BBC and ITV continued with 405 past any reasonable date for switching them off. Switched off at start of 1985, duplication of services on 625 started in 1969, It would have been cheaper to switch them off some years earlier (perhaps 1980 or so) and give anyone legitimately still watching on 405 a new set.

I don't know the politics of the timing of the 405 switch off. "Granny watching on 405" was surely urban myth. By comparison the digital switchover was done from 2008 to 2013 though DTV had been transmitted as early as 1998. Set top boxes were given free to certain vulnerable and elderly people.

A single low band transmitter covered almost all of northern England, it was Holme Moss channel 2 TX'ing at 100 KW's high up in the Penines, it's signal reached both the north & Irish sea coasts, North Wales & the Eastern coast of Ireland. It's now an FM only TX now but still travels, I can receive BBC radio 2 on 89.3 here in my home near Nottingham & received it in Blackpool last week so it still travels far...

A big problem with low band here was co-channel interference: In summer reception would often be ruined by patterning &/or distorted sound. It'd usually be 625 line TV stations from the European mainland coming in via sporadic E, most of these used negative video modulation & FM sound, the 405 British system used positive modulation & AM sound (Belgium used positive modulation & AM sound for their 625 lines system) & a 405 set couldn't resolve a 625 transmission properly. Received French 819 lines TV a few times with a split picture on UK channel 3, there was no sound though...

This is interesting:
1) That anyone outside of RCA had the resources at the time to build the CY.

And:

2) That there was enough demand to actually bother, given color was barely selling in the US, and PAL was still over the horizon.

In the US, wasn't Zenith the second one to build color tubes?

(Ok, this starting to become serious drift, I guess...)

When you say maker of color CRTs you fail to differentiate whether the CRT was prototype or production...RCA, Zenith, Dumont, CBS, and Philco (I'm probably forgetting others) all had prototypes that were revolutionary in some way or another but when color was standardized LATE in 1953 only 2 OEMs actually made CRTs for production TV as far as I know. They were RCA and CBS.
CBS developed and sold the 15HP22 (basically a 15GP22 with phosphor directly deposited onto the inside of the envelope instead of using a separate phosphor dot plate (RCA later bought the patent from CBS). They also made a 19" version of the 15HP22 for a few months before the 21AXP22 from RCA obsoleted it.
In 1958 when nearly every maker except Motorola had given up on making color sets and simply rebadged RCAs Westinghouse briefly made and recalled a 23" rectangular color with a CBS CRT. That CRT had both purity and convergence design flaws that led to the recall (2 examples are known to survive).

Zenith did not make a consumer market color TV until 1961 and though they had color CRT prototypes in 1954 they didn't gear up to make consumer CRTs until after they entered the consumer market....I have owned early Zenith branded 21FJP22s with an EIA code that indicated that they had been manufactured by RCA.

It would be interesting to know which OEMs produced color CRTs besides RCA in the years 1954-1964... If that data exists and is compiled it would tell you who started when and if any of the original OEMs took a break in the leanest years of color sales.

It is known that Japan had adopted NTSC color by 1960 and made roundy color TV for both their domestic market and export. I wonder if RCA exported enough to supply them or if they made their own plant.

Long before PAL Brittan and parts of europe were experimenting with color after NTSC came into existence. I could see a large tube and set OEM like philips making their own color CRTs on an experimental basis. Philips actually produced a roundy color for both Canada NTSC and european PAL markets, but I believe it used a 21FJP22....It would be interesting to know if they made their own CRT or bought American.

Long before PAL Brittan and parts of europe were experimenting with color after NTSC came into existence. I could see a large tube and set OEM like philips making their own color CRTs on an experimental basis. Philips actually produced a roundy color for both Canada NTSC and european PAL markets, but I believe it used a 21FJP22....It would be interesting to know if they made their own CRT or bought American


I have two Philips TVs with a round color picture tube.
The Philips 21KX100A has a RCA 21FBP22.
The Philips EL-5793 has no numbers on the picture tube. This has a brown connection to the picture tube. According to Philips an AX53-14. I don't know if Philips made this picture tube itself, but someone might recognize this picture tube.


Also two photos of a new RCA 21FBP22, bought in the Netherlands.

The Philips EL5793 http://www.marcelstvmuseum.com/photoalbum85.html
The Philips 21KX100A http://www.marcelstvmuseum.com/photoalbum30.html

That "Philips" 21KX100A is something that I wish me.

Same here. I understand they made an NTSC version for the Canadian market... I've never been to Canada before but I would make the trip for one.

The 21KX100A's in the Netherlands are original NTSC, later converted to PAL, PAL modules were made for it. These TVs are also very rare here in the Netherlands. I've never seen a picture from Canada with this 21KX100A. Maybe a member in Canada knows if these TVs were sold there, maybe under a different model number.

On the photo my 21KX100A in my living room together with an EL3400 video recorder from 1964, is black en white. Picture on tv from DVD player.

I've seen pictures with that V.T.R., but didn't imagine it was that huge!

Another problem with low band TV here in England was car/motor bike ignition interference, because it used positive video modulation & AM sound any interference pulses caused white flashes on the screen & pops & crackles in the sound, this could be quite annoying.... One sunny Sunday afternoon I'd replaced the chain on my Honda 50 motor bike & was riding it up & down the road to bed the chain in & get the tension right. An irate lady came out of her house saying I'd ruined her Sunday afternoon viewing with my interference - oops, I then went on country roads to bed the chain in...

While I was looking for something else, I found this: https://www.transdiffusion.org/2017/...to-625-line-tv
If you people do have time, take a look. From a historically point of view, it's very intresting.
Anyway, did any private tv station broadcasted in V.H.F. band in Great Britain?

All the ITV companies transmitted on VHF high band/band3, only the BBC ever transmitted on the 5 low band/band1 channels..

I've often wondered why ITV didn't use low band/band 1? I'm thinking the London area could have used channel 5 & the north of England reused channel 1 as used by BBC in London as was far enough away from London to avoid co-channel interference. The gap between channels 1 & 2 was quite big because the original channel 1 from Alexandria Palace was double sideband so would have hopefully avoided adjacent channel interference. I suspect the real reason is the BBC took the hump & blocked ITV from using low band/band 1 for political purposes...

But did band 1 was more suitable for long transmision broadcast or why it was so intresting?