Methods for the measurement of direct interelectrode capacitances of electronic tubes and valves

Applies to the measurement of the direct interelectrode capacitances of electronic tubes of the following types: receiving tubes, cathode-ray tubes, gas tube and gas-filled valves, phototubes, photocells and multiplier types, high-power vacuum tubes.

Methoden zum Messen der Zwischenelektrodenkapazität von Elektronnenröhren

Méthodes de mesure des capacités entre électrodes des tubes électroniques

Concerne la mesure des capacités entre électrodes des tubes appartenant aux classes suivantes: tubes de réception, tubes à rayons cathodiques, tubes à gaz, tubes photoélectriques et photomultiplicateurs, tubes à vide de puissance.

Methods for the measurement of direct interelectrode capacitances of electronic tubes and valves

General Information

Status
Published
Publication Date
30-Jun-2004
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Jul-2004
Due Date
01-Jul-2004
Completion Date
01-Jul-2004

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SLOVENSKI SIST HD 148 S2:2004
STANDARD
julij 2004
Methods for the measurement of direct interelectrode capacitances of electronic
tubes and valves
ICS 31.100 Referenčna številka
SIST HD 148 S2:2004(en)

© Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

---------------------- Page: 1 ----------------------
NORME CEI
INTERNATIONALE IEC
60100
INTERNATIONAL
Deuxième édition
STAN DARD
Second edition
1962-01
Méthodes de mesure des capacités
entre électrodes des tubes électroniques
Methods for the measurement of direct
interelectrode capacitances of electronic
tubes and valves
© IEC 1962 Droits de reproduction réservés — Copyright - all rights reserved
Aucune partie de publication may be reproduced or utilized in
cette ne peut être reproduite ni No part of this publication
forme

utilisée sous quelque que ce soit et par aucun any form or by any means, electronic or mechanical,

procédé, électronique ou mécanique, y compris la photo- including photocopying and microfilm, without permission in

copie et les microfilms, sans l'accord écrit de l'éditeur. writing from the publisher.

3, rue de Varembé Geneva, Switzerland
International Electrotechnical Commission
Telefax: +41 22 919 0300 e-mail: inmail@iec.ch IEC web site http: //www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
PRICE CODE
International Electrotechnical Commission
IEC
MenayHapoOHaH 3neKTpQTexHHVecnaR HOMHCCHH
Pour prix, catalogue en vigueur
voir
• • For price, see current catalogue
---------------------- Page: 2 ----------------------
CONTENTS
Page
FOREWORD 5
PREFACE 5
Clause
Scope 7
1. Definitions 7
2. General rules for interconnections 7
Systems of symbols used for interelectrode capacitan ces 9
4. Conditions for measurements . . . 15
5. Capacitance measuring circuits 17
6. Standard sockets used for measurements 19
7. Standard shields used for measurements 25
8. Standard cap connectors used for measurements 31
APPENDIX
I List of descriptive terms in common use 33
APPENDIX II List of descriptive terms in common use in some countries only 51
---------------------- Page: 3 ----------------------
— 5 —
INTERNATIONAL ELECTROTECHNICAL COMMISSION
METHODS FOR THE MEASUREMENT OF DIRECT INTERELECTRODE
CAPACITANCES OF ELECTRONIC TUBES AND VALVES
FOREWORD

(1) The formal decisions or agreements of the I.E.C. on technical matters, prepared by Technical Committees on which all the

National Committees having a special interest therein are represented, express, as nearly as possible, an international

consensus of opinion on the subjects dealt with.
(2)

They have the form of recommendations for international use and they are accepted by the National Committees in that

sense.
(3) In order to promote this inte rn

ational unification, the I.E.C. expresses the wish that all National Committees having as

yet no national rules, when preparing such rules, should use the I.E.C. recommendations as the fundamental basis for

these rules in so far as national conditions will permit.

4) The desirability is recognised of extending international agreement on these matters through an endeavour to harmonize

national standardization rules with these recommendations in so far as national conditions will permit. The National

Committees pledge their in fluence towards that end.
PREFACE

This publication has been prepared by Technical Committee No. 39, Electronic tubes and valves.

Work on the second edition was started directly after the publication of the first edition in 1958.

Drafts were discussed at meetings in Zurich in 1957, Stockholm in 1958 and Madrid in 1959. At the

Madrid meeting, it was decided that the work was sufficiently advanced for a draft to be submitted to

the National Committees for approval. Accordingly a final draft was circulated under the S ix Months'

Rule in May 1960.
The following countries voted explicitly in favour of publication:
Austria Netherlands
Belgium Poland
Canada Romania
Czechoslovakia Sweden
Denmark Switzerland
France Union of Soviet Socialist Republics
Germany United Kingdom
Israel United States of America
Italy
---------------------- Page: 4 ----------------------
METHODS FOR THE MEASUREMENT OF DIRECT INTERELECTRODE
CAPACITANCES OF ELECTRONIC TUBES AND VALVES
Scope

This recommendation covers the measurement of direct interelectrode capacitances of tubes and

valves within the conditions outlined in Clause 4 for the following classes:
Receiving tubes and valves
Cathode-ray tubes
Gas tubes and gas-filled v alves
Phototubes, photocells and multiplier types
High-power vacuum tubes and valves
1. Definitions
In this recommendation the following definitions apply:

1.1 Element (of an electronic tube or valve). Any integral part of the tube or valve that contributes

to its operation and to which external connections can be made.

1.2 Electrode (of an electronic tube or valve). A conducting element that performs one or more

of the functions of emitting, collecting, or controlling by an electric field the movement of elec-

trons or ions.

1.3 Filament (of an electronic tube or valve). A hot cathode (usually in the form of a wire or ribbon)

which is heated directly by current flowing in it.
2. General rules for interconnections

2.1 The specified interelectrode capacitance shall be measured directly rather than derived from

combinations of two or more individual capacitance measurements. In the measurement,

elements to be excluded are connected to the reference earth. This is not to be confused with

earthing in circuit applications. A connection which is not identified, for instance to a pin

or lead marked "internal connection", shall be left floating.

2.2 When measuring cathode-ray tubes, the post-deflection accelerators (intensifier electrodes) are

left floating.

2.3 When measuring tubes and valves with a metal base sleeve not connected internally, the metal

base sleeve is left floating.

2.4 On all types where elements are connected to two or more pins or leads, all such pins or leads

shall be connected together.

2.5 In those cases where two or more elements are declared to be internally connected, the major

element is used to describe the combination. For example, the combination of a grid inter-

nally connected to a cathode shall be regarded as a cathode in the tables of connections.

2.6 For directly-heated filament types, the filament is regarded as the cathode electrode.

2.7 In all cases, when stating capacitance values, it shall be made clear which elements are connected

to the active terminals of the measuring equipment, and which are connected to the reference

earth. This may be done either in words or symbols. Certain descriptive terms are in common

use and where they are used they will have the meaning given in Appendix I or Appendix Il

of this publication.
---------------------- Page: 5 ----------------------
— 9 ---
3. Systems of symbols used for interelectrode capacitances

In the tables of the Appendices 1 and II of this publication two symbols are given for each interelec-

trode capacitance. They refer to two different systems: A and B. System A which is outlined in

Clause 3.1 is a simple system for normal use, while system B which is outlined in Clause 3.2

is a more complex system which may be used in those cases where it is desirable to give more infor-

mation.
3.1
SYMBOL SYSTEM A

3.1.1 The symbol consists of a capital C followed by a suffix of one or more small letters and digits.

The small letters, sometimes in combination with a digit, each indicate a pa
rt of the tube or
valve according to the system given in Clause 3.3.

3.1.2 Unbracketed letters in the suffix following the capital C indicate the parts of the tube or valve

to be connected to the active terminals of the measuring equipment. An oblique stroke

separates the parts to be connected to the different active terminals, but see also 3.1.6 and 3.1.7.

3.1.3 If parts of the tube or valve are indicated in the suffix on both sides of the oblique stroke,

all parts that are not mentioned are connected to the reference earth during the measurement

(except those referred to in Clauses 2.1, 2.2 and 2.3).
Example:
Symbol Cf
kia
Type of tube or valve unit: triode, tetrode, pentode
Measure between: cathode + heater
and anode
Connect to the reference earth: all other elements, shields, metal parts, etc.

3.1.4 If in the suffix no letter follows the oblique stroke, this means that the second active terminal

of the measuring equipment is connected to "all other elements, shields, metal parts, etc.",

and not to some separate part.

3.1.5 If one or more electrodes are excluded from "all elements, shields, metal parts, etc.", and

these electrodes are to be connected to the reference earth, this is indicated by showing the

letters for these electrodes between brackets.
Example:
Symbol
Ck£/(au)
Type of tube or valve: triode, tetrode, pentode, with other units
Measure between: cathode + heater
and grid + screen + suppressor + shield
+ metal parts, etc.
Connect to the reference earth: anode + elements of other units.

3.1.6 If, in the above system, the unbracketed part of the suffix consists of only one letter, the oblique

stroke will be omitted.
Example:
Symbol Ca (instead of
Ca/)
Type of tube or valve unit: mixer
Measure between: anode
and all other elements, shields, metal pa rts, etc.
Connect to the reference earth: none.
---------------------- Page: 6 ----------------------
— 11 —

3.1.7 If, in the above system, the unbracketed part of the suffix consists of only two letters and the

oblique stroke appears between them, then the oblique stroke will be omitted.
Example:
Symbol Cga (instead of Cgia)
Type of tube or valve unit: triode, tetrode, pentode
Measure between: grid
and anode
Connect to the reference earth: all other elements, shields, metal parts, etc.

3.1.8 If the tube or valve is a multi-unit type, containing two or more dissimilar units, the parts of

each unit will be indicated in the symbol by a subscript in accordance with Clause 3.4.1.

Example:
Symbol Cg
IT P
Type of tube or valve: triode-pentode
Measure between: g 1 of triode
and anode of pentode
Connect to the reference earth: all other elements, shields, metal pa rts, etc.

3.1.9 If the tube or valve is a multi-unit type containing two or more similar units, the part of each

unit will be indicated in the subscript of the symbol in accordance with Clause 4.3.2.

Example:
Symbol Clete
Type or tube or valve: twin unit
Measure between: cathode of first unit
and cathode of second unit
Connect to the reference earth: all other elements, shields, metal parts, etc.

3.1.10 From the above rules for system A, the following forms of symbols may be expected to occur:

Measure Connect to the
Symbols Capacitance
between reference earth
Cx x to all x R, u
x to all except y x R, u y
CX(y)
Cxkyz)
x to all except y ± z x R, u y, z
Cx(u x to all of same unit
) x R u
CXtyul x to all of same unit except y x R y, u
C yzÛ)
X( x to all of same unit except y ± z x R y, z, u
Cxy between x and y
x y R, u
Cxyi x y to all x, y R, u
CXy tzl
/ x -I- y to all except z x, y R, u z
Cxyjtul x + to all of same unit x, y u
y R
CXy/(zll) x -I- to all of same unit except z x, y R z, u
Cx/yz
x to y + z x y, z R, u
x, y and z = individual electrodes or elements of tubes and valves

R = Remaining elements of the active unit (units), shields, metal parts (such as external shields, base sleeves which have

internal connections, unused pins or leads, etc.)
u = Inactive units of multiple unit tubes and valves
Note: Where no confusion is likely to result, qualifiying symbols shown
as suffixes (inferior) may be in line with the
main symbol for typewritten documents.
---------------------- Page: 7 ----------------------
— 13 —
3.2
SYMBOL SYSTEM B

3.2.1 The symbol consists of a capital C followed by a suffix of one or more letters and digits. The

small letters, sometimes in combinations with a digit, each indicate a part of the tube or valve

according to the system given in Clause 3.3.

3.2.2 Unbracketed letters in the suffix following the capital C indicate the parts of the tube or valve

to be connected to the active terminals of the measuring equipment. An oblique stroke sepa-

rates the parts to be connected to the different active terminals.

The suffix letters shown in brackets indicate those parts of the tube or valve which are con-

nected to the reference earth.
Example:
Symbol
Cfk/a(R)
Type of tube or valve unit: triode, tetrode, pentode
Measure between: cathode + heater
and anode
Connect to the reference earth: all other elements, shields, metal pa
rts, etc.
3.2.3 If the tube

or valve is a multi-unit type containing two or more dissimilar units, the parts of

each unit will be indicated in the symbol by a subscript in accordance with Clause 3.4.1.

Example:
Symbol: T
Cg/aP(RZRP)
Type of tube and valve: triode-pentode
Measure between: grid of t riode
and anode of pentode
Connect to the reference earth: all other elements, shields, metal parts, etc.
3.2.4 If the tube

or valve is a multi-unit type containing two or more similar units, the part of each

unit will be indicated in the subscript(s) of the symbol in accordance with Clause 3.4.2.

Example:
Symbol:
Ca'/g'(Ru)
Type of tube or valve: double triode
Measure between: anode (of first unit)
and grid (of first unit)
Connect to the reference earth: all other elements, shields, metal parts, etc.

3.2.5 From the above rules for system B, the following forms of symbols may be expected to occur

Measure
Connect to the
Capacitance
SymbolsSym
between
reference earth
between x and y
Cx/y(Ru) x y R, u
between x and y+
Cx/yz(Ru) z x y, z R, u
CX/Ru x to remaining elements x R, u —
C x to remaining elements except
x/Ru(y) y x R, u y
Cx/Rutyzf x to remaining elements except y and z
x R, u y, z
x/R(u) x to remaining elements of the same unit x R
Cx/R(yu) x to remaining elements of the same unit except y x R y, u
x to remaining elements of the same unit except y z
CX/R(yzu) and x R y, z, u
x and y to remaining elements except z
Cxy/Ru(z) x, y R, u z
x and y
Cxy to remaining elements of the same unit except z x, y R z, u
/R(ZU)
x, y and z = Individual electrodes or elements of tube or valve

R = Remaining elements of the active unit or units, shields, metal parts (such as external shields, base sleeves which have

internal connections, unused pins or leads, etc.)
u = Inactive units of multiple unit tubes and valves
Note:

Where no confusion is likely to result, qualifying symbols shown as suffixes (inferior) may be in line with the

main symbol for typewritten documents.
---------------------- Page: 8 ----------------------
— 15 —
3.3
LIST OF SYMBOLS FOR ELECTRODES AND OTHER ELEMENTS
The following symbols will be used:
a — anode
(Note: In some countries "p" is used).
d — diode anode
dy — dynode in photo-multiplier
g grid
g 1 grid 1
g 2 — grid 2, etc.
f — heater
k — cathode and in the case of directly heated tubes and valves: filament
m — external conductive coating
2 — deflection plates in cathode-ray tubes
x 1, x2, y' , y
(Note: In some countries D 1, D2, D 3 , D4 are used).
s — internal shield
3.4 SUBSCRIPTS

3.4.1 For combinations of dissimilar units in multi-unit tubes and valves, the following subscripts

will be used to designate the electrodes of the different units:
D — diode
T — triode
Q — tetrode
P — pentode
H — hexode or heptode

3.4.2 For combinations of two or more similar units in one tube or valve, several systems are used

to distinguish the electrodes as follows:
a' a"
a a'
la 2a
al all
The system a' a" is recommended
4. Conditions for measurements

4.1 For all tubes and valves, interelectrode capacitances shall be measured with the cathode cold

and with no direct voltages present, unless otherwise specified.

4.2 For all tubes and valves, interelectrode capacitances shall be measured using the standard sockets

and the standard cap connectors described in Clauses 6 and 8.

4.3 The socket face-plate on the standard socket shall be connected to the reference earth.

4.4 In those cases where the terminals do not fit the standard sockets or cap connectors, connections

shall be made directly to such terminals by using flexible shielded leads. Shielding on the

connecting leads shall be carried as close to the terminals as possible. Shielding between ter-

minals shall be used, where necessary, in order to have the capacitance measurement exclude

the capacitance between terminals outside the base or bulb.
---------------------- Page: 9 ----------------------
— 17 —

4.5 Standard shields (see Clause 7) shall be used where specified. When used, cylindrical shields

shall sit squarely on the socket face-plate and concentric with the tube or valve being measured.

When both a shield and a cap connector are used, the cap connector shall be concentric with

the opening of the shield.

Note: The dimensions and shapes of the standard shields have been kept as simple as possible to accommodate

the maximum number of outlines consistent with acceptable accuracy of measurement and have also been

selected to provide for maximum repeatability of measurement and ease of use.

The standard shields therefore do not necessarily provide the most perfect shielding for any particular

individual outline.

4.6 All metallic objects or dielectric materials having a dielectric constant appreciably greater than

air should be at such a distance from the tube or valve under test that a change in the relative

position between the object and the tube or valve does not affect the capacitance measurement.

This requirement does not apply to the use of the standard sockets, shields and cap connectors

described in Clauses 6, 7 and 8.

Where shielded leads are used to make connections to the tube or valve terminals, the leads

shall be arranged to have the smallest effect on the capacitance measurement.

4.7 When measuring the capacitance between the internal and external conductive bulb coatings

of cathode-ray tubes, connection shall be made to the external coating by means of a conductive

ring, such as braided bare wire wrapped around the bulb at a point approximately at the coating

centre. If the external coating has been applied in a patch so that it does not extend around

the entire bulb wall, connection shall be made by means of a finger contact located at the

approximate centre of the coating.
5. Capacitance measuring circuits

5.1 The radio-frequency bridge method and the transmission method as shown in Clauses 5.3 and

5.4 shall be the recommended methods of measuring interelectrode capacitances. These two

methods are applicable throughout the usual range of tube and valve capacitances i.e. 0.0001

to 100 pF.

Note: An advantage of the bridge method over the transmission method is that the conductive components of

the tube or valve admittance due to insulation losses, getter deposits or other leakages, can be measured

and balanced out independently of the capacitance reading.

5.2 The reference measuring frequency for capacitance measurement is 1 MHz (Mc/s). However,

frequencies ranging between 1 000 Hz (c/s) and 5 MHz (Mc/s) may also be used.
5.3
RADIO-FREQUENCY BRIDGE METHOD

An example of a bridge circuit for the measurement of direct interelectrode capacitances of a

tube or valve is shown in Figure 1. A stable oscillator, such as a crystal-controlled oscillator,

supplies radio-frequency power through a closely coupled balanced transformer (T).

Balance is indicated by a null-indicating device. For convenience the capacitors are ganged

differentially so that an increase AC, of one capacitance is accompanied by an equal decrease

AC, of the other. Balance may then be effected by varying the two capacitance branches of

the bridge until they are equal (when C„ = C l — C 2), then at balance C x = 2 AC, = 2 AC,.

The effect of capacitance to earth is negligible as point B is at a location in the bridge where

capacitance does not influence balance, and the capacitance from C to earth is across a closely

coupled low-impedance winding which does not affect the capacitance balance or the voltage

applied to the bridge.
---------------------- Page: 10 ----------------------
— 19 —
C2 =
2. —
FIG. Transmission method
FIG. 1. - Radio-frequency bridge
5.4
TRANSMISSION METHOD

An example of a circuit for measuring the direct interelectrode capacitance of a tube or valve

by the transmission method is shown in Figure 2. The radio-frequency oscillator voltage is

attenuated according to the range desired. The current in the unknown tube or valve capaci-

tance is amplified and measured by a tube or valve voltmeter, or by compensation.

The amplifier input is attenuated in conjunction with the oscillator output so that the various

ranges may be obtained. The oscillator-output and amplifier-input attenuators may be operated

from a common control and calibrated in convenient decade steps. It is to be noted that large

capacitances are required across the input and output so that the effects of the tube or valve

capacitances shunted across the input and output are negligible. The device is calibrated by

using a known standard capacitor or a resistor of negligible shunt capacitance which may be

calibrated in position. It is necessary to shield the parts from one another to eliminate stray

capacitances because there is no way of balancing them out with this method. (Errors may

be introduced as a result of conductance in shunt with the capacitance being measured.)

6. Standard sockets used for measurements

6.1 The details of standard sockets for measurement for tubes and valves having the bases listed

in Table I, p. 23 are as follows:

6.1.1 The construction and shielding of standard sockets and leads shall be such that, when the

holes for the insertion of the base pins and the spigots or locating lugs are covered with an

earthed flat metal plate, the capacitance between any one socket terminal and all other socket

terminals connected together does not exceed:
0.00010 picofarad for receiving tubes or valves,
0.0050 picofarad for cathode ray tubes,
0.00050 picofarad for all other types.

A spigot or locating lug contact (where present) shall be considered as an additional socket terminal.

---------------------- Page: 11 ----------------------
-21 —

6.1.2 Holes for the accommodation of spigots or locating lugs shall not exceed the maximum dia-

meter stated in Table I.

6.1.3 The diameter of the holes for the insertion of the base pins (Dimension A, Figure 3) shall

not exceed the maximum diameters stated in Table I.

6.1.4 The socket face-plate shall be flat. The diameter (Dimension B, Figure 3) shall not be less

than the minimum values stated in Table I. The socket face-plate may have a smaller dia-

meter provided complementary screening is present, so that when the holes in this plate are

covered with an earthed flat metal plate, the capacitance between all socket terminals connected

together and an object simulating the inserted tube or valve shall be less than the capacitance

values mentioned in Clause 6.1.1.

6.1.4.1 A thin insulating film with a maximum thickness of 0.010 in (0.254 mm) may be permanently

attached to the face-plate of standard sockets to isolate non-earthed shielding members.

6.1.5 The socket shall be so constructed that the base of the tu be or valve under test will seat on

the face-plate.
Hole for spigot or
locating lug if required
FIG. 3.
---------------------- Page: 12 ----------------------
- 23 -

Table I. - Diameter of holes for insertion of base pins and diameter of socket face plate of capacitance

sockets for various tube and valve bases
Maximum diameter Maximum diameter
Minimum diameter
(A) of holes of holes
Sheet
(B) of socket
for the insertion for spigots or
number of
face plate
Base description of base pins location lugs
I.E.C. Publi-
cation No. 67
milli- milli-
milli-
inches inches inches
metres metres metres
67-I-la 0.250 6.350 3 76.2
Dwarf shell small 4-pin base
67-I-2 Medium 4-pin base 0.250 6.350 3 76.2
67-I-3 Medium 4-pin base with bayonet 0.250 6.350 3 76.2
0.250 6.350
67-I-4a Medium 5-pin base 3 76.2
0.175 4.445 3 76.2 0.500
67-I-5a Octal base 12.700
0.093 2.362 3 76.2 0.500 12.700
67-I-6a B9G base
67-I-7a Locking in base 0.093 2.362 3 76.2 0.500 12.700
67-I-8a Continental loctal or B-base 0.093 2.362 3 76.2 0.500 12.700
67-I-9a B8G base 0.093 2.362 3 76.2 0.500 12.700
67-I-10a Small button miniature 7-pin
0.075 1.905 2 1/2 63.5
base
0.075 1.905 2 3/4 69.8 0.375 9.525
67-I-1 la Rimlock base
67-I-12a 0.075 1.905 2 3/4 69.8
Small button noval 9-pin base
67-I-13a B12B 12-spin spigot base 0.250 6.350 3 1/2 88.9 0.700 17.780
67-I-15a Magnal 11-pin base 0.175 4.445 3 76.2 0.500 12.700
0.175 4 102 1.000 25.400
67-I-16a Diheptal 14-pin base 4.445
0.175 4.445 3 76.2 0.813 20.650
67-I-17a Duodecal 12-pin base
67-I-18a 0.175 I 4.445 3 76.2 0.500 12.700
Sub-magnal 11-pin base
67-I-19a Pee. Wee 3-pin base 0.175 !! 4.445 2 63.5
67-I-20a Septar 7-pin base 3 76.2 0.500 12.700
for thin pins 0.093 2.362
for thick pins 0.250 6.350
67-I-21a Medium shell giant 5-pin base
0.325 8.255 3 76.2
with bayonet
67-I-21b B5E base 0.325 8.255 3 76.2
674-21c Giant 5-pin base 0.325 8.255 3 76.2
67-I-23 Jumbo 4-pin base 0.375 9.525 3 76.2
67-I-24 Super Jumbo 4-pin base with
bayonet 0.375 9.525 3 76.2
67-I-27 Sub-miniature base E8-10 0.065 1.651 2 50.8
---------------------- Page: 13 ----------------------
— 25 —
7. Standard shields used for measurements

Standard shields shall be made as shown in Table II. Material shall be copper, brass or an equiva-

lent metal and shall have sufficient thickness to maintain shape under conditions of use.

In using the receiving tube and valve shields, the shielded top cap connector shall slide inside the

shield.

Note: It is recommended that in future for any new receiving tubes and valves with parallel sided bulbs, the shielding

can's internal diameter shall be equal to the maximum diameter of the base or bulb and the length shall not be

less than the overall seated height of the valve including tip or top cap.

Table H. — Standard shields to be used when measuring tube and valve capacitances

Sheet number
Shield
of I.E.C. Outlines
number
Publication 67
67-II-1 Tube and valve outlines used with small button 7-pin base — 1
all types
Tube and valve outlines used with small button novai 9-pin 2
67-II-2
base — types 1, 2 and 3
67-II-2 Tube and valve outline used with small button novai 9-pin 3
base — type 4
67-II-3 Tube and valve outlines used with Rimlock base 4
67-II-4a Inline lead T2 x 3 subminiature outlines 5
67-II-5a Inline lead T3 subminiature outline 6
T3 subminiature tube outlines used with subminiature base 6
67-II-6a and 6b
E8-9 — all types
and T3 subminiature tube outlines used with subminiature base 6
67-II-7a 7b
E8-10
67-II-8 Tube and valve outline used with B5B/F base 7
---------------------- Page: 14 ----------------------
— 26 —
Blindage N° 1 — Shield No. 1
Note 1
des dimen-

Les dimensions en millimètres sont déduites The millimetre dimensions are derived from the original

sions originales en inches. inch dimensions.
inches
millimetres
ref.
min. nom. max. min. nom. max.
21/4
A 2 56.76 57.15 57.54
15/64 21764
D 3/4 3/4 49/64
19.05 19.05 19.44

1. Un congé de rayon maximal 3/32 in (2,3 mm) sur 1. A maximum radius of 3/32 in (2.3 mm) is allowable

les bords intérieurs est autorisé. on all internal edges.
Blindage N o 2 — Shield No. 2
Note 1

Les dimensions en millimètres sont déduites des dimen- The millimetre dimensions are derived from the original

sions originales en inches. inch dimensions.
inches millimetres
ref.
min. nom. 1 max. min. max.
nom.
2 56.76 57.15 57.54
A 2 15/64 2 1 /4 I 17/64
7/8
D 22.22 22.22 22.62
7/8 57/64

1. Un congé de rayon maximal 3/32 in (2,3 mm) sur 1. A maximum radius of 3/32 in (2.3 mm) is allowable

les bords intérieurs est autorisé, on all internal edges.
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— 27 —
o 3 — Shield No. 3
Blindage N
Note 1
des dimen- The millimetre dimensions are derived from the original
Les dimensions en millimètres sont déduites
originales en inches. inch dimensions.
sions
inches millimetres
ref.
min. nom. max. min. nom. max.
2 63/ 64 3 3 75.81 76.20 76.59
1/64
22.22 I 22.22 22.62
D 7/8 7/8 57/64
1. A maximum radius of 3/32 in (2.3 mm) is allowable
1. Un congé de rayon maximal 3/32 in (2,3 mm) sur
les bords intérieurs est autorisé. on all internal edges.
Blindage N° 4 — Shield No. 4
Note 1
II■PIIINV/■^ ^ -^•^•^■^■^ ^ ^ ^ ^ ^ ^ ^
The inch dimensions are derived from the original
Les dimensions en inches sont déduites des dimensions
millimetre dimensions.
originales en millimètres.
millimetres inches
ref.
i max.
min. nom. max. min nom.
3.090
A 77.5 78.0 78.5 3.052 3.071
0.413
B 9.5 10.0 10.5 0.375 0.394
0.158 0.177 0.196
C 4.0 4.5 5.0
22.5 23.0 0.886 0.886 0.905
D 22.5
2.0 2.5 0.079 — 0.098
E —
1. A maximum radius of 3/32 in (2.3 mm) is allowable
1. Un congé de rayon maximal 3/32 in (2,3 mm) sur
on all internal edges.
les bords intérieurs est autorisé.
---------------------- Page: 16 ----------------------
— 28 —
Blindage No 5 — Shield No. 5

Les dimensions en millimètres sont déduites des dimen- The millimetre dimensions are derived from the original

sions originales en inches. inch dimensions.
inches millimetres
ref.
min. nom. max. min. nom. max.
A — 1.750 — — 44.450 —
0.415 — 0.418 10.541 — 10.617
C 0.286 0.288 —
— 7.265 7.315
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29 —
Blindage No 6 — Shield No. 6
Note 1

Les dimensions en millimètres sont déduites des dimen- The millimetre dimensions are derived from the original

sions originales
en inches. inch dimensions.
inches millimetres
ref.
min. nom. max.
min. nom. max.
13/8 1 25/64
A 34.53 34.93 35.32
1 23/64
D 0.402 0.405 0.408
10.211 10.287 10.363
1. Un congé
de rayon maximal 3/32
...

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