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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's prominent feature is the 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.


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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 area 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 higher-powered transmitter, 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 306 metre (1000-ft) mast for the station in order to achieve the aerial height objective.

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

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 Presely-dependent sites at Bala (via Moel-y-Parc), Ffestiniog (via Arfon), Llandovery and Llandrindod Wells (via Llandovery).

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 serviceable condition and were consequently being donated to hospitals for use in chemotherapy treatment.

TELEVISION HISTORY - UHF

Following the completion of the six UHF main stations across Wales in 1973, Arfon was added to the UHF relay station network in October 1975.

It had originally been scheduled for Arfon to become a UHF main station as part of the initial proposal for sixty-four main or higher powered sites across the UK, but this was eventually scaled back to fifty-one.

Once its UHF relay-only status was confirmed, it was initially scheduled as a dependent of Blaenplwyf but this was later changed to Llanddona.

DIGITAL SWITCHOVER (DSO)

Upon Digital Switchover, completed on 18 November 2009, Arfon remained a dependent of Llanddona.

Notably, the Effective Radiated Power (e.r.p) of transmissions at Arfon changed at DSO from 3.6kW to 2.0kW, essentially a power increase based on the standard analogue-to-DSO power ratio of 5:1, which in this instance would normally have produced a post-DSO e.r.p of 720 Watts.

 

700MHz CLEARANCE

Another unusual development at Arfon was the addition of three extra channels upon 700MHz clearance within the Llanddona transmitter group, allowing the provision of a higher-powered transmission to the north of the service area rated at 8kW e.r.p.

(Details in the Station Information table at the bottom of the page).

This resulted in the administrative renaming of the station to Arfon (South) and Arfon (North) with respective transmitter numbers for each service replacing the original single UHF number.

(See table immediately below).

 

SITE NUMBERING

The actual and proposed usage of Arfon has resulted in an extended allocation of site numbers, a summary of which follows -

 

 

 

SITE NUMBER

PERIOD ACTIVE

FUNCTION

29.1

1962-1984

Original VHF Band III relay station number - dependent of Presely (Station 29.0)

14400

 Tentative only

UHF main station - CANCELLED

13503

 Tentative only

UHF relay station of Blaenplwyf - CANCELLED

11806

1975-2018

UHF relay station of Llanddona until 700MHz clearance

11898

2018 - Current

UHF relay station of Llanddona post 700MHz clearance (Arfon South)

11899

2018 - Current

UHF relay station of Llanddona post 700MHz clearance (Arfon North)

 

 

 


 

 

 

 

 

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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:

11898/99

(+) 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)

 

 

 

 

 

 

 

 

 

Mux

: Ch/Polarisation/e.r.p

 

 

 Service:

(MHz)

(e.r.p)

PSB1 (S)

: 41 / V / 2kW 

 

 

Classic FM :

100.7

18.75kW

PSB2 (S)

: 44 / V / 2kW 

 

 

Capital FM (Cymru):

103.0

5kW

PSB3 (S)

: 47 / V / 2kW

 

 

Heart FM (North Wales):

107.2

3.125kW

 

 

 

 

 

 

 

PSB1 (N)

: 29 / V / 8kW

 

 

 Digital Radio

PSB2 (N)

: 31 / V / 8kW

 

 

 

PSB3 (N)

: 37 / V / 8kW

 

 

BBC National (Block 12B)

 

 

 

 

Digital One (Block 11D)

(S)= Arfon South

 

 

 North West Wales (Block 10D)

(N)= Arfon North  

 

 

 

 

 

 

 

 

 

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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