AVO THE “AVO” VALVE CHARACTERISTIC METER MK II Válvula metros característica
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Modelo:
THE “AVO” VALVE CHARACTERISTIC METER MK II
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Información
'The problem of designing a Valve Testing Instrument capable
of giving a true and A comprehensive picture of the state of
any valve, has always been one of considerable magnitude,
increasing in complexity as new valve types are brought into
general use.
For a quick general purpose test necessitating a minimum of
time and technical effort, a mutual conductance figure will
give an adequate idea of a valve’s usefulness, and the
original “AVO ” Valve Tester was designed to test the
efficiency of valves on this basis.
Whilst a Valve Tester must, of necessity, be accompanied by
a data book correlating the results of the Tester with the
condition of the valve in question, a purely empirical
figure, if used as a standard, will always give rise to
doubts in the mind of the operator. The instrument should
therefore, produce a figure which can be compared with some
standard quoted by the valve manufacturer, if the operator
is to use his instrument with confidence. For this reason
the “AVO ” Valve Tester used the static zero bias mutual
conductance figure as a basis of comparison, this figure
being at that time almost universally quoted by the valve
manufacturer.
In order to reproduce this standard correctly, it was also
necessary to reproduce the stated values of DC anode and
screen voltage, a matter of some considerable difficulty
when it is realised that for any stated condition of anode
and/or screen volts the corresponding electrode currents can
vary over very wide limits, and in the case of valves of low
initial anode current and high slope, the actuation of the
control which produces the milliamp-per-volt reading might
easily double the anode current flowing. With D.C. methods
of testing the inherent internal resistance of the
rectifying circuits used could be such as to give regulation
errors which could cause results to be meaningless unless
complicated thermionic stabilising circuits and a vast array
of monitoring meters were used in all voltage supply
circuits. Such complications would not only render the
Tester of prohibitive price and size, but would considerably
increase the complication of operation for the non-technical
user.
The problem was overcome by the introduction of the AC
method of operation (Patent No. 480752) by which means the
necessary DC test conditions were correctly simulated and a
true mutual conductance figure produced by the application
of AC voltages of suitable amplitude to all electrodes. This
enormously simplified the Power supply problem, rendered
regulation errors negligible, and obviated the necessity for
voltage circuit monitoring.
The “AVO ” Valve Tester thus fulfilled normal testing needs
for a long period. During recent years, however, electronic
techniques have become much more precise and the nature and
multiplicity of valve types have continuously increased. The
zero bias mutual conductance figure is seldom quoted by the
valve manufacturers, who, usually, publish the optimum
working point mutual conductance and voltage figures, and in
a large number of cases give full families of curves, from
which, precise operation, under a variety of working
conditions, can be judged. To cater for present day
requirements therefore, a valve testing device should not
only be capable of producing a working point mutual
conductance figure at any reasonable value of anode, screen
or grid voltage recommended by the manufacturers, but should
also be capable, if necessary, of reproducing any one of the
mutual characteristics associated with the valve in
question. The instrument thus has to simulate the
performance of a comprehensive valve measuring set-up of
laboratory
Type manuel:
Servicio y Manual del usuario
Páginas:
30
Tamaño:
2.02 Mbytes (2121134 Bytes)
Idioma:
english
Revisión:
Third Edition
Manuel-ID:
Fecha:
Formato:
Documento Scaned, todo legible.
Fecha de subida:
2014 05 09
MD5:
6bb80648f523f0954c8426aedf8d1b87
Descargas:
1967
Información
Foreword .. .. .. ...
... .. 3
Introduction
...
5
The Basic Method of characteristic
checking ... 7
The Basic Method of checking diodes and
rectifiers ... 7
Insulation Testing .. .. .. .. .: .. .. .. .. 8
The Safety Cut-out..
...
9
The Valve Panel and Selector
Switch ...
9
Procedure for setting up valve base connections .. ,, .. .. 10
Provision for new valve bases
...
12
The prevention of Self oscillation of valves under
test ... 12
Diagram of Standard base pin connections
... 14
The controls on the front panel, their functions and
operations ... 15
The Set 'v Control
...
16
The Electrode Leakage
Switch ...
16
The Circuit Selector Switch
...
16
The Anode and Screen Voltage Switches
... 17
The Heater Voltage Switches ..
...
17
The Negative Grid Voltage Control
...
17
The Press Buttons ..
...
... 17
The Set Zero Control
...
17
The Meter Selector
Switch ...
18
The Set mA/V
Control ...
18
The Anode Selector Switch
...
18
The Special Adjustment Panel at the rear of the instrument
.. .. .. .. 19
General Procedure for testing a
valve ...
19
Mains voltage adjustment and panel set up—cold and hot
leakage tests—mutual characteristic checks and gas
tests—diode and rectifier tests made under load.
Instructions for testing specific valve types
... .. 22
Multiple diodes and rectifiers—double triodes and double
pentodes—combined diode and amplifying valves—frequency
changers of heptode and hexode types—frequency changers
employing separate electrode assemblies.
The Use of the Link on the Back Panel of the Instrument ..
... 24
Tuning Indicators .. .. ..
... .. .. 24
Gaseous Rectifiers ..
...
.. .. 24
Cold Cathode
Rectifiers ...
24
Thyratrons .. ..
...
.. ., 24
Neon Indicators .. .. .. .. .. .. .. .. .. 25
General Precautions to be observed when using the Valve
Characteristic Meter ., 25
Notes upon simple maintenance of instrument .. .. .. .. .. 26
Circuit diagram of Valve Characteristic
Meter ... ... 27