Tech Chat 1975 Ceefax A Communications REVOLUTION?

The very start was outside Kingswood Warren, then the home of BBC R&D.

Sold in 2010 and subdivided into apartments.

Apart from the reduction of electronics with specialist IC’s the introduction of SAW filters made set design much easier for Teletext. Group delay in the IF amps was a problem and careful alignment at the factory was very important. 
The SAW filters took much of that problem away.

Of course, just a short couple of years later, Thorn again with a first, the 3782 with built-in teletext decoder (Tifax module) with Thorn's own in house sophisticated designed interface module, for connectivity to the rest of the TV. All commands available via the Ultrasonic remote.

This is another holy-grail set on my list, if you've got one, and it's up for sale or perhaps a swap, contact me.

Not seen that 3722 test set before but now I know what that square cover with the locking screw on the back of 9000s was for. Entry point for that big bunch of cables to and from that adaptor box, check out the back of your 7773 Chris.

I missed Teletext when it went. To me digital teletext was a classic case where more was less.

The 9600 with teletext using an ulatrasonic remote was updated with an infrared remote.

@jayceebee Yes it was a mixed bag, at least it was easy to flick though multi park pages rather than having to wait for them to turn.

@richardfrommarple Later sets had lots of memory and all pages and even sub pages were stored.Once you had been on the channel for a few minutes and all the pages were in memory there was almost no delay. This was great for scrolling the Teletext Holiday pages, got a deal from them for flights to Florida for just over £100, only thing was out from Manchester return into Gatwick. 

I also believe the Teletext clock was accurate to within 0.25 seconds?

The founder of a video users group I once belonged to had a theory that the tube geometry on Teletext sets was much better than on the non-teletext equivalent, this was especially useful when watching letterboxed movies. Can anyone confirm if that was really the case?

@ntscuser 

I don’t know about later TV’s but the first few years up to 1980/81 they were standard TV’s with the added decoder. 
Some sets also had a few extra “bells and whistles”, tint or sound tone control, perhaps bigger speaker but nothing in geometry. 
By the middle/late 1970’s there were the 20AX and 30AX CRT’s and similar in which geometry was  excellent.

The D|E|R badged version  of the 3782 (rear set).

The Thorn 26" Teletext set retailed at around £750 in 1976 or about £13 a month to rent (which was £5 a month more than the non-text version). The Labgear Teletext box retailed at £399. I kind of remember talk about a GEC/IBA adapter box back in 1975 but I'm a bit hazy about that.

In 1976 Bush introduced the model BC6333 into the marketplace. Receiver employed the Texas Instruments Tifax decoder.

In 1978 Rank-Radio-International released a book for their dealers titled: "The Service Engineers Guide to Teletext".

Till Eulenspiegel.

Posted by: @jcdaze

I kind of remember talk about a GEC/IBA adapter box back in 1975 but I'm a bit hazy about that.

I’ve seen and played with the GEC experimental set which did the rounds at trade shows. Used thumb wheel switches for page selection and was monochrome.

Radio Rentals used to have a kit to upgrade the 3500 chassis, I did have the document with circuit details but now long gone. Apparently you needed to live in a pretty decent reception area for good results. The 9650 IF panel was heavily modified but was still just an updated version from the later 8500. The 9653 used a SAWF IF stage identical to the TX9/10.

Posted by: @jcdaze

The Thorn 26" Teletext set retailed at around £750 in 1976 or about £13 a month to rent (which was £5 a month more than the non-text version). The Labgear Teletext box retailed at £399. I kind of remember talk about a GEC/IBA adapter box back in 1975 but I'm a bit hazy about that.

When you consider that, those are quite shocking prices for the time, and pretty much only an option for the well healed.

The closest I have to the Thorn setup above is the Labgear (Tifax) with wired remote, and my only 9000, the Multibroadcast 773 (see below).

Sadly, the Labgear 7026 cannot decode Teletext, shortly after its release there was a standard modification to the Ceefax service that caused it to miss lines of text out. The 7026 unit was the first to use the Texas Instruments TIFAX (74S262) character generator and were easy to spot because of the curious designs of the 6 and 9 characters.

Posted by: @till

In 1978 Rank-Radio-International released a book for their dealers titled: "The Service Engineers Guide to Teletext".

Till Eulenspiegel.

My Wife bought me a mint copy of this for my Birthday a couple of years back!

Posted by: @crustytv

Sadly, the Labgear 7026 cannot decode Teletext, shortly after its release there was a standard modification to the Ceefax service that caused it to miss lines of text out. The 7026 unit was the first to use the Texas Instruments TIFAX (74S262) character generator and were easy to spot because of the curious designs of the 6 and 9 characters.

I remember Manor Supplies selling both the Tifax boards and the Mullard VM6101 boards: when Sendz started offloading VM6101s a good few of us at work started building our own outboard decoders.

Blue Peter covering CeeFax

@crustytv Mort Smith (the guy with glasses editing the Ceefax page in that clip) says Peter Purvis stubbed his toe on the huge box. When he asked what this thing was doing in the studio he was told it was the Ceefax decoder he said: "Who the bloody hell is going to want this thing in their house?!"

Another great video on CeeFax I'd not seen before. Lots of consumer TV's of the period and an abundance of the LabGear decoder in use.

p.s.

Keep watching after 23:00 for some further technical info regarding Ceefax signal insertion, and a Philips N1500, coupled to a G8.