On Friday, 9 February 2018 10:43:31 UTC, Terry Casey wrote:
In article b032ddcf-aa49-4fc1-bb7c-8c6128ebc3a9
@googlegroups.com, tabbypurr says...

Older ones ... had valves. And at least some proudly
declared 'transistor' on the front regardless.


The process of evolution was the development of valves that
would work with an HT of only 12 volts, rather than the normal
200 - 250V, so that a vibrator was no longer needed for all
the small signal stages.

The only thing that wouldn't work @ 12V was the output valve
which drove the loudspeaker but, by this time, power
transistors capable of doing the job had been developed so one
of those was used to drive the loudspeaker instead.

So the word Transistor (in the singular, as you posted, was
100% correct!

The first TV that PYE sold claiming to be 'transistorised' had
one transistor - used as sync separator, IIRC - but everything
else remained valve driven. You might call that a sales
gimmick - and you would be right - but the car radio was a
genuine way of operating a car radio from 12V without any
complicated high voltage generation required and was a real
advance.

correct yes, just very misleading.
The one odd thing about it was that the output tran ran cold. Not what I'd expect for a class A output.

The other end of tv development was when they were all transistor except for the LOPT valve.


NT