AlesaVaicVacuumTechnology
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AV 20B / AV 20M Datasheet
- LAST PRODUCTION WAS IN 2001 -
AVVT 20M replace by:
EML20A-Mesh
AVVT 20B replace by:
EML20B
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The AV 20B / AV20M is a very universal and stabile tube, combining high gain, with a low output impedance. At a gain of 20, at only 11 Watt dissipation, there is no comparable directly heated tube, that offers a plate impedance of 3200 Ohm.
As a driver tube, when using a plate resistor, it can work with high voltage circuits is typically used for an 845, 211, or VV520B, using a supply voltage of 500...1200 Volts. For lower Supply voltages the use of a plate choke is recommended. With a plate choke the tube can run at Supply voltages of 350...450 Volt. (See Note4 for use with HV tubes)
As a lower signal tube, you can work at any required lower voltage, since you don't need to generate a maximum voltage swing.
As an output tube, use 450 Volt supply voltage for obtaining the maximum output power of 2.5 Watt.
Features
- AVVT's parallel ribbon filaments with 16 flat Surfaces, for more linearity
- Two extra large getters
- White nickel plates
- Unbreakable Hard-Glass Bulb, or thin C37 Shaped Glass
- Anti-microphonic Suspension in Tube Top
- Hard-metal filaments, which can never break. ( Note1)
- Ceramic UX4 Socket with Gold Plated pins
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AVVT20B plate curves.
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Filament Ratings
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| Filament Voltage |
5 Volt (AC or DC)
AC only as Output Tube
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| Filament Current |
1.3 Ampere
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Maximum Conditions See Note2
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| Plate Voltage |
450Volt
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| Plate Current |
100mA
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| Plate Dissipation |
16Watt
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| Power Output in Class A |
2.5Watt
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Typical Data
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| Plate Voltage |
350V
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| Plate Dissipation |
11 Watt
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| Plate Current |
30mA
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| Grid Voltage |
-10Volt
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| Plate Impedance |
3200 Ohm
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| Grid-Filament capacitance |
4pF
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| Amplification Factor |
17,0
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| Transconductance |
5,3 mA/V
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| Grid Resistor |
100k Ohm
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| Operating Lifetime |
40.000 hours
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Bias suggestions (with Plate Choke)
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| Ua / Ia / Ug |
Uin-max / Gain / Load
See Note3
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| 350V / 32mA / -10V |
7,1V / 16,0 / 100k |
| 400V / 40mA / -11V |
7,8V / 15,9 / 100k |
| 450V / 35mA / -15V |
12,0V / 15,8 / 100k |
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Bias suggestions (with Plate Resistor)
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| Ua / Ia / Ug / Ra / Ub |
Uin / Gain / Load
See Note3
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| 325V / 24mA / -10V / 12k / 600V |
7,1V / 13,1 / 100k
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| 350V / 21mA / -13V / 22k / 800V |
7,1V / 14,4 / 100k
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| 375V / 18mA / -15V / 35k / 1000V |
7,8V / 15,0 / 100k
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| 400V / 16mA / -17V / 50k / 1200V |
10,0V / 15,5 / 100k
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Mechanical Data
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Tube Size including Socket: 170 x 60mm
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| Tube Weight |
130 Grams
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For further information about our products, please visit http://www.jacmusic.com
Note 1) Hard-metal filaments are operated at much higher temperature than normal tubes. This tube will glow bright orange, instead of the dark orange color of nickel filament tubes.
Note 2) Individual Test data, such as: Matching Data, Grid Current, Vacuum, Filament Current, etc, are on the Certificate that comes with each individual Tube. Each tube is numbered, inside the glass with a metal Tag
Note3) These are just suggestions. Other bias points can be constructed using the tube curves. Va=DC Plate Voltage, Ia=DC Plate Current, Vg=DC Grid Voltage, Vb= Power Supply voltage. Vin=Maximum effective AC input voltage, Gain=Amplification Factor, Load=The Input Impedance of next stage.
Note4) When the operating voltage of an 845 circuit is for instance 1100Volt, choose a plate resistor for the 20B / 20M that will give the operating points as in the table " Bias suggestions with Plate Resistor" The voltage over the plate resistor will be 700...750Volt. Do not use one single resistor, because the types with cooling mounting, or any other type that is sand filled, will produce pop noise, that you think may come from the tube. For the plate resistor you will get best results with metal film resistors of maxium 5Watt in Series, to obtain the required value. At 1200 Volt Vb, you will need five of these. When switching on the HV, you MUST pre-heat the filaments first. Otherwise you are limited to 450Volt supply voltage.
Tube pictures with courtesy of VT-Components
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Counter since 18.12.99 
JAC-MUSIC ©2001. All Rights Reserved.
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