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UK Broadcast Transmission |
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THE TRANSMISSION GALLERY
Photos by Bill Wright
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Stein is a village consisting of one very good pub and little else that matters, on the coast of Waternish . Waternish, as every skuleboy kno, is the middle finger of the north-west pointing digits that form the Isle of Skye . Stein is very remote, very quiet, and resembles my conceptualisation of Heaven, with views that take your breath away and a good supply of real ale.
Arriving at Stein I noticed immediately (being a bit sad) that the TV aerials were horizontally polarised, channel group C/D, and pointing north-west. Consulting the mb21 World Atlas of TV Transmitters I found that the nearest possible listed transmitter to the north-west was in Reykjavik. It seemed unlikely that reception at that distance would be possible just above sea level on aerials bought at B&Q, so I scanned the horizon for possible alternative sources of signal. Sure enough, there was a likely looking protuberance on a hill about a quarter of a mile along the coast. "Get yer coat on, lass, there's work to be done for mb21!" I cried.
There was no obvious route to the (hypothetical) transmitter. From the top of the road I could see an aerial poking out from the spiky gorse at the top of a rise on the coastline, but cottages, dense undergrowth, Keep Out notices, and high fences made a close approach seem impossible. Giving Hil the price of a pint I pointed her in the direction of the Stein Inn. "I might be gone some time," I warned her.
"Can I have enough for another pint then?" Not being made of money I ignored this, and set off. Some considerable time later I arrived at the transmitter site, having had to jump a ravine and push through dense gorse.
Stein is half way down a little sea loch, and opposite the village across the water is a huge lump of assorted minerals 314m tall called Beinn Bhreac. [These Gaelic names really upset Word, I'm pleased to say.] Now if Beinn Whatsisname wasn't there Stein would have a lovely view of the Scoval transmitter. But it is, so Stein had a problem - no telly.
At some point in the unknown past someone decided to solve the problem, and a self-help transmitter was installed. It receives from Scovel and transmits on the same channels, but with the opposite polarity. I think this self-help station must have a long history, because the equipment appears to be 'second generation' at least. Even the hinges on the little hut have been replaced due to rust.
The aerial that receives from Scovel is fixed to a length of telegraph pole at the top of the cliff about a hundred yards from the rest of the equipment. The aerial is a vertically polarised 18-element, and it is just far enough along the cliffs to 'see' Scovel around the side of Beinn Bhreac.
Planting the pole and fitting the aerial must have been difficult because the pole is some distance down the steep bank at the top of the cliff. I think the original intention might have been to have the receive aerial far enough down the bank to screen it from the transmit aerial, in order to reduce the chance of the station receiving it's own output. In fact, the two aerials have line-of-site, just, but of course they are of opposite polarity and are facing away from each other.
There's a masthead amplifier, and an intermediate amplifier about halfway along the cable.
The Transmitter Hall at Stein consists of a small breeze block hut which doesn't look weatherproof enough to me.
Inside there are the remains of a previous installation and also the equipment presently in use. The old equipment (on the right hand wall) comprises a Wolsey four-channel filter leveller and two long-obsolete Labgear CM7049 broadband UHF amplifiers. These amplifiers by themselves would not really be able to deliver adequate signal levels to the whole of the target area. The new equipment is altogether more ambitious. The incoming feeder passes through a line power injector (just visible below the old equipment). This powers the masthead and intermediate amplifiers. The signal then goes to a Taylor TCFL4 four channel filter/leveller (centre right, upside down). Next is a four channel filter block holding four single channel pre-amplifiers. The four larger finned objects to the left are single channel Taylor output amplifiers capable of producing about 70dBmV. These feed out via a Taylor filter/combiner (front, slightly to left of centre). Finally the output passes through an old Wolsey test socket. The overall gain of the system will be something in the order of 65dB. There's no channel changing, of course. What comes in goes out. Power appears to be from the large Taylor 14VDC 5A unit near the middle of the picture. Whether the blue PSU and the lethal-looking device on the back wall contribute anything I don't know. Nor do I know how the mains supply gets to such a remote location, or what the '3 in 1' oil is for. I think there ought to be a bottle of beer in there though, for those who have staggered up the hill. The transmission aerial is a four-bay bowtie type. This is a good choice because when these aerials are used for horizontal polarisation they have a very broad forward lobe, ensuring coverage of the whole target area. Incidentally, I saw a self-help scheme some years ago that used this type of aerial, but for vertical polarisation. The target area was 90 degrees across and consisted of cottages widely spread out around the bay. Field strength varied by 20dB from one cottage to the next, thanks to the narrow main lobe and adjacent nulls exhibited by these aerials when used vertically. |
Soon after this page was first published we were delighted to hear from Allan Macdonald: I was quite amazed at the weekend to find pictures of the Stein self help gracing the pages of mb21. I used to live in Stein. I was 18 and built the Tx in it’s first form in 1978. It was one of the first in the country and I had a lot of help from the BBC Engineering Information Service at the beginning but as you quite rightly surmised has evolved a lot over the years.
I became very interested in RF and got my amateur radio licence not long
after. The haphazard nature of the inside came about due the repeated failure of the TCFL 441 filter block which was once home to the final amplifiers. Those amps run really hot. Too hot to touch! I surmised the heat was too much for the 441 so got individual filters and spread the amps out a bit to dissipate the heat. You will note the channel leveller upside down due the having given Taylors the channels in the wrong order! Doh! The tin of 3 in 1 was for the aforementioned rusty hinges and padlock which I had to smash off the last time I was there. |
Back at base (parked in the harbour area) I turned the telly on and pointed my aerial towards the transmitter. Quite frankly, having seen the rather haphazard physical arrangement in the little hut I wasn't expecting to see brilliant reception. In fact the four channels were cleaner than the outputs of many 'official' transmitters in these parts, with no visible faults at all.
At some point in the future analogue TV transmissions will be discontinued in the UK . It will be interesting to see how the great digital change over will affect self-help schemes like the one at Stein. If the four analogue signals are replaced by digital ones on the same channels there shouldn't be too many problems, but there is talk of a wicked plot to steal many of the UHF TV channels and sell them to the highest bidder for other uses. Does this mean that remote transmitters like Scoval will have to be re-channelled, along with all the self-help stations?
Self-help stations need some degree of communal will. Looking around the more remote parts of the UK I see a lot of Sky dishes, and I wonder how many self-help schemes will fall into disuse in the years to come. It seems unlikely that stations needing serious cash to achieve the digital switch will survive the transition.
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