Restoration methods

6AE8 Replacement

The 6AE8 tube was a 9 pin triode-hexode frequency converter used in sets from the early to the late 1950's.

It can be a little hard to find a replacement in your valve stock so to avoid having to actually buy a tube you can substitute a much more readily available 6AN7. However the 6AN7 while very similar in characteristics is not a direct plug-in replacement for the 6AE8. All that is required however is some very minor rewiring of the valve socket.

Before doing anything compare the characteristics of the two devices as shown below:

6AE8
Plate volts: 250	Plate current: 3.5ma	Grid bias: Negative 2Volts	Screen volts: 85	Screen current: 3.2ma	Mutual conductance: 750mmhos
6AN7
Plate volts: 250	Plate current: 3.0ma	Grid bias: Negative 2Volts	Screen volts: 85	Screen current: 3.0ma	Mutual conductance: 750mmhos

As you can see the valves are very similar.
You might need to check the value of the oscillator grid resistor if you are replacing a 6AE8 with a 6AN7. The former typically uses a 30,000 Ohm resistor while the 6AN7 may well be happier if you increase that to 47,000 Ohms. Anyway you can check with a milliameter to sensure that the oscillator grid current is acceptable. Expect a figure of around 0.2ma here.

You will need to alter the wiring of the socket slightly as well when making the replacement. Disconnect the wires from pins 6 and 7. Reconnect the wire that originally went to pin 6 to pin 7 (this is the anode of the hexode). Attach the wire that originally went to pin 7 to pin 9 of the socket. This would have had no connection for the 6AE8. With the 6AN7 in place, pin 6 will be vacant.