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From: John R Walliker <jrwalliker@gmail.com>
Newsgroups: sci.electronics.design
Subject: Re: Who remembers how bad analogue television was?
Date: Sun, 2 Mar 2025 17:48:31 +0000
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On 02/03/2025 01:52, Edward Rawde wrote:
> "Jeff Layman" <Jeff@invalid.invalid> wrote in message news:vprrbe$3in6g$1@dont-email.me...
>> On 28/02/2025 03:03, KevinJ93 wrote:
>>> On 2/27/25 12:45 PM, Martin Brown wrote:
>>>> On 27/02/2025 19:58, KevinJ93 wrote:
>>>>> On 2/26/25 8:52 PM, Sylvia Else wrote:
>>> <...>
>>>>>
>>>>> Are you sure that 1984 date is correct? By 1970 in the UK colour TVs
>>>>> used transistor signal processing stages and many had already changed
>>>>> to transistors for the power stages such as line and frame output as
>>>>> well as using chopper stabilised power supplies.
>>>>
>>>> The first two colour TVs I recall owned by friends or family were about
>>>> the time of Apollo 8 in 1968. Memorable for the Earth rise shot. Both
>>>> were entirely valves and my uncle's caught fire leaving a nasty brown
>>>> burn mark on their wool carpet and smoke damage on the ceiling.
>>>>
>>>> The earliest was at a school friends house and was in pastel shades pre
>>>> Nd glass. It was in colour but only just... Joe 90 launch was the first
>>>> programme I can recall watching there in colour. Test cards in shops
>>>> don't count.
>>>>
>>>> I'd believe 1974 as a date for hybrid colour TVs that almost worked
>>>> correctly and didn't need a service engineer visiting them every other
>>>> week. By 1980 I'm pretty sure they were almost entirely semiconductor
>>>> based.
>>>
>>> My father bought a Ferguson 19" colour TV at the end of 1970 that was
>>> fully semiconductor (it was my first term at university and he got it
>>> just before I came back for Christmas). It seemed to work fairly well -
>>> he would tinker with it but I don't remember it needing any significant
>>> repair. I gather it was one of the first such sets.
>>
>> The first domestic UK colour sets were valve-based. However, it wasn't long before transistor sets came in. See page 22 at
>> <https://americanradiohistory.com/UK/Practical-Television/60s/Practical-Television-1968-06.pdf#search=%22practical%20television%22>.
>> This was the June 1968 edition of Practical Television, and it refers to the new 19" Marconiphone Model 4701 as being "fully
>> transistorised".
> 
> I think they worked with a Texas Instruments facility in the UK where the necessary transistor was produced to make it possible to
> do the line scan and EHT without valves.
> R2008B I think. Doesn't seem possible to find any data on it now.
> https://www.google.com/search?q=R2008B+npn+transistor

Some sets used the BU105 transistor which was rated for 1500V for
line drive and EHT.  I once salvaged one from the junk pile at the
back of a TV repair shop and was able to get about 10W out of it
at about 1MHz.
https://www.silicon-ark.co.uk/datasheets/bu105%20datasheet%20Inchange.pdf


John

> 
>> More details can be found in Practical TV July and September 1967. What's amazing to me is the price - "284 guineas". So just
>> short of Ł300 in 1968; equivalent to Ł4500 today!!!
>>
>> -- 
>> Jeff
> 
>