet cam is using a very wide angle lens. Your field of view in real life wouldn't be as wide or distorted, and it would be a little less scary. A little. My main concern would honestly be the structural integrity of small parts that he's grabbing. Rust and all that.

author: rolandpenplotter
author_rank: Regular Contributor
timestamp: January 18, 2014, 05:24:45 pm
content: You couldn't pay enough money for me to do that, even if you emptied the world banks into my account, NO WAY.

author: Zad
author_rank: Super Contributor
timestamp: January 18, 2014, 11:35:41 pm
content: For those people complaining about a lack of detail - look how long this video is already. What would you take out to add something else? You could have a 10 hour video and still miss something. The 2 Daves did perfectly fine! Talking of which, Dave - when you do a tear-down of the gear, might it be possible to invite the other Dave along to the lab? With the best will in the world, you know a lot about a lot, but you aren't a radio bloke, and an experienced eye could add quite a bit.I think this is one of those videos that people will watch over and over as it gains awareness through the ham radio communities. It isn't often that people get to see big infrastructure installations like that. I would have loved to have seen inside my local transmitter (Emley Moor) when they dropped the analogue 5* 870kW ERP - no idea what the TX antenna gain is, but that's a lot of welly (technical expression).I know it is all filtered positive pressure air, but wow, that really is incredibly clean. Normally HV really does pull all the minute particles out of the air and deposit it in obscure places. Aesthetically that hardware looks fantastic. To an RF-head like me, it is comparable to high Victorian engineering like Papplewick.Incidentally, here in the UK, main transmitters tend to be vertically polarised, with repeaters being horizontally polarised. Obviously for channel separation, and so the consumer has better rejection of distant co-channel transmitters.

author: IanB
author_rank: Super Contributor
timestamp: January 19, 2014, 02:35:33 am
content: Some may have seen these videos by following YouTube suggestions, but I am watching with my jaw resting on the floor:When I reached the point in the second video where there was a single turn air cored variable transformer transferring 250 kW from primary to secondary my head exploded. At some point I think RF engineering becomes indistinguishable from magic...

author: IanB
author_rank: Super Contributor
timestamp: January 19, 2014, 03:59:25 am
content: "This is an audio pre-amplifier. We want to get a voltage swing of about 1000 V p/p on the output of this amplifier..."

author: Zad
author_rank: Super Contributor
timestamp: January 19, 2014, 04:26:48 am
content: This is pretty much what I imagine the engine room of the TARDIS to look likeThat transmitter is approximately the right age for Dr Who too!

author: IanB
author_rank: Super Contributor
timestamp: January 19, 2014, 04:29:02 am
content: That's not a power supply.Thisis a power supply..."We're looking to get 11,000 V DC at about 50 or 60 A, so about 600 kW of h.t. supply..."

author: vk6zgo
author_rank: Super Contributor
timestamp: January 19, 2014, 10:16:56 am
content: Quote from: mikeselectricstuff on January 17, 2014, 09:31:07 am20000 hours plus!

author: SeanB
author_rank: Super Contributor
timestamp: January 19, 2014, 10:20:10 am
content: Reminds me of when i was an apprentice and GI Joe comes in and says he has to change the signage 30m up on the sides of the hanger. I asked how, and he replied that "we" would be using the mobile crane. I asked what harness and got the reply back - cargo sling. Asked about safety harness and - none available. I said that I would bring one in the following day, helps having a dad who was a Mechanical and Civil engineer, and who did a fair amount of climbing up structures to inspect, so had the right kit for himself. Next day I was swinging at the end of a crane, with an air drill and a long air line on one shoulder, a rivet gun in pocket, a lot of spare drill bits and a box of rivets in the other. Plus a bag with a dozen signs as well. Safety harness clipped to the hook as well, when I was on the top of the framework i clipped to the steel structure and started with the sign work. GI Joe joked that he would go to lunch and leave me there, I replied I know where he parks his car and would go and attach the signage to it when I climbed down the structure. He had a late lunch......

author: vk6zgo
author_rank: Super Contributor
timestamp: January 19, 2014, 10:33:18 am
content: Quote from: robbak on January 18, 2014, 06:47:45 amYes,this can be done,& was by some manufacturers.The problem isn't bandwidth---it's intermodulation!It can be overcome,but is messy enough with high power Transmitters,that the approach used by NEC is just as cheap,& eliminates the problem entirely.

author: TheWelly888
author_rank: Frequent Contributor
timestamp: January 19, 2014, 11:21:00 am
content: Another one here who appreciates the tour given by David Kilpatrick - thanks David for showing Our Dave around! I admit that high power RF engineering went a bit over my head but the 5kW valve was actually smaller than I thought it would be!! High Power RF was one of the few areas where valves were still superior to silicon transistors back in the 1980s.

author: SeanB
author_rank: Super Contributor
timestamp: January 19, 2014, 11:30:31 am
content: Linear amplification is difficult if you want high power and a wide bandwidth along with power efficiency. Thus they are all amplified separately, filtered then combined in a separate mixer with notch filters on the inputs to attenuate the signal from the other chain. This is done in the massive cavity resonators which are tuned to attenuate the signal other than the transmitted band and then they are all mixed together. This also allows for expansion, like adding the NICAM stereo signal ( still sent here though the number of sets with the decoders is vanishingly small) to the transmitted signal, or to have a ZWEITONE stereo pilot and the associated second audio difference channel as well as the mono audio. Also allows use of different audio carrier frequencies and offsets, along with also allowing for different modulation methods.High power amplifiers are typically not going to be more than about 1% broad with any efficiency, though they often can handle the digital signal quite well with only a reduction of power and broadening of the tuned circuits slightly to allow this. The only issue is that a class C amplifier will happily mangle higher than QAM signals quite well, though many are capable of being tuned to handle QAM very well. High power gain but not exactly monotonic, but pretty good at converting AC power from the mains into RF power fed up a coaxial cable to the antenna.BTW high power valves are still cheaper than silicon, imagine doing a changeout of 500 power MOSFETS in a blown transmitter versus changing the faulty component in the tuning side that just caused the valve to glow cherry red until the thermal cutout tripped the unit.

author: vk6zgo
author_rank: Super Contributor
timestamp: January 19, 2014, 12:05:48 pm
content: Quote from: johnh on January 17, 2014, 07:04:02 amSimilar at 6WF/WN.which had a 55 kW (WF) & a 10 kW fed to a combining unit at the bottom of the "Dual Mast".They were both fed by "6 wire lines",which consisted of 4 outer conductors which were at Earth potential,& 2 parallel "centre conductors"(not sure what the idea was,as both the inners were at the same potential all the time)It was effectively a "pretend" coax!The birds would perch on the outer wires,get curious,& peck at the centre conductors.The Transmitter would "grunt" & recycle.Next time we looked at the feeder we would see a couple of bird feet!They were real Transmitters---you could walk around inside them!Their replacements just look like TV Transmitters from the outside,with big Coaxes coming out of the back!

author: Steffen
author_rank: Regular Contributor
timestamp: January 19, 2014, 01:06:28 pm
content: That was a nice video Dave & Dave. From my small experience with high power RF equipment like klystrons, waveguides and components, amplifiers and auxilliary stuff like high voltage power supply for andode and some misc. stuff for filaments it was very interesting to know how such kind of plant is constructed.Any data how rigid coax compares to traditional waveguides? Sure waveguides at that frequency are large and could be more challenging to keep it compact. As I know Size WR650 type flanged waveguides very well (f01,3 Ghz) it can be quite challenging to match lenght and phase when using parallel lines. But for few hundred KW CW it could be nice to have classic coax connections.Looking forward to new RF plant videos.

author: vk6zgo
author_rank: Super Contributor
timestamp: January 19, 2014, 04:20:06 pm
content: Quote from: SeanB on January 19, 2014, 11:30:31 amCH7's TV Tx is within 1dB up to 7Mhz wide--about 3.8% .Ch2 is more like 10%.Remember,TV finals normally have fairly moderate power gains,of around 13dB.Class C?-------NoTV Tx built since the late 1960s use class C output stages.These older units grid modulated.the Final PA stage,with much of the bandwidth shaping for VSB achieved using high level "Filterplexers" which combined the VSB filter with the sound & vision combiner.Modern Analog Transmitters include the VSB filter in the IF stage.The PA stages are linear stages ,but that said,may not be "linear enough" for Digital,especially in the phasedomain.

author: vk6zgo
author_rank: Super Contributor
timestamp: January 19, 2014, 04:23:04 pm
content: Quote from: TheWelly888 on January 19, 2014, 11:21:00 amThe same tube is used in 10kW & 13kW Transmitters!

author: vk6zgo
author_rank: Super Contributor
timestamp: January 19, 2014, 04:36:57 pm
content: Quote from: RetroSwim on January 18, 2014, 03:21:40 amIt always was Composite video in the old days,as it is a more rugged format than the others,needs only one cable/link channel,& everything is designed for it.I'm suspicious that it may have been sent in digital form & converted on site in more recent years.About the time I left TVW7,they were rewiring the Studio for Digial video,so it is probably the same in Sydney.This would make it more convenient to stick with Digital up the link.Guys,I'm sorry about this great slather of postings,but itisa field I know quite a lot about!

author: mj0rgr
author_rank: Newbie
timestamp: January 19, 2014, 04:37:56 pm
content: I really enjoyed this EEVBlog episode: particularly David K's contributions. My understanding is that the signal combiner is, in essence, a cavity tuned to the amplified signals. It would be interesting to learn more about cavities and particularly how the input signals are introduced to the cavity, and the output signals derived: are they electromagentically / capacitively coupled with the cavity acting as a form of low loss faraday cage?

author: RetroSwim
author_rank: Contributor
timestamp: January 20, 2014, 01:48:05 am
content: Quote from: vk6zgo on January 19, 2014, 04:36:57 pmWasn't it all Betacam in those days? They stored video as separate luma/chroma.Quote from: vk6zgo on January 19, 2014, 04:36:57 pmI wouldn't be surprised.

author: vk6zgo
author_rank: Super Contributor
timestamp: January 20, 2014, 02:27:28 am
content: Quote from: RetroSwim on January 20, 2014, 01:48:05 amOnly inside the machines/tapes-----the workhorse signal format wasalwaysComposite in TV Broadcasting.Domestic & Quasi-Pro stuff played around with different formats a bit,but Broadcasting requires precise timing,& using multiple cables everywhere has the inherent risk of different time delays between the two component signals,unless each one of a cable pair is exactly the same length.Multiply this by the thousands of Coax runs in a TV Studio!The other formats could be derived from Composite if you needed them.At TVW7, the AVA-Graphics suite used RGB for the Pix Monitors,& probably internally ,but the suite output was Composite.The Studio Cameras did use various versions of Component Video internally,but what appeared as "Camera Output" to the Vision Switcher input was also always Composite.Note on Betacams, etc:-Where I worked,Betacam was used by the News Dept mainly--The large VTRs were mainly reel to reel Sony Helical scan,with some similar Bosch units,& an old Quad scan cartridge unit for Commercials.Later,Panasonic Digital Videocassette machines (Large Broadcast format) were used.

author: SeanB
author_rank: Super Contributor
timestamp: January 20, 2014, 06:35:14 pm
content: Composite works well, you just need a bandwidth of about 15-20MHz and good DC response. I used a potted module made by Opamp Labs for both audio and video distribution. Was a pain to depot the one to fix it when the output stage died. Simple inside, a 709 opamp and a discrete output stage with 2 small signal diodes to provide bias. One of the 2N3904/5 transistors had died, so they were replaced with a 2N2905/2N2222 combo with a new set of diodes. Had to add a small pair of heat flags to the devices as they ran warm, probably what had cooked the originals. It was driving 20 75R terminated video inputs. Might be considered a little high load wise but it did drive it for a decade or so before failure.

author: rolandpenplotter
author_rank: Regular Contributor
timestamp: January 21, 2014, 03:04:59 am
content: Well Dave, looks like it'sTuesdayagain...*AHEM!*

author: warp_foo
author_rank: Unknown
timestamp: January 21, 2014, 04:13:14 am
content: Quote from: rolandpenplotter on January 17, 2014, 03:18:59 amI got the exact opposite reaction. Dave¹ asked a question, and Dave² answered quickly and comprehensively. I quite like the interchange between the two.m

author: vk6zgo
author_rank: Super Contributor
timestamp: January 21, 2014, 06:39:28 am
content: Quote from: warp_foo on January 21, 2014, 04:13:14 amI've done more of these tours than I care to remember,& it is hard to get the balance just right!Some groups are more technical than others,so you tend to drop some of the more basic stuff.In this case,there is a wide spread of technical levels.

author: Co6aka
author_rank: Unknown
timestamp: January 21, 2014, 12:27:53 pm
content: Quote from: IanB on January 19, 2014, 02:35:33 amNot jaw-dropping, but on a related note...http://englishrussia.com/2014/01/19/the-main-russian-tv-tower/http://englishrussia.com/2011/08/02/a-visit-to-the-almaty-television-tower/http://englishrussia.com/2013/08/01/date-with-lena-m/And, an unrelated teardown:http://englishrussia.com/2013/11/17/disposal-of-old-stuff-in-russia/

author: Rasz
author_rank: Super Contributor
timestamp: January 21, 2014, 01:01:45 pm
content: ok thenhttp://en.wikipedia.org/wiki/Warsaw_radio_masthighest manmade object until 2008, or 1991 if you count the day it collapsed due to retarded service crew error2MW at 225 kHzYT clips (in Siema language/Polish) show transmitter,glowing tube(50 second mark in first clip), tube teardown, mast itself, collapsed mast (third clip)http://altao.pl/artykuly/najwyzszy-maszt-na-swiecie-zbudowany-w-polsce–-646-metrow-.htm

author: dave_k
author_rank: Frequent Contributor
timestamp: January 22, 2014, 09:50:55 am
content: Quote from: Co6aka on January 21, 2014, 12:27:53 pmWow! Would love to have seen that Lena M radar operating back in it's day. That installation makes the Ch 7 transmitter look rather pissy.

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: January 24, 2014, 03:21:23 am
content: Quote from: mj0rgr on January 19, 2014, 04:37:56 pmI agree here David K. was great (okay he got the acronym wrong for the CIND no big deal) he knew his way around and answered every question.I also would like to have seen the inside of that combiner. The first time I saw rf equipment I thought all the parts were missing from the inside.Great video, I've never seen any equipment like that. I'm not even sure what I was looking at in some cases. I'm still pondering what that was that required the "widow stick"?

author: IanB
author_rank: Super Contributor
timestamp: January 24, 2014, 03:24:21 am
content: Quote from: GiskardReventlov on January 24, 2014, 03:21:23 amIf something is charged up to thousands of volts and you touch it you are dead, leaving your wife a widow. So you short it to earth using said stick to make sure it cannot be charged up to thousands of volts before you work on it.

author: IanB
author_rank: Super Contributor
timestamp: January 24, 2014, 03:44:00 am
content: Quote from: GiskardReventlov on January 24, 2014, 03:21:23 amWatch this, if you haven't already:(Note the comments at 1m55s...)

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: January 24, 2014, 04:39:59 am
content: Quote from: IanB on January 24, 2014, 03:24:21 amI know, I know, but what was that part that he pulled out? It was a tube, it had rf shielding, it was heated, they could have told me it was a warp core.The prop makers could not have made cooler looking stuff than what's there.They should have dismantled all of it, trucked it to another location and started a geek museum. My god those UHF waveguides are so amazing. It's heartbreaking to think it'll all be discarded. It really is a work of art and it was the state of the art, no doubt, at the time. Sydney has 4million folks, that could support 1 geek museum. Sydney Steampunk Geek Museum.

author: vikpc
author_rank: Newbie
timestamp: January 24, 2014, 07:20:32 am
content: So clean in the facility.. i want to see their air conditionersAnd cooper RF tubes looks amazing!

author: Moshly
author_rank: Regular Contributor
timestamp: January 24, 2014, 07:48:47 am
content: Here's a few pics of one of the Melbourne Mt.Dandenong towers.Have a look at the 'rats-nest' of wiring inside the towerYou can see the 2 coaxes running up the inside left back tower leg

author: hikariuk
author_rank: Unknown
timestamp: January 24, 2014, 03:57:08 pm
content: Quote from: GiskardReventlov on January 24, 2014, 04:39:59 amIt was a valve (or vacuum tube, if you prefer). A very big expensive one.

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: January 24, 2014, 08:20:13 pm
content: Quote from: hikariuk on January 24, 2014, 03:57:08 pmI found out after watching another vid that they cost $30-40 thousand each. They had extras stored in a plain old metal cabinet.This was the video that Dave said "had stuff they weren't supposed to show" . But I guess it'd take a trained eye to know what stuff that was.FWIW widow's stick is a.k.a earth grounding stick and probably a lot of others.

author: Globe Collector
author_rank: Contributor
timestamp: March 23, 2014, 01:01:12 pm
content: You know the travesty of all this is that all that beautiful gear was probably bound for some scrap metal yard where a "ham-Fisted" yargon was waiting with a ten pound hammer in his hairy paw.Dave K. should be "spewing" as you can see those cabinets were his "babies". The only bit which will survive is the exciter that Dave J. walked out with.I still can't believe that at least some of this beautifully crafted gear is not diverted to our musea for future generations to marvel at and learn from. Even our electrical engineering schools could benefit handsomely from a bequiethment of such gear, give the next generation a sample of how it should be done.Here in Hobart, when Pay TV went digital and to Ku band satellite, the old E-PAL 2.5GHz band transmitter ended up in a scrap yard. I remember seeing the klystron after the Yargon had "adjusted" it, just silver plated rings and cavities all dented and bits of beryllium oxide everywhere.

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: March 25, 2014, 04:15:53 pm
content: Quote from: Globe Collector on March 23, 2014, 01:01:12 pmI suggested a museum too. Maybe it's a matter of someone local initiating it, but maybe there's some secret knowledge they want to keep close. It definitely won't happen if nothing's done. Locals clubs should get together and make it happen. Start a kickstarter campaign?

author: dave_k
author_rank: Frequent Contributor
timestamp: May 16, 2014, 11:05:38 am
content: Sad to report that the transmitter has mostly been torn apart and scrapped now .. however I have managed to save a few sub-assemblies. Have been scrapping a lot of old analogue TV transmitters, including some German made ones featuring gold-plated tube cavities .. might have to get Dave around to shoot some more videos?

author: StjepanV
author_rank: Newbie
timestamp: February 24, 2017, 02:56:50 pm
content: Hi there guys/gals!I have a question what is "filament supply" mentioned athttps://youtu.be/mR_wJkxKSXU?t=34m57s. I don't understand what that filament is used for, and how?@Mods: apologies if I'm posting it in wrong location since there was warning that: this topic has not been posted in for at least 120 days.Unless you're sure you want to reply, please consider starting a new topic.

author: f4eru
author_rank: Super Contributor
timestamp: February 24, 2017, 04:00:08 pm
content: Vacuum tube electronics usually use heated cathodes to have a better electron emission :https://en.wikipedia.org/wiki/TriodeThis heater filaments, like in a light bulb, need a separate supply.