Dual Standard and Single Standard CTV’s

Submitted by Member: Nuvistor

1967 dual standard CTV installs and the first a single standard sets I saw.

Dual Standard Colour TV’s in 1967 were expensive and few available for sale or rent, well they were for our shop, for others they may have been plentiful. The first one we sold was the Bush CTV25, nick named the burning bush on account of the LOPTX possibly catching fire. By November 1969 we had sold a few, very few, I did the Davy lamp mods to them all but never had the LOPTX fail, I suppose if I hadn’t been diligent one would have definitely caught fire, Sod’s law.  The picture on the CTV25 was never that great, if you hadn’t seen other makes it wouldn’t be noticed but side by side it was very noticeable. We couldn’t understand why this was so since RBM had lots of experience with colour, see.

Rank Bush Murphy: ColourVision

We decided to make the dual standard Pye/Ekco the ones we wanted to stock, we were RBM and Pye/Ekco agents. The pictures were to us much better than the CTV25, reliability, install and setup very similar. The Pye set used many Mullard designs, I think some were straight from Mullard design labs, Pye by then was partially if not fully, can’t remember, owned by Philips, Mullard being part of Philips.  I went to a technical lecture in Belvue Manchester given by Len Briggs of Pye were he described the workings of their CTV, excellent day, very enjoyable and instructive. The lectures given by Len Briggs were well known as being excellent.

One aspect of the sets being scarce and expensive was that it allowed us to “cut our teeth” on the technology without being overwhelmed by trying to look after lots of the sets while still on a learning curve. By the time Single Standard sets were available for the start of three channel colour, which was November 1969 from a Winter Hill, we had two years of experience and City and Guilds certificates.

The Pye Single Standards were an evolution of the Dual Standard, the RBM was a completely new design with an Integrated Circuit performing many of the colour decoder operations, something else to lean about. The LOPT stage used a quadrupler for EHT generation, the salesman pushing this point as much safer and even better than others who were using triplers by then. They were very much aware of the burning CTV25’s and it’s Public Relations problem.

I don’t really know why, the RBM A823 chassis picture was good but still not as good as the Pye 691 design. Unfortunately I presume cost cutting at Pye saw the 697 chassis introduced as a stop gap to the all solid state 725 chassis. The 697 chassis although an evolution of the 691/693 was not a good set for reliability, CDA and Power/LOPT printed circuit problems.

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