"tony sayer" wrote in message
...
In article , Dave Plowman (News)
scribeth thus
In article ,
David Looser wrote:
- the 500vA or so
transformer needed to isolate the chassis was an expensive component.


The standard all-valve "large screen" TV of the 50s/early 60s consumed
150W, of which half went into keeping the heaters alight. So a 250VA
transformer would have been plenty big enough.

Even so that was a very expensive component and the way TV design was
costed to the nearest fraction of a penny made it a no go!..

Indeed, and it also added significantly to the weight and bulk to the set.
In my "den" I have a Pye B16T (which has an isolating mains transformer) and
a transformerless Bush TV22 sitting next to each other. Both have the same
tube type (9" Mullard MW22-16) but the difference in the size and weight of
these two is considerable. It was the advent of the AC/DC TV which made TV
cheap enough for it to become a mass-market product.


David.