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January 18, 2011


George Storm

"I would expect the line switch in the *phase* lead".
If a good proportion of sets had the plug reversed you might want the switch in the lead that connected to the chassis. Then at least there would be some resistance in series with the supply.
I guess that users assumed there could be a problem whent the TV was switched on, so the "safety officer" made a choice for the off-state (been between "always bad" and "sometimes OK but sometimes terrible").

Cor van de Water

@George, that sounds rather ridiculous, because the resistance of the filaments is so low that there will be full Phase on the chassis with the set switched off in the Neutral lead. So with your proposal there is an even more sneaky problem than chassis direct connected to Phase when ON and that is: the chassis is at Phase potential via less than 100 Ohms when the set is OFF!
The only good solution is the polarized plugs and the only alternative is a very well encapsulated/isolated chassis.
BTW, in India they have an interesting arrangement where the Phase can be switched off for every wall outlet.

William DeHaven

You remember the CK722?? I thought only I was that old!

I remember the hot chassis days well. It didn't take too many close encounters of the shocking kind before I invested in an isolation transformer for my radio workbench. That, and a ground clip I attached to every chassis "just in case", did wonders for my skinned elbows and my vocabulary.

William Ketel

These radios worked fairly well, and then the next generation came along that used the miniature tubes, still the 5-tube line-up, but now with a 150Ma heater string. They were sold for another 20 years or so. But just think about the raucous "hue-and-cry" if somebody marketed one like this today! Of course, that is because presently the presumption is made that no person is responsible for their own safety, and that safety is always somebody else's responsibility. Really, though, these radios would be safe today if the line cord used the ground pin as the common connection, and took power from the line pin, leaving the neutral connection open.

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