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One place Gray missed the boat, so to speak, was his assertion in the Tube patents that the carbon resistor can be either internal or external to the Tube. With his motor carts, he showed a carbon rheostat plugged into one of the holes in the side of the control cabinet. (The Demo Cart motors are not complete without these current limiting resistors closing the various circuits). The LV current contributes to the Overshoot potential, and this current must be regulated, to prevent inefficiency, and even potential damage to the capacitors during the recharging pulses. This rheostat box he was holding was around four inches on each side, and contained a number of thin carbon discs tensioned against a spring, with greater pressure between the discs resulting in lower resistance. The resistor in the patent drawing is depicted as a number of discs (one option) so this provides a clue to the CSET's anticipated diameter.
The four point spark gap switch in the circuit diagram will work with an external resistor. But my tests have shown that it is an essential internal element of the CSET itself.
The first picture shows Gray's four point gap switching element and how the yellow arc transfers to the grid, on each side of the internal arc, when the grid is commutated to a polar mass, such as a coil or tape measure, using a single wire connection.
The second picture shows my test component, without the carbon, or any input connection to the LV rod. It just has the grid wire coming from the T-tap between the system capacitor and the 'one way energy path' diode, for which Gray used an Ignitron.
Next, I have the carbon slipped over the LV rod, and the grid input. It still has the faint sparks between the grids and the end of the HV rod. But there's also a spark between the rods, with no LV connection. The longer, stronger spark from the T-tap connection at the grid, over to the piece of charcoal, then through the carbon, and the spark gap, proves that the carbon resistor does increase the spark's voltage. (The weak sparks between the grids and the HV rod are still there).
This demonstrates that the two grids have different potentials when the LV rod is connected. (Fourth picture). Energy has more carbon to travel through to reach the outter grid, from the contact points between the carbon and the LV rod. So the outter grid has a higher potential than the inner grid.
For pulse forming applications, in a delay line, a higher potential should begin slightly later than a lower one.
Part of the Scientific Method is to report your findings.
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Topic: Edwin Vincent Gray's conversion tube (Read 96303 times)
