INTERVIEW WITH BRYAN MADELEY


21/3/2006 BY DOUG GRANT
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Bryan - The 5th of November 1956 was a very meaningful date for me being an Englishman - because it is Guy Fawkes night. It was really not a propitious day because we had no back-up. At that stage we had a nominal 5 kW transmitter, but the nominal 20 kW (which in fact was an 18 kW) was not there. It didn't come until very considerably later. If anything had gone wrong, it really could have been Guy Fawkes night you know.

Doug - I believe it was stretching the friendship to get the stand-by transmitter to perform to the technical specifications laid down for the Australian Television Service.

Bryan - Absolutely, it was a very nasty piece of gear actually. It was a low-level modulated transmitter with linear amplifiers, and they're an absolute bugger to adjust. This was the worry of not having a back-up. Trying to get that thing to perform was no mean task. It took a lot of work.

Doug - I believe the group delay was a problem?

Bryan - The group delay was absolutely hopeless. Once we got the nominal 20 kW, by comparison it was better than a million dollars, but there were so many things which were just not foreseen. Things that you had to put as unique. We had this very considerable length of coax between Master Control (the Arcon MCR) and the transmitter. In Melbourne a couple of years earlier, no one had thought, not unreasonably so, of the impact of the trams going past
the transmitter (from Lane Cove back to Crows Nest). Every time they went past, the current that flowed across the transmitter site and down through the Studio (the Arcon) into the brick-pit, was horrendous.

Doug - You described it as a sort of natural buss-bar.

Bryan - Yes - for reasons none of us understood, there seemed to be a natural path from directly outside the transmitter building, but this seemed to flow straight down through the site, exactly where our coax went. Of course it was a "great joy" to go down the coax - there was this incredible current flow in the braid of the coax. The voltages generated were absolutely unbelievable. Quite typically, depending on the weather, it was 5 volts peak-to-peak, remembering the video was 1 volt peak-to-peak. Frequently it got to 10 volts peak-to-peak, the noise, when the trams went past. Of course the program-input equipment was absolutely "bog" standard which was designed to handle 1 volt peak-to-peak and not much noise. It couldn't hack the mission. We had to find a way out and I spent about a fortnight trying to dream up ways how we might attack it. Then another fortnight trying to implement my ideas, and thank God they worked. On opening night it was a real Heath Robinson lash-up which was tidied up subsequently, but there was no piece of equipment on the market you could buy to handle that sort of voltage. It was the first ever piece of equipment to have lashed up to deal with the noise at Gore Hill.

Doug - This was done before the installation of the main Studio Technical earth because that didn't take place till about mid 1957.

Bryan - Indeed. The interesting thing was that both the transmitter's earth and the Studio's earth really seemed to have no great beneficial impact. There seemed to be this natural course down our piece of coax regardless. It just seemed to like our piece of coax and that's where it went. It was a ghastly waveform, it wasn't 50 hertz, it wasn't 100 hertz, it was a formidable waveform. The proposed program-input equipment was a standard line-clamp amplifier which at worst would handle about a volt of noise. But the problem there with the line-clamp is that the noise had the clamp worked, is then part of the signal, and you can't subsequently get it out. Over the remaining 60 odd microseconds (following the back-porch clamp), whatever variation there is in there, then it becomes part of the signal, and you can't subsequently extract it. If you're going to get rid of meaningful levels of noise, you've got to do it before you hit a clamp amplifier. The circuit I designed was specifically a noise reduction amplifier with a technique which as far as I know, had never been devised before. I had to think, "How could you do it, how could you possibly get rid of a signal of this level?" I thought of a way of doing it and it worked. Subsequently, and you may find reference to this elsewhere, Neville Thiele used exactly the same technique on his transistorised equipment. I did it with valves. Your basic problem is you have to find some way to divide the noise, and it is really very simple, when you get the message. (Draws a circuit) It needs to be a pentode and the equation is RL + RA + (u + 1)RK . Now RA + (u + 1)RK you can make astronomically high. And you can make RL very low. The secret of doing it is to have the "earth" end at the far end ground i.e. the Master Control end. The anode side (the power supply) side should be at the transmitter ground. The 250 volt power supply was very highly stabilised and so it turned out to be a straight potential divider. The RL was 1K ohm and because I left the cathode resistor un-bypassed, it looked to be around 10 Meg-ohms. The division was astronomical. It looked an impossible problem. It had never been struck before, nobody had previously had a situation like this where they had this very long length of coaxial cable, on a path that had a very large noise current. You often have reasonable lengths of coax, but in benign environments. You couldn't have had a less benign environment than this. No one had thought about it. This now only takes about 10 seconds to recall, but it took me about a couple of weeks to think how we might do it. And then a couple of weeks to build it, and make it work. On November the 5th it was very Heath Robinson-ish, a month later it was a very nice looking piece of equipment. We were really under pressure to have something up and running for Opening Night.

Bryan - The liaison between the Marconi guys and our guys and your guys was fantastic and with Channel 7. We were all scratching. We were pushing everything to the limit. No time off as always. The information flow was fantastic. The cooperation was fantastic. We all had problems, and they were different, but by pooling the knowledge, we got each other out of trouble.

Doug - When did the first test pattern go to air?

Bryan - It came from a monoscope. At the outside it would have been a month before November 5th. Everything was temporary. We had no aerial system other than "Little Toot" which comprised a couple of bat-wings on top of "Little Toot" approximately 160 feet high

Bryan - As I found problems and solved them in Sydney, they used to fly me down to Melbourne and I used to fix the things down there as I'd fixed up here. When they recruited me in 1955, I was doing a second Degree at Southampton. They had a recruiting team from Australia House, and they went around all the UK Universities. I was doing an Honours Degree in Electronics at Southampton University (first Chair in Electronics in the World) and they said that Australia wanted Engineers and asked was I interested in coming. I said "Yes I am, but what work is available?" They gave me a straight long list of Telephony, and I said " I not interested - it's of no consequence to me at all. All I've been doing here is digital, time-domain technology. The nearest you'll get because I've read it in the literature, is you're going to get television". They said "Yeah, but the Government can't decide when we're going to get television. If we get it will be for the Olympic Games, but no decision has been made". So I said "I'll tell you what, if you can guarantee that I can work on the installation of these television transmitters, and can be headquartered in Sydney, then I will come". The next thing I knew was that I received a telephone call to say, "Do you want the job? The decision's made," I came out on the Orion. And I operated out of Sydney. Once the decision was made for the BAPH States, Vern Kenna obviously wanted me down in Melbourne, so I went to Melbourne. A lot of people didn't like Vern but I found him to be a magnificent guy - a pragmatist. If there was a difficult decision to be made, Vern knew how to think about it and make it work. And he made it, would stick with it and would argue with anyone who chose to argue.

I'll tell you something that amazes me about the Gore Hill installation. It amazes me that we're able to use some of the equipment that we are at the North Shore Hospital. If you go up into the Cardiac Department, with which I have had an association, when I go up there and look out of their windows, we're looking right into the antenna. It amazes me, they've got all this fantastic equipment, which measures infinitely small signals, and they've managed to keep the rf out. It just amazes me. I think there has to be some shielding, some of this kit just couldn't work without it. The signal levels are ghastly.

Doug - I haven't got the chronology right about your career movements.

Bryan - I was recruited in 1955, and came to Australia to the PMG to Sydney in 1956. The PMG had booked 2 First Class passages. At that time I didn't have a wife - we weren't going to get married until September or October (1956). My fiancée was very brave because we had 10 days notice of the ship sailing (Orion). The bridesmaids were from all over the UK. 10 days later we were married and on the 11th day we were on the boat. We arrived in Sydney and stayed at Gore Hill until we'd totally finished the installation at Gore Hill.


Other thoughts:
Maurie Menier (on the Marconi Installation Team in 1956 at Gore Hill) was an ex BBC transmitter guy.

The nominal 20kW (18kW) transmitter at Gore Hill was high-level modulated. The 6166 final tubes had a video swing peak-to-peak of 360 volts. We used that tube in the subsequent building of Australian made AWA transmitters.

 

Bryan Madeley obtained his engineering qualifications in England. His involvement at Gore Hill started in 1956 when Bryan was Group Engineer Television with the PMG. During his career Bryan had various engineering positions with PMG, ABC, AWA, OTC and Department of Defence.When he retired in 1992 he was Chief Engineer of SBS.

 

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