Car aerial

[Burnerman]

Six volts usually John, they were connected in series parallel. I remember a 12 volt powered TV for 'portable' use, an Ekco TMB something, it took so much current that the car dynamo could only just about keep up with it.

We had reels of linecord in stock for all the different currents, 0.1 amp, 0.15 amp and 0.3 amp. Lots of American imports about in the '50s

They were that days .

Peter

Thanks for that Peter - I guess that is DC.
I've always wondered why the usual heater supply was 6.3v AC.
John

 

[AlanE]

John they were 6.3V AC or DC. A lot of common valves had 12.6 volt heaters for the same reason. Many of the 12.6 heaters were centre tapped so you could use them on either supply.

Simple aerial query actually had the effect of my thinking back to a lot of the old stuff I used to work on!

The TMB272 was the first valve 'portable TV' mid 50's I think, the Perdio Portarama was the first all transistorised one which caused a few comments at the time because although advertised as all transistor it also came with a single valve (EY51 maybe).

But thanks for the memory journey back in time. Forgot most of these old things before various unintentional prompts.

 

[Peter.N.]

Hi john

I think the main reason for the A/C rating is that indirectly heated valves were made specifically for mains operation, early ones had 4 volt heaters and then 6.3 volts became the norm but some of the same valves were used in A/C - D/C sets so they would then have run on D/C. European valve types prefixed with 'E' were all 6.3 v but there is no stipulation as to the type of supply.

Some valve amplifiers had DC powered valve heaters to reduce the hum level and there are a few indirectly heated valves designed for DC circuits such as PA valves in mobile communication equipment but these are the exception.

The heater voltage does just that - provides heat.

Peter

 

[Peter.N.]

You obviously type faster then me Alan - nice to meet a couple more ex TV engineers.

Peter