Thyratron voltage regulation

[rcavictim]

The requirement of how to best regulate the B+ voltage in a tube amp power supply is often dealt with by the use of either a pass regulator in series with the unregulated power supply and the amplifier circuit, or a shunt regulator, or a simple choke input filter.

I have observed that the use of mercury vapor rectifier tubes like the 866A is popular with some builders because of the attractive blue glow.

It has occured to me that one could combine the glow of Hg rectifiers with the functionality of Hg or Gas filled thyratron tubes to take care of both rectification function as well as voltage regulation of the power supply. Such a scheme used to be standard fare in industrial power electronics but I have never yet seen a tube amplifier builder employ this technique.

What you do is make a bridge rectifier using two Hg rectifier tubes and two Hg or gas filled (like Hydrogen) thyratrons. You need to fire the thyratrons into conduction at the correct phase angle of the incoming AC mains waveform each cycle depending on how much charge you need to send to the supply filter/reservoir. The technique is exactly the same as a typical SCR light dimmer control.

I got thinking about this because I have a box of suitable thyratrons that are in similar size and power league to the 866A.

Comments?

[peranders]

I once owned a tyratron... very nice looking and big

[EC8010]

Originally posted by rcavictim
The technique is exactly the same as a typical SCR light dimmer control.

Which means that you can expect to have to deal with similar RF and mains-borne noise problems. Having said that, the range of conduction angles would not be as great, so the problem shouldn't be nearly as severe.