Resistor Metaloxide 2 Watts / 1 MOhms

Raised Head with cross recess

• Material: Steel
• Strength class: 4.8
• Surface: Zinc-plated
• DIN: 7985
• Price: pack with 50 pcs.

Panel Mount Potentiometer

• Power Rating: 0,125 W
• Voltage Rating: 150 V AC
• Tolerance: 20%
• Shaft: 6 mm, Splitt Shaft (knurled)
• Shaft length: 20 mm
• Drill Ø: M7 (6,8 mm)
• Termination: PCB
• Dimension: 16 mm

Kit of a bias probe for indirect measurement of the quiescent bias current of a tube. The adapter is placed between the tube and the socket and is connected to a standard voltmeter (not included). Pay attention to the quality of the meter and to sufficiently charged batteries!

The quiescent current is measured indirectly via a precision resistor built into the adapter. The advantages of this measuring method are harmless voltages in the mV range at the measuring plugs as well as short ways for the current, since it does not have to be led through the measuring device (common practice with many measuring adapters of Far Eastern production). As a result, there is no risk of oscillation of the amplifier, which could damage the tubes or the amplifier itself.

Note: This adapter cannot be used when additional tube brackets are installed. These must be removed before using the measurement adapter and reattached after the measurement is complete.

Measurement procedure
Determine the resistance of the adapter, including the test leads. Connect the adapter to the meter, but do not connect it between the tubes and the amplifier. Select the ohms range on the meter and note the reading, e.g. 1.1 ohms.
For the final measurement, insert the adapter between the tube and the de-energized amplifier, connect it to the meter, select the mV range and switch on the amplifier. When the amplifier has reached a stable operating condition, read the value in mV from the meter and calculate the quiescent current using Ohm's law.

Example
Measured voltage = 47 mV, adapter resistance = 1.1 ohms.
Formula (I = V / R) or in this case
Bias Current (in A) = Measured Value (Voltage in V) / Measured Value (Resistance in Ohm)
0.047V / 1.1 Ohm = 0.042A or 42mA

For the calculation of the correct bias current as well as further information on bias measurement please refer to further documents or the bias setting instructions in the info section as well as the manual of the amplifier itself.
This adapter is suitable for all EL34, 6L6, 6550, KT88, 6V6, 6CA7 and other tubes with the same pinout.

Attention HIGH VOLTAGE ! Measurements and work on tube amplifiers should only be done by qualified personnel.

Files:

• Datasheet

Panel Mount Potentiometer

• Power Rating: 0,125 W
• Voltage Rating: 150 V AC
• Tolerance: 20%
• Shaft: 6 mm, Splitt Shaft (knurled)
• Shaft length: 20 mm
• Drill Ø: M7 (6,8 mm)
• Termination: PCB
• Dimension: 16 mm

Raised Head with cross recess

• Material: Steel
• Strength class: 4.8
• Surface: Zinc-plated
• DIN: 7985
• Price: pack with 50 pcs.

4 tubes, matched as quad

The 6CA7 is a powerful power tube developed in the 1950s by General Electric (USA). It is electrically largely compatible with the European EL34, but more robust in construction and differs in sound behavior. Both tubes are electrically interchangeable. The 6CA7 offers an alternative sound color and more robust operation at high power due to its Beam Tetrode design. Those who prefer more headroom, warmth, and depth in sound often choose the 6CA7.