The tube of the month of October is again a rectifier. When you read my blog, you know that I'm very fond of TV damper tubes as rectfiers and use them in almost every project. I already presented the 6AX4 which suitable for almost all my needs. This article is about a TV damper which can handle more current: The 6CG3.
The 6CG3 can handle a peak current of over 1A and a DC output current of 350mA. This means a pair of them in a full wave rectifier scheme with center tap can deliver up to 700mA of current when used with a choke input filter. The same for a full wave bridge with 4 of them. If you are conservative you can still easily draw half an ampere from a power supply with 6CG3s. I have used it in a power supply which had to deliver such a current. That is the same you can get from the big mercury vapour 866A.
Pins 3, 5, 9 and 11 are removed. The anode is brought out to pins 4 and 10, so it is just the pins beside the anode connections, which carries the AC input voltage in a full wave rectifier. Pin 7 is connected to the cathode which of cause also carries high voltage (rectified output). The two pins beside the cathode could also be removed. I left them in so that the socket still has a good grip on the tube. With too many removed, the tube would sit quite loose in the socket. This practice enables save operation of the tube even when used with high voltages. Remember high voltages do not need direct contact. Electrons become quite sneaky at voltages in excess of 1kV. They can jump distances through the air, so that a few mm of air is nothing but a short for them.
Ok, the sockets are covered. What about the tube itself? Also no problem to obtain. Almost every major tube dealer has 6CG3s in stock. Often at ridiculously low prices. Sometimes they can be found for a buck or two. I usually buy them in bulk of 100 pcs: