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Re: Max anode voltage?

Original poster: Ray von Postel <vonpostel@xxxxxxxxxxx>

The maximum anode voltage, more commonly called plate voltage in tube manuals, is the d.c. voltage between the cathode and the anode, a.k.a. plate, terminal. This voltage may be lower than the d.c. power supply voltage depending on the circuit. Example: A d.c. power supply with the negative terminal at ground potential and the cathode of the tube connected to ground through a resistor. The anode or plate is connected to the positive terminal of the supply. The voltage applied to the plate would then be less than the power supply voltage by the amount of the IR drop in the cathode resistor. This assumes little or no d.c. resistance in the plate circuit.

What will happen when you exceed the maximum cathode to anode voltage depends to large extent on the total circuit. In practice I doubt you can operate the tube that way for long without exceeding the plate dissipation of the tube. At the very worst the tube will arc internally performing as a flash bulb.. At the least you will shorten the tube life. It will over heat. Some tubes will have the seals around the element connections fail and the tube implode. That is why manufactures call for forced air blowers on some tubes. It is possible to calculate what will happen from the tube characteristic curves. Most tube manuals give "typical" operating conditions for a tube. The C.C.S (Continuous Commercial Service) and the ICAS (Intermittent Commercial and Amateur Service) are often given for various types of operation and use. The self rectifying oscillators powered directly with a.c. as in most Tesla coil applications, operate as Class C amplifiers. Operation using ICAS will give satisfactory tube life but is not used if money is riding on continuous operation. Broadcast stations charge by the minute for their services so their equipment is designed for C.C.S.


Tesla list wrote:

Original poster: "Bob (R.A.) Jones" <a1accounting@xxxxxxxxxxxxx>

Hi all, in particular tube experts (yes I am talking the old big metal
glass/ceramic things with heaters)

Anybody know what the max anode voltage rating in a triode spec means?
specifically the GU5B
i.e. does it mean the maximum supply voltage or the maximum peak voltage
that is allowed on the anode.
What may happen if the maximum peak anode voltage is exceeded, assuming the
maximum anode dissipation is not exceeded.
Thanks in advance.

Robert (R. A.) Jones
A1 Accounting, Inc., Fl
407 649 6400