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Old 5th Jan 2016, 11:56 pm   #341
Synchrodyne
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Default Re: 405-Line VHF Aerials 2013 to the present day.

The attached BBC document dated 1964 May shows the Winter Hill channel B12 transmitter as having a service date of 1964 April 20, and at that time, a mean aerial height of 150 ft and a mast height of 450 ft, and an ERP (directional) in the range 0.4 to 10 kW.

As I understand it, the Winter Hill transmitter had a twofold purpose. One, as already noted upthread, was to improve reception in areas not well-served by Holme Moss, and the other was to allow the previous North region to be separated into two, namely Northwest and North. The latter likely would have required higher ERP and less directionality than the former in order to provide reasonably full coverage west of the divide. So did the apparent increase to 125 kW ERP omnidirectional coincide with the regional division, whenever it actually occurred?

A 1971 January BBC list (EID 2001 Issue 20) shows Douglas, Kendal and Morecambe Bay as satellites of Winter Hill (which was by then listed as 125 kW ERP omnidirectional), whereas I think that Douglas at least was originally a satellite of Holme Moss.

Cheers,
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Old 6th Jan 2016, 10:24 am   #342
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Default Re: 405-Line VHF Aerials 2013 to the present day.

In 1964 it would definitely have been on the old mast, another piece of information I have learned. It would appear that there was an increase in power when it went onto the new mast to 35Kw ERP, so as you say did the 125Kw ERP occur due to region split?
Thanks for that.
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Old 6th Jan 2016, 11:05 am   #343
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Default Re: 405-Line VHF Aerials 2013 to the present day.

This BBC document re the UHF aerials at Winter Hill shows the Band 3 ITV and BBC positions on the mast transposed compared with the 1967 document.
Mistake in this 1965 document or a change of plan when the installation was started?
http://downloads.bbc.co.uk/rd/pubs/reports/1965-45.pdf

The split of BBC Look North/North West seems to have occurred in 1968, possibly due to the ITV regions splitting the providers for Lancashire and Yorkshire.
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Old 6th Jan 2016, 11:43 am   #344
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Default Re: 405-Line VHF Aerials 2013 to the present day.

My experience of TV reception in the NW was based upon what I saw (on the screen and on the rooftops) at the time in the 60s/70s. On the Fylde Coast you could see Winter Hill in the far distance and so a piece of 'dry string' would give good Band III (B9 and B12) reception. Whereas, if you went further up the Coast, say to Morecambe Bay, then - on the coast - good reception of VHF and UHF Winter Hill was still possible with small aerials (for example, I saw Antiference brand TC6 aerials in use in Grange-over-Sands). Go inland and you rapidly ran out of micro-volts ! The Morecambe Bay BBC 1 CH B3 relay was a great help here (as seen, for example, in the village of Cartmel which had a good collection (back then) of H-pol Antiference brand B3 'H's).

Further inland in that part of the NW and you met 'desperation' installations - 4 element B2 aerials and double 8 B9 aerials were common.
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Old 6th Jan 2016, 12:52 pm   #345
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Default Re: 405-Line VHF Aerials 2013 to the present day.

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Further inland in that part of the NW and you met 'desperation' installations - 4 element B2 aerials and double 8 B9 aerials were common.
I remember seeing those but never had the pleasure of dealing with that area.

Some of the problems were the big mills in the towns of Bolton and Wigan, no doubt others as well. Get on the opposite side of the mill from the transmitter and it not only ghosts and weak signal but all tbe electrical interference the mills produced.
There were other areas Parbold and Ramsbottom come to mind, depending on which side of the valley in Ramsbottom decided whether it would be ITV from Winter Hill or BBC from Holme Moss that was watchable. This was early 60's before BBC1 from Winter Hill. Parbold only got good reception when they put in the UHF repeater, VHF was always poor.

Frank
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Old 2nd Feb 2016, 6:23 pm   #346
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Default Re: 405-Line VHF Aerials 2013 to the present day.

Having lived here some 15 years I am amazed I didn't spot these before, pretty awful picture I am afraid I will have to try and get closer but was on my way to the dentist so couldn't take the time over this hastily snapped shot, they look pretty old and the top floor of the building looks derelict to me.
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Old 2nd Feb 2016, 11:38 pm   #347
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Default Re: 405-Line VHF Aerials 2013 to the present day.

Re post #320. B1 indeed looks for Crystal Palace ch1 with the horizontal BIII for Anglia tv Mendlesham ch11H which opened on 27/10/59.
BBC Manningtree ch4H opened on 22/05/62 which could explain the Crystal Palace aerial? The installation could date between 1959-1962 therefore!
I would have thought Talconeston ch3H would've been available in that area.
Interestingly Talconeston was in the BBC Midlands region and Manningtree BBC London and South East according to the BBC 1966 book.
Pictures are excellent. The French 819 era is also of great interest. There was a fascinating article by Roger Bunney on receiving ORTF in the UK. Two Telerection BI aerials were employed cut for the vision and sound frequencies. 1971 issues of "Television" I think it was.

Cheers
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Old 5th Feb 2016, 3:58 pm   #348
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Default Re: 405-Line VHF Aerials 2013 to the present day.

Quote from Focus_Diode:

"There was a fascinating article by Roger Bunney on receiving ORTF in the UK. Two Telerection BI aerials were employed cut for the vision and sound frequencies. 1971 issues of "Television" I think it was."

Does anybody have this article in a scanned form?
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Old 5th Feb 2016, 6:13 pm   #349
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Default Re: 405-Line VHF Aerials 2013 to the present day.

And here it is. Scanned as greyscale as the pictures would not come out too well as a black & white scan.

Keith
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Old 6th Feb 2016, 11:18 am   #350
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Default Re: 405-Line VHF Aerials 2013 to the present day.

Excellent article indeed which is to be expected from Roger. I'd forgotten that three Telerection aerials were used! There was a follow up article showing off screen photos of ORTF on 819-lines.
Thanks for the upload Keith.
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Old 6th Feb 2016, 12:54 pm   #351
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Default Re: 405-Line VHF Aerials 2013 to the present day.

Thank you KeithsTV for the scan.

It makes for informative reading. Amongst other things, I've come across the point that some nominally B1 aerials did not cover the sound carrier part of the channel B1 spectrum well. I assumed it was penny-pinching on the part of the manufacturers since other aerials for higher channels out of the same manufacturer's range did cover the spectrum correctly.

Roger's description showed that it was not a "plug and play" installation !
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Old 6th Feb 2016, 1:07 pm   #352
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Default Re: 405-Line VHF Aerials 2013 to the present day.

Quote:
Originally Posted by SteveCG View Post
]Amongst other things, I've come across the point that some nominally B1 aerials did not cover the sound carrier part of the channel B1 spectrum well. I assumed it was penny-pinching on the part of the manufacturers since other aerials for higher channels out of the same manufacturer's range did cover the spectrum correctly.
Part of it was also simple maths: at the bottom end of B1 the 'split' between the sound and vision carriers is a more-significant percentage than at the top end! Designing Yagis that uniformly covered something like a 10% frequency-difference between sound and vision was hard.
As an antenna designer, the higher up the spectrum you go, the less the sound/vision split affects you.
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Old 6th Feb 2016, 1:16 pm   #353
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Default Re: 405-Line VHF Aerials 2013 to the present day.

G6Tanuki,

Agreed. Your point makes me wonder just how well French channel F2 aerials performed?

I remember that a Thorn 405 line-only valve portable had a resistor across its channel B1 biscuit (RF coil) "to flatten its response" - If B1 needed it then F2 would doubly so !
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Old 6th Feb 2016, 2:44 pm   #354
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Default Re: 405-Line VHF Aerials 2013 to the present day.

Does the diameter of the elements affect the bandwidth? Seem to remember something like that. Large enough diameter at 50Mhz though would probably make the aerial impractical for domestic use.
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Old 6th Feb 2016, 2:51 pm   #355
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Default Re: 405-Line VHF Aerials 2013 to the present day.

Fat [or flat] elements can improve the bandwidth, yes - but it's hard enough to get a Yagi perking properly when you're only after a 5% bandwidth, let alone 10%. You have to compromise over the element spacing, so lowering the gain and worsening the sidelobe-exclusion (or at least having different setss of sidelobes at each end of the coverage-range...)
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Old 28th Feb 2016, 10:42 pm   #356
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Default Re: 405-Line VHF Aerials 2013 to the present day.

I noticed this today just off the A4312 (Oxford Road, Swindon) - a horizontal B1 antenna (channel 3) that clearly dates from the time of the Swindon 405-line relay. Picture is from Google Streetview.

Note that the pigeon is not a permanent part of the antenna.

Swindon was (is) notorious for flakey TV reception: the W.H.Smith building, along with blocks of flats in Penhill and Walcot, caused bad ghosting - to this day there are local 'infill' transmitters to cope with this.
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Old 28th Feb 2016, 11:39 pm   #357
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Smile Re: 405-Line VHF Aerials 2013 to the present day.

Hi,
The last time I visited the Irish Republic, over twenty years ago, I was travelling south out of Dublin where I saw some impressive aerials in the suburbs, I can't remember if they were VHF or UHF. They were high gain aerials on tall, guyed masts and pointed 'backwards' into large wire mesh 'dishes' to try and capture a signal from across the Irish sea.
No photos. alas.
Cheers, Pete.
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Old 29th Feb 2016, 12:33 am   #358
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Default Re: 405-Line VHF Aerials 2013 to the present day.

Quote:
Originally Posted by G6Tanuki View Post
I noticed this today just off the A4312 (Oxford Road, Swindon) - a horizontal B1 antenna (channel 3) that clearly dates from the time of the Swindon 405-line relay. Picture is from Google Streetview.
Are we sure that's not an FM Band II? It looks a bit small & flimsy for ch B3.
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Old 29th Feb 2016, 9:52 am   #359
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Default Re: 405-Line VHF Aerials 2013 to the present day.

It's aimed in the same direction as the UHF antenna below it - both pointing at the old 405-line local infill TX.

I don't think said infill TX ever radiated any BII FM.
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Old 1st Mar 2016, 3:40 pm   #360
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Default Re: 405-Line VHF Aerials 2013 to the present day.

IMHO it looks like B3. Although i agree it is odd it was not removed when the UHF aerial was installed, perhaps the owner has a Band II tuner connected to it ??

By the way, G6Tanuki - is that a second pigeon just behind the junction box?
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