SIST HD 351.4 S2:2004

Rigid precision coaxial and their associated precision connectors - Part 4: 21 mm rigid precision coaxial line and associated hermaphroditic precision coaxial connector - Characteristic impedance 50 ohm (Type 9/21) - Characteristic impedance 75 ohms (Type 6/21) (IEC 60457-4:1978)

Describes the mechanical, electrical and environmental specifications of the 21 mm pecision connector, the reflection coefficient and attenuation of which have to be measured up to 6 GHz.

Präzisionsrohrleitungen und zugehörige Präzisionssteckverbinder - Teil 4: 21 mm Präzisionsrohrleitungen und zugehöriger Zwittersteckverbindung - Wellenwiderstand 50 Ohm (Typ 9/21) Wellenwiderstand 75 Ohm (Typ 6/21) (IEC 60457-4:1978)

Lignes coaxiales rigides de précision et leurs connecteurs de précision associés - Partie 4: Ligne coaxiale rigide de précision de 21 mm et connecteurs coaxial de précision hermaphrodite associé - Impédance caractérisitique 50 ohm (type 9/21) - Impédance caractéristique (75 ohms) (type 6/21) (CEI 60457-4:1978)

Décrit les spécifications mécaniques, électriques et climatiques du connecteur de précision de 21 mm dont le coefficient de réflexion et l'affaiblissement doivent être mesurés jusqu'à 6 GHz.

[Not translated]

General Information

• Status: Published
• Publication Date: 07-Nov-2010
• ICS: 33.120.10 - Coaxial cables. Waveguides
• Technical Committee: iTEL - Communication cables
• Current Stage: 6660 - Retro National Implementation/Publication (Adopted Project)
• Start Date: 22-Oct-2010
• Due Date: 27-Dec-2010
• Completion Date: 08-Nov-2010
• Ref Project: HD 351.4 S2:1984 - Rigid precision coaxial and their associated precision connectors - Part 4: 21 mm rigid precision coaxial line and associated hermaphroditic precision coaxial connector - Characteristic impedance 50 ohm (Type 9/21) - Characteristic impedance 75 ohms (Type 6/21)

Overview

The SIST HD 351.4 S2:2004 standard, published by the CLC, defines stringent mechanical, electrical, and environmental specifications for 21 mm rigid precision coaxial lines and their associated hermaphroditic precision coaxial connectors. Covering two characteristic impedances - 50 ohms (Type 9/21) and 75 ohms (Type 6/21) - this standard ensures high performance for RF applications requiring precision and reliability up to 6 GHz frequency operation. This standard corresponds to the IEC 60457-4:1978 international recommendation and forms part of a comprehensive series on rigid precision coaxial connectors.

Key Topics

• Mechanical Specifications
  The standard details precise dimensions and mechanical tolerances for both the coaxial lines and connectors. The outer conductor has a nominal inner diameter of 21 mm, with maximum deviations tightly controlled to minimize impedance uncertainties (±0.004 mm for 50 Ω, ±0.008 mm for 75 Ω). The center conductor diameters differ based on impedance, ensuring optimal signal integrity.

• Electrical Parameters

  • Characteristic impedance: 50 Ω (Type 9/21) and 75 Ω (Type 6/21) connectors
  • Maximum frequency range for testing: 6 GHz for 50 Ω; 4.5 GHz for 75 Ω
  • Attenuation: Attenuation levels are specified with limits proportional to frequency (e.g., A = 6×10⁻³ × N/frequency in GHz dB)
  • Reflection factor: Reflection factor thresholds are set to very low values for minimal signal loss and reflection, critical for precision RF measurements
  • Contact resistance: Maximum DC resistance values for center and outer conductor contacts are strictly defined to ensure reliable electrical connections

• Environmental and Durability Testing
  The connectors and cables must maintain performance after exposure to a range of environmental conditions, including dry heat (+70 °C) and cold (-55 °C), following the IEC Publication 68-1 testing procedures. Mechanical endurance tests require connectors to withstand 5000 engagement and separation cycles with stable electrical properties.

• Mechanical Forces and Endurance
  The standard defines minimum and maximum axial forces on the center contact, bending moments applied to the outer conductor, and deflection limits under stress to ensure robust mechanical integrity during use.

Applications

This standard is essential for industries and applications that demand precision RF connectivity with minimal signal degradation, including:

• Telecommunication equipment requiring high-frequency, low-loss coaxial connections
• Measurement instrumentation where exact impedance and reflection characteristics enable accurate test results
• Broadcasting and aerospace systems for reliable transmission of high-frequency signals under varied environmental conditions
• Scientific research involving RF and microwave experimentation that needs repeatable, calibrated coaxial interfaces

Implementing connectors and lines conforming to SIST HD 351.4 S2:2004 ensures compatibility and interoperability in complex high-frequency systems, facilitating global standardization and quality assurance.

Related Standards

• IEC 60457-1: General requirements and measuring methods for rigid precision coaxial lines and connectors
• IEC 68-1: Basic environmental testing procedures - General considerations for environmental testing
• HD 351.1 series: Broader guidelines on coaxial cables, connectors, and their testing associated with telecommunications
• Other IEC publications on precision connectors and waveguides, supporting comprehensive electromagnetic compatibility and performance testing

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By adhering to the SIST HD 351.4 S2:2004 standard, manufacturers and users benefit from reproducible, high-performance coaxial connections meeting international quality benchmarks for demanding RF applications. This standard supports the integration of hermaphroditic precision connectors optimized for both 50 Ω and 75 Ω systems with guaranteed mechanical endurance and environmental stability.

Standards Content (Sample)

SLOVENSKI STANDARD
01-januar-2004
[Not translated]
Rigid precision coaxial and their associated precision connectors - Part 4: 21 mm rigid
precision coaxial line and associated hermaphroditic precision coaxial connector -
Characteristic impedance 50 ohm (Type 9/21) - Characteristic impedance 75 ohms (Type
6/21) (IEC 60457-4:1978)
Präzisionsrohrleitungen und zugehörige Präzisionssteckverbinder - Teil 4: 21 mm
Präzisionsrohrleitungen und zugehöriger Zwittersteckverbindung - Wellenwiderstand 50
Ohm (Typ 9/21) Wellenwiderstand 75 Ohm (Typ 6/21) (IEC 60457-4:1978)
Lignes coaxiales rigides de précision et leurs connecteurs de précision associés - Partie
4: Ligne coaxiale rigide de précision de 21 mm et connecteurs coaxial de précision
hermaphrodite associé - Impédance caractérisitique 50 ohm (type 9/21) - Impédance
caractéristique (75 ohms) (type 6/21) (CEI 60457-4:1978)
Ta slovenski standard je istoveten z: HD 351.4 S2:1984
ICS:
33.120.10 Koaksialni kabli. Valovodi Coaxial cables. Waveguides
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

NORME CEI
INTERNATIONALE IEC
60457-4
INTERNATIONAL
Deuxième édition
STAN DARD
Second edition
1978-01
Lignes coaxiales rigides de précision
et leurs connecteurs de précision associés
Quatrième partie:
Ligne coaxiale rigide de précision de 21 mm et
connecteur coaxial de précision hermaphrodite
associé —
Impédance caractéristique 50 ohms (type 9/21) —
Impédance caractéristique 75 ohms (type 6/21)
Rigid precision coaxial lines
and their associated precision connectors
Part 4:
21 mm rigid precision coaxial line and associated
hermaphroditic precision coaxial connector —
Characteristic impedance 50 ohms (Type 9/21) —
Characteristic impedance 75 ohms /Type 6/21)
© IEC 1978 Droits
de reproduction réservés — Copyright - all rights reserved
Aucune partie de cette publication
ne peut être reproduite ni No part of this publication may be reproduced or utilized in
utilisée sous quelque forme
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.
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: [phone] e-mail: [e-mail] IEC web site http: //www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
F
PRICE CODE
International Electrotechnical Commission
IEC
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Pour prix, voir catalogue en vigueur
• • For price, see current catalogue

— 3 —
CONTENT S
Page
FOREWORD 5
PREFACE 5
Clause
3.1.7.2 Maximum frequency 7
3.1.15 Electrical length 7
4.
Type designation (provisional) 7
5.
Standard atmospheric conditions for testing 7
22. Dry heat 7
23. Cold 7
8. Dimensions 9
10.1 Centre contact force of mated hermaphroditic connectors 9
11. Bending moment on outer conductor 9
12. Centre contact deflection 9
13. Mechanical endurance test 11
15. Attenuation 11
16. Reflection factor r 11
17. Contact resistance 11
18.
Screening effectiveness of connectors (leakage) 11
FIGURE 1 12
— 5 —
INTERNATIONAL ELECTROTECHNICAL COMMISSION
RIGID PRECISION COAXIAL LINES
AND THEIR ASSOCIATED PRECISION CONNECTORS
Part 4: 21 mm rigid precision coaxial line
and associated hermaphroditic precision coaxial connector
Characteristic impedance 50 ohms (Type 9/21) — Characteristic impedance 75 ohms (Type 6/21)
FOREWORD
The formal decisions or agreements of the I E C on technical matters, prepared by Technical Committees on which all the
1)
National Committees having a special interest therein are represented, express, as nearly as possible, an international
consensus of opinion on the subjects dealt with.
They have the form of recommendations for international use and they are accepted by the National Committees in that
2)
sense.
In order to promote international unification, the I E C expresses the wish that all National Committees should adopt
3)
the text of the I E C recommendation for their national rules in so far as national conditions will permit. Any divergence
between the I E C recommendation and the corresponding national rules should, as far as possible, be clearly indicated
in the latter.
4) The I E C has not laid down any procedure concerning marking as an indication of approval and has no responsibility
when an item of equipment is declared to comply with one of its recommendations.
PREFACE
This standard has been prepared by Sub-Committee 46D, Connectors for Radio Frequency Cables, of I E C Technical
Committee No. 46, Cables, Wires and Waveguides for Telecommunication Equipment.
It contains Part 4: 21 mm Rigid Precision Coaxial Line and Associated Hermaphroditic Precision Coaxial Connector,
Characteristic Impedances 50 0 (Type 9/21) and 75 0 (Type 6/21), of the complete standard on rigid precision coaxial lines
and their associated precision connectors, and it is intended to be used in conjunction with Part 1, General Requirements and
Measuring Methods.
The second edition resulted from the addition to the first edition, which was restricted to a connector with characteristic
impedance of 50 0, of a connector of the same general design but with characteristic impedance of 75 0.
The first draft for the 75 S2 version was discussed at the meeting held in Bucharest in 1974. As a result of this meeting, a
draft, Document 46D(Central Office)30, was submitted to the National Committees for approval under the Six Months' Rule
in June 1975.
The following countries voted explicitly in favour of publication:
Poland
Austria
Belgium Romania
Canada Spain
Sweden
Denmark
France Switzerland
Germany Turkey
United Kingdom
Israel
Italy United States of America.
Japan
At a last discussion at the meeting held in Stockholm in 1976, the proposal was approved to combine the 50 S2 and the 75 0
versions of the connector in a second edition of Publication 457-4.
Other IEC publications quoted in this standard:
Publications Nos. 68-1: B asic Environmental Testing Procedures, Part 1: General.
457-1: Rigid Precision Coaxial Lines and Their Associated Precision Connectors, Part 1: General
Requirements and Measuring Methods.

RIGID PRECISION COAXIAL LINES
AND THEIR ASSOCIATED PRECISION CONNECTORS
Part 4: 21 mm rigid precision coaxial line
and associated hermaphroditic precision coaxial connector
Characteristic impedance 50 ohms (Type 9/21) — Characteristic impedance 75 ohms (Type 6/21)
.
Clause and
sub-clause
of IEC Item
Publication
457-1
3.1.7.2 Maximum frequency
The maximum frequency at which the reflection factor and attenuation are
measured is:
— for 50 S2: 6 GHz;
— for 75 S2: 4.5 GHz.
3.1.15 Electrical length
The electrical length, expressed in millimetres, of a connector pair shall be specified
by the manufacturer. The inaccura
...