405 might be coming back (for a day)

Ulsterman 1690 · 04-06-2006 10:26am #1

from Television magazine June 2006 p498

The British heritage television Project and the Alexandra Palace Television Society have approached OFCOM for permission to make a commemorative broadcast marking seventy years of high definition television

.

If permission is recieved the one day broadcast will take place on 2/11/2006 on 405 line Channel 1 From Alexandra Palace in London.

Those of us not living in SE England can still watch via that internet thing. (Not much chance of Sporodic E in November)

Foggy43 · 05-06-2006 9:20pm

Do you mean it will be transmitted on Band 1 VHF?
I can just about remeber those days. Waiting for the TV to 'warm up'

I suppose it will be, if allowed, interesting for those who have kept the old TV's but saying that we are going through change again with LCD and Plasma.

Will modern TV's be able to show this transmisson. I suppose firstly does my TV have a VHF tuner? I must look into that.

L1011 · 05-06-2006 10:54pm

It'll have VHF Band III tuner, thats for sure. Used too commonly to ignore. Band I is used in a number of countries too (including the US, which is rather big to just ignore), but at least one my TVs doesn't support it.

But I doubt any recent TV will actually show 405.

Foggy43 · 05-06-2006 11:40pm

About 15 years ago if you bought a TV in the UK for use in the Republic of Ireland it may not have had a VHF Tuner. You had to buy another piece of equipment to receive Band 1 and 111.
This piece of equipent cost a fortune in Ireland and but was dirt cheap here in the UK. I had one and cannot remember what it was called? At that time I think there was only one UHF Transmitter in the Irish Repuplic and it was Cairn Hill, Longford. Not sure about Clermont Carn.

Current TV's here in the UK do have VHF Tuners and even some LCD and Plasma's have Digital TV tuners built in as standard.

L1011 · 06-06-2006 12:25am

15 years ago was 1991. By 1991 we had:

Cairn Hill
Three Rock Mountain
Clermont Carn
Holywell Hill

And probably at least 40 relays all entirely on UHF.

I have also -never- seen a TV without a Band III VHF tuner because you effectively limit your sales area to.... the UK.

watty · 06-06-2006 8:20am

Most non- UK European TV do 45MHz to 860MHz mostly to allow for analog cable.

I doubt if any TV made in the last 30 years can receive 405 lines. I just junked my old Ferguson a Thorn TX9 chassis 15" set from 1976. It was 625 line only.

The last new 405/625 dual standard sets must have been sold in very early seventies.

I last physically saw a 405 set in 1990 (single standard). It lit up and showed noise. definately 405 lines. It was in a house belonging to a lady who went into a nursing home many years before and the family would not change anything in the house, not even move the furniture.

I havn't seen any TVs / VHS that have band III and don't have band I also. Some older ones don't have Hyperband (cable 270MHz to 460MHz approx).

Lots of UK TVs don't have any VHF.

Any only an old 1950s or 1960s set is really any good for this. AM sound instead of FM, and opposite sense of modulation of picture and 405lines instead of 625line. A modern set even with Band I won't demodulate either sound or video properly and can't sync at the low line frequency.

watty · 06-06-2006 8:26am

A labgear VHF UHF convertor. I had one in 1983 for my 8" TV and portable VHS from UK to work it in Limerick / Clare, this was before Woodcock hill UHF.

Not much price difference if you knew where to buy one.

Ulsterman 1690 · 06-06-2006 10:10am

The plan is to transmit on the old Channel B1 (VHF Band 1) It would only be recievable on some aincent TV sets (some have suggested it might be possible to pick it up on modified tuner cards ????)

These frequencies are allocated to the MoD in the UK but dont appear to be in use however its possible theyre using some kind of spread specturm transmission ?

A lot of people have expressed doubts about whether this project can/will get clearance to use these frequencies

watty · 06-06-2006 11:21am

50MHz to 52MHz is now also legal Amateur Radio / Wireless Experimenter in a lot of Europe, thought the French above 50.2MHz.

Ulsterman 1690 · 06-06-2006 12:20pm

True but Channel B1 is well below that.

SRB · 07-06-2006 1:25am

MYOB wrote:

15 years ago was 1991. By 1991 we had:

I have also -never- seen a TV without a Band III VHF tuner because you effectively limit your sales area to.... the UK.

I've 4 in the house and none have VHF tuners, the newest was bought 5 years ago, the oldest 8, all bought in Belfast.

L1011 · 07-06-2006 7:18am

So how do they expect you to use analogue cable?

watty · 07-06-2006 8:55am

Traditionally UK had almost no cable. They used a set box.
My Dad has Analog + Digital NTL and no VHF tuners.

Ulsterman 1690 · 07-06-2006 10:09am

Some sets sold in the UK have no VHF tuners some do

Why they would leave out a UHF tuner I could never figure out since surely the cost saving (minimal) by doing so is outweighed by the extra costs incurred by having seperate models for the UK and Irish market not to mention lost sales to viewers wanting cable or in parts of NI (and possibly Wales) RTE channels ?

Most newer sets not only have VHF/Hyperband/UHF but can pick up European (5.5 MHz audio) and/or SECAM as well

L1011 · 07-06-2006 5:45pm

I thought NTL Cablevision in the North didn't use a STB for normal channels, ala Chorus, etc?

At least a friend of mine who had it had no STB when I was in his house last.

That said, the ICDG listing for it (years old - Rapture (weekends only) listed, thats the old Sky Analogue config of Rapture, the cheap bastards must not have got a proper cable feed

) has the TV channels numbered but the radio on FM.

watty · 07-06-2006 6:34pm

I havn't examined how it works but he has no VHF and he has a Cable box. They have Sky but NTL to get RTE

Blocked by Cavehill from Clermont Cairn reception

Ulsterman 1690 · 07-06-2006 6:58pm

NTL do use STB's

BBC1/2/UTV/C4 are carried on UHF all other analouge channels (the majority of them encrypted) are Carried on either VHF or Out-Of-Band channels. Channel 5 is transmitted on UHF and VHF for some reason The picture on the VHFchannel is slightly better !

There are also a large number of UK and Irish radio stations transmitted on the FM band along with soundtracks of some TV channels.

I cant for the life of me figure out why they bother with the encrypted analouge channels anymore. Last time I checked there was only £1/month difference between the basic analouge and basic digital packages (plus the encryption on digital is more secure)

L1011 · 07-06-2006 7:20pm

Hrm, might have been a local firm then. I'll ask him, but he doesn't live there anymore (he lives in England now).

I've never got encrypting cable channels either, but it seems to be us, the Germans and the yanks that don't encrypt the basic package - and thats about it.

The Germans generally don't encrypt the basic DVB-C either.

Antenna · 07-06-2006 7:33pm

Ulsterman 1690 wrote:

If permission is recieved the one day broadcast will take place on 2/11/2006 on 405 line Channel 1 From Alexandra Palace in London.

Those of us not living in SE England can still watch via that internet thing. (Not much chance of Sporodic E in November)

It would be fairly low ERP, if it happens at all, so limited coverage of London rather than the SE of England.

I wonder has this group considered putting the 405 line signal on an analogue Satellite transponder for this experiment, surely one on Astra 19.2 East could be used?, either a spare transponder or perhaps during the downtime of one of the existing analogue channels.

Viewers would of course have to build modulators (many 405 line set collectors would have one already), or 'cheat' by interfacing inside the TV set without modulation/demodulation. Not all analogue satellite receivers would be OK for such an experiment (many would mute an 'invalid' signal) , and would have to be modified. The Lidl variety would be OK

L1011 · 07-06-2006 8:01pm

No spare transponders at 19E (seriously), unless you count the one thats currently being unused by that shopping channel that just went bust. It should work fine though, as the transponders are just passive in the whole affair.

lawhec · 08-06-2006 1:38pm

My (limited) knowledge of NTL in Belfast tells me that BBC1, BBC2, UTV, Channel 4 and Five are carried unencrypted on UHF on frequencies E22, E25, E28, E32 and E35 respectively. Remaining channels are encrypted in the VHF and "hyperband" channels which require what is nowadays a rather obselete STB. I "think" the encryption used is simply a sync-suppression system, maybe something similar to the SIS system used by the EBU in their analogue days at Eutelsat 7 deg. East. For obvious reasons I won't explain much more but I have seen the system cracked.

Also I believe NTL have a small cable system in Derry city but its digital offering is not available.

marksi · 10-06-2006 12:08pm

Is this not one of the most pointless comemmorations ever?

Why on earth would you go to a lot of bother to transmit something for one day that no one can receive?

watty · 10-06-2006 1:56pm

Well actually *SOME* people have 100% restored working 405 line totally valved TV sets. Even Image Orthicon 405 Line cameras etc etc.

Not very many though.

If you think the 405 line societies are bad, there are a few MECHANCICAL TV clubs too with US Mechanical TVs as well as the Baird 32 line system.

Thats why in 1937 405Lines was called "high definition" TV.

David Robinson · 01-07-2006 10:01am

Yes, there are quite a few of us crazy enough to play with 405-line sets. Here's a picture of one of my sets, running from a standards converter I built:

KB Majestic

There's plenty of discussion here:

Vintage Radio forum

There is also a Collectable TV Sets category on eBay.

As for this commemorative broadcast, I can't see them getting permission to do it to be honest. It's hard enough in the UK to get a licence for a temporary FM station, and that's for 100kHz bandwidth in a band allocated for radio for one month with typically next to no power. Imagine the difficulty of getting 5MHz bandwidth with kW of power in a band no longer allocated to TV...

Propellerhead · 02-07-2006 12:42am

Well done Sir!

Are you in Ireland or elsewhere? The first television that my family had that I can remember was a dual standard KB (405 Band I/III - 625 Band IV/V) that we got converted in 1974 to run with Irish Band III 625 lines for cable.

My late grandmother in Donegal ran a Ferguson Dual Standard 405/625 ("Piano key Tuner" for UHF/Dual standard automatic switcher 405/625). 405 at its best wasn't bad at all.

David Robinson · 02-07-2006 10:40am

I'm in Nottingham, but it makes no difference - still no 405 transmissions! At the time of shutdown (1985) the idea of 405 sets being collectors' items never occurred to me - my only thought was to get rid of the old technology ASAP and bring in the new.

When hearing about this hobby most people's reaction (well, people of a certain age) is 'can you get the valves?'. The answer is yes, there are plenty of dealers with 'new old stock', but you don't often need to replace them. A valve will generally last the life of the set provided it is not abused by a fault elsewhere. The KB in the photo has all its original valves. The main problem with 1950s sets like these is paper dielectric capacitors, which over the years have all transformed themselves into resistors. Certainly any capacitor with the name 'Hunts' on it is replaced on sight.

The circuit design of the KB is basic but works well, and the build quality both of the cabinet and chassis is superb. KB were very reluctant to go over to PCBs, my set has a 3" square PCB with just 2 valves and the rest of the set is hand wired, as if they didn't trust this new fangled technology but decided to give it a trial.

Subjectively the sharpness of the 405 pictures is surprisingly good, helped no doubt by the quality of modern cameras which even after conversion to 405 will be a lot sharper than the cameras used in the 405 days.

If this London trial does go ahead on Band 1 with high power, I guess I might pick up a trace of it here. It's a pity they're not doing it in summer when the chances of long distance propagation on Band 1 are greater. On Band 2 at the moment I have been picking up Irish channels from Leinster on 89.6, 91.8 and 94.0, and occasionally Kippure on 91.3. At times the Leinster signals are of listenable quality for long periods. I have been checking Band 3 for TV signals, but nothing yet!

watty · 05-07-2006 4:58pm

Sampling theory. A downsampled higher res image reduces moire fringing effects and looks subjectively sharper. So if scanning or using a digital camera, scan at twice the x & y resolution and downsample later is much better!

10000maniacs · 21-07-2006 11:29pm

Our family finally went colour in 1979. But up to that point we depended on the 405 line broadcasts of BBC1 and UTV from the North. (We lived in County Meath)
Interesting point, BBC 2 was never broadcast 1n 405 lines from the North.
RTE stopped broadcasting 405 lines in 1978 which was just as well, because the feed was just a 405 line camera pointing at a 625 line monitor showing RTE in Television Centre Donnybrook and the picture was appalling.
Our TV up to that point was a Ferguson 3652 dual 405/625 with 4 pushbuttons for the 625 line channels and a turret selecter for the 405 channels. Happy days:)

watty · 21-07-2006 11:42pm

BBC2 was only 625 from the beginning. It was never 405 anywhere.

[Deleted User] · 22-07-2006 2:37am

Slightly off topic, but is it true that the first batch of colour sets were fire hazards? I seem to remember hearing people mentioning on-air announcements reminding people to stay in the room for a while after turning the set off in case it overheated! But one of my friends does have a Mitsubishi colour TV from the 1960s/70s and its still working today. UHF only by the way so it was a strange set up to get the former VHF RTÉ relay in the area.

I'd be far too young to remember any of this, 405 was on its death bed when I was born (September 1984).

watty · 22-07-2006 12:31pm

All TV sets are fire hazards. Just recently a TV in Standaby went on fire in friend's kitchen.

If the TV does not have a real on/off switch it should be unplugged at night. Also never near soft furnishings or curtains.

405 might be coming back (for a day)

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