Radio Frequency by Steve Winder and Joe Carr - HTML preview

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23.2 Co-axial connector

The most commonly used connectors for RF cables are:

Type Impedance, Max. Maximum Notes Z₀ (ohms) VSWR to proof RF
(frequency voltage
GHz)

N 50 or 75 1.30 (4) 1.5 kV Screw together (5 MHz at
sea level)

Z₀ (ohms) VSWR to proof RF (frequency voltage GHz)

BNC 50 or 75 1.01 (1) 1 kV 1.30 (4) (5 MHz at sea level) TNC 50 or 75 As BNC As BNC

SMB 50 1.46 (4) 1.5 kV (At sea level. Cable dependent)

SMC 50 1.41 (4) As SMB 1.69 (10)

SMD 50 As SMB As SMB BT 43 75

7–16 50 1.3 2.7 (5 GHz) (connector)

PL259/ 50 – 500 (pk) SO239/
UHF 83

C 75 – – Miniature. Bayonet fitting

Miniature.
Robust screw together

Sub-miniature. Snap
together

Sub-miniature. Screw
together

Sub-miniature.

Push together Developed from
SMB range
for use in
telecomms
and data
transmission Suitable for
medium to
high power
applications
in the cellular
and broadcast
industries.
Screw
together
Non-constant
imp. High
VSWR makes
it unsuitable
for use above
144 MHz and
for extending
RF cables.
Very robust.
Screw
together
Bayonet fitting

Z₀ (ohms) VSWR to (frequency GHz)

F 50 –

proof RF voltage

–

Belling 50 – Lee

–

GR 50 1 MHz max. frequency –

Phono – – –

American
CCTV
connector
used on some 144 MHz
hand-portable transceivers. Plugs use
inner
conductor of cable as
centre pin

British TV
antenna
connector.
Aluminium versions may corrode when used outdoors

Constant imp. sexless
connector

American
connector for audio use

Examples of assembly instructions for co-axial RF connectors (by kind permission of M/ACOM Greenpar Ltd.)

Measuring instrument − a rule is shown, but better results are obtained by using a Vernier gauge
Stout trimming blade, suitable for cutting copper wire braid
Crimping tool Soldering iron
Side cutters, also for trimming braid
Spanner, of the relevant size for the connector
Small screwdriver

Hacksaw, sometimes appropriate for semi-rigid cable, although for repetitive operations a power trimmer should be considered