I have a Tecnico Aristocrat radio. I'm not sure of the model, but the circuit, as far as I've looked, is almost identical with model 651. It has five valves (6J8G, 6U7G, 6B6G, 6V6GT, 5Y3G). The circuit diagram that I have for the 651 says that it was made in 1946. The chassis of the my radio looks like the photos of the 651 that I've found. However, the 651 has a bakelite case whilst the case for my radio is made of wood.

What's strange is that there is no power switch, the mains leads go directly to the input winding of the transformer. The volume control pot looks original, and it's the same style as the tone control pot, so I don't think that it has been replaced. But it's just a three terminal pot with no switch in it.

Did they really make radios without power switches?

Dan

Did they really make radios without power switches?

Yes. In fact IIRC, at one period there was a regulation prohibiting on/off switches on appliances. Brad may be able to verify that.

For me it has never been unusual to find sets with no power switches and I have seen the inside of a lot of sets. The final arbiter on it being fitted with one originally, or not, lies on the circuit diagram. If shows none that's the way it was.

It was never unusual to find the same chassis in several models and that valve layout with a few different valves which pretty much did the same thing, was almost a standard for BC / SW Octal valved sets from the time 6J8 & other Triode Heptodes with their separate exciter superseded 6A8 Heptode and other Converters that were less efficient at higher frequency.

STC was one that often had a chassis number that had no resemblance to the case & model it was in.

Marc

Good to know, thanks.

Dan

I have a Tasma Baby
that doesn't have a power switch. I suppose you were to use the switch that is part of the powerpoint (outlet as we Americans call them). My Tasma has a new power cord, and it has a cord mounted power switch like this:
(though mine has 2 poles),
as American outlets are always powered (usually the only switch is the circuit breaker in the breaker distribution box in the basement). I have this outlet providing 240V60Hz, a pair of 120V lines feeding both angled slots. Which accepts Aussie plugs.

Power switches were generally not installed on Australian radios because of the cost (supposedly) and during most of the valve era, if a power switch was installed it had to be double-pole - ie: switch both the active and neutral conductors. This was not only to allow for those who would make their own extension leads and mix up the polarity but also with the double adaptors of the time, which had the active on the right for one of the two sockets.

Because manufacturers didn't want to include the cost of a double pole switch, they simply didn't install one and the man of the house was expected to climb on the coffee table and plug the bayonet adaptor (where the polarity could also go either way) into the double adaptor on the light fitting to make the radio work and he'd be plugging in a load with the power applied, which to me is less safe than installing a single pole switch.

The in-line switch shown in the post above was indeed available as an option on the Tasma 100X series and a few other radios but most just didn't have one. My Tasma 1001 has one with the more familiar lamp socket switch (double pole) rather than the rocker switch shown. When the plastic era arrived, the rule was relaxed and radios from then on came with a combined power/volume switch.

From my experience tagging at the local Mens Shed; It is at the point where nothing mains escapes checking, its quarantined before it goes anywhere. A massive number of donated cables especially, have been found cross wired, or defective.

Many double adaptors have the neutral and active crossed on the lower outlet - something to watch out for.

Many double adaptors

I think I'd make that many old double adaptors. Stores and suppliers were cleared of the dangerous crossed-over ones a few decades ago.

This reverse of polarity was also limited to those adaptors that had mirror-reverse socket configurations. Those with the earth pin facing down on both sockets had the correct polarity on both sockets.

I've got a question about the double poled switch and the worry about reversing active and neutral. I'm not clear as to why that would be a problem. They both go to the primary of the transformer so aren't the outputs of the transformer effectively floating? Why does it matter which way they might be connected? What am I missing?

the worry about reversing active and neutral.

In the case of radios, this is only a concern in transformerless sets, where the neutral is usually connected directly to the chassis and hence a touch hazard because of the possibility of active being connected there by mistake.

A single pole switch that isolates the neutral instead of the active removes a layer of safety. Some people won't be told that working on something that is plugged into the power comes with dangers so it is said that the switch must at the very least always isolate the active conductor.

Of course, for experienced radio restorers to get a radio working again must face the time when working on a connected chassis needs to happen in order to take voltage readings, and so on. Those new to this sort of work do not readily understand what they are getting themselves into though.