Ultra 1984C- UHF Adapter

[Niechcial,Steve]

I see this 405 set was designed to be fitted with an optional adapter for UHF 625 operation. I presume it was a complete UHF receiver , but looking at the circuit of the TV I can see no options for line switching. Does anyone know how that worked? Was it an internal or external unit? Thanks

[frsimen]

Looking at the manual for the UHF adaptor (available "up top" if you want to look at it yourself!), the UHF adaptor included the system switching.

You are right in that it has a new IF strip, but the existing video and audio output stages from the main TV are retained. Some of the system switch wiring connected to the line and frame stages.

There were several flavours of the adaptor, the one for the 1984 was intended to fit inside the cabinet. Some models used a box which was placed underneath the television.

Fitting the UHF adaptor doesn't look like an easy job.

Paula

[Niechcial,Steve]

Thanks Paula- it's good to hear from you again. Sorry I don't understand the 'up top' to access the manual?

[Simon Gittins]

That's the banner at the top right of every page.
There is a manual for the TV and one for the converter:
https://www.service-data.com/section.php/16937/1/1984c
https://www.service-data.com/section.php/16957/1/625-line-uhf-converters

[Niechcial,Steve]

Thanks Simon- got it. I noticed on the back of one of these sets it says 'This receiver if easily convertable to 625/UHF'. I think that is what you call being economical with the truth!

[Nuvistor]

I don’t think many “convertible” sets were modified in the Winter Hill region, I never did any. By the time WH was on the air the cost of the conversion for a 3 or 4 year old TV in parts and labour would be a good part of a new set. The lack of popular entertainment on BBC2 perhaps didn’t help.
However we did fit UHF tuners to dual standard sets but again it wasn’t a roaring trade.

[Niechcial,Steve]

Yes, dear old Gerry Wells used to describe the appeal of the BBC2 of those days as 'Radio 3 with pictures'

[Niechcial,Steve]

The MK 2 Perdio Portarama must have been another expensive nightmare to convert. I know a few were done because I have seen them about. But like the Ultra, there is no system switching of any kind as part of the original chassis. In fact the sole sign of convertibility is a 3 pin power socket to power the converter unit. A bit of a joke to provide this when the rest of the convesrion would have involved a lot of cutting and soldering elsewhere. No doubt the socket was fitted purely to meet Trades Description requirements as a 'convertible' set.

[Heatercathodeshort]

Many Ultra 1984 series passed through my hands around 1964. None had been converted and their owners had no intention of doing so. The push button VHF tuner was horrible. The Mazda CME1901 had a VERY low life expectancy.
All adding up to a completely uneconomic project. The 1984 gave a very good picture but all the delay caused by the Pilkington committee in deciding line standards resulted in enormous costs to manufacturers that resulted in their collapse or take over. Regards, John.

[marceljack]

Originally Posted by Heatercathodeshort

... but all the delay caused by the Pilkington committee in deciding line standards resulted in enormous costs to manufacturers that resulted in their collapse or take over.

We had the same problem in France where the first programme was in 819 lines and it was expected until 1960 that the second programme in UHF would use the same standard, so until late 1960 there were TVs marked "ready for the second programme" by just adding a UHF tuner.
However end 1960 it was finally decided that the second and all future channels would be 625 lines in order to simplify exchange of future color TV content between countries.
However contrary to what was done in UK they decided to keep positive modulation and AM sound in order to simplify adaptation of existing sets.
And since IF bandwith for 819 was larger than for 625 the IF adaptation was relatively simple.

[Niechcial,Steve]

That's interesting about the French system. Do you know why such a high number as 819 lines was chosen in the first place compared to most of the rest of the world?

[marceljack]

Originally Posted by Niechcial,Steve

That's interesting about the French system. Do you know why such a high number as 819 lines was chosen in the first place compared to most of the rest of the world?

It was believed at that time (1949) that we should aim at having the highest possible resolution obtainable with the means of the moment, and maybe that other countries would follow. There was a sentiment of pride to have "la plus belle image du monde" ... (before that we had 441 lines but only in Paris).

However there was not much money available after the war and other european countries (Germany mainly) found easier and more reasonable to adapt the american standard to the 50 Hz mains frequency, which gave birth to the 625 lines so-called Gerber standard (CCIR B).
This allowed to use american chassis concepts with minor modifications.

[Graham G3ZVT]

Originally Posted by Niechcial,Steve

That's interesting about the French system. Do you know why such a high number as 819 lines was chosen in the first place compared to most of the rest of the world?

Kell factor, anyone?

[Niechcial,Steve]

Yes the subjective definition must have been well below what 819 lines could theoretically offer. On smaller screens the spot size must have been a limiting factor in itself.

[marceljack]

Originally Posted by Niechcial,Steve

Yes the subjective definition must have been well below what 819 lines could theoretically offer. On smaller screens the spot size must have been a limiting factor in itself.

On good TVs, 850 dots/line were visible.

[dazzlevision]

The Ultra UHF converter chassis had a long cable form emanating from it which plugged into a female "Cinch" brand PCB edge connector, to plug into the mating fixed connector on the left and aide member of the TV's chassis.

The assembly also included the system switch and an actuating handle.

The UHF converter chassis was clearly made after Thorn acquired Ultra Radio & Television Ltd from Ultra Electric in 1961 (and when the technical standard for the new TV service (BBC2 on UHF 625 lines, with negative video modulation and FM 6MHz intercarrier sound) was finalised). The plating and IF cans are very Ferguson, together with the B7G socket for the UHF tuner. The smaller cable form fed the 625 baseband video to two contact pins on the set's "swing-out" hand wired IF chassis.

The fixed connector strip had a dummy connector (with various s/c links) plugged into it, to maintain normal operation on VHF/405 until a UHF converter as fitted.

The UHF converter, with UHF tuner, was fitted (on a 1984c) vertically in the space behind the two speakers, which were on the right of the chassis looking from the rear.