5
20-740/745
RF MULTIPLEXER MODULE
pickering
Section 1
20-740R.F. Multiplexer Module
1.1 Features
• Dual 8 to 1 Multiplexer with 2000MHz Bandwidth
• Configurable as 16 to 1 Multiplexer
• Available in both 50 and 75ΩVersions
• Choice of Front Panel Mounted Connectors: BNC, SMA and Type N
• Automatic Termination of all Unselected Inputs
• Ideal Building Block for Large R.F. Switching Networks
• 75ΩVersion Suitable for Telecoms and Video Switching
1.1.1 Description
The20-740seriesarearangeofhighperformancedual8to1RFBi-DirectionalMultiplexerswithabandwidthof2000MHz,
available in 50 or 75Ωversions. All non-selected input lines are terminated into a matched load. This module may also
be configured (via DIP switches) as a 16 to 1 multiplexer but with reduced r.f. performance.
Applications include routing high frequency signals to and from oscilloscopes, analysers, signal generators and
synthesizers,video/audioswitching,switchinghighfrequencylogicandmanyothersituationsinvolvingcoaxialswitching.
All inputs are automatically terminated into matched loads (50 or 75Ω).
Larger multiplexer/matrix switching networks may be constructed by interconnecting individual modules, see section 4
for further details.
1.1.2 Operation
This module is factory configured as a dual 8 to 1 multiplexer, see fig 1.2. Performance figures are given in table 1.1.
However it may also be configured (using dip switches) as a 16 to 1 multiplexer. Please note that the R.F. performance
for this configuration is to a slightly reduced specification (please refer to table 1.3 for further details).
Self-Test is performed both at power up and at any other time either manually or under program control. In the unlikely
event of relay failure the front panel will indicate a fault. The diagnosis - including the position of the suspect relay - will
be indicated using the DIAGNOSTIC? command.
This is a double height module and must be mounted into a double height (6U) case.
1.1.3 Front Panel
The module front panels are illustrated in Section 6, they include:
Status Display, 4 LED Indicators:-
Power LED. Connected to power system supply.
Active LED. On whenever one or more switches are closed. For a list of all active switches use the VIEW?
command.
Self-Test LED. Active when self-test in progress.
Error LED. Indicates that error found during self-test.
Self-Test Button. Press to initiate a self-test. While in progress the “Self-Test” LED will be on, if a failure is detected
thenthe“Error”LEDwillbesetonpermanently. UsetheDIAGNOSTIC? command to find the exact cause of any failure,
refer to section 5 for further details. NB: Self-Test button will only respond when module is inactive.
1.1.4 20-740 Module Model Numbers
The following table lists the standard options available with the RF multiplexer module:-
Model Number Configuration Connector Impedance
20-740-501 Dual 8 to 1 MUX BNC 50Ω
20-740-511 Dual 8 to 1 MUX SMA 50Ω
20-740-521 Dual 8 to 1 MUX Type N 50Ω
20-740-701 Dual 8 to 1 MUX BNC 75Ω
Further connector types may be available (particularly 75Ω), please contact factory for further details.
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