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THE WENVOE TRANSMITTER is the UHF and National FM/DAB main station for Cardiff and South Wales.

It is the site of the first television transmitter in Wales providing the original BBC 405-line VHF service from 1952.  Since 1958, it has shared the vicinity with St Hilary, the site of the first ITV transmitter in Wales.

The current mast entered service in 1986 as replacement for the original structure and then height-extended in 2007 as part of the engineering refurbishment for Digital Switchover.  Through changes such as this and past provision of dual services, the station has featured two masts for several periods in its history.

Although now requiring only one mast on site, it is accompanied by a small self-supporting tower which was built around 2002 for use mainly by commercial tenants.

In view of the mountainous valley range across South Wales, Wenvoe is the most relay-dependent UHF main station in the UK with seventy-five smaller transmitters required to support it.  The density of these relays is such that many of them are within view of each other from neighbouring hills.

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mast Images

 

 

 

 

Aerials

 

 

 

 

DSO Images

 

 

 

 

 

 

 

 

 

 

 

 

 

 


STATION HISTORY

WALES AND WEST OF ENGLAND TELEVISION SERVICE

The BBC constructed the Wenvoe transmitter to extend their 405-line VHF Band I television service to South Wales and the West of England, with provision also for their forthcoming national VHF Band II radio service.

The station was the corporation's fifth permanent television transmission site and also the last of their four provincial high-power faciities, preceded in opening by Sutton Coldfield (December 1949), Holme Moss (October 1951) and Kirk o'Shotts (March 1952).

Combined, these four stations extended coverage beyond the London service area of the Alexandra Palace transmitter to the largest most densely populated regions outside the capital.

Wenvoe was actually the last site the BBC assessed for the Wales/West transmitter, from which they wanted to achieve coverage across Swansea, Cardiff and Bristol including surrounding districts, plus Somerset, North and Central Devon, as well as areas to the east and south-east that would adjoin the coverage of current and future transmitters.

Wenvoe was compared against two sites in Somerset, one in the Brendon Hills (Treborough Common) and the other in the Mendip Hills (Leaze Lane, Blagdon) which themselves were among a larger group of sites that were initially assessed in 1948. 

Both these shortlisted sites and Wenvoe offered similar ranges of coverage but none were considered able to cover the entire area, whilst other issues included the significant overlap with the Sutton Coldfield transmitter and likely overlap with the proposed South Hampshire transmitter (Rowridge) if the Mendip site was used.

Whilst Wenvoe was predicted to be weaker than Brendon Hills across Devon, preventing a full link-up with coverage from the proposed South Devon station (North Hessary Tor), it was on balance considered the best option based on its coverage across the critical arc from Swansea to Bristol and down to Somerset.

It also aligned well with the coverage of adjacent transmitters and furthermore was a suitable location for BBC National FM VHF Band II radio transmission.

Having been selected, Wenvoe adhered to the established design for the 228 metre (750-ft) mast with the now familiar composition of lower triangular-cross section lattice, upper cylindrical Band II aerial slot section and surmounting Band I aerial spine.  The station design and layout also emulated the earlier sites.

The maximum Effective Radiated Power (e.r.p) of transmissions from Wenvoe would be 100kW (Band I) and 120kW (Band II), also standard across all four high-power stations.

The station was originally scheduled to transmit BBC Television on VHF Channel 3, based on the nearest co-channel station being the distant Kirk o'Shotts.  However, the channel allocation plan was revised once construction of further stations was approved, including the adjacent Rowridge transmitter which was assigned Channel 3.  Consequently, the allocation for South Wales and the West was moved to VHF Channel 5 and being no longer co-channel with Kirk o'Shotts also meant that none of the high-powered stations would be co-channel with each other.

Additionally, the intention to synchronise with the high-powered Kirk o'Shotts transmitter to avoid mutual co-channel interference was changed to medium-powered Pontop Pike as this became Wenvoe's nearest significant co-channel equivalent in the north.  

BBC Television entered service from Wenvoe on 15 August 1952, transmitting on Channel 5 vertically polarised and initially operating at reduced power from reserve transmitters rated at 5kW (Vision) and 1.25kW (Sound).

Full power operation commenced on 20 December 1952 when the permanent transmitters entered service.  These were rated at 50kW (Vision) and 12kW (Sound) and once amplified delivered the maxiumum (vision) e.r.p of 100kW.  This was based on the Actual to Effective Power ratio of 1:2 that was standard at the time.

At full power, the transmitter performed better than cautiously predicted although some of the deeper valley areas did stretch the capabilities of VHF Band I propagation.

There was also weak and interference-prone reception around Bristol and Bath (identified during the site tests) that required remediation.  This eventually came on 16 October 1967 with the opening of the Bath relay station.

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Site & Station Plates

 

 

 

 

 

 

 


FM RADIO

The BBC successfully launched national radio on FM in May 1955 from their Wrotham (Kent) transmitter and then proceeded with roll out elsewhere with Wenvoe commencing from 22 Decembr 1955 with the Welsh Home Service, followed by the West of England Home Service and Light Programme (22 December 1956) and the Third Programme (2 March 1959).

Repeating the configuration used at the earlier sites, polarisation was horizontal using four-sided aerials aligned vertically with slots on the lowest eight of the ten cylinder tiers.

 

 


 

WELSH TELEVISION SERVICE (BBC WALES)

Broadcasting on a single frequency to both South Wales and the West of England severely limited the provision of separate regional programmes, particularly in the Welsh language.  This was an issue also affecting the Independent Television Authority (ITA) service from their single channel VHF Band III transmitter at St Hilary, located a few miles west of Wenvoe.

With Band I overcrowded, providing a separate television service for Wales was one of a number of BBC aspirations contingent on additional spectrum, hence the corporation continually pressing the government for access to VHF Band III.

Authorisation eventually came, with the creation of a separate Welsh channel on Band III allowing the existing Wenvoe Band I transmission to focus on the West of England service (as BBC1 post-launch of BBC2).  

There was insufficient space on the existing Wenvoe mast for the Band III antennas so a second mast, 189m (620-ft) in height, was erected close to the existing structure to carry the directional aerials.  

Wenvoe was allocated Channel 13, the highest in Band III, with an e.r.p of 200kW.  Notably this matched the power of the ITA St Hilary Channel 10 transmission, the authority having openly acknowledged that their service performed least favourably across the Welsh valleys.

The BBC were less transparent in such matters so it was not entirely clear how their Band III transmission compared against both Band I and ITA Band III across this area, but any such comparisons needed to factor in the differences in transmitter locations, aerial heights and channel allocation.

Furthermore, the ITA were due to launch their own separate Welsh service from St Hilary, on Channel 7 but limited to 100kW from a lower mounted aerial, so this for certain was at a disadvantage compared to the existing ITA transmission.

The BBC Wales service from Wenvoe commenced on 8 February 1964.  It was then extended to all other BBC-TV transmitter sites in Wales, including Blaenplwyf, Haverfordwest and Llanddona on their existing Band I channels, plus a further BBC VHF Band III transmitter was installed at the ITA site at Moel-y-Parc to serve North-East Wales.

As for relays of Wenvoe Channel 13, several emerged with one in common with St Hilary Channel 7.  This was at Abergavenny which was an ITA site and one of two of theirs (the other being Brecon) required to boost their Channel 7 transmission, this being a possible indicator of how the Band III services from Wenvoe and St Hilary compared.

The BBC service from Abergavenny was on VHF Channel 3(H) and commenced soon after the opening of the station in April 1969.

 


 

 

 

 

 

 

 

 

 

 

 

 

 

The Band I/II mast and Band III mast

 

 

 

The 1986 mast replacing both earlier structures

 


 

625-LINE UHF

When it was agreed the BBC and ITA would site share for UHF, Wenvoe was deemed preferable to St Hilary for delivering these services to South Wales.

For the West of England, the service would come from the new high-power UHF main station at Mendip, located on a site near Wells rather than the Mendip (Blagdon) site originally considered alongside Wenvoe for the Band I station.

This two-site configuration for UHF would succeed the existing dual-services on VHF from both Wenvoe and St Hilary.

BBC2 was the first UHF service and as elsewhere the first to be installed at Wenvoe.  As per other BBC-TV sites upgrading to UHF, this required the removal of the original Band I transmitting aerial from the top of the mast to make way for installation of the cylinder-contained UHF aerial.  

A replacement Band I aerial was provided first and installed around the vacant top two tiers of the cylindrical slot section, reducing the aerial height for the Band I service by 11 metres (35-ft).  This aerial came into service on 8 December 1964, enabling the old Band I aerial removal and UHF aerial installation to proceed.

Transmitting on UHF Channel 51, BBC2 began the inital monochrome service on 12 September 1965 with colour following just under two years later on 2 September 1967.

The maximum e.r.p for these UHF transmissions was 500kW, exemplifying the substantial power increases required in comparison to both Bands I and III, coupled with the reduced service area and increased network of relay stations.  

UHF Colour on BBC1 and ITV began national rollout in November 1969, with BBC1 commencing from Wenvoe on 4 April 1970 (Channel 44) and ITV on 6 April 1970 (Channel 41).

The fourth channel, S4C, was launched across Wales on 1 November 1982 with transmission from Wenvoe on Channel 47.

 

MONITORING OPERATIONS

In April 1978, the BBC opened their Monitoring and Information Centre (MIC) at Wenvoe, from where all BBC transmitters across Wales and South-West England could be remotely monitored in order to identify faults and maintainence issues, with engineers despatched to site if necessary.  This was the second centre to enter service (the first opening at Kirk o'Shotts in 1975) and was of particular significance to South Wales given the number of UHF relay stations it required.

The Independent Broadcasting Authority (IBA) opened their equivalent Regional Operation Centre (ROC) for the area at St Hilary in 1981.

 

405-LINE VHF CLOSURE

The BBC Wales Band III Channel 13 service was a relatively early closure in the phased 405-line VHF shutdown, ceasing transmission in January 1983.

By then, most viewers had switched to UHF Colour, enabled by the large network of UHF relays that had been built across the Welsh valleys to support the signal from Wenvoe.  This included Abergavenny, upgraded to include UHF from 28 September 1973 and ceasing all 405-line transmission in July 1982.   

The main Band I Channel 5 service ended two years later in January 1985 when all remaining 405-line services were closed nationwide, the wider event marking the end of UK television broadcasting in VHF Bands I and III.

 

 

MAST REPLACEMENT

As of January 1985, both the main and secondary (Band III) masts at Wenvoe were still in place, the latter no longer of use and simply requiring removal.

As for the main mast, the BBC used the 405-line closure to embark on a project to modernise their earliest television sites, driven mainly by the upgrade of their National FM radio service to mixed polarised transmission, the dual-component aerials for which were obviously bulkier and also incompatible with the existing cylindrical slot mast section.   

Accordingly, new masts for all services were specified for Wenvoe, Sutton Coldfield and Holme Moss, whilst Kirk o'Shotts had its FM service transferred to nearby Black Hill.

With the redundant Band III mast removed from site first, construction of the new Wenvoe mast commenced alongside the original structure, producing a new combination of dual masts on the local landscape.

Upon completion of the new 225 metre (738-ft) mast, transfer of services was done in two stages, UHF television moving across in 1986 and FM radio the following year.  Soon after, the original 1952 mast was dismantled with the station reverted to a one-mast site for the first time since 1964.

 

DIGITAL SWITCHOVER

In 2007, Wenvoe again became a site with two high masts, albeit temporary and necessitated by major engineering works required for Digital Switchover (DSO).

In addition to the UHF antenna overhaul necessary at all main sites, Wenvoe also required a raise in aerial height.  To facilitate this, a temporary 217.7 metre (714-ft) mast was erected to carry UHF and FM radio transmissions whilst the main mast was extended and re-fitted.

The principal work required was (1) removal of the two-section main analogue UHF aerial cylinder from the top of the mast (2) construction of the mast extension and associated stregthening works (3) installation of the new main and reserve UHF aerials.

Upon completion, the mast was raised to an overall height of 261 metres (856-ft) including the top mounted UHF aerial, an extension of some 20 metres (65-ft) above the summit of the previous UHF cylinder.

The UHF and FM services were transferred back to the mast in 2009 with dismantling of the temporary mast commencing soon after.

At Sutton Coldfield, where the replacement mast built in 1984 was near identical to the 1986 Wenvoe mast, a similar extension project was carried out for Digital Switchover.  

From the extended Wenvoe mast, Digital Switchover commenced with Stage 1 (BBC2 analogue closed/PSB1 Multiplex launched) on 3 March 2010 and completed with Stage 2 (Remaining analogue service closed and all other multiplexes launched) on 31 March 2010.

 

 

 

 

 

 

 

 

 

 

Pre-DSO main UHF aerial

 

The temporary and main mast during DSO work in 2007

 

Post-extension UHF aerials


Mast Images>  Aerials>  DSO Images>  Site & Station Plates


STATION INFORMATION


Location:

Wenvoe, Vale of Glamorgan

Grid Reference:

ST110742

Landlord:

Arqiva (Legacy: BBC/Crown Castle UK/NGW)

Ground Height:

128.0m

BBC Region:

Wales

Mast Height:

260.7m

ITV Region:

Wales

Aerial Height (*):

382m

 

UHF Tx Number:

10600

(*) Average UHF aerial height above sea level (a.o.d)  

 

 


  CURRENT TRANSMISSIONS

Digital Television  

 

Analogue Radio (FM)

 

 

 

 

 

 

 

 

 

Mux

: Ch/Polarisation/e.r.p

 

 

 Service:

(MHz)

(e.r.p)

PSB1

: 41 / H / 100kW 

 

 

BBC Radio 1:

99.5

250kW

PSB2

: 44 / H / 100kW 

 

 

BBC Radio 2:

89.9

250kW

PSB3

: 47 / H / 100kW 

 

 

BBC Radio 3:

92.1

250kW

COM4

: 42 / H / 50kW 

 

 

BBC Radio 4:

94.3

250kW

COM5

: 45 / H / 50kW

BBC Radio Cymru:

96.8

250kW

COM6

: 39 / H / 50kW

 

 

BBC Radio Wales:

103.9

40kW

COM7

: 55 / H / 40.7kW

 

 

Classic FM:

101.7

250kW

LOCAL

: 37 / H / 10kW

 

 

(+) Nation Radio:

106.8

4.54kW

 

 

 

 

 

 

 

 

 

 (+) Nation Radio DAB service from St Hilary

 

 

 

 

 

 

 

 

 

Digital Radio

 

 

 

 

 

 

 

 

 

BBC National (Block 12B)

 

 

 

 

 Digital One (Block 11D)

 

 

 

 

South East Wales (Block 12C)

 

 

 

 

 Sound Digital (Block 11A)

 

 

 

 

 

PRE-DIGITAL SWITCHOVER UHF TRANSMISSIONS

(Shutdown completed 31 March 2010)

Analogue Television 

 

 

 

Digital Television

 

 

 

 

 

 

 

 

 

Service

  Ch/Polar/e.r.p

 

 

 

 

Service

 Ch/Polar/e.r.p

BBC1

: 44 / H / 500kW

 

 

 

 

Mux1

: 30 / H / 10kW

BBC2

: 51 / H / 500kW  

 

 

 

 

Mux2

: 34 / H / 05kW

ITV1

: 41 / H / 500kW 

 

 

 

 

MuxA

: 40 / H / 05kW

S4C

: 47 / H / 500kW

 

 

 

 

MuxB

: 50 / H / 05kW

Ch5

: No Service

 

 

 

 

MuxC

: 53 / H / 05kW

 

 

 

 

 

 

 

MuxD

: 46 / H / 05kW

 

 

 

 

 

 

 

 

 


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