UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Television Standards Converters, Modulators etc

Notices

Television Standards Converters, Modulators etc Standards converters, modulators anything else for providing signals to vintage televisions.

Closed Thread
 
Thread Tools
Old 11th Aug 2005, 11:09 am   #1
Panrock
Nonode
 
Panrock's Avatar
 
Join Date: Feb 2005
Location: Worcestershire, UK.
Posts: 2,525
Default A tantalising possibility (how the British Heritage Television Project was born)

There's a tantalising bit of news from Stephanie (New York) in another thread about how a commemorative FM broadcast was made in New York on the original frequency of 42.8 MHz.

This got me thinking...I went to the OfCom radio allocations page it appears 'our' old Channel 1 television slot actually is still unused. Nothing substantial there anyway. What a waste!

Would it be at all possible I wonder, for low power Channel 1 405-line television broadcasts to recommence from Alexandra Palace, say for a few hours on say, Sundays? All the programme material radiated might be vintage recordings and well out of copyright. All radiated from a simple dipole strapped to the south side of the mast putting out a few hundred watts? Is this something the BVWS and APTS could discuss with OFCOM?

Reading some of the entries here, there seem to be ample technical skills already present in the BVWS to re-create such a virtual 'London Television Station'. Imagine erecting an 'H' on your chimney once again and tuning in to decent programmes and interludes - with a picture so sharp you can see the lines! (Sadly though here in Sedgeberrow I would be out of range).

I expect there must be sensible reasons why this idea is crazy, but I can't presently think of any. Please enlighten me...
Panrock is offline  
Old 11th Aug 2005, 12:04 pm   #2
stubbyeddy
Pentode
 
stubbyeddy's Avatar
 
Join Date: May 2005
Location: Newtown, Mid Wales, UK.
Posts: 186
Default Re: A tantalising possibility

Sounds like a great idea! I would also be out of range sadly but it would be great to know that 405 line was being broadcast once again here in the UK.

When you think about the idea more deeply its really very important that something like this is taken very seriously indeed. Its of very historical importance as well. I think if you went about it in the right way it would be possible, you really have to play on the fact its of historical importance, part of UK TV history.

But why stop there, how about the 30 line system on the medium wave? We could build our own televisors and the range would be much greater, it would open it up to a much wider audience not just us old TV nuts!
stubbyeddy is offline  
Old 11th Aug 2005, 12:32 pm   #3
Biggles
Rest in Peace
 
Join Date: Feb 2004
Location: Hexham, Northumberland, UK.
Posts: 2,234
Default Re: A tantalising possibility

Surely it would be even better if you could set up a community TV repeater (like they can with the amateur radio licence), so you could actually transmit your own program content, using the 405 line spec, but perhaps using a specially allocated frequency for this purpose. Not sure if you would get a channel allocation in the bands you wanted though. you would probably have to settle for a convertor. Or you could use a 625 line uplink to the repeater with a 405 modulator to rebroadcast on that standard. Probably wouldn't be allowed but it's a thought!

Biggles
Biggles is offline  
Old 11th Aug 2005, 1:23 pm   #4
Dave Moll
Dekatron
 
Dave Moll's Avatar
 
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,118
Default Re: A tantalising possibility

Quote:
Originally Posted by stubbyeddy
But why stop there, how about the 30 line system on the medium wave? We could build our own televisors and the range would be much greater, it would open it up to a much wider audience not just us old TV nuts!
... and until your televisor is up and running, the picture can be viewed by connecting the radio receiver to the sound input of your computer and running the NBTV Viewer or its bigger brother from http://www4.tpgi.com.au/users/gmillard/nbtv.htm.
Dave Moll is offline  
Old 11th Aug 2005, 2:29 pm   #5
Sean Williams
Dekatron
 
Sean Williams's Avatar
 
Join Date: Feb 2005
Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW
Posts: 3,517
Default Re: A tantalising possibility

I for one would be interested in helping this project to get off the ground - There must be an old 405 line tx kicking around somewhere, I do not know too mch about television, but I do play with high power RF at 50mhz......

Any enthusiasm to set up a working party?

Cheers
Sean

Oh, did I mention I am a trustee of the Communications & Electronics museum?
__________________
Engineers make things work and have spare bits when finished
Sean Williams is offline  
Old 11th Aug 2005, 2:36 pm   #6
Panrock
Nonode
 
Panrock's Avatar
 
Join Date: Feb 2005
Location: Worcestershire, UK.
Posts: 2,525
Default Re: A tantalising possibility

As someone who has built a complete 30-line mechanical system I'd be as much in favour of this as anyone. But as I see it, whereas there's no room on MW, there probably is on Band I Channel 1 !

If the BVWS (say) were to run an 'authentic' limited 405-line service, I think it would have to reproduce the original conditions as closely as possible; namely: an appropriate transmitting location, the correct system-A standard and original frequencies. I wonder how much 'ignition interference' we'd pick up nowadays too...

Anything less, and in my book we might as well continue what we're doing now - using closed circuit.

Steve
Panrock is offline  
Old 11th Aug 2005, 2:36 pm   #7
mickjjo
Rest in Peace
 
mickjjo's Avatar
 
Join Date: Jul 2004
Location: Dartford, Kent, UK.
Posts: 1,661
Default Re: A tantalising possibility

Quote:
Originally Posted by Sean Williams
There must be an old 405 line tx kicking around somewhere
Have a word with Gerry Wells, I believe he has one in his garden...... .

Regards, Mick.

Last edited by Dave Moll; 27th Jun 2007 at 10:15 pm. Reason: correct for username change in quote
mickjjo is offline  
Old 11th Aug 2005, 2:38 pm   #8
Panrock
Nonode
 
Panrock's Avatar
 
Join Date: Feb 2005
Location: Worcestershire, UK.
Posts: 2,525
Default Re: A tantalising possibility

Quote:
Originally Posted by Sean Williams
Any enthusiasm to set up a working party?

I'm game... Anybody else ?

Steve

Last edited by Dave Moll; 27th Jun 2007 at 10:15 pm. Reason: correct for username change in quote
Panrock is offline  
Old 11th Aug 2005, 3:01 pm   #9
Sean Williams
Dekatron
 
Sean Williams's Avatar
 
Join Date: Feb 2005
Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW
Posts: 3,517
Default Re: A tantalising possibility

OK,

Thus far we have Steve, and myself, I would think that the BVWS ought to be involved.

We need to tackle this from both ends I feel, We need to gain a sympathetic ear from OFCOM (no mean feat......), and of course if we have some hardware ready to go then that would also be a way forward - Can anyone confirm the existence of an old transmitter (small one please, im thinking no more than 1KW carrier)

Im happy to help out wherever im needed, Perhaps a list of parties interested would be a good start, as several voices are better than one or two.

Hmm, now a steep learning curve for 405 line generation......

What say you 405 enthusiasts?

Sean
__________________
Engineers make things work and have spare bits when finished
Sean Williams is offline  
Old 11th Aug 2005, 3:16 pm   #10
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,193
Default Re: A tantalising possibility

Ofcom regularly grant Restricted Service Licences (RSLs) for limited periods of about a month on both MW AM and VHF FM. These are often granted for the celebration of a notable event in broadcasting history. The MW transmissions generally have quite a large service area, even though they use low power.

I can't see any reason (ha ha) why an RSL shouldn't be granted for a 30 line service on MW, although I understand this requires two frequencies. Sound and vision.

If plenty of publicity was given in advance this might inspire people to build new 30 line mechanical receivers, or bring old ones back into use. I have no doubt that there is PC software to do the same job.

Having checked my Amateur Licence there seems to be no reason why a licensed amateur shouldn't transmit TV pictures using any standard he likes. However fast scan (405 line) transmissions would need to be above 430 Mhz. Probably on 13 or 23 cms. This would need a convertor in front of an existing 405 line set.

How about 30 line transmissions on topband (1.8 - 2 MHz)? There seems to be very little activity there at all these days.

Graham.
Station X is online now  
Old 11th Aug 2005, 3:30 pm   #11
turret_tuner
Retired Dormant Member
 
turret_tuner's Avatar
 
Join Date: Jul 2003
Location: S. W. Midlands, UK.
Posts: 36
Default Re: A tantalising possibility

A tantalising possibility indeed. And what an attractive idea. I haven't looked at Ofcom's site, but is it really true that no-one is actually using any part of the Channel B1 spectrum?

Count me in for moral support and any other support I could realistically give at 100 miles distant from AP. Lets hope for a bumper lift on transmission day! We used to get CP on B1 loud and clear under the right conditions, despite the presence of a fairly local B1 relay at Churchdown Hill (Gloucester/Cheltenham).
turret_tuner is offline  
Old 11th Aug 2005, 3:58 pm   #12
Panrock
Nonode
 
Panrock's Avatar
 
Join Date: Feb 2005
Location: Worcestershire, UK.
Posts: 2,525
Default Re: A tantalising possibility

I live 100 miles away from London too and did receive an emasculated Crystal Palace signal here in the last days, in foggy conditions.

As for 30-lines, I believe NBTVA members already are transmitting occasionally on Sunday morning on one amateur band and recently someone in Australia has even succeeded in transmitting over 100 miles on an optical frequency! Ideally I think any NBTV scheme for MW should originate with them.

Similarly I think it essential that a 405-line television 'service' should be conducted under the auspices of the BVWS, who possess the necessary weight for negotiations with OFTEL and others. Also, such a BVWS working party should certainly include the technical heavyweights from this group (you know who you are !)

To dream on... each Sunday afternoon there might be 2 hours of recorded programme material broadcast from a different decade - from the 30s to the 60s - presented using announcers of appropriate standard and conforming to the theme of each period.

The first thing would be to find out what (if anything) was permissible from OFTEL's point of view and what their conditions and requirements would be. Also we should talk to Alexandra Palace (Harringay Council?/ APTS ?) Then if everybody involved was still giving the green light, we would work out our proposals properly, including programme materials and details of the technical apparatus and room required.

I suppose all the effort would have to be provided for free and this might have to be one of the conditions we stuck to when negotiating with other bodies. Good publicity for them though and a real 'heritage' bonus point.

Steve
Panrock is offline  
Old 11th Aug 2005, 5:09 pm   #13
ppppenguin
Retired Dormant Member
 
ppppenguin's Avatar
 
Join Date: Dec 2003
Location: North London, UK.
Posts: 6,168
Default Re: A tantalising possibility

Gerry Wells definitely has a small VHF TX at his museum. I think it's tuned to channel 3 or 4 so that would need to be fixed. Power output, probably no more than 1kW. I believe it was originally installed in the Isle of Man for the coronation and ended its service lfe as a backup at Sutton Coldfield. It was retrofitted with modernised controls (in the 1960s?) using norbit logic. Looks complete and a plausible project from a technical point of view. As for the legal side??
ppppenguin is offline  
Old 11th Aug 2005, 6:35 pm   #14
turret_tuner
Retired Dormant Member
 
turret_tuner's Avatar
 
Join Date: Jul 2003
Location: S. W. Midlands, UK.
Posts: 36
Default Re: A tantalising possibility

By the time we had got all the necessary approvals for this project we would probably be marking the end of analogue TV broadcasting. How about using the pre-war 5:4 aspect ratio. The perfect antidote to 16:9?
turret_tuner is offline  
Old 11th Aug 2005, 7:07 pm   #15
Panrock
Nonode
 
Panrock's Avatar
 
Join Date: Feb 2005
Location: Worcestershire, UK.
Posts: 2,525
Default Re: A tantalising possibility

I thought actually 2nd November 2006 would be more suitable for the launch of our service; that's precisely 70 years later (a lifetime) than the original!

I've been to the OFCOM site and found this. Coloured red for allocations directly affecting the 7-metre vintage television band, assuming vestigial upper sideband working.

It seems all we have to contend with are "Meteor Burst Data Systems". How vital it is that these must occupy this allocation I don't know, but it doesn't look too problematical...

From: 41.4 MHz To: 48 MHz
Sector: All sectors
Purpose/Licence Class: All Purposes/Licence Classes




Meteor Burst Data Systems 46.4 - 46.4 MHz Open N Open: Licence Exempt Status Details

Meteor Burst Data Systems 46.95 - 46.95 MHz Open N Open: Licence Exempt Status Details

Meteor Burst Data Systems 46.975 - 46.975 MHz Open N Open: Licence Exempt Status Details


Vehicle Paging Alarms 47.4 - 47.4 MHz Open N Open: Licence Exempt Status Details

Cordless Telephone Apparatus (CT1; extended CT1; CT2 and DECT) 47.41875 - 47.43125 MHz Open N Open: Licence Exempt Status Details

Programme Making and Special Events (Fixed Site) 47.55 - 48.8 MHz Open N 1st Come 1st Serve Details

Programme Making and Special Events (Link) 47.55 - 48.8 MHz Open N 1st Come 1st Serve Details

Programme Making and Special Events (Low Power) 47.55 - 48.8 MHz Open N 1st Come 1st Serve Details
Panrock is offline  
Old 11th Aug 2005, 8:04 pm   #16
Photo_Tube
Retired Dormant Member
 
Photo_Tube's Avatar
 
Join Date: Mar 2005
Posts: 118
Default Re: A tantalising possibility

It would be nice to get this up and running for next year as the BVWS celebrates it 30th anniversary. If you could receive the service at Harpenden it would be great to bring a 405 line TV set along. The 30 line-Mw service sounds good as well, would Steve be willing to release constructional details for a 30 line set ?
Photo_Tube is offline  
Old 11th Aug 2005, 8:19 pm   #17
Panrock
Nonode
 
Panrock's Avatar
 
Join Date: Feb 2005
Location: Worcestershire, UK.
Posts: 2,525
Default Re: A tantalising possibility

You never know, perhaps an 'early' opening for the British Vintage Television Service service will have to be arranged for the benefit of the BVWS anniversary, just as happened for 'Radiolympia'.

Come on...there must be some sensible people with their feet firmly on the ground out there who can tell us why we can NOT do this. Otherwise, what are we waiting for?

Re: 30-lines, constructional details and circuitry for a camera and monitor are already available in the NBTVA Handbook (I think this is online too). You can visit the NBTVA here: http://www.nbtv.org/ and some pics of my own outfit (with colour and using larger discs) are here: http://www.radiocraft.co.uk/nbtv1.htm
Panrock is offline  
Old 11th Aug 2005, 8:44 pm   #18
Photo_Tube
Retired Dormant Member
 
Photo_Tube's Avatar
 
Join Date: Mar 2005
Posts: 118
Default Re: A tantalising possibility

Quote:
Originally Posted by Panrock
Re: 30-lines, constructional details and circuitry for a camera and monitor are already available in the NBTVA Handbook (I think this is online too). You can visit the NBTVA here: http://www.nbtv.org/ and some pics of my own outfit (with colour and using larger discs) are here: http://www.radiocraft.co.uk/nbtv1.htm
Thanks for that It would be nice to have a repro mechnical TV for the collection
Photo_Tube is offline  
Old 11th Aug 2005, 9:32 pm   #19
Heatercathodeshort
Dekatron
 
Heatercathodeshort's Avatar
 
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,145
Default Re: A tantalising possibility

As far as I am aware, Channel 1 [45mc/s] is unused by other services. It would be possible to set up a limited transmission rather like local radio does from time to time [Wimbledon Tennis for example] Problem today are JOBS WORTHS that tend to crush anything they don't understand. For the record my modulator output when connected to a simple dipole radiates sufficient RF to allow single channel sets to operate on simple indoor aerials...In the confines of the museum of course..Regards JOHN.
Heatercathodeshort is offline  
Old 11th Aug 2005, 9:32 pm   #20
Sean Williams
Dekatron
 
Sean Williams's Avatar
 
Join Date: Feb 2005
Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW
Posts: 3,517
Default Re: A tantalising possibility

Hi All,

Ok Steve, one grounding aspect wil be that at present OFCOM are selling spectrum space to the highest bidders, with this proposal we would be offering nothing for two spot frequencies in what is effectivley an ISM band now.

We would therefore have to accept the band on a secondary basis - allowing for interference to our service on an unprotected basis - the other edge of this sword will be that we must not interfere with services outside of the uk.....

Jeffrey, I am encouraged to hear of a suitable tx, before we go mad proposing to OFCOM that we want to do this we ought to see if it is technically feasable for us equipment wise.

Of course the good folk at Ally Pally neet an early heads up on this idea as well.

The BVWS would be needing an early input to the idea, as there will likely be some expense in putting the project together - my time is free to whom ever wants it, but there are always costs involved in any project.

If this is to be a BVWS project will this mean that all participants will need to be members?

Lots of questions, and few answers - lets see what we can acheive before alerting the authorities to our plan......

Cheers
Sean
__________________
Engineers make things work and have spare bits when finished
Sean Williams is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 3:48 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.