Knob Classic Pointer - Black

• Length: 51 mm
• Size: 1,5 mm

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

The quiescent current is measured indirectly via a precision resistor integrated in the adapter. The advantages of this measuring method are harmless voltages at the measuring plugs, which are in the mV range, as well as short ways for the current, since it does not need to be fed through the measuring device (common practice with many measuring adapters of Far Eastern production). As a result, there is no risk of oscillations of the amplifier which can lead to possible damage of 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.

Procedure for the measurement

Determine the resistance of the adapter, including the measuring leads. To do this, connect the adapter to the meter, but do not plug it between the tubes and the amplifier, yet. Select the measuring range “Ohm” on the meter and note the measured value, e.g. 1,1 ohms.

For the final measurement insert the adapter between the tube and the currentless amplifier and connect it to the meter, select the measuring range mV 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 based on Ohm's law.

Example:
measured voltage = 47 mV, resistance of the adapter = 1,1 ohms.
Formula (I = U / R) or in this case:
bias current (in A) = measured value (voltage in V) / measured value (resistance in ohm)
0.047V / 1.1 ohms = 0.042A or 42mA respectively

For the calculation of the correct bias current as well as further information on the bias measurement, please refer to further documents or the bias setting instructions in the info area, as well as the manual of the amplifier itself.

This measuring adapter is suitable for all EL34, 6L6, 6550, KT88, 6V6, 6CA7 and other tubes with the same pin layout.

Attention high Voltage! Measurements and work on tube amplifiers should only be carried out by qualified persons.

Active, serial FX-Loop for a subsequent installation in an existing tube amplifier
The FX-Loop works with  two LND150 in the send and in the return stage. The send and return level can be adjusted to their optimal value with two potentiometers. The Loop works with the present high voltage of the amplifier.
It has two inputs for low and high signal levels.

Input Levels:
InA: 30 - 60 Vpp, max. 65 Vpp
InB: 10 - 15 Vpp, max. 18 Vpp

The FX-Loop utilize POTENTIALLY FATAL HIGH VOLTAGES.
Seek help from a competent technician if you are in any way unfamiliar with high voltage circuits.
Use at your own risk.

Files:

• Documentation

• Length: 51 mm
• Size: 1,5 mm

Filter choke, open bracket

• Inductance (+/- 15%): 5 H
• Resistance (+/- 15%): 105 Ohm
• max Current DC: 150 mA
• max Voltage DC: 400 V
• Leads: min 12 cm
• Hipot tested (100%) mit 1500 VAC

Files:

• Datasheet

4 tubes, matched as quad

EL34 II has fuller low mids and low end but does not lose headroom in the high end. Stronger than regular JJ EL34 but not as aggressive as the JJ E34L.

Typical Characteristics

• Ua = 250 V
• Ug3 = 0 V
• Ug2 = 265 V
• Ug1 = -13,5 V
• Ia = 100 mA
• Ig2 = 14,9 mA
• S = 11 mA/V
• Ri = 15 kΩ
• μg2/g1 = 11

Limiting Values

• Ua0 = 2000 V
• Ua = 800 V
• Wa(max) = 25 W
• Ug20 = 800 V
• Ug2 = 450 V
• Wg2(max) = 8 W
• Ik = 150 mA
• Uk/f = 100 V
• Rk/f = 20 kΩ

Files:

• Datasheet

• Type: Aluminum Electrolytic Capacitors, BIPOLAR
• Capacitance: 10 µF
• Voltage Rating: 100 V
• Tolerance: +/- 20%
• Operating Temperature Range: - 40°C / + 85 °C
• Dimensions: Ø 10 mm x 30 mm
• Termination Style: axial

Screw set for power jack chassis mounting

• 2 x screw M3 x 10 mm
• 2 x nut M3
• 2 x tooth lock washers