Taylor 45C User manual

INSTRUCTION MANUAL
i.
-
for
Windsor Model 45C
VALVE TESTER
kJVtt \
TAYLOR ELECTRICAL INSTRUMENToLTD
MONTROSE AVENUE •SLOUGH •BUCKS •ENGLAND
Telephone: SLOUGH 21381 Telegrams: TAYLINS, SLOUGH

VALVE
tester SCliCtt*
TAYLOR ELECTRICAL INSTRUMENTS LIMITED
MONTROSE AVENUE SLOUGH BUCKS ENGLAND
Telephone
:
Slough 21381
Telegrams &Cables
:
‘1Taylins ,Slough ’
'
PRICE 2s. 6d. POST FREE

CONTENTS
1.DESCRIPTION
1/1 General ...
1/2 Mains adjustment
1/3 Controls ...
1/4 Meter scales
1/5 Valve holders ...
2. OPERATION
2/1 Application of tests
2/2 Rectifiers
2/3 Diodes
2/4 Filament continuity
2/5 Element shorts ...
2/6 Cathode leakage
2/7 Mutual conductance
2/8 Gas button
3. PRINCIPLES OF OPERATION
3/1 Rectifiers
3/2 Diodes
3/3 Filament continuity
3/4 Element shorts ...
3/5 Cathode leakage
3/6 Mutual conductance
3/7 Gas button
4. VALVE DATA
4/1 Method of working out settings
Valve bases wiring chart
5. GUARANTEE
Circuit diagram
Page
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8-9
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1.DESCRIPTION
This Manual is for use in conjunction with the Valve Chart published separately.
1/1 GENERAL
The Model 45C Valve Tester caters for practically every known type of electronic
valve except the larger transmitting types. Any normal fault can be quickly detected and
the general condition of avalve is precisely measured by the Mutual Conductance Test.
The instrument is self-contained and A.C. operated.
1/2MAINS ADJUSTMENT
A3-pin plug should be fitted to suit the sockets available.
Red —Line
Black —Neutral
Green—Earth
If a2-pin plug is used the green wire is preferably connected to aseparate earth.
The instrument is designed to operate from supplies of 105-125 or 200-250 volts
40-100 cycles. The voltage adjustment panel will be found on the left hand side of the
instrument; the bakelite-hecded plug should be plugged firmly into the socket most
nearly corresponding to the actual voltage, i.e.:
—
For 105-125 volts use the 115V. socket
„200-224 ,, •,, fl 210V. „
,, 225-250 240V. „
The consumption is approximately 30 watts
.
1/3 CONTROLS
The Main Selector at top right-hand side of panel enables the required type of test
to be selected.
Below this is the Grid Volts control, calibrated in volts 0-15.
Op the left-hand side are the selectors for Anode and Screen voltages, and for filament
voltage
.
Below the meter are the ABC selectors by means of which the correct pin connections
are made.
The right-hand push button and the knobs marked Aand Bare used on Mutual Con-
ductance Tests.
Tests for Gas are made with the left-hand push button.
The fuse (mains circuit) is fitted inside the instrument immediately above the mains
adjust panel. The mains ON/OFF switch is at the front of the instrument.
1/4 METER SCALES
The outer scale is calibrated direct in mA/V, the two sets of figures referring to the
two ranges available on the Main Selector.
The arc marked “Replace—?—Good ”is used on Rectifier and Diode Tests only.
3

The inner arc is calibrated in Megohms and is used on Cathode Leakage Test only.
1 / 5VALVE HOLDERS
There are 20 valve holders and three; sockets on the top of the instrument. The
valve holder nomenclature and numbering system are given in the Valve Chart. The Red,
Black and Green sockets are used to connect the valve top cap, if any, to the Anode, Cathode
or Grid circuits respectively as required by the nature of the test and specified in the Valve
Chart. Aclip lead is supplied with the instrument for this purpose.
2.OPERATION
2/1 APPLICATION OF TESTS
The seven different tests available are briefly described in the seven following
paragraphs and are considered in more detail in Section 3,
Which tests should be applied, and the order in which they should be carried out,
depends on the type of valve and what is known about its condition.
The following table lists the recommended sequence of tests on valves of six general
categories
.
VALVES
Main
Selector Rectifier Diodes Triode or
screen
grid Gas
rectifier
Gas
triode
&tetrode Magic
eye
Remarks
Rectifiers 3— — 34—
Diodes 3———__
Filament 1111 1 1Unless
Continuity
Element 222
cold
cathode
Shorts
Cathode 223233Unless
Leakage
Mutual 44
directly
heated
Conductance
Gas button ——5— — 5
The full sequence of tests is suitable for testing valves of unknown condition. Under
these circumstances it is advisable not to omit the Element Shorts test otherwise the fuse
may trip on switching to Mutual Conductance. Discretion can often be used and if, for
example, avalve, working in an amplifier, is suspected of low gain it can be tested for
Mutual Conductance only.
Multiple valves, such as double triodes, or diode triodes, are treated as several
separate valves, the proper test conditions for each section being listed in the valve chart.
This applies also to frequency changers (mixers) which have separate tests for the oscillator
and mixer sections.
5

Tuning indicators (“magic eye "valves) are also tested in sections, first normal
tests on the amplifier section, then atest on the shadow section. For the latter, moving the
Anode and Screen volts selector from the position given opposite “Shadow” mthe valve
chart, to that opposite “Test should cause adistinct change in shadow angle.
In the case of gas -filled valves, particularly mercury vapour types, it is important
to wait for one minute on the “Cathode Leakage 11 position before switching to “Rect "
or to !‘Mutual Conductance
.
1
1
This is to ensure that the cathode is at operating temperature
before anode voltage is applied.
Mercury vapour ana gas -filled triodes (thyratrons) are tested with the voltage settings
given but on Rectifier ”position. The grid volts should be reduced slowly from 15 and
at some lower '^alue the valve should start to conduct, as shown by movement of the meter
pointer to the “Good ”sector. The value obtained varies considerably with the type of
valve, and its rated “control ratio,” i.e., anode voltage /grid voltage at start of conduction.
NOTE :In the following six sections the setting of switches not mentioned is immaterial.
2/2 RECTIFIERS
•
Set ABC selectors to positions specified in Valve Chart, Anode/Screen switch to 100/100
then turn main selector to “Rect ”and read on coloured meter scale. Repeat for second anode
if any.
TESTING COLD CATHODE RECTIFIERS
When testing cold cathode rectifiers e.g. OZ-4 the anode screen volt switch should be
set to 250/200, which will cause the OZ-4 to strike. The anode screen volt switch should then
be returned to the 100/100 position when the correct emission will be indicated on the meter.
Failure of the OZ.4 to strike or the stopping of emission before the 100/100 switch position is
reached indicates afaulty valve.
Care should be taken when testing other rectifiers that the anode screen volt switch be
set to 100/100 as failure to do so will damage smaller types of rectifiers.
2/3 DIODES
Same as for rectifiers but main selector is at “Diodes.”
2/4 FILAMENT CONTINUITY
Set main selector on “Fil. Cont.” and if pointer moves to about half scale then the
filament is intact.
2/5 ELEMENT JjHORTS
Set main selector to “Element Shorts ”and the top cap, if any, io green socket. Set
ABC selectors initially to 000. Turn Aselector slowly from 0to 17 and back. If there is a
definite frieter reading on any switch position there is an internal short circuit in the valve.
Repeat with Band Cselectors. Also see Section 3/4.
2/6 CATHODE LEAKAGE
Set ABC selectors and filament volts as specified, then set main selector to “Cathode
Leakage.” The meter pointer will kick to the right, then fall back to some steady reading.
It is not possible to lay down ahard and fast rule as to the minimum acceptable
resistance as so much depends on the type of valve and the circuit in which it is used. As
ageneral guide, however, at least 2megohms should normally be obtained and areading
of 1megohm or less will usually indicate afaulty valve. Whether it need be rejected on
this account depends entirely on the circuit in which it is used.
2/7 MUTUAL CONDUCTANCE
Set filament volts, anode /screen volts, grid volts and ABC selectors as specified and
turn Aand Bknobs fully anti -clockwise then, and then only, set main selector to “Mutual
6

Conductance.7’(Two ranges are provided, the 15 mA/V or 3mA/V positions being selected
according to the anticipated result.)
Turn knob Aclockwise until pointer reaches the XI mark. Turn knob Bclockwise
until pointer returns to zero. Press meter switch and read mA/V directly.
(Note a) :With afew valve types with low emission it may not be possible to reach the XI
mark even with knob Afully clockwise. In these cases use the X2 mark and
multiply the mA/V reading by 2.
(Note b) :If main selector is moved to Mutual Conductance position before ABC selectors
are correctly set, voltage may be applied to the wrong electrodes. This may
damage the valve or meter or blow the fuse. (See Section 1/3 for fuse replace-
ment.) It is best to leave the main selector on Cathode Leakage whilst ABC
selectors are altered, as this keeps the valve heater at operating temperature.
(Note c) :If the meter pointer is seen to be vibrating this is due to unrectified A.C. across
the meter circuit and is probably caused by an internal short in the valve under
test. The instrument should be switched off immediately to avoid damage to the
meter, or the main selector can be turned back to Cathode Leakage.
2/8 GAS BUTTON
After the meter switch has been used for measuring Mutual Conductance as described
in the last section, the valve can be tested for excessive grid current as follows, leaving
selector switches, bias control and anode Screen volts control in the same positions.
Turn knob Bin fully clockwise position. Turn knop Ain clockwise position up to
point when meter pointer reaches centre scale. Then press Gas Button. If meter pointer
goes off scale in either direction the valve has excessive gria current. The pointer deflects
to the right for positive grid current, to the left for negative grid current. The latter may
be due to grid emission.
3. PRINCIPLES OF OPERATION
(See circuit diagrams, centre pages.)
3/1 RECTIFIERS
In this test 100 volts A.C. is applied to the anode circuit via aload resistor chosen
so that the average good rectifier will pass acurrent sufficient to give ameter reading in
the “Good ”sector. The meter is shunted to about 22 mA. full scale. Screen voltage is
not applied but Grid Volts are available for tests on grid controlled rectifiers.
3/2 DIODES
This test is similar to that for rectifiers except that the test voltage is reduced to 60
and the load resistor is much higher. The shunt is removed from the meter so that its full
sensitivity of 250 jxA. is available. Neither Screen nor Grid voltages are available.
3/3 FILAMENT CONTINUITY
Approximately £volt rectified A.C. is applied to the filament through the meter and a
limiting resistor.
The maximum current is about 200 microamperes and is quite safe for all valves
7

P'QPES

3/4 ELEMENT SHORTS
The same arrangement is used as on Filament Continuity except that the test points
are applied to all electrodes in turn by rotating the selectors. Should there be ashort it
must be shown on at least one position.
(With afew valves spurious results may be obtained. Such are those having heater
centre taps or internal connections on pins which would otherwise be 11 blank.”)
3/5 CATHODE LEAKAGE
In this test all the elements except cathode and heater are joined together and acon-
denser is connected between heater and cathode. An A.C. voltage is applied so that the
valve acts as arectifier and generates about 50 volts D.C. between heater and cathode.
The meter then reads any leakage current and this can be interpreted in terms of megohms
leakage on the lowest meter scale.
3/6 MUTUAL CONDUCTANCE
In this test achoice of anode, screen and grid voltages is provided. These are A.C.
except that the grid voltage is prevented from going positive by asmall rectifier. The
transformer windings are phased so that the anode and screen voltages are in phase whilst
the grid voltage is out of phase .When the anode and screen voltages are positive ,therefore
,
the grid voltage is negative and meter current passes. When the anode and screen voltages
are negative, the grid voltage is zero and no meter current passes. The inertia of the meter
causes it to read steadily although the current through it is intermittent.
Knob Acomprises an adjustable meter shunt. When it is fully anti -clockwise the
meter is shorted and reads zero.
Knob Bcontrols abucking voltage derived from aseparate transformer winding and
small rectifier. When it is fully anti -clockwise the extra bucking voltage is zero.
On the Mutual Conductance test the screen voltage is applied between cathode and
screen, the grid voltage between grid and the lower end of acathode resistor, and the anode
voltage between the anode and the lower end of the cathode resistor. The cathode resistor
therefore carries anode current only. The meter reads anode current and is initially shunted
to zero. As soon as the valve warms up pulsating anode current flows and the meter reads
when knob Ais turned clockwise, The XI mark is at 3/5 of full scale. Next knob Bis turned
so that sufficient bucking voltage is applied to the meter to reduce its reading to zero.
Pressing the meter switch then shorts out the cathode resistor and the resultant anode current
increase is shown on the meter on the Mutual Conductance scale.
The cathode resistor has avalue of 555 ohms on the 3mA/V range and 111 ohms on
the 15 mA/V range.
The theory of operation is as follows :
—
Suppose the meter is shunted so that it reads xmA. full scale. Since the XI mark
is at 3/5 full scale the anode current is 3x/5 mA. =3x/5000 amps. On the 3mA/V range
the cathode resistor is 555 ohms so the cathode bias voltage =555 x3x/5000 =x/3 volts.
Suppose the valve on test has amutual conductance of 3mA/V under the specified test
conditions. Then its anode current increase when the cathode resistor is shorted is
3xx/3 =xmA. The meter therefore reads full scale corresponding to 3mA/V. Similarly
for lower values of mutual conductance on this range
.
Operation on the 15 mA/V range is the same except that the cathode resistor is 111
ohms and the meter is read on the 0-15 mA/V scale.
10

3/7 GAS. BUTTON
When knob Ais fully clockwise the meter is shunted to approximately 500 fxA. full
scale
.
The grid resistor is 270 kilohms, so with alow slope valve the usual grid current
limit of 2fxA. produces avoltage change of 0-54 volts which is likely to cause an Iachange of
about 0-54 mA. With ahigh slope valve the grid current is usually limited to 0*7 y.A. which
produces 0-19 volts which is likely to cause about the same Iachange.
4. VALVE DATA
4/1 METHOD OF WORKING OUT SETTINGS
The Valve Chart, published, separately, gives data for nearly 3000 valves, but new
types are constantly being added. Space is left for the user to fill in settings for new types
as these are encountered. The settings are easily worked out as follows. It is assumed
that manufacturers' data is available as to base connections and electrical characteristics.
Column 1
2
3
4
5
6
7
8
9
10
Valve Type
Manufacturer
Holder No.
Base Type
Heates Volts
Type
Voltages
Cap
ABC Selectors
Mutual Conductance
Columns 1, 2, 3, and 4are filled by inspection. International Octal based valves
with heaters to pins 2and 7are tested in No. 12 holder (108/1) but those with heaters to pins 7
and 8are tested in No .13 holder (108 /2) .Similarly miniature 7-pin based valves with heaters
to pins 1and 7are tested in No. 15 holder (B7G/1) but those with heaters to pins 3and 4are
tested in No. 16 holder (B7G/2).
Columns 5and 6are filled in from manufacturers data.
In Column 7enter suitable test voltages as follows :
—
60V. anode/60V. screen —small triodes and pentodes, high dissipation triodes and
pentodes.
100V. anode /60V. screen —small triodes and pentodes, high dissipation triodes and
pentodes and R.F. pentodes.
100V. anode /100V. screen —small triodes, high slope R.F. pentodes, most output
pentodes.
200V. anode /100V. screen —high mu triodes, normal R.F. pentodes.
250V. anode /200V. screen —high mu triodes, R.F. pentodes with high rated screen
voltage.
11

In general voltages nearest to normal operating conditions can be used, except for
power valves taking over about 30 mA. anode current normally. For these, reduced voltages
should be used to avoid testing them with an unnecessarily high anode current.
The grid voltage should be that recommended for normal operation (usually Class A
amplifier conditions). If, however, lower anode and screen voltages are used, the grid
bias voltage should be reduced in proportion to the reduction in anode voltage in the case
of atriode, or the screen voltage of. atetrode or pentode.
Column 8is blank unless there is atop cap. If this is agrid connection, enter Gfor
green, if anode enter Rfor red. If the electrode is not used during tests of another section
in the valve (e.g., the diode of adiode --triode) enter Bfor black.
To work out the ABC selector settings in Column 9, refer to the wiring chart (Page 4).
There are 10 circuits to whicn me pins of all valve Holders are connected mme manner
shown by the chart, the right-hand side of which also lists the switch connections of the ABC
selectors. The letters C, A, S, G, refer to cathode, anode, screen grid and control grid
respectively. The top line on the chart, shows that selector Aconnects circuit 1to cathode
in position 0, grid in position 1, cathode in position 2, anode in position 3and so on. Only
the first 7circuits are controlled by the selectors. Circuit 8is permanently connected to
cathode arid anode respectively, and circuits Sand 10 carry the heater supply.
EXAMPLE 1. Triode type 30, having the following pin connections :
—
(UX4 base) pin 1filament
2anode
3grid
4filament
The circuit connections for this base are given in the fourth column from the left.
Selector Acontrols circuits 1and 2, i.e., pin 2on circuit 2, circuit 1not being connected
on this holder. Now pin 2is anode, so the right-hand columns are scanned for aselector
position giving anode on circuit 2. Positions 1and 2satisfy this requirement, no account
being taken of the circuit 1connections as these are immaterial in this instance. Selector A
position 1is therefore chosen. Similarly selector Bcontrols pin 3on circuit 3, circuit 4
not being connected. This pin is grid, so position 2is chosen, although position 7would
do as well. Selector Ccontrols no pins so it is left on position 0. The settings are therefore
120. The filament connections on pins 3and 4are made automatically as circuits 9and 10
are permanently on the filament supply.
EXAMPLE 2. Indirectly heated pentode type 6K7G having the following pin connections
on an international octal base :
—
pin 1blank (or shell if metal type)
2heater
3anode
4screen grid
5suppressor grid
6blank
7heater
8cathode
top cap—control grid
The 108/1 holder (No. 12) must be used, as the heaters are on pins 2and 7. Selector
Acontrols pins 5and 4, i.e., suppressor and screen respectively. It should therefore be
on position 6(cathode, screen) since the suppressor grid is at cathode potential. Selector B
controls pins 1and 3, i.e., shell and anode. Its correct position is therefore No. 3(cathode,
12

anode) since the shell or metallizing if any should be connected to cathode. 'Selector
controls pins 6and 8, i.e., blank and cathode, and is therefore left on 0. The whole setting
is thus 630, with top cap to Green socket.
EXAMPLE 3. Frequency changer type X61M Osram, having the following connections on
on an international octal base :
—
pin 1metallizing
2heater
3anode
4screen grid
5oscillator grid
6oscillator anode
7heater
8cathode
top cap—signal grid
The correct holder is 108/1, No. 12. Separate tests are made on triode and mixer
sections. Triode setting 507 is worked out first, with mixer section electrodes such as those
on pins 3and 4as well as the top cap to cathode. Next the mixer section is specified as
630, the triode connections on pins 5and 6being connected to cathode, and the top cap to
the green socket.
EXAMPLE 4. Rectifier AZ31 Mullard, having the following connections on an international
octal base :
—
pin 1blank
2filament
3blank
4anode
5blank
6anode
7blank
8filament
The main selector is switched to “Rect.” on which position the screen voltage is no
longer applied. The grid voltage, however, is still available for testing thyratrons and
grid -controlled rectifiers.
Pin 2on filament is correct, but the other filament connection does not go to pin 7
but to pin 8. However, since circuit 9is the cathode side of the filament, the filament circuit
is completed by seeing that pin 8is connected to cathode.
The two rectifier sections are tested separately, the anode voltage being connected
to each anode in turn with all other electrodes to cathode. This gives settings of 100 and 007.
In column 10 is entered the manufacturers’ figure for mutual conductance unless the
anode or screen voltages used are different. In this case the figure should be reduced by
the square root of the ratio between the test voltage and the normal voltages. The anode
voltage of atriode is meant, or the screen voltage of apentode. E.G., if atriode listed as
having aslope of 4mA/V at 200 volts on the anode, then if it is tested at 100 volts the slope
to be expected would be
—
4xV(100/200) =2-8 approximately.
Similarly with apentode the reduction of screen voltage is taken into account.
13

Very occasionally valves are encountered which cannot be tested owing to the base
connections. Sometimes this is due to aheater centre tap being connected to a pin which
cannot be isolated, and sometimes to internal connections being made on certain pins of
glass-based valves.
Filament centre taps are taken if possible to ablank position on the selectors. E.G.,
type 3S4 has afilament centre tap on pin 5, and selector Cis on position 8which leaves
circuit 6disconnected.
14

We hereby guarantee each new instrument manufactured by us to be free from
defective materials and workmanship and agree to rectify any such defects free of charge
for aperiod of six months from date of registered purchase. This guarantee is subject to
the following conditions :
—
1. That the instrument has had, at all times, normal use and has not been tampered
with .
#
2. That the registration card has been correctly completed and returned to us within
seven days of purchase.
3. That in cases of complaint the instrument is returned to us securely packed and
carriage paid.
4. That this guarantee is non -transferable and applies only to the registered user.
5. That any Valves, Rectifiers or Components not of our manufacture but incorporated
in our instruments and subject to their Manufacturer’s Guarantee are not covered
by this guarantee.
6. In the event of repairs being carried out by the purchaser, the Company cannot
be held liable for any expense incurred.
7. Under no circumstances can the Company be held responsible for indirect damage
caused by any defect. Our liability in all cases is limited to making good any
defective part.
8. In the event of any dispute arising as to the interpretation of this guarantee, the
decision of the Company must be accepted as final.
TAYLOR ELECTRICAL INSTRUMENTS LIMITED
Head Office
419-424 MONTROSE AVENUE .SLOUGH .BUCKS .ENGLAND
15