thebigtower


arfon

 


THE ARFON TRANSMITTING STATION is situated at Nebo in North-West Wales and provides UHF, FM and DAB coverage to a coastal part of the area based principally around the town of Porthmadog.

The station is notable for its use of a 317.4 metre (1041-ft) UHF-aerial-inclusive mast, the tallest man-made structure in Wales. Despite this, the station has for the purpose of television transmission only ever functioned as a relay, originally supporting the Presely transmitter in respect of the ITV 405-line VHF service and currently the Llanddona main station in respect of UHF.

The mast is one of seven lattice stayed structures based around a height of 306 metres (1000-ft) that were constructed by the Independent Television Authority (ITA), the other structures being sited at Black Hill, Caldbeck, Durris, Lichfield, Mendlesham and Strabane.

DIGITAL SWITCHOVER

As part of the Llanddona transmitter group, Arfon completed the Digital Switchover process on 18 November 2009.

Re-engineering works at the station included the deployment of a new six-tier main UHF aerial, replacing a slightly shorter aerial which was also a six-tier multi-panel installation.  (See Aerials for images of the current arrangement).

As with all other relays within the Llanddona transmitter group, Arfon carries only the PSB multiplexes as the parent main station is the sole provider of COM multiplex transmission.


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TELEVISION HISTORY - VHF

The Arfon station was built by the Independent Television Authority (ITA) as the first and principal of five relays that supported the main 405-line VHF Band III transmitter at Presely in Pembrokeshire.

The opening of Presely on 14 September 1962 formally marked the extension of ITV coverage into West and North Wales, at the time a separate franchise to the South Wales and West region as served by the St Hilary transmitter near Cardiff.  However, this service expansion also required transmitters in both the north-west and north-east of Wales to cover the whole area.

Whilst North-East Wales would need a high-power transmitter of its own, the north-west required a smaller station to pick-up the signal from Presely and re-broadcast it both north and south over the higher terrain alongside the North-West Wales coastline and across Anglesey.

With these coverage parameters, the effectiveness of the station would be contingent on a transmitting aerial height of close to 2000-ft (610 metres) above sea level.  Having found an available site grounded at 951-ft (290 metres), just south of the village of Nebo, the ITA designated a 1000-ft mast for the station in order to achieve the aerial height objective.  A structure of this scale at a relay station was a new and costly development, only to be repeated once at Strabane in Northern Ireland, with anticipated future use for UHF likely to have been factored into its justification.

Vision and sound transmitters rated at 500 watts and 125 watts respectively, together with reserve transmitters of matching power were installed.

A directional aerial with an average height of 1904-ft (580 metres) above sea level was provided, radiating the highest Effective Radiated Power (e.r.p) of 10 kilowatts north towards Anglesey and south-west towards Barmouth, whilst 5 kilowatts was directed in-land to the east and south-east and just 2.5 kilowatts to the very small area of coverage lying directly west of the station.

Arfon entered full programme service from 9 November 1962 on VHF Channel 10.  The main station for the north-east of Wales became operational from 28 January 1963 at Moel-y-Parc, to which Arfon provided the programme feed by an off-air link.  This essentially completed the ITV 405-line VHF transmitter network across Wales, allowing for the addition of a number of relays between 1967 and 1970 including four further Presely-dependent sites at Bala, Ffestiniog, Llandovery and Llandrindod Wells.

However, one significant development came on 15 February 1965 with the extension of the Welsh service to South Wales by means of a second transmitting aerial on the St Hilary mast using Channel 7, a consequence of the merger of the two Welsh franchise areas in 1964.

The 405-line VHF service from Arfon came to an end during the first week of January 1984.  The Independent Broadcasting Authority (IBA) reported at that time that Arfon was one of number of their later generation stations where power amplifiers were still of a servicable condition and were consequently being donated to hospitals for use in chemotherapy treatment.

TELEVISION HISTORY - UHF

Following the principal roll-out of UHF-Colour across West and North Wales from five UHF main stations in 1973, Arfon was from October 1975 added to the rapidly expanding network of UHF relays supporting the coverage of the main transmitters.

In this capacity the station was associated with the Llanddona UHF main transmitter on Anglesey, fundamentally serving the southern part of its VHF Band III coverage area, with the northern sectors being covered predominantly by the parent station.


 

 

 

 

 

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  STATION INFORMATION


Location:

Bryn-ffynnon, Nebo, Gwynedd, North Wales

Grid Reference:

SX578742

Landlord:

Arqiva (Legacy: ITA/IBA/NTL Broadcast)

Ground Height:

290m

BBC Region:

Wales

Mast Height (+):

308.5m

ITV Region:

Wales

Aerial Height (*):

601m

 

UHF Tx Number:

11806

(+) Main structure height only - height including UHF antenna is 317.4m 

 

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

 

 


  CURRENT TRANSMISSIONS

Digital Television

 

 

Analogue Radio (FM)

 

 

 

 

 

 

 

 

 

Service

: Ch/Polarisation/e.r.p

 

 

 Service:

(MHz)

(e.r.p)

PSB1

: 41 / V / 2kW 

 

 

Classic FM (VP):

100.7

15kW

PSB2

: 44 / V / 2kW 

 

 

Classic FM (HP):

100.7

3.75kW

PSB3

: 47 / V / 2kW

 

 

Heart FM (Cymru):

103.0

2.5kW

COM4

: No service

 

 

Real Radio North Wales:

107.2

2.5kW

COM5

: No service

 

 

 

COM6

: No service  

 

 

Digital Radio

 

 

 

 

 

 

 

 

 

BBC National (Block 12B)

 

 

 

 

 

  Digital One (Block 11D)

 

 

 

 

 

 

PRE-DIGITAL SWITCHOVER UHF TRANSMISSIONS

(Shutdown 18 November 2009)

Analogue Television 

 

 

 

Digital Television

 

 

 

 

 

 

 

 

 

Service

  Ch/Polar/e.r.p

 

 

 

 

Service

 Ch/Polar/e.r.p

BBC1

: 54 / V / 3.6kW

 

 

 

 

 

 

BBC2

: 44 / V / 3.6kW  

 

 

 

 

No pre-DSO service

ITV1

: 41 / V / 3.6kW

 

 

 

 

 

 

S4C

: 47 / V / 3.6kW

 

 

 

 

 

 

Ch5

: No Service

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Llanddona      Moel-y-Parc

 

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