Active of the Week

This will be a spot where a random active component will be posted. Usually it’s things that were stumbled on in every day life and have some relationship to Radio or some outlier. A few interesting things will be said about the component, why it’s valuable and what its potential interests would be in radio. This can be anything from a discreet component such as a transistor or tube to an integrated circuit of some kind.

To that end, I’m happy to announce that our first active component will be the 6J6 vacuum tube. This little guy is a dual triode with a very unique construction. If you notice the cathode (grey, in the middle) is shared between two units. The copper colored rods hold the wires for the grids and the blade outer pieces of metal are the plates which are totally separated from each other. Some other tubes have shared cathodes on paper, but are actually two individual cathodes which are tied to a common point.

The realm of a tube like this is simple in most cases. It’s designed for a mixer circuit and anything else that requires balance with a measure of precision. With a conventional dual triode such as a 12AT7 matching becomes an issue as does how evenly emissions changes. With a tube like this that becomes less of a concern. Although different in function (they are beam deflection tubes vs a conventional Triode 7360s and 6AH8s are similar in principle that two plates receive emissions from a single cathode.

I hope you learned something from this. Stop by next week, it is likely I will have an unorthodox transistor on the bench to look at. If not, who knows what it will be.

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