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Thyratron proper bias
Hi, ghjkl67. Looks that the thyratron´s curve is puzzling you. ¨Proper bias¨ is not a fixed single value, but depends on the plate voltage. Look at the 2A4G´s curve. The conducting zone is above the curve, the cut-off zone is below it.
At -2V on the grid, the thyratron will start conducting (and will stay conducting) if the plate voltage is 25V or greater. But, if the grid is at -8V, you will need 175 or more plate volts to make the tube conductive. It most likely will not conduct.
If the grid is about -9V, the tube will not conduct at any value of plate voltage (up to the 200 V limit).
When the thyratron has fired (is conducting), on the following negative cycle of the AC the tube will be cut off, and on the next positive cycle will start conducting again if the grid voltage is not negative enough (that is, if enough RF keeps coming out of the transformer after the 6J7G and the 6ZY5G). The brief 60 Hz interruptions will not de-energize the relay coil(s).
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