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Used GE 6414 Vacuum Tubes
Item: [6414-11] $5.00

6414 Vacuum Tube

Title: Used GE 6414 Vacuum Tubes
Item: [6414-11] $5.00

Used GE 6414 Dual Triode Vacuum Tubes

Here is a lot of ten untested GE 6414 dual triode tubes.
Test them yourself and save!
We have found that these tubes generally test out to be in good condition (90% to 100% or better emission).

These are sometimes referred to by the IBM Part Number 3000528, which is sometimes shortened to 0528.
These tubes are similar to a large plate 12AZ7 tube (same pin-out), but with lower gain (42x imstead of 60x).
(So they are not a direct replacement. For best operation they would need to be rebiased to the 6414 design center.)
The tube heater operate on 12 Volts at 0.225 Amp or 6.3 Volts at 0.45 Amp (center tapped heater).
The maximum plate voltage is 200 Volts, although this is a conservative rating.

These tubes are specially designed to operate in computer systems in which the tubes can be idle for long periods of time, which in normal tubes can cause them to become noisy and the emissions to be reduced when the tube is activated.
However the 6414 also work well in audio applications. Especially given that the solid construction helps to reduce microphonics.
They are also intended to operate for longer duration than regular tubes.
They usually have a mica getter shield to prevent the getter splat from contaminating the tube elements when it is fired.
This is especially important as the getter flash is larger than normal for these tubes.
The large getter flash helps reduce contamination of the cathode which contributes to the longer tube life as well as helping to reduce noise.
(The JAN 6414W tubes usually don't have the getter flash shield. Which just goes to show that JAN tubes are not always better.)

They have tripple thick mica supports which helps to reduce microphonics by keeping the tube elements stable.
They have ribbed rectangular plates which helps them disipate heat and also reduces microphonics.
The GE tubes use gray plates. The Raytheon tubes use black plates.
(The color of the plates is not important other than helping to identify who made the tube.)

The tubes were made by GE, Raytheon and Sylvania. GE tubes have a dot code below the 6414 number etched on the top edge of the tube.
The GE information is normally painted in the usual white paint that can be washed off.
(Note: JAN GE tubes (6414W) usually had green paint.)
Raytheon tubes just have the tube number (in red) painted on the side of the tube along with the other usual information.
The Sylvania tubes have oval plates and thinner mica element supports.

The Sylvania and JAN tubes are usually not as good as in addition to the lack of the getter shield, the mica element supports are thinner, which causes the tubes to tend to be more microphonic and noisy than the correctly built 6414 tubes.

The best tubes are the ones made to the full IBM specification which includes the thick mica element supports and the getter flash shield.
These tubes were made by GE and Raytheon and have the IBM part number 3000528 printed on the tube.

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