Sunday, February 03, 2013

The Social Sides of BBC Shortwave Senders at OSE10 and OSE8/9

UPDATE Feb 3rd 2013: Brian G3LOX, who lives 2 kms from Rampisham, in the UK confirmed this morning that within the last few days 80% of the towers at the former BBC World Service site in Dorset have been felled, complete with antennas. The building is in a similar state. (see later post on Feb 5th for the video)

I deal with the latest cutting edge technology every day. But I confess I've also become fascinated with the high-powered engineering that was used to beam signals around the world. AM broadcasting is going through it's last phases now, with stations being dismantled. YouTube seems to be capturing quite a lot of "end of era" videos at the moment. So, on the side, I'm collecting stories where I can find them. This one was from Norway earlier this year, the site that used to put out NRK Radio Norway and Radio Denmark.

Dave Porter, who is a senior engineer at the Woofterton shortwave transmitting station, responded to my call out for stories about the other side of international broadcasting. We've seen a lot of coverage by journalists about the exit from Bush House by BBC World Service and the closedown of the radio activities of Radio Nederland Wereldomroep. But the stories about the transmission side of things are often neglected - on the assumption that no-one is really interested. 

Perhaps it's the fact that shortwave transmitter sites are purely operational places and the broadcasters behind the microphone don't really know (or care) how the signal eventually gets to boom out of the radio loudspeaker. Shortwave transmission centres have always fascinated me because the ones I have visited have always been full of stories. Unlike medium or long-wave stations, these transmitters were continually being retuned to other parts of the radio dial as broadcasting stations signed off morning broadcasts to one part of the world and then opened up an evening transmission to somewhere else. This constant hopping around the dial meant there had to be staff on site while they were on the air. 

In the case of the older sites like Wooferton, near Ludlow there were also shifts were aerial engineers had to travel out to the antenna to throw a switch at the right moment, so that the beam of the shortwave signal went in the right direction. Since a lot of this had to be done in the early morning hours (with broadcasts towards the Soviet Union), there are amazing stories of bravery on stormy evenings or when thick fog descended on the place. 

Changing the beam by hand. If only listeners knew.
Dave pointed me in the direction of an excellent write up by Jeff Cant of the first 50 years of Wooferton. It's over 60 pages - and indeed it is exactly what it says in the title. It's not just the engineering side of things. It's the social side too, with all the fascinating collections of stories explaining what went right and wrong - and the characters that ran the place. I'm sure that many people who relied on those operational engineers to get the signal out had no idea of the efforts being made at the transmitter site itself. Jeff has done a brilliant job in giving us the insight to a profession which largely goes unrecorded. The story starts with the decision by the UK Ministry of Information to treble its efforts in external broadcasting. The BBC translated that into a plan for 18 new transmitters, most of which were manufactured in the US and sent over on ships. Wooferton was chosen as the site for because it has excellent ground conductivity (wet marshy land) and was halfway between a transmitter site in Cumbria (Skelton) and Rampisham in Dorset. I didn't know about the early BBC nomenclature of calling shortwave transmitting station an "Overseas Station Extension". 

Work at such a station can often be a stressful job, because when things go wrong there's huge pressure to fix it fast. Equipment was designed for an operational lifetime of around 20 years - but in many cases that was extended by modifications done on site. And the stories of explosions, fires and flashovers indicate that when a sender goes bang, it's often a lot of work to repair the damage. 

Lawrence Ivan, the first Engineer in Charge
at Wooferton was a really tough manager
Dave Porter has also written a series of articles for the Vintage and Military Amateur Radio Society bulletins and some, pertaining to BBC operations and history, have been reposted onto the same site. There are more articles including a link to Practical Wireless and SW Magazine articles that were published around the 60th anniversary in 2003. 

It seems that staff at the Skelton have updated a series of articles about that famous transmitting site and that's also on line. It was originally written by G P Lowery in 1990 and contains a fascinating section about challenges facing engineers at the time. I remember visiting the site in 1979, getting their by moped while studying at Durham University - I must have been mad. But that's another story. Here's a quote from the article.

In 1939, Mr MacLarty, O.B.E., was co-author of a paper referring to the “Empire Broadcasting Station” at Daventry. Some of the subjects discussed therein obviously had an effect on the thinking which went into the planning of Skelton, the construction commencing some three years later. By 1940 the short wave service to Europe had been established but the number of languages involved meant that transmissions in each were comparatively short. It was decided to build a new transmitting station capable of radiating on eighteen frequencies at the same time. This would help to combat the jamming already being used by transmitting each programme on a number of frequencies. The use of highly directional aerial arrays would enable field strength to be increased in the target area. It was necessary to cover Europe from Norway to Greece twenty four hours a day which implied the use of short waves. Considering what we take for granted now, it is quite astonishing to read how much trial (and error) was involved, the more so when the latest developments are seen to have a remarkable amount in common with some earlier alternatives.

Anyone who has seen the Skelton A aerial feeder matrix would be astonished to read that the switching of six transmitters to twenty two aerials was regarded as impossible, although it was realised that for long periods a transmitter could be associated with perhaps only four to six aerials. The difference between daily switching and seasonal switching was apparent.
Skelton B in Cumbria

The actual means by which metallic continuity was achieved was the hook and eye with which so many HF engineers are familiar. The transfer of two hooks attached to maybe twelve feet of trailing feeder by use of a soaking wet Ash Pole, at two-o-clock in the morning, half a mile or more from the building whilst being watched by incredulous sheep, is not soon forgotten.

Site, Power, Programme feeds and buildings

Although the perimeter fences were pulled back some years ago, at that time the site covered 750 acres at height of 600 feet above sea level. The site is reasonably flat and programme circuits from London were within easy reach, as were adequate power supplies (not a small consideration - at one time I was told the station was the largest consumer in the area. I believe that at the time the maximum demand was in the order of 4 MVA, a figure which by 1998 was exceeded by over half as much again). The situation also meant that no intended target area was within the skip distance (the minimum range of a radio wave reflector from the ionosphere).
In order to minimise the risk of damage by air attack two stations were erected about one mile apart (0SE 8 & 9). Fifty three aerials were provided, supported on no less than thirty one masts ranging in height from 200 to 325 Feet. 

Rampisham SW Station photographed at sunset by Nigel Mykura. (Creative Commons Licence)

There are some notable ommisions on the BBC site. I can't find anything of a similar nature about Rampisham. There are on-line articles published before the recent closed down of this large BBC shortwave transmission centre. And the stories behind the overseas transmitting sites are also not in one place. I wonder if their stories have been recorded? 

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