Loctal Tubes

[benman94]

Another fun fact about the loctal types, though rather useless for TV, is that they have a ruggedized heater-cathode assembly to allow overvoltages of up to 7 volts. This is the approximate voltage from a fully charged 6.3 volt car battery with the alternator running as well.

I have a Williamson I built with 7A4s in the first four stages and Sylvania 807Ws for the output tubes, with a regulated 6.3 volt heater supply. I expect the loctals out front to last until Armageddon...

[init4fun]

Originally Posted by benman94

Another fun fact about the loctal types, though rather useless for TV, is that they have a ruggedized heater-cathode assembly to allow overvoltages of up to 7 volts. This is the approximate voltage from a fully charged 6.3 volt car battery with the alternator running as well.

I have a Williamson I built with 7A4s in the first four stages and Sylvania 807Ws for the output tubes, with a regulated 6.3 volt heater supply. I expect the loctals out front to last until Armageddon...

Small correction , but since you didn't grow up with 6 volt cars you are automatically forgiven ;

All cars in the 6 volt era had generators , in fact the generator outlived the 6 volt system and the earliest 12 volt cars still had an actual DC generator . My 53 Buick was the last GM 6 volt car , and the last straight eight engine , in 1954 GM eliminated both the straight eight and the 6 volt system but the generator still hung around in GM cars till at least 1961 because my 61 caddy had a generator (with it's 12 volt system) . My 64 caddy was the first car I owned that had an alternator , which BTW in car use the alternator IS by far the better suited machine , generators with their full current brushes were a far more frequent replacement item than today's alternators are

[init4fun]

Oh , and I forgot to mention , yea I've always been a fan of loctal tubes as well , to me it seemed a more robust design having a tube that wouldn't wiggle it's way out of it's socket with vibration present .

[Josef]

Originally Posted by benman94

...I expect the loctals out front to last until Armageddon...

I inherited a test transmitter which was owned by my grandfahter since it was new in 1952. Last December I had to replace the original european made ECH21 loctal tube due to the fact that the test tone oscillator didn't work any more. The RF carrier was still there. Not too bad for it's age
In the meantime I already bought a few nos tubes for safty reasons
I'm looking forward to do a little introduction of this device sooner or later.