I have a set of tubes to test for an amplifier. I'll go through them.
5V4G
First is the rectifier/dual diode used in power supply.
Pinout:
1 | A | NC |
2 | B | Heater 1 |
3 | C | (Missing) |
4 | D | Plate 1 |
5 | E | (Missing) |
6 | F | Plate 2 |
7 | G | (Missing) |
8 | H | Heater 2 / Cathode |
The letters correspond to how the tester refers to the pins.
The tube data lists these values:
Element 1 | Element 2 | |
Type | 3 | 3 |
Filament | 5 | 5 |
Plate | 25 | 25 |
Top (Plate) | F | D |
Bottom (Cathode/Filament) | (H) | (H) |
Not listed in there, but all other switches are middle, which is connected to the other side of the filament voltage, "positive".
Type 3 means, a B+ of 30v, plate R of 0 ohm and meter R of 1500.
6SN7 *2
A dual triode, used in preamp and phase inverter.
Pinout:
1 | A | Grid 2 |
2 | B | Plate 2 |
3 | C | Cathode 2 |
4 | D | Grid 1 |
5 | E | Plate 1 |
6 | F | Cathode 1 |
7 | G | Heater 1 |
8 | H | Heater 2 |
The tube data lists these values:
Element 1 | Element 2 | |
Type | 2 | 2 |
Filament | 6.3 | 6.3 |
Plate | 26 | 26 |
Top (Plate) | DE | AB |
Bottom (Cathode/Filament) | (F)(G) | C(G) |
Not listed in there, but all other switches are middle, which is connected to the other side of the filament voltage, "positive". It's puzzling that F is bolded, but not C. Seems like F shouldn't be.
Type 2 means, a B+ of 30v, plate R of 820 ohm and meter R of 360
5881 (6L6?) *2
A beam pentode used as output drivers.
The catch here is that with the tubes I have, no markings are visible. The version w3 schematics these are marked as 5881, but the tube shape doesn't seem right, and doesn't match the pictures. Other sources suggest they could be 6L6. So I'll look up values for both and we can see what it looks like.
Pinout:
1 | A | Shell / NC |
2 | B | Heater |
3 | C | Plate |
4 | D | Grid 2 (screen) |
5 | E | Grid 1 |
6 | F | (Missing) |
7 | G | Heater |
8 | H | Cathode / Grid 3 |
Both 5881 and 6L6 share the same pinout, so that's a good start.
The tube data lists these values:
6L6 | 5881 | |
Type | 3 | 3 |
Filament | 6.3 | 6.3 |
Plate | 27 | 20 |
Top (Plate) | CDE | CDE |
Bottom (Cathode/Filament) | (G)H | (B)H |
Not listed in there, but all other switches are middle, which is connected to the other side of the filament voltage, "positive". It's interesting that the only pinout difference here is the "polarity" of the filament, which wouldn't seem to matter.
Type 3 means, a B+ of 30v, plate R of 0 ohm and meter R of 1500.
Reference 6DJ8 / ECC88
As we still have one missing value from the circuit, I'm going to use a reference tube that I have a lot of, in this case a set of Amperex 6DJ8/ECC88 's. While these are all used, my hope is that by testing a bunch, I can find a common value and build certainty with that
This is a dual triode
Pinout:
1 | A | Plate 1 |
2 | B | Grid 1 |
3 | C | Cathode 1 |
4 | D | Heater |
5 | E | Heater |
6 | F | Plate 2 |
7 | G | Grid 2 |
8 | H | Cathode 2 |
9 | J | Shield |
The letters correspond to how the tester refers to the pins.
The tube data lists these values:
Element 1 | Element 2 | |
Type | 2 | 2 |
Filament | 6.3 | 6.3 |
Plate | 21 | 21 |
Top (Plate) | AB | FG |
Bottom (Cathode/Filament) | C(E) | (E)H |
Not listed in there, but all other switches are middle, which is connected to the other side of the filament voltage, "positive". The bolding didn't make sense, so I updated here to be what I think it is
Type 2 means, a B+ of 30v, plate R of 820 ohm and meter R of 360.
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