Out with the Old, In With The New
It’s not every day a radio station gets a new transmitters, let alone a complete new tower and antenna array at the same time.
We caught up with Matt Paton – Chief Engineer – Radio – Northern Queensland for the low down on the project that saw both HOT FM and 4TO FM in Townsville get themselves a whole new Air chain.
So it’s not very often as a Chief Engineer you get to put in a completely new tower and antenna but you had some extra legwork to do as well?
That’s right Blair, our building at Mt Stuart was the original TNQ7 studio and transmission complex. The first floor area where our transmitters were, was a rabbit warren with equipment spread out over three small rooms. We took the opportunity to relocate our transmitters down into what was Studio 2 (later the analog TV transmitter room) which is essentially a large concrete bunker. This gave us the space to install all our equipment neatly into one room, and due to the better floorplan, we were able to simplify the RF plumbing, reusing all our existing copper feeders.
The Tower and antennae array for Hot and 4TO FM in Townsville… they are up top of Mt Stuart… that’s a bit of climb up from memory?
Mt Stuart is 584 meters high. Our FM tower is 65 meters high, with our FM antenna at the top. I’m scared of heights, so I stuck to the ground.
What was the main reasons for making a move – the old gear was had it?
The catalyst for the project was the replacement of our old broadcast tower and parts of the antenna. Due to the constant sea breeze over the tower, and possibly due to close proximity to a concrete plant for many years, the old tower had corroded beyond repair. It had large hollow legs, which filled with salty water and rusted through from the inside out. The antenna was also made of galvanised steel which had rusted terribly over its 23 year life so we decided to replace the tower and antenna (we re-used the power dividers and feeders).
We had had a lot of problems with the old BE FM20B transmitters that had been cooled by sucking humid outside air through them, causing a lot of corrosion – during the wet season the top of the mountain can be in the clouds for days at a time, which isn’t great for electronics. Over the last 2 years they became increasingly unreliable, so we decided to replace them with Nautel NV20LT solid state transmitters. These were installed in the new transmitter hall in a closed-loop air conditioned environment.
We retained our standby transmitters (BE FM2C) and audio processors, but re-built the rest of the PIE racks with new equipment, running AES audio from the studios, all the way into the transmitters.
And you would also need to factor in Cyclonic weather right?
In Cyclone Yasi our 30 year old generator blew up which took our stations off the air. We were able to rely on the AM service until we could get power back on to the site. We learned a lot from that disaster and have put some good measures in place – we replaced the generator, added extra redundant audio links and installed a low power backup transmitter on the link pole at our TV office. This covers the main population of Townsville so if there are problems with Mt Stuart we can remotely fire this up. We have also put a two way interconnect between the SCA generator and the Grant Broadcasters generator, so we can each back the other up should there be a disaster in the future and one of our generators fails.
When did you start mapping out the project?
Preliminary works began in November 2014 when we issued the order for the new mast. Design and construction took about 6 months. Installation took 8 weeks on site, including the removal of the old mast. While this was going on, I did a complete set of drawings and documentation for the new transmitter and PIE installation before we began the installation.
This is not something you just go and buy off the shelf…
No, broadcast equipment tends to be pretty specialised, so there’s not many people who do it. The mast was supplied and installed by Future Engineering who are based in Perth. The mast was built out of solid steel segments and shipped over on a truck. They then assembled it like a giant meccano set on site into three sections that they then craned into place over a two day period. Future also beefed up all the old guy anchor points and installed new guy ropes as part of the project.
The antenna was manufactured in Melbourne by RFS. This model has stainless steel dipoles with galvanised reflectors.
The new transmitters came from Nautel in Canada via sea freight (8 weeks) into Adelaide as a bulk SCA order, then shipped via road to Townsville.
We used new Deva DB8008 program switching units from Bulgaria (I found these at the Agile Broadcast stand at SMPTE), TJH Systems transmitter controllers and Kingfisher RTU’s for remote control.
It would have cost a fair amount of coin?
Yes, it was a significant investment in the Townsville market, which shows the confidence that SCA has in its regional operations.
Steps us through how it all worked out.
The mast change was the first part of the project. Keeping the stations on air while removing the antenna and mast is generally a bit of a challenge. Thankfully back in the late 90’s, Steve Adler and Jim Vasey (dmg and RG Capital radio at the time) decided it would be a good idea to put some cross-connect RF plumbing between each company’s antenna systems. This allows any of us to patch our transmitters into the other stations’ antenna, on the adjacent tower. We utilised this to stay on air while our mast and antenna was replaced.
Once the new mast and antenna were in place, we embarked on a four week long project to relocate into the ground floor of the building. Firstly we installed stacks of unistrut and cable trays into the room, then installed the Nautel transmitters and built the PIE racks in the new area.
We then needed to liberate our combiner system that is used to feed both HOTFM and 4TOFM into the single antenna, so we borrowed a couple of Nautel VS2.5 low power transmitters from elsewhere in SCA, and put one to air direct on our new antenna, and the other to air direct into the Grant Broadcasters combiner system. We then moved and reassembled our combiner and all the associated RF plumbing into the new area. Once we had that in place, and the new Nautel transmitters were plumbed into the SCA combiners, we cut across to our new transmitters and antenna system.
Who was part of the team build?
Shane Geary led a team of riggers from Future Engineering who did the mast replacement. Trevor Harwood and Frank Mancini did the installation of the mechanical components and Nautel transmitters and I built the PIE racks. We also had assistance from John Hawkins, Brett Mulhall, Russell Fox and Andrew Young from our TV engineering department with working on feeders, switchboards, some cable runs etc.