Welcome I'm here with Dave Killpatrick and he's kind enough to uh, well here we are in front of the old Channel 7 transmitter. uh, this is that was to air right up until 9 uh 9:00 a.m. on December 3rd last year a a red letter day it was. Was it a sad day? Uh, it was mixed emotions.

It was uh, saying goodbye to the past but also saying uh acknowledging that technology changes, um more efficient ways of doing things come along and this is all this huge amount of racking. Here is the uh old um CH just Channel 7 just Channel 7 just Channel 7 cuz there's different racks for each Channel there are different transmitt theal Chels are also and the digitales as well and you work for TX Austral and you're Tech You're actually a private company. We are a private company that service the uh commercial broadcasters 79 and 10 right? Yeah, okay, but there is other gear here cuz this. R Tan transmitter.

uh, this is a fairly significant Tower in Sydney cuz it also handles Digital radio uh and some analog FM radio uh, some mobile phone, cell towers and other miscellaneous services and all the channels. All the TV channels AB TV channels ABCs 79 and 10 Yep, uh, the only one we don't handle is the community TV channel which comes from Gill up near the TA got it for those living in Sydney Yep, but this is not the only transmitter in Sydney it's part of a network of transmitters. Uh, that's right. we have uh, smaller transmitters dotted around Sydney to fill in various Pockets that that the coverage of the main site here doesn't fill in and we added some more last year.

Uh, because of the switch off of analog there were Pockets where analog could cover but digital couldn't so we added some some extra little infill sort of transmitters to right to help fill in those uh, those areas. and they get a signal feed from here from here via what mechanism? Uh, basically they have an internal set toop box. Oh right. Okay, so they just pick up the weak signal they pick up, but because it's on top of a or a mountain, got it? bit of elevation will will make sure it gets a great signal it and then it'll pick that up, demodulate it and then remodulate it onto a new frequency.

transmit it out generally on UHF right? I' take it slightly better than a set top box box from Dick Smith though uh, slightly better. but when you believe it or not, when you actually get down to the core of it, it does use the same uh nxp Philips of course, uh, silicon on chip digital tuner. Yep, yeah, got it, but with a lot better. RF Front end, uh, protection.

there's some preamps and attenuation Rather B some pieces that sure help help make it work properly and this is all powered off. It's completely most. this is all off. this is all.

Stone Cold yep and we can tear it down and check this out, folks. We have all of the original documentation for it as well, which I'll be able to Uh, take back to the lab. not all of it, but uh, certainly take back some schematics and stuff like that. So that's all the original um, schematics, service, documentation, testing, commissioning.

It still has that that smell. all the electronic smell that that smell of the past. And there's stuff in there dating from the 80s we saw before. Well why don't Why don't we start out T down.

Yeah, let's I mean let's have a look I'll I'll let you be the guide. But all right, let's start with this plate down here and that's made in Japan made in Japan in I can read that from here June 1981 Yep, Nipon Electric Car of course is NC. So yep as most of the gear here is NEC made NEC were a very, uh, popular supply of transmitters. uh, from the sort of mid-70s right through until the current day.

How many transmitter racks? Uh, so there There were three of these cabinets. Uh, well. three of these transmitters. So they have sort of three doors each.

Um, the reason for that was when this was installed in the 80s, this was it. This was the only transmitter they had, right? and they needed extra redundancy in case there was a problem with one. There was, always, uh, another one sitting on standby ready to take over. MH Uh, so essentially one of these could be a transmitter on its own.

Yep, Uh, 5 Kow Transmitter 5 Kow Yep. Analog Analog? Yes, which is different to digital? Yes, analog works on Peak power and the digital power is is measured in an average fashion. right? Y And were they automatic switch over on the two transmitters? Yes, if one failed, Yep, there's a control rack up the end which will show you uh, that could either automatically or manually select the required transmitters to go to. A Got it And all the switching for the input and output was done automatically.

Uh, in in days gone by, there would be an operator here to switch it off at night or switch it on in the morning. Uh, nowadays with with computer control and remote control. Um, practically you could do it from your iPhone your tablet halfway around the world. So they could have switched all this off by some.

They they could have switched this off in Melbourne in Melbourne with Via by their remote control by their remote control. but that's not as fun is it? So they had to push a button and no, no, no, they they got some of their, um, some of their old guys out of retirement I Believe. Yep, Uh to come in and actually flick the uh, flick the switch. There is no knife switch there.

There is no. although we might be able to show you that one on the Channel 9 transmitter later. Maybe. Maybe.

Anyway, we'll see and behind you is some very serious looking fire extinguishers. That's right. So these are automated fire extinguishers for the rack, are they they? They have smoke sensors and the the idea is if there's a fire, uh, the gas from this bottle will discharge and smother the Uh basically removes the oxygen from the atmosphere and the fire can't spread in just the rack that's on fire. The transm, just the transmitter.

So that's that pipe work. That's that galvanized pip, galvanized pip work. And yes, we'll take a that is copper pipe work up the top. that is rigid coax folks, which we'll take a good look at.

Uh, later. Yep. But uh. all right.

So we've got two transmitter racks. Uh, we have one here. one transmitter rack yep and then an identical one. yep and then another identical one.

And yes, for those playing at home, they are all in sequential serial number right and then down the end here. Uh, this was the parallel control rack. All right. And it its job was to monitor the transmitters that we operating.

Uh, if if a fault is signaled in one of them, it can then automatically switch and place the other one online. Got it. And with virtually would the Uh viewer at home know that it's been like would they see a glitch or would they uh uh. There would be a brief Interruption of of transmission, maybe about a second Uh to to prolong the life of the contacts.

in the actual RF switches. they're generally not switched with Uh with power applied right RF can cause a massive Arc of course you know, charring and burning the uh the actual switch contacts which could be uh, silver or or gold, or some precious sort of metal to ensure a excellent contact. So um, yeah, there'd be maybe a a half second glitch while it turned off the power of the transmitter. Flick the switch and then turn it back on right? Can we have a can? We have a look behind some of these? Yeah, absolutely.

Let's go. So this is the Uh hybrid and phase adjuster. Hybrid and phase adjuster sounds impressive. Well, it's its job is to take uh the exiter which is the the the piece of gear that actually makes the RF which we'll have a look at soon and it splits it and switches it and directs it into the appropriate transmitters as required.

All right, let's have a look look at this coax running everywhere and uh, these, Check these out. These RF coaxial reays. You'll notice that there's a uh, there's a Reay contactor down in there and you'll see a little plastic uh shaft coming out of the RF switching can there so that Reay is just sitting there on its own and pushes the contactor of that can I push that in there we go. Oh, there we go.

That pushes that in and that's it's. just an RF switch. So this is one very complicated RF switching box pretty much. yeah, customade I would think for uh, this type of installation um, may have even been slightly customized for this particular installation as well.

Probably sure it was. yeah, um, a lot of this gear. A lot of it is Um is made for worldwide applications and then some of it is also made for specific applications. They were very good at at combining custom made Gear with with standard offthe shelf gear.

Got it! And hence why there's so many manuals cuz there'll be a manual for the standard Parts there'll be a manual for the Uh, the custom parts. and um, when I did the video for the switch off, a lot of people, uh, wondered if this gear could be repurposed for digital. Tell us about that in theory, and in practice, this one in theory. possibly.

Although I wouldn't like to try it. Um, all the digital transmitters you'll find uh, at least the VHF ones that I've come across. uh, solid state, they all transistorized, and we do have another old analog transmitter that might possibly be able to be converted into digital. Uh, there's enough linearity in the amplifiers to do that.

so it's all about the how linear the amplifier is. Pretty much so. if it's linear and wide enough bandwidth, it could be used for analog or digital. Correct that, right? Okay, Excellent.

So these are all valve based. These are valve based transmitters. So how many hours total operation on these? 80? 8,275 plus 0, 100,000 plus 100,000 Because it didn't have enough, it ticked over in 999. It ticked over in 99 folks.

There you go. So that's how long this thing has been in continuous generally apart from about an hour per week where they would switch to the backup transmitter when it was finally installed later on in the'80s Uh, these would have been in in continuous operation, right? Uh, only two running ever at a time. so the third one sitting as a as a standby Mhm. But they would be rotated to ensure you know even where So these are five.

So at any one time it's 5 Kow to the antenna. 10 10 10 Total 5 plus 5 5 plus 5 10 Total Y Brilliant. But if one of them failed, it would half P It go half power to five only for a brief amount of time. The auto control would sense that failure, switch and switch the back up.

If backup failed, then you'd only be operating on. Then you drop down to one. Yeah, y yeah. Um, but chances that are pretty rare.

Okay, yeah y um a lot of this stuff was was really well over engineered. Um, maximum reliability was the key. Not so much cost. Yep, um and then of course the engineers over the years tread it like absolute.

um absolutely pamper it. Make sure every little thing is perfect. Got it? Every little adjustment is perfect which is what you want to do if you you want to prolong the life of these things. y um for sure this this was in continuous operation since 1981.

Fantastic. That's a long time we going a Galaxy? far far away folks. can we have a look inside the auto control? All right, All right that's got lob. This is the actual one where they switched it off right? They came in and they pushed the button.

Yep y on the news they had someone coming in here and pushing the off buttons. Although they didn't get it right the first time, the camera guy wanted another angle I Think they wanted a few more angles so there were a few attempts. You're right, Okay, but they made sure the transmitter was disabled at that point so it was a dummy. It was a dummy switch off.

So what we saw on the news was probably a fake button push. may have may have been, but you know they always do these tricks on TV don't they? They do And look at that. that's some lovely uh Loom work there. Check that out.

They've got the all individually wrapped and very nice whole bunch of resistors over there. Look at that. that's very nice and this is all wire wrap stuff folks and we you might be able to take a look at that uh later once we get the rack out. but yeah oh it looks like no P some wire wrap in there and some looks like a regular PCB stuff.

So yeah, and that interesting mix and that probably relates to the uh, the customization of this thing. They would have been able to build a basic um you know functionality out of the the circuit boards and then wire wrap in the specific requirements to this site. Now what are we going to? Well let's uh, let's look at the well know. Let's start at the input.

the input. This is. uh, this is where the audio and the video came in from the broadcaster. Yep, and it's actually converted into RF right? And this is what does it.

Um, and how does the audio and video get here from the broadcaster? Uh, in the back in the day it would have been via microwave link. Yep, uh from the for channel 7. at least it would have come from heing, right? Uh, but now it's all centralized out of a location interstate and it arrives via fiber optic along with the signals for the digital. Got it and that is a that's a bit of Phillips gear.

That's pretty rare here. everything's NEC except for this puppy. This was a later installation to convert it to Stereo Sound Oh, so originally this was a Monot transmitter and when stereo came along, uh, that require this to be installed right so it takes the left and right. Um, modulates it down to a IF frequency.

So what actually comes out of the modulator here is not on channel, it's not on Channel 7. It comes out at an IF frequency and then it goes through uh, a corrector to make sure that, uh, the signals coming out of this transmitter can match the signals of the other transmitter. Make sure they're exactly aligned because then when they're combined. yep, they will combine U efficiently.

So there's yeah. So that's audio. The left hand side there is audio and then video on the right, and video pretty much through the entire transmission transmitter right until the uh, very last end. Audio and video are separate.

Yep. and they're even modulated separately as well. The audio is modulated. Uh.

FM Frequency modulation. The video was modulated Am. Got it? Yeah. and they love drawing block diagrams on this gear.

There's lots of all the gear I've seen around here. all has block diagrams all written on it, which is really quite nice. Yeah, not only block diagrams, but these fault leads as well. so it can even direct you to uh, which part of the so it's got the basically built-in self test? Yeah, kind of yeah.

Really handy for when you're troubleshooting. yep, can imagine. Um, and as as we we look further up as well. So what frequency is that that's got 22115 MHz written on it? I Believe Uh, that is the transmit frequency plus the IF frequency plus the the If right? So when you subtract the IF frequency from that, you'll get your Yep because Channel 7 is 184 MHz I think y or was H Have they sold off the Spectrum Now haven't they? Oh well, Channel 7 will now be used by SPS Oh S SPS That's right.

they're going to switch it over right? Uh which is actually active in Sydney as of Um 3 hours after this was turned off. Oh right there you go. So they had the transmitter ready and waiting and then this was switched off and there's a nice little Pro here. Yeah, now this is Again part of the uh, the test and maintenance and troubleshooting.

Uh, these solid state amplifiers. Uh, in the case of the audio, these two amplifiers, uh, output the final amount of power for audio, right? Uh, it takes a lot more power to get the visual data out there or the visual information. Uh, the audio you can just do with these. Uh, oh.

Okay, so that's there's no further amplification required. No to go to the trend to go to the antenna correct, right? Uh, there's another pair of of course in the other transmitter to air. So essentially there was four of these, all operating in parallel. Do you know the power output of the audio transmitter? I''d say they're 360 W Amplifiers? Yep.

and nice big kilowatt meter up there. I Love it. Yes. Brilliant.

old school. And what's the? They've got a yellow one there and a red is like I Guess that is that like a peak hole kind of thing? Uh, well. these are the uh, these are the low highest head points. Oh right.

Okay, uh. so there's actually a tiny little metal contact as the needle swings past it. Uh, it goes above the low set point. Nice.

And if it was to go too high, it would trigger off that it trigger an alarm somewhere. That's right. Fantastic, good old mechanical sensing. Yeah, yeah, yeah.

So back to this little probe. Yep, that was for probing into these different uh test points here to measure the the current of the transistors inside. Brilliant. And it makes sense to have a probe rather than a 50,000 position switch.

Y Yeah, Yeah, Absolutely. So you could. You could put your test meter onto the transistor, PA current, um, setting and then plug your probe into the socket. We come up with a reading.

So for the audio side of things, this is where life finished. Yep. Uh, for the video side of things, we're just getting started. We're just getting started.

Yep. so in this case, this is acting as a preamplifier, right? Because it is still a 3. It's the same amplifier as the others, not probably 360. OD Wats it it it produces enough drive to send it next door.

Yep to this panel. Yes, this looks ominous. Well, it looks ominous. Well, it's huge.

It's a giant beige panel, but a few things will give it away. You've got uh. Plate Voltage Meter Plate voltage meter 7.5 kils and that would suggest it normally run at about ,000 Vols 4,000 Vols Yeah, Plate Current Plate current 4,000 Vols at a couple of amps. Yep, do the math folks bit of power.

Yep, and then uh, these are RF power meters. Um, to record how much RF power was going into the antenna system and if any was being reflected back if there was a falter. Got it and that's just a some Ming for the actual valve y y So you can measure the incoming RS And we do have one of the valves here. Oh, we have some on the floor we will take a look at in a second.

Unless we can see it inside, we should be able to see what inside. What's sind absorb the Syn is a common impedance non-directional uh combiner. There you go. I'm glad you you knew that the Syn is.

uh, the Syn is actually what combines the analog, the audio and video. RF Together got it? Um, so that's that's the last sort of block before it leaves the transmitter. W Look at this that looks impressive folks, that looks look powerful and we have is that a There we go. Is that a schematic? That's a block diagram? A block diagram.

I'll try and get that. It helps you locate where all the parts are. if you need to check something out or replace something. There we go.

And the 8 F76 R is the valve that is the valve that is the model number of the valve which we'll be able to show you in a minute. and oh look at that verer for the plate voltage. Oh beautiful. These will be uh.

input matching. Oh okay, right. so that that'll probably be uh, adjusting a capacitor or quite literally a plate inside right? Um, to to change? Uh, it? its coupling. This one here is pretty cool.

Check that out. What is? It's a little chain dve it's a little chain drive right? Excellent. That takes it back into that which then goes into this big beast some more. Uh yeah, some more trimmers there.

Okay, let's have a look at the valve. let's have a look at the valve. This is the transmitter valve so that that that we took off was just the chimney cuz of course these valves run really hot. There's a there's a big air blower that du that blows massive amounts of air through there Mhm and so what's this single valve capable off? Well this will do the 5 KW Visual 5 KW valve.

This is actually what's get get sent or did get sent to the Uh antenna here in Sydney to you might be able to see a bit of it through the mesh. Oh no, it's a bit hard. We just undo these and W There we go folks. Look at that.

that is the 8f 76r transmission valve made in Japan and that's the 5 kilow transmitter. Look at that. What is that ring around the that that uh coil? Okay, around there, it's like some sort of sense coil. Uh, that will be an inductor.

Yeah, more. yeah. that will probably conductor. We can actually look.

um no, it's not. Oh there it is there. L201. So here it is.

Uh, on our little plate here. So we got the plate voltage coming in. Yep, which is our 4,000 volts right? Uh, through a bypass capacitor and then we've got a bypass inductor. Ah, okay, and that's that inductor over there.

That'll be that. Yeah, Okay, yeah, this is where all the vaults come in. Yep into this ring. Um, this sheet will be.

they'll form a Capac right between this outer copper and this inner copper here. Okay, and that feeds the inductor. Okay, got it. and and it comes.

Tada There it is. That is a 5 Kow valve. That is brilliant. And of course the new ones are all B in solid state right? Yeah, still still very specialized transistors.

but uh yep. you know there's the socket down there it plugs into. There's our socket. I'll see if I can get that folks there we go look at that.

Oh, and check out the RF gaskets around the edges of that I mean that's just fantastic. those all the fingers. Of course they I can poke my hand in here because it is, uh, all turned off, but otherwise I' probably be thrown across the room ordinarily if you uh, tried to get in here while this sucker was powered on. Now we you know this has been turned off for a while.

the the chance of any residual current is going to be pretty low, but y in general practice you would pull out the Widow stick. Ah right, the Widow stick. Yeah, so we got giant fiberglass Rod nice big, yep, brass or yep, chromium plated something and you would Huge big strap on it going huge big strap and you would generally y touch that to the high voltage parts and leave it hooked on and leave it hooked on while you worked on it. Yeah, yeah right.

Um, but this thing is really welld designed. There are safety interlock Galore Yep, um, because even with that sort of capacitance, you'd get some dialectric absorption I would and and uh, recharging up of that voltage I would assum so you know. um, but there are also other discharging circuits when you flick off the main switch. uh, that also puts a physical contact between the plate voltage and Earth and physically shorts it out shorted out so the residual charge can't build back up.

Yep, sensible. And yeah, these are all interlocked uh switches as well. We have to. Uh, that's right.

So safety was. Paramount We're working on these. Uh, you've got these little oh yes, the door interlocks. Micro switches everywhere.

Swit y Uh, there'll be door switches here and here. Yep. Um, there'll also be an air switch as well. probably up here, right? Uh, so it has to sense that there's air flow, otherwise it won't switch on.

Yep, all of these interlocks have to be in place before it will even apply. Uh. power to the tube. Got it? Yep.

And then to get in and service the thing. Um, normally that key would be in position. Okay. I Think we've been physically locked out because the the door open.

Oh, there we go. That's probably it. There we go. we bypass, there we go.

Clunk all right? So that would be normally in and the control key would be out. Yep. so that you can put it into the control panel right and turn it on. Got it? So y to actually get into the thing means turning it off.

MH Removing that key and now this has been locked out? Yep. Uh, you would put the control key down there. Flick that off. Mm HT is shorted Main's power is off.

Then you can take out the rear door key. Yep. But to actually switch off the signal, they just push the button over. They push the button over there.

Yeah, boring cuz You' have to turn off right? You got to turn them all off. Yeah, yeah. And behind this panel, here is the sind. That is the sind.

Can you explain that again? For those who have forgotten common impedance: nondirectional Combiner combiner? Yeah, it's just. um, this is basically all rigid coax. Yeah, these pipes are rigid coax. This is a giant empty can mhm uh with these adjustable filter tuning prongs.

and there's other adjustable sort of traps and uh, little stubs here as well. So if they're um, okay, traps. uh. but that is basically the combiner for the high powered anal L and high powered U V visual RF Power, right? Uh, so that's why everything's so big.

it's it's all at uh, huge power levels and also, um, the bandwidth required to transmit the whole signal. And this. These are air cord rigid coax. so there's no dialectric.

Well, the dialectric is air inside these things. so there's like a half in Copper tube or something inside that and we'll be able to show you that in a sec. But yeah, that's impressive. And of course, uh, they, they can get bigger.

These are about an inch and 58, but they can go up to five or six inches in diameter to handle hundreds of thousands of kilow. Yes. And these are some of the output rigid coaxes. And they run.

and you'll notice that uh, some of them bend backwards before they Bend yep over towards the switching gear and again, they have to be all exactly the same length. Yes, they have to be Len match. So Leng matched Indeed so that when the two signals come to the combiner, they're at the correct phase so that they can be combined properly and length match to what a few millimet or something? How critical is it at VHF frequency? Um, you can usually have a couple of millimeters I Mean Obviously, exact is ideal. Yep, Um, but of course the lower in frequency you are.

little bit more leeway you've got. And how do you measure that? How do you what? What gear do you use to measure that and make sure their length? Uh, you can. You can measure it with a a TDR Usually a Um Network analyzer can actually measure the uh, the length of the line. You can input the velocity factor of it as well which this stuff is is pretty close to one.

Yep, being uh yeah, as close to a ideal coaxis you can get exactly yeah and it needs to be at these power levels. Otherwise your loss would be your loss would be very great. Yeah yeah yeah. so the loss through this is extremely low.

y. Um, you'll get small losses at the Uh Junctions there where they actually connect together. Yes, those are right angle Junctions Yep so there'll be a little um, silverplated brass bullet which goes inside the internal pipes to to join them together. And we've got some control stuff in here.

Do you know what that is? Looks like? We've got some bare circuit boards yeah, these would be miscellaneous power supplies for, uh, various control systems and and uh, you probably got the screen Supply down there as well, right? uh which is generally a small current power supply. Yep, the big Power suppli is the tube though around the back. Let's have a look around the back. It's a bit noisier around here.

It is a bit noisier. We're adjacent to some more gear um, which we're not allowed to look at because it's it. Used to be a lot noisier in here with all of this running. With all this running, you've got all this forced air coming up through these ducts, being squeezed through these, uh, the fins of the tube and around sharp Corners which makes a lot of noise.

and even on the back of this cabinet. Of course, we've got a blower as well coming out of there. And what's the back? Which cabinet is this? uh, this is the back of the cabinet with the exiter and the solid state powerfi in it. So what we're actually looking at here are the Uh power supply um boxes for those Solid State power amps.

Got it! So we've got a large one here for the two audio ones, a smaller one here for the visual one and this is actually the combiner for the two audio Mhm power amplifiers and they are NEC The even look the right angle join is are NEC branded. That's right. Look at that whether or not they manufactured them, but they certainly got their brand on them. Looks like we got a couple of look, it's just tapped into the oh, they're they're the video outputs.

sorry no audio. uh what? they are uh I thought it was the same Cox um uh so this is your your main audio output and that will go into that syn yes uh but what these are are uh, samples of the power going along that right coax. So we've got a monitor Point M So you can sample. It's called a directional coupler and you can adjust it so that you can sample a known um amount of power off this transmission line.

Uh, and you can use that for monitoring or power measurement, alignment testing, whatever. This other one drives the AGC circuit for the audio. so it's it's sampling the the output of the entire system and that's where it's AGC Feedback comes from Manufacturing Date: 1981 Takaka Electric Manufacturing Co Made in Japan Brilliant and everything's nicely tagged and uh yeah, nicely. Tagged So you can take one of these out and know exactly uh, where that goes.

Uh, Tb2 Terminal 1 right there. Yep, brilliant and all beautifully uh. shielded. You just don't see manufacturing like this very often.

No, you don't. And down the bottom here there some big ass Transformers Yes so what we what we have down here is a uh three-phase DC Supply and its job is to power those um power supply modules we looked up looked at up there Y and one of the reasons NEC do it this way is to make these as worldwide compatible as possible. so there'll be multiple Taps on the Transformer Uh, there'll be different Transformers depending on 50 or 60 HZ and that's all they have to change out to. uh change it from one part of the world to another and you down here you've got all of the uh um cables which interface back to that parallel switching uh unit Mhm.

Nice serious looking ground Point down there too. I mean what would be the ground point for this entire for this entire building entire facility? Yeah uh, that would be the tower. the the tower that would be the tower and that is really well grounded. Y And then we use that as our ground reference for everything in here.

Um if you look behind you there you see that. Oh yeah oh wow. look at that 120 mil Earth wire oh 120 mm yeah wow oh how much would that cost per meter I Don't want to know that is serious amount of copper and they just they're running all over the place here and the idea behind that is they're all bonded to the tower in more or less a direct fashion. Uh, lightning doesn't.

Lightning will see a sharp Bend as an inductor or a high impedance of course, so it might want to follow that path so they. it might look messy the way it's installed, but it's done that way for a reason. so that there's a direct path as possible. And the idea is to remove, uh, as much voltage differential between all the various bits of gear and the tower.

So doesn't matter so much that in a lightning strike. Um, this might be a potential of 5,000 volts as long as it's at the same potential everywhere. You won't get aring. Yep, that's right.

the gear. All right. now. The back door to our transmitter.

Uh, this is the key. This is what gets you in Magic Key. once everything's been turned off and interlocked of course. Um, check that out.

This is the back of our 5 Kow transmitter. Oh, look at, there's our S. There's our. There's our big empty box.

Yeah, that's our huge empty box. Yeah, why does it need to be so large? The frequencies where oh again, just for power handling and power handling and bandwidth. So and there's some more. uh, couplers.

There's some more couplers. Yeah, yeah, so that is. that is the output of the transmitter. That Ah, right.

this. that's your video and audio combined. That's video and audio combin' going up there and buggering off somewhere else, going to the parallel rack which we can have a look at. Excellent.

Uh. and basically the back of this is all power supply. There's some impressive looking capacitors yeah, he big beasts and uh, some huge power resistors up here. They're what? 50 ohm each? 50 ohm? 50 ohms of pop.

And and it looks like there's some sort of measurement shunt something like that. Yeah, that'll that'll be a high impedance. Um Network So you can sample your HT voltage. Obviously, you don't want to drive 7,000 volts directly to the panel meter.

That's right. And uh, they 50 W Huge power resistors. Very impressive. And down here and down here we have, uh, this is the filament supply for the valve.

Um, being a very high powered device, it'll need a lot of electrons and this is a three-phase DC power supply. Uh, which culminates up to these uh, screw terminals here. and the reason it's DC Uh, most most tubes as you know run off AC Um, because this is modulating the uh visual carrier and it's using am you don't want any hum superimposed on the picture, right? So that's why using DC DC is the order of the day. Yep, and what about the filament? Supply Uh, it would be approximately 6 Vols at 13 O amps, 130 amps.

nice There a nice plate on the top of the Transformer There all all the details. probably read that one later that has all the details on it. brilli and again all these multiple Taps Yeah all the tap points y so 50 HZ 60 HZ different voltage adjustments that makes it World compatible right? Okay, so they just sell these racks to every country are are any SE The major one of the major ones who do this. Are there any back in the day? They were.

Of course you. You would have found these um uh a a lot of a lot of them in Australia a lot of them in America Um, not so much in uh Europe Um. Over there you had rhen Schwarz Marone and other English and European manufacturers. Yeah, sure, they're very protected of their industry over there.

So yeah yeah, and the digital ones who makes the digital ones these days? Uh NC NC is still in. They still make transmitters and um, we use a few of them here and we'll check those out as well. Yeah, we can. Excellent Great That is a very impressive 5.

KW transmitter rack. Well this is where all the 5 Kows come from. Oh, this is the 5. KW Okay, behind this panel is a giant three-phase Transformer Yep, so 415 Vols in.

uh we have 3,180 Vols out at 3phase to rectifiers rectifier stack there U DC out of there choke. So that's a they're huge rectifiers there. Once again, they're NEC branded rectifiers. Yep.

Brilliant. Yeah, you'll find a lot of custom parts uh, made for these transmitters Mhm. And you were telling me that, um, you're sometimes requested to, um, switch to backup power here by the by the local power companies. Yeah, because this site uses so much power.

Um, especially during hot weather when you've got everyone using their air conditioner. Um, it can put quite a strain on the grid. so we can be, um, requested to go off grid if you like, by turning on one of our big diesel generators. right? And yeah, just to help Sydney out because there's too many people that's right, just running their airons in their big Mcmansions.

And and also, uh, for continuity of service as well. if we've got a big storm coming in, if we're worried that lightning strikes might take out the power grid or wind or trees over onto lines, uh, we can. We can turn the generator on for that too. And how much notice will they give you for that? Oh um, for the storms.

Well, for the storms, we're always monitoring the radar. Yep, um, if if we have to go off grid. yeah, we got about 10 minutes, right? But we can do a a site change over in maybe 2 minutes. And what size generator have you got here to power this whole 500? KVA 500 KVA And that's now because you switched off the analog.

that's Way over power. That's that's a lot. Yeah, a lot. of power you don't need.

Oh well, you can do something else interesting with it. I Don't know. I'm not going to make any suggestions I'm surprised there's no flux capacitor in here I'm just I wanted to install one. Yeah, you've got the shirt on it.

I I Do have the shirt? look? Yes. There we go. Brilliant. No, we've just got regular, uh, regular capacitors and that little capacitor there.

4 microfarads, 6,000 working volts. There you go. Awesome. All right.

And what have we got here at the end of the rack? Yeah, So this is where the three separate transmitters come in to be switched, uh, selected to A and eventually combined. Uh. And you can also direct the transmitter that's not to air into a test load if you want to test it prior to putting it on air, or just for maintenance. And in fact, you can direct the entire output of the entire system into a test load as well.

A 5 Kow Test Load 10 K 10 KW Test load. That's right. Brilliant. So the three transmitters come in.

Um, there. There's patching available on the panel, so if one of these switches were to fail, you can. you can switch around it so there's three of them. Yeah, so one, two, three for each transmitter and they're interlocked in such a way that, um, the correct selection of transmitters can be made right and you can just turn the dial And that's a manual, but you can do it automatically.

You can do it via the control around panel and turn it. Yeah, nice. And that's a just a huge big physical. A Driven R switch Yeah Motor driven RF switch.

That's right. Very impressive And that and you can see the diameter changes in the Uh coax. You got to remember folks, this is not. You know, there's not liquid flowing through here.

these are all coaxes. That's right, rigid coax cables. So this is the end of the journey for the Uh transmitters. Um, we have the number one transmitter input, number two transmitter input.

Yep, and the number one transmitter will arrive. Um, Now there's a bit of because there's phase shifting that goes on is here as well, which is why the length of these lines. the phasing between the Uh transmitters is critically important. Uh, what comes in here will be considered at 0.

Uh, what comes in here will be at 90. When they're combines, they both come out there right. And and if if there's any mismatch whatsoever, uh, that will come out this port uhhuh uh which is then sensed and goes into a uh, a little reject load sitting down there. A reject load? Yeah, yeah.

Reject load. Look at the size of the reject load In in practice there might be a few Watts a few Watts right? But you have to cater for in utter catastrophe, You could end up with all 10 Kow in there. Uh. But generally the protection circuits would kick in and stop that from uh, turning into a flaming mess, right? Yeah, But yeah, you're absolutely right.

The the diameter steps up cuz that's 10 KW going up. and there's our final output couplers that they sent in the output. That's the final output signal. Yep, yep.

and again, that's uh, patchable on the front panel. Oh yeah, so cuz it goes, you see, it goes out there and it actually goes down into the front panel and we can walk around and take a look at that. but uh, yeah. then it eventually goes up and it transitions into rigid copper instead of the much more expensive copper one.

I Guess these would have been the original ones installed. Absolutely. this. uh, any of this aluminium stuff is is original.

Yep, uh. and it would have all been um, cut and and labeled. and and every single piece would have been made at the factory for a specific position according to the installation and drawing. Yep, so they they supplied as a ready to install.

Wow. Pre-made kit and you just add your own. That's a hell of a job. And there's the final output.

It goes all the way along there. Can we follow it? Yeah, here we go. Oh and oh, we can see some uh, trans there. There there's the there's the cricket.

There we go England Not doing so well England not doing that great. This is the old are we allowed to view? see? This is the old. Uh, this is the old NEC um backup transmitter for Channel 9 Channel 9. It's also 10? KW Yep, uh, physically a lot smaller because there's no redundancy.

un. it's just one transmitter, right? Okay, but a little bit more modern too. This would have been maybe 1986. Yep, Um, oh, there we go.

Look little plack down here says 86. There we are. 1986. There we go.

Yep, um. same tube. same pretty similar as Um valve as the old ones. Um.

I'm getting blown by. Lots of fans here folks. There's just tons of other gear around here. and yeah, lots of other stuff.

I'm not allowed to show you. but uh. anyway. we're following.

Oh, we can see the end on the rigid coax there, which will show you one actually down on the ground in a minute, but there's one that's not terminated there and you can see the copper inside it. Yeah, we'. We've already started pulling out some of the old analog gear right? uh to to make way for a new S SPS transmitter and here we go explain this cuz look at this. This is impressive.

Look at the size of those rigid coaxes tell us all of this is still operational. This is all part of the digital setup and this is where each of the individual transmitters are again combined to uh one single signal that goes up the Uh, up the tower. All of the different channels look, yeah, they're numbered six, 6, 8, 11, and 12 12. And and so they're actually at each stage they're just added.

That's why they're cascaded. Is that right? Yeah, So yeah. so it comes into one That's impressive. That's where analog used to connect into.

Ah, right. Um, so that's now been Terminator That's just a little 50. Ohm. They got a little 50.

Oh, they pluged, turned off analog and whacked in a 50 Ohm. Terminator Correct. Yes, great. But each of the digital transmitters come in.

it's it's cascaded along. Um, again with this much bigger yeah, That is a massive rigid coap. There's nothing inside that except a another diameter. that's unbelievable.

And it all culminates into this one piece which is then, uh, split. So there's a there's a big power divider there and that's split. Uh to go up two feers up the tower. and that's what actually goes up to the right, up the tower, up to the approximately 180 M up in the air.

180 M Abolutely? Yeah. Fantastic. And they're huge, massive interlocks so you can switch. so there's two antennas up there effectively there.

Twoes, there's an upper and a lower. Um, and the reason for that is if you know through lightning strike or some sort of other damage, if if half of it damaged we can then put the other half into full operation at slightly reduced power. And because these uh, coxes go up the tower and they're exposed to the elements. um, we dry, You don't want any moisture in them as well.

So we actually pressurize those cables with dry air and that's what. That's what this contraption do. And and so that's the dry air. Yeah, so it's just an air compressor.

It goes through a uh, a desant dryer and then pressurizes the the line so that no, no water can get in. If there's a if there's a crack or a leak, it just blows air out and stops the water from getting in. And what are we transmitting that at the moment? Look at that 50 full scale deflection: 50 KW Fantastic. So we're at about we're just under about 5 Kow about 5 Kow on that one.

Remember, that's half y so there's another 5 Kow up the other antenna, up the other antenna. Brilliant. Have you ever had to actually switch them like that? I Haven't No. Oh, there's the air dry going.

Oh, there we go. No, that's not the antenna exploding folks. And so yeah, that's very impressive. So this is the active transmitter for just the digital.

Just digital now. yeah, just digital at the moment. Yeah, okay, and that's what. The back.

That's what. The back of these units. All right. And what is this? Beast Oh, this is more, uh, just more switching, More switching.

Yep, you'll find there a lot of uh, a lot of switching. A lot of uh. patching available just to, uh, get things back on air if there's a a problem with anything. Yep this is the SPs Yeah and this is all about to uh to go because SPS Analog no longer exists, right? SPS Digital is about to change to Channel 7, right? And what's this impressive looking thing? It's it's not a cyclotron.

It's not a particle accelerator, right? Uh, this is a UHF uh combiner. and this is all comb. This is all basically wave guide. So it's all.

that's all. Oh right. It's not like this where there's an in conductor. It's yeah, just Hollow just just wave.

Yeah yeah, wow, that is. and so quite literally is is that is that that's a splitter? That's it. physically splits it. yeah and then converts it back to um, converts it back to normal car there, right and again, just a smaller version of what was up the road or up the hall.

Uh, splits it into two antennas and goes up, goes up the tower. Got it. And is this the Uh. I've got some discarded panels and is this all the power for? Uh yeah.

this is some of our power switching. This is the the generator control so it does the change over sequence from Mains to generator. Does it in such a way that the generators will synchronize to the grid when they change. yep, in either direction.

Got it? Uh, And then down on the floor is actually some of the parts. some of the rigid coax from the analog transmission chain, which is just recently discarded. so let's take a look at those. Yeah, so this is what the rigid, uh, here's some of our.

this is some of a rigid coex and uh, basically just an inner conductor. That's what carries the actual power. Mhm. And and it's got a Um separator in it.

Yeah, uh. it has these Teflon uh, spikes. Mhm. Um, and that basically holds it up.

if it's a long run, you don't want it sagging, sagging of course. even though it's it's pretty tough as it is. But over a long run, you don't want it to. Sag So that'll that'll That'll be every wat meter or half or something spaced at regular intervals.

Yeah, yep. and that just, uh, goes down like that. And that is. That's probably the lowest loss coax cable you can get.

Yeah for for this sort of application. Yeah, it's just ridiculously expensive cuz they're what a 2 mm thick or something like that? They're uh yeah, it's just air air dialectric and that is that is the best way to transmit kilowatts and fantastic, that's still a certain frequency. And then you know, when you get up to really high powered high frequency stuff, then wave guide tends to be right. Better than yep.

Got it. But at sort of the you know few hundred MHz where looking at here, it's a broadcast. Yeah, what is the Um antenna capable of transmitting here? Do you know? Oh, that's a good question. Um, it.

It's certainly sized so that every single transmitter we have here can be comfortably put to air, right? Um, so that was analog and digital combined. of course. Now it's just digital to it. It's It's massively oversized.

but y um, you know, a little bit of head room is is not a bad thing in this game. And it's all horizontally polarized television ision. So if if your antenna's pointing at this Tower then it's horizontally be horizontal. I Went Uh I Went on a holiday a couple of months ago and I drove through a town and all the antennas are vertical.

vertical freaks freaks. I Thought no, they've been stall them all. Wrong. No, they I know you can get vertical ones.

What's the advantage and disadvantage of both, do you? Sometimes it can be to geography, geography, so your vertically polarized signals uh, might work better in different types of terrain. Uh, or with digital transmission where you can have. uh, now this is interesting I'm not sure if you know this, but the UHF transmitters around Sydney all transmit on the same frequency, right in what's known as a single frequency. Network And you can't do that on analog.

You can do it on digital. Uh, because of the way the um. the digital scheme works. So you can have Uh transmitters Manley and King's cross all working on the same channel Mhm and all transmitting the same data and they can be timed so that the interference Zone might sit above the harbor.

I Got it right? Impressive. So you might use vertical polarization if you've got closely spaced transmitters and that vertical polarization might give you an extra 25 or 30 DB of Separation Got it? Uh, when you change the polarity of the antenna, these are 3 couplers. So just as we saw on the back of the Channel 7 transmitter, Yep, um, these can be used to either split or combine. uh, high power AR signals.

Got it. And there's the check it out is that's a Teflon uh spacer in teon insulator. Yeah, and this this will just be silver. um coated brass, silver coated brass? Yeah, Wow.

that uh. Also, then you'll have one of these sort of brass machined um bullets as called, right? and that's what the inner conductor slips over and tell us about this cuz it just looks so impressive. The Houston Fearless Corporation or is fearless or is. Yeah, it's Fearless There you go.

they're Fearless in Los Angeles car I Wonder if they still exist? but tell us about this that's a rotator controller for a steerable antenna and for as ath an elevation for for um, television OBS or um, just remote reception? Yeah, right. Okay, so is that used anymore here? I Don't think that's been used for a long time. Yep, it's just sitting in the rack there. That's right.

Fantastic. with some very much old gear as well. Yep, uh, from some older string made um microwave link gear that's old STC Oh oh STC right. yes it is standard telephoning cables.

There you go. A classic. They calibrated that in ' 92, no longer used. yeah, although it's still on, still switched on I Can see some leads up.

so yeah, it's all on. Don't know what it's doing though. Not much warming up the room. and yes folks I am allowed to take the gear and uh, keep it because they don't want it anymore.

Go figure. Well you know got my screwdriver So out it comes the old analog transmitter I Can take it back to the lab and uh, tear it down in my own good time. Beautiful! What a score! and yeah, I'm not kidding. I'm allow the keepy it cuz going to scrap all this gear.

it's all going to be. uh, it's all going to be scrapped. Um you know they'll uh get all the uh, they'll sell it for scrap metal prices pretty much. Um, it's a real shame.

So what can we do? Does this just pull out? Oh oh oh that feels like it's on slid. it is on sliders. Oh I Love it. Look at that! There we go.

Brilliant! Fantastic. Oh whack that in the boot of the car and we'll take it back to the lab and uh, yep, you'll see some excellent tear Downs coming up. Beauty There it is. It's all mine.

all the back. Beautiful. The old Channel 7 analog transmitter. Fantastic.

And he there we go. Oh oh, look at the switches. Oh and that's the underside of the transmitter panel. oh cow button.

There we go and uh yeah, it's all beautiful. Look at all those uh, coaxes and various uh sensor modules I take it or Splitters or whatever. Not sure what that is, what's that? oh that's the uh meter. That's yeah, that's the panel meter.

There you go. Oh look at that. There we go. We actually have a PCB in there somewhere doing something.

So yeah, that's just the uh PCB for that front panel there for the main transmitter control and uh, inter. that would, uh, you know, handles all the control and interlock and uh, some uh, fault sensing as well. So there's um, some in circuit testing. that's the final output.

uh y so switch. That's where it transitions from the uh, rigid copper to what's called a semi- rigid caral cable y um which as I said was, it goes out the door and whoa here we go out the door, out the door, and up the tower. Here folks is the Tower so they're are semi- regid. Yep coming out and as long as you keep The Benin radius under a certain amount, you're uh, you're good to go.

You're good to go So but that goes all the way up the tower which will go to the center and have a look. but that's the main tower and there our generators. the green there are our backup generators. Awesome! If we take a look inside the old uh Channel 10 NEC transmitter then uh yeah.

we actually have have some real Electronics in here folks. so not sure what that one's doing. Any idea there? Yeah, that's the Uh detector board for the um various directional couplers. So the the sniff points from the RF oh yeah.

cables. Uh, they'll come in here. They'll be uh detected and converted to a linear DC voltage for Um and metering on the back of the door here. let's get in here like this.

and what's that's just the back of the LCD display? That's the LCD display. Nothing interesting here. this is that's the transmitter controller. Yep.

CPU and of course it's an NEC processor. Yeah, there you go. look at that. Uh, but we do have and uh, little FP Oh, there's an Altera Fpga Okay, no that's a Cpld C Yes, Y Proba woulded and this is quite fascinating.

I Like this logic I presume it's a TX control unit interface to the rest, to the transmitter interface to it all. Yeah, look at that. Lovely, Beautiful. So there you go.

We do have some Electronics in uh, these sort of beasts and even more here. Check it out. What's this? This is the Exciter the Exciter yeah. So rather than having an entire rack full of uh, bits and pieces, it's been condensed.

Uh, this is probably from about 2,000 so few Generations few Generations on right and those cars just slide out and uh yeah, there we go. Oh look at that beautiful look at those RF cans there. Fantastic. MSO made in Japan H NEC I Mean how big must the groups be at? NEC that just design all this stuff.

And how many would they sell? I Mean it's not high volume stuff? No, it isn't. Uh, but it's high reliability. Yep, so they charge a fortune for it. They do.

Oh yeah, you, you will get. uh, you would get another 10 years of use out of this easily. Y No problem, Have you? you got any idea how much like you know, all this rack gear would have cost originally any inkling more money than I would dare to think? yeah, um, that's the correct answer bit insignificant in the scheme of things really. So so there you go.

That is the Um Channel 9 Channel 10 the channel 10 sorry Channel 10 transmitter Tada and that one's also going to be scrapped. Uh, Maybe not, maybe not. You probably. Uh, this one may be able to turn it into a digital transmitter.

see? Oh, of course, right? Yeah. Could uh, recommission it and check out these huge jumpers here. with the you know, the antenna in and the Channel 9 transmitter out there and the test load. So the CH channel Channel 10 transmitter output can be switched through to the test load.

Brilliant. And there's a control panel for that's just the cooling system. This is a water cooled transmitter. Yep, uh.

so the water comes in right? And there's uh, more power amplifiers. Um, that we saw on the Channel 7 one. But these are these in the Channel 9 transmitter Channel 9 transmitter and again, the that's exiter. Woohoo.

There it is. there. It is. More.

Wow. Beautiful. But just the engineering that goes into producing all this is are phenomenal. Look at that.

Oh, and some uh. rigid coax on there as well. Oh yes, yeah. there we go.

Some there, there you go. They're headed out there like that. Rigid coaxes all around them so this could be reused. maybe? uh.

bits and pieces. You're right. Yeah, these just pull out. Take A Yank There we go.

and the modular look at that. That's right. So power RF and water power. Oh, and water as well.

Okay, Water Co Yeah, So there's our water. There's water. There's your Um Power and and signaling. Yep, and there's your RF RF out.

Wow. Oh, that's impressive. Oh, that's pornographic, really is. And that one's date.

Uh, 2000. Yep, there you go. Pretty modern. And here's what the antenna looks like up there.

Can you explain that? Dave Yeah, these are the dabs. So this is the upgrade that was, uh, done in 2009 to add Dab. So there's a horizontally polarized radiators for TV yeah, and the vertically polarized radiators for okay, right. They're two separate antenna systems that share a common Bay, a common reflector panel right and then just above that, you can see the bottom of the uh UHF panel array.

Yep, and and that's approximately 200 m in the air. 200 M up Mhm. Fantastic pumping out 10 KW or thereabouts thereabouts all there give all take. Fantastic.

Unfortunately, we can't get up that high folks. We're only allowed to go up to like like 80 M or something. So oh well, that's what it looks like. Got the transmitter catch you next time.