EH EL34 - PAIR

Metaloxide film resistor

• Nominal Power: 1 Watt
• Max. cont. Working Voltage:: 500 V RMS
• Tolerance: +/- 1%
• Temperature range: -55° C...200° C
• Flame retardant
• Very Small Size
• Size: 6,3 x 2,4 mm

• Type: Alpha Rotary Switch
• Version: 2 pole / 6 positions, non-Shorting
• Shaft lenght: 19 mm
• Rating: 0.3 A / 125 V/AC
• Contact resistance: max. 50 mΩ
• Insulation resistance: min. 100 mΩ / 500 V/DC
• Termination Style: solder lugs
• Shaft: 6,3 mm
• Drill Ø: 8,9 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

Octal Socket Belton VTB8

• High quality Micalex socket
• Glassfiber filled PPS black body
• Chassis mount
• Termination Style: solder lugs
• for Tube Type: EL34, E34L, 6L6, 6V6, 6550, KT66/77/88 etc.

Marshall Style Knob, Gold

• Material: Phenolic
• Shaft Size: 6 - 6,4 mm
• Size: 19,5 x 15,3 mm
• Mounting: Set-Screw, hexagon

Vacuum Tube Damper made of silicon, helps to reduce noise and rattle of vacuum tubes. But it will not turn a bad tube into a good tube.
If a higher level of damping is needed, than use more than one damper per tube.

• Inner diameter ca. 32 mm
• Use tt-da15 for EH EL34
• Price per damper

BEFORE ordering check the exact outer diameter of the vacuum tubes and compare it with the diameter of the damper to make sure that the damper fits.

Soldering Lug, Size M3

• Made of brass, silver-plated
• Angled
• Pack of 5

• Type: Noval Socket Belton VT9-ST-C
• Version: Chassis mount
• Termination Style: solder lugs
• for Tube Type: 12AX7, 12AT7, 12AU7, EL84,
•   EZ81, EL844 etc.