gareth evans wrote:
On 20/12/2020 16:53, Max Demian wrote:
On 20/12/2020 14:42, williamwright wrote:
On 15/12/2020 15:42, Dave Plowman (News) wrote:

Think it's a very long time since I've had a radio that would run the
battery flat while stopped for half an hour or so?


Don't they have a row a little valves nowadays then, and an inverter?

An inverter would be rather posh. More likely a vibrator power supply.


AIUI there were valves developed to run off 12v HT specifically for
use in automobiles.

Yes, but they used transistor output stages with those, you couldn't
drive a loudspeaker with 12v HT valves.

So the evolution sort of went:-

'Ordinary' valves using 'high' voltage (i.e. 100 volts or more)
with a vibrator power supply stepping up the voltage from the 12v
car battery.

12v HT valves for the RF and IF stages followed by transistor
output stages, all running off 12v.

All semiconductor radios when RF transistors became available
economically.

--
Chris Green
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