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Bias-Probe Octal, KIT

Description

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

Manufacturer

Herstellerinformationen | Manufacturer Information

Tube-Town GmbH
Rumbergring 37
D-66969 Lemberg
eMail: info@tube-town.de

Customer reviews (5)

Essential information about customer reviews We do not verify that the published reviews come from such consumers who have actually used or purchased the rated goods or services. All reviews, i.e. positive and negative, are published. No reviews that are unobjective, offensive or unrelated to the product will be published.

Andrea B., 03/24/2024

good quality board, excellent kit, but unusable on amplifiers that have metal elastic tongues to hold the tubes, base diameter of the cup that encloses the board is excessive, I was forced to purchase octal extensions. encloses the board is excessive, I was forced to purchase octal extensions.
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Peter, 02/28/2013

Superb quality ! Really a must-have tool for setting up bias.

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Specifications:

Operating Tempeature Range: –55 ºC to +125 ºC (derate linearly to 50% rated voltage at 125 ºC)
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Insulation Resistance: 10,000 MO x µF, 30,000 MO Min.
Self Inductance: 1 nH max. per 1 mm lead and body length
Life Test: 1000 hrs @ 85 ºC 1.25 x Vn
Damp Heat Test: 95% RH @ +45 ºC for 21 days
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Sommer Cable - SC-SPIRIT LLX LOW LOSS, Instrumenten cable - 5 Meter

Making the impossible come true… -

when dealing with a new guitar cable, this involves creating an extremely low capacitance together with a breathtaking flexibility. Developing an insulation which ensures super low values by means of a gas-injected foaming – this is not an easy job, but well within the bounds of possibility for a professional cable maker. However, protecting this fragile insulation also against motion, creasing or twisting, is indeed a true challenge.

With the SC-SPIRIT LLX "LOW LOSS" we have fallen back on the same insulation design as it is used in professional HD-SD video cables. For extra stability of the inner construction we use an optimised concentrical litz stranding and a special insulation curing on the surface. For the outer jacket we have applied a rubberlike soft PVC jacket, which is highly flexible, extremely compact, stretches hardly and protects the whole inner structure from exterior influences.

Due to its low capacitance and its very special construction the SC-SPIRIT LLX "LOW LOSS" is one of the world’s ultra-low loss guitar cables.

With DIY assembly please watch out that the black carbon screen (sitting on the white insulation) is conductive and must therefore be removed to avoid ground contact with the inner conductor.

ADVANTAGES:

Extremely low capacitance values
Robust, twist-proof and easy to reel
Low-loss, detailed and neutral transmission properties
Double shielding by Cu mesh plus conductive carbon screen

APPLICATION:

Highly flexible cable for the demanding studio and live guitarist
High-quality patch cabling in the professional studio technology
High-end cable for the live DJ

TECHNICAL DATA

Construction LI2Y(LS)CY 1x0,38mm²
Jacket, Diameter PVC 7,5 mm
AWG 21
Inner Conductors 1 x 0,28 mm²
Copper strand per Conductor 19 x 0,16 mm
Conductor insulation Foam/skin-PVC
Shielding Copper braiding tin-plated + Semiconductor
Shielding factor 100 %
Temperature range min. -30 °C
Temperature range max. 70 °C
Fire load per m 0,26 kWh
Color black

ELECTRICAL DATA

Capac. cond./shield. per 1 m 52 pF
Cond. resistance per 1 km 48 Ohm
Insulation resistance per 1 km 1 GOhm

14,90 €
2,98 € per m