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Saffron Green transmitting station

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Saffron Green
Saffron Green transmitting station is located in HertfordshireSaffron Green transmitting stationSaffron Green transmitting station (Hertfordshire)
LocationHertfordshire
Mast height71.3 metres (234 ft)
Coordinates51°39′55.8″N 0°14′31.2″W / 51.665500°N 0.242000°W / 51.665500; -0.242000
Grid referenceTQ216977
BuiltMarch 1975

Saffron Green transmitting station is a facility for medium wave broadcasting near Saffron Green Meadows in Hertfordshire, 19km north-west of London. It was built by the Independent Broadcasting Authority in March 1975 to transmit two Independent Local Radio stations - Capital Radio and LBC. An earlier medium wave transmitting station is Brookmans Park, also in Hertfordshire and built by the BBC in the 1920s. The last station broadcasting from this site stopped in October 2024 and the future of the site is unknown.

Until the 1970s the BBC had a monopoly on radio broadcasting in the UK, with the exception of pirate stations and Radio Luxembourg. This changed in 1972 with the Sound Broadcasting Act and the IBA let two contracts for commercial radio in London, one for "news and information" and one for "general and entertainment". The news and information contract went to London Broadcasting Company (LBC) which started broadcasting on 8 October 1973; the entertainment contract was won by Capital Radio which started broadcasting on 16 October 1973.

Engineering

All ILR stations were allocated an FM frequency and a MW frequency which had to broadcast the same material. Both stations launched using temporary MW transmitters and a T-antenna strung between the chimneys at Lots Road, a power station in Chelsea used by London Underground. The IBA struggled to get planning permission for the permanent station but after appealing, planning permission was granted in 1972, allowing the station to open in 1975.

The station was designed to operate without staffing and monitoring of the output was done by the radio station, error codes were transmitted on a 4.7 kHz subcarrier which were picked up by remote monitoring but were too quiet to be audible. There were two input feeds - one was a single Tariff M music circuit from the studio, and provided by the Post Office. The back up was the feed from the FM transmitter.

The MW frequencies allocated to the two stations were 1546 kHz and 1151 kHz, shared with other stations in the UK. In order to avoid interference the new station needed to use a tower array directional antenna so that the broadcasts were focused on London rather than interfering with other transmissions such as 1546 kHz in Bristol and 1151 kHz in Birmingham.

Saffron Green has a line of four mast radiators 71 m tall and 61 m apart at an angle of 161° ETN . Buried 30–45 cm underneath each mast there is an earth mat of copper wire. The site had seven Marconi B6029 transmitters running at a power of 10 kW, 5 main and 2 standby.

On 1 July 1985 there was a fire in the LBC reserve transmitter which took out both services over night. Services were restored next day, although the reserve transmitter needed to be replaced. In September 2020 one of the masts in the array was struck by lightning which damaged the antenna tuning unit. Since then the reserve antenna, a wire from one of the masts, has been in use instead.

Transmissions

In 1987 the IBA required stations to stop simulcasting on AM and FM and to provide different services. Capital radio split into Capital FM and Capital Gold, an oldies station. In 2007 Capital Gold was merged with Classic Gold to produce Gold, a similar oldies station. Gold stopped broadcasting on MW in London on 29 September 2023, as part of a move by owners Global to stop using medium wave. It remains on DAB.

LBC has a complicated history of takeovers and renames. It remained broadcasting on medium wave until 30 October 2024. It remains on DAB and in London on FM 97.3.

Frequency Power Service
1151 kHz until Nov 1978

1152 kHz

5.5kW transmitter power
23.5kW maximum EMRP 		LBC (1975–1989)

London Talkback Radio (1989–1994)
London News Talk 1152 (1994–1995)
LBC News 1152 (1996–2015)
LBC London News (2015–2019)
LBC News (2019-30 October 2024)

1546 kHz until Nov 1978

1548 kHz

27.5kW transmitter power
97.5kW maximum EMRP 		Capital Radio (1975–1988)

Capital Gold (1988–2007)
Gold (2007-29 September 2023)

References

  1. ^ "Saffron Green". tx.mb21.co.uk. Archived from the original on 30 November 2024. Retrieved 17 November 2024.
  2. ^ Ford, E T (June 1981). Lovell, John (ed.). "A dual-frequency, highly-directional MF aerial for IRL London". IBA Technical Review (14: Latest Developments in Sound Broadcasting). Winchester: IBA: 44–47. ISSN 0308-423X. Archived from the original on 17 April 2024. Retrieved 28 November 2024.
  3. ^ Martin, Roy (18 October 2024). "LBC News to vacate 1152 AM frequency in London". RadioToday. Archived from the original on 27 November 2024. Retrieved 18 November 2024.
  4. BFI researchers' guide - legislation. Retrieved 4 January 2006
  5. Croston, Eric (Ed.) Television and Radio 1985 - Guide to Independent Broadcasting Independent Broadcasting Authority, London 1984.
  6. "LBC Turns 46! Hear Our Very First Broadcast From 1973". LBC. Archived from the original on 15 July 2024. Retrieved 18 November 2024.
  7. "1973: Commercial radio joins UK airwaves". BBC. 8 October 1973. Archived from the original on 8 October 2015. Retrieved 18 November 2024.
  8. "Isn't it good to know…. Capital Radio". RadioToday. 16 October 2013. Retrieved 18 November 2024.
  9. "No date named for London ILR frequency change". Broadcast. No. 769. 22 July 1974.
  10. Wise, F H (September 1974). "The Engineering Planning of Independent Local Radio". IBA Technical Review 5: Independent Local Radio. Independent Broadcasting Authority. p. 10. Archived from the original on 17 April 2024. Retrieved 18 November 2024.
  11. Dunn, Peter (4 March 1973). "A towering blot in the Green Belt". The Sunday Times. Archived from the original on 11 August 2023. Retrieved 25 November 2024.
  12. ^ Chambers, D S (September 1974). "Independent Local Radio Transmitting Stations". IBA Technical Review 5: Independent Local Radio. Independent Broadcasting Authority. p. 13. Archived from the original on 17 April 2024. Retrieved 18 November 2024.
  13. Porter, Dave (August 2020). "Tricks of the Trade" (PDF). Signal (56): 39–42. Retrieved 17 November 2024.
  14. Porter, Dave (November 2020). "Tricks of the Trade" (PDF). Signal (57): 17–21. Archived (PDF) from the original on 17 October 2021. Retrieved 18 November 2024.
  15. ^ "IBA Engineering Announcements - 9 July 1985 'London ILR Update'". YouTube. 26 November 2017. Archived from the original on 30 November 2024. Retrieved 18 November 2024.
  16. Martin, Roy (14 August 2023). "Gold to lose its London 1548 frequency ahead of 50th anniversary". RadioToday. Archived from the original on 29 January 2024. Retrieved 18 November 2024.

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