Wavescan radio history features 1500 Meters Longwave

1500 Meters Longwave

Part 1 – Before and During World War II

The Wavescan staff does it again .... a new and fascinating feature in radio history. on longwave. Thanks once again to our friends.

Jeff: Unique to Europe, North Africa, and parts of Asia is the use of longwave for AM radio broadcasting.  These days, many former longwave transmitters have been closed down, and the few that remain probably won’t do so for much longer.  But there is still a famous one that’s active in the British Isles, on 

198 kHz.  Ray Robinson has been looking into its history, which will be covered in two parts, this week and next.  Here’s Ray. ...

Ray: Thanks, Jeff.  When I was growing up in London as a young teenager in the 1960’s, one of my prized possessions was a small pocket radio I had been given for my 13th birthday.  I carried it everywhere, and I made good use of the single-piece earphones that came with it.  It was a 6-transistor, two-band model, but the two bands were not AM and FM as you might expect today.  They were medium wave and longwave, as was common in Europe at that time.

Today, the BBC still broadcasts their Radio 4 programming on 198 kHz longwave (as well as on FM and digital), and in fact, since the 1930’s, the BBC has used a high-power transmitter on longwave to achieve near national coverage.  But with the announcement that this will finally be shut down on September 26 this year, I thought it might be interesting to review the British use of longwave for radio broadcasting.

From 1922-1924, the BBC opened no less than nine medium wave stations in cities around the UK, beginning with 2LO in London.  These were all relatively low power – 1.5 kW each – and coverage in many parts of the country was poor to non-existent.

In October 1926, a 25 kW longwave transmitter was inaugurated at Daventry in the English Midlands on 1600 metres, 187.5 kHz, and this filled in a lot of the coverage gaps in central and southern England.  Then on March 9, 1930, a new ‘National Programme’ was launched by the BBC, using the longwave transmitter at Daventry and a new medium wave one at Brookmans Park in Hertfordshire, on the northern outskirts of London.  The National Programme was further extended to the north of England on July 12, 1931, again on medium wave, from a new transmission site high atop the Pennine Mountains, midway between Manchester and Leeds.  Other transmitters were added in central Scotland and Somerset in 1932 and 1933.

But by that time, it was planned that much of the medium wave network could be freed up for regional programming by instead utilizing a single high-power longwave transmitter for the National Programme.  Commercial stations were already heard with good signal strength in central and southern England from both Paris and Luxembourg, and so based on that evidence, it was hoped that a high-powered longwave transmitter somewhere in the heartland of the English Midlands would be able to provide near-nationwide coverage of the UK for the BBC.

The attraction of longwave, and specifically the part of the spectrum from about 150-300 kHz, was that signals could reach long distances by ground wave – up to 700 miles or more – with stable reception unaffected by ionospheric conditions, more or less around the clock.  Longwave was therefore of great interest to national broadcasters, especially in Europe and North Africa, which had large domestic territories to cover.  Unlike shortwave, longwave doesn’t rely on skywave propagation, and so doesn’t have a skip zone, fading, or any other atmospheric challenges.  It behaves much more like medium wave does during the daytime, but it has a much greater range, provided a high-power transmitter is used.  And in the 1930’s with 10 kHz bandwidth, the audio quality was pretty good for the monaural phonograph records of the day.

And so it was that in March 1933, a decision was made to purchase a site three miles northeast of Droitwich in Worcestershire, and the foundations for a transmitter hall there were laid in May.  By November 1933, the plans called for a 150 kW longwave transmitter to be constructed – the maximum power level allowed under the new Lucerne Plan, which was to take effect on January 15, 1934.  The Lucerne Plan was also the first international agreement that assigned frequencies to countries rather than to individual transmitters, and the frequency assigned to Great Britain was 200 kHz, exactly 1500 metres.  On the date the Lucerne Plan went into effect, January 15, 1934, the 150 kW transmitter at Droitwich was still under construction, so the existing 25 kW transmitter at Daventry was moved to the new frequency.  

The callsign 5XX which previously had been used at both Chelmsford and Daventry was also assigned to the new 150 kW longwave transmitter, which began testing on Monday, July 30, 1934, from midnight to 3am, daily except Sundays, after the Daventry transmitter had closed down for the night.  To radiate on the new longwave frequency of 200 kHz, a T-aerial was used, suspended between two 700-foot-high guyed steel lattice masts, standing 590 feet apart.

There was a soft launch of the new transmitter for some programming in the September, but the final cutover with an opening ceremony featuring an overture by the BBC Symphony Orchestra was on Sunday, October 7, 1934.  It’s interesting that this came a full 18 months after the opening of Radio Luxembourg’s all-day longwave broadcasts in English to the UK, which began in March 1933.

On Sunday morning September 3, 1939, the Prime Minister spoke to the nation in a broadcast to inform the people that Britain was now at war with Germany.  However, two days earlier, at 6:55pm on the evening of Friday, September 1, 1939, a message had been received by the B.B.C. from the government ordering all transmitters, including Droitwich, to be closed down and changed over to a pre-arranged wartime broadcasting system.  This involved wavelength changes for all medium wave transmitters so that they could operate in two synchronised groups, to avoid the possibility of them being used for direction finding.  At 8.15 that same evening, the medium wave transmitters returned to service with the Regional and National services now replaced by a single ‘Home Service’.  The medium wave transmitter at Droitwich, 5GB, was now broadcasting on 391 metres instead of 296 metres, and the longwave transmitter there, 5XX, had been closed down indefinitely.

By late 1939, many complaints were being received about the lack of choice and lighter entertainment for people serving in the British Armed Forces, both in the UK and that point, in northern France and the Low Countries.  In response to this, a new channel was formed called the BBC Forces Programme, which was launched on January 7, 1940, initially only from 6-11pm, although it was later extended to an all-day schedule.

The BBC Forces Programme was launched to appeal directly to those members of the armed services during the Phoney War who were mainly sat in barracks with little to do.  Its mixture of drama, comedy, popular music, features, quiz shows and variety was richer and more varied than the former National Programme, although it continued to supply lengthy news bulletins, informational programming and talk shows.

Use of the longwave transmitter, 5XX, resumed on November 16, 1941 with the European Service on 1500 metres, and from then on, coded messages were often sent to the French Resistance via that transmitter.  These were read during normal programmed broadcasts, usually at the end of news bulletins.

However, when American servicemen arrived en masse in 1943 and 1944 in preparation for Operation Overlord – “D-Day” – they found even the BBC Forces Programme to be staid and slow compared with the output of the American networks they were used to.

So, in response to appeals from General Dwight Eisenhower, the BBC abolished their Forces Programme and established the General Forces Programme instead, designed to provide a mixture of content suitable for both American and British servicemen, and also to appeal to the "Home Front", which research had shown wished to listen to the same type of output as the forces, once fighting had broken out.  The General Forces Programme replaced the BBC Forces Programme on February 27, 1944, and the main difference was that now a large number of American network and Canadian Broadcasting Corporation programmes were also included, alongside British programming such as the ‘Forces Favourites’ request show and comedies such as ‘Much Binding in the Marsh’ set in a fictional RAF station.

The General Forces Programme was on the air daily from 6:30am to 11pm, and in addition to the medium wave transmissions, it was also broadcast on the shortwave frequencies of the BBC’s Overseas Service, so it could be heard in North Africa, Italy, the Middle East and the Far East.  But the war in Europe ended on May 8, 1945, and so far as the British home audience was concerned, it was decided to replace the General Forces Programme with a new channel called the BBC Light Programme, and this was inaugurated on July 29, 1945, on 1500 metres longwave.  The General Forces Programme continued to be aired on shortwave only, primarily for forces stationed in the Far East, until December 31, 1946.

And we’ll pick up the story again with the new post-war BBC Light Programme on 1500 metres next week.

(Ray Robinson/Wavescan)