Tektronix KEITHLEY 7712 User manual

Keithley Instruments
28775 Aurora Road
Cleveland, Ohio 44139
1-800-935-5595
tek.com/keithley
Model 7712 3.5 GHz 50 Ohm RF Module
Instructions for use with DAQ6510
077147700 / June 2018
*P07714700* 1
Introduction
The 7712 switching module offers a 50 Ω dual 1 × 4 multiplexer configuration with 10 rear-panel SMA
connectors. Multiple multiplexers can be cascaded to build scalable matrix and multiplexer systems for a large
number of devices under test and RF source/measurement instruments. One channel in each multiplex bank is
always closed to the corresponding OUT connector. The 3.5 GHz RF switching capability of the 7712 makes it
ideal for testing wireless modules operating in the 2.4 GHz and lower industrial, scientific, and medical (ISM)
radio bands.
Figure 1: Model 7712
Item shipped may vary from model pictured here.
The 7712 includes the following features:
▪3.5 GHz bandwidth
▪Dual 1 × 4 multiplexer configuration
▪Onboard switch closure counter
If you are using this switching module with the 2700, 2701, or 2750, please see Model 7711 and
7712 User's Guide, Keithley Instruments document number PA-818.

Model 7712 3.5 GHz 50 Ohm RF Module Instructions for use with DAQ6510
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Installation
Before operating an instrument with a switching module, verify that the switching module is
properly installed and the mounting screws are tightly fastened. If the mounting screws are
not properly connected, an electrical shock hazard may be present.
If you are installing two switching modules, it is easier to install one switching module into slot 2 first, then install
the second switching module into slot 1.
If you have a Keithley Instruments Model 2700, 2701, or 2750 instrument, you can use your existing
switching module in the DAQ6510. Follow the instructions in your original equipment documentation
to remove the module from the instrument, then use the following instructions to install it in the
DAQ6510. You do not need to remove wiring to the module.
For inexperienced users, it is recommended that you do not connect a device under test (DUT) and
external circuitry to the switching module. This allows you to exercise close and open operations
without the dangers associated with live test circuits. You can also set up pseudocards to experiment
with switching. Refer to "Pseudocards" in the Model DAQ6510 Data Acquisition and Multimeter
System Reference Manual for information on setting up pseudocards.
To prevent electric shock that could result in injury or death, never handle a switching
module that has power applied to it. Before installing or removing a switching module, make
sure the DAQ6510 is turned off and disconnected from line power. If the switching module is
connected to a DUT, make sure power is removed from all external circuitry.
If a card slot is unused, you must install slot covers to prevent personal contact with high
voltage circuits. Failure to install slot covers could result in personal exposure to hazardous
voltages, which could cause personal injury or death if contacted.
Before installing or removing a switching module, make sure the DAQ6510 power is turned
off and disconnected from line power. Failure to comply may result in incorrect operation and
loss of data in the memory.
Required equipment:
▪Medium flat-blade screwdriver
▪Medium Phillips screwdriver

Model 7712 3.5 GHz 50 Ohm RF Module Instructions for use with DAQ6510
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To install a switching module into the DAQ6510:
1. Turn off the DAQ6510.
2. Disconnect the power cord from the power source.
3. Disconnect the power cord and any other cables that are connected to the rear panel.
4. Position the DAQ6510 so you are facing the rear panel.
5. Use the screwdriver to remove the slot cover screws and the cover plate. Retain the plate and screws for
future use.
6. With the top cover of the switching module facing up, slide the switching module into the slot.
7. Press the switching module in firmly to make sure the switching module connector is connected to the
DAQ6510 connector.
8. Use the screwdriver to tighten the two mounting screws to secure the switching module to the mainframe.
Do not overtighten.
9. Reconnect the power cord and any other cables.
Remove a switching module
Before you remove a switching module or begin any testing, make sure that all of the relays are
open. Since some relays may be latched closed, you must open all of the relays before removing the
switching module to make connections. Additionally, if you drop your switching module, it is possible
for some relays to latch closed.
To open all channel relays, go to the CHANNEL swipe screen. Select Open All.
To prevent electric shock that could result in injury or death, never handle a switching
module that has power applied to it. Before installing or removing a switching module, make
sure the DAQ6510 is turned off and disconnected from line power. If the switching module is
connected to a DUT, make sure power is removed from all external circuitry.
If a card slot is unused, you must install slot covers to prevent personal contact with high
voltage circuits. Failure to install slot covers could result in personal exposure to hazardous
voltages, which could cause personal injury or death if contacted.
Before installing or removing a switching module, make sure the DAQ6510 power is turned
off and disconnected from line power. Failure to comply may result in incorrect operation and
loss of data in the memory.
Required equipment:
▪Medium flat-blade screwdriver
▪Medium Phillips screwdriver

Model 7712 3.5 GHz 50 Ohm RF Module Instructions for use with DAQ6510
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To remove a switching module from the DAQ6510:
1. Turn off the DAQ6510.
2. Disconnect the power cord from the power source.
3. Disconnect the power cord and any other cables that are connected to the rear panel.
4. Position the DAQ6510 so you are facing the rear panel.
5. Use the screwdriver to loosen the mounting screws that secure the switching module to the instrument.
6. Carefully remove the switching module.
7. Install a slot plate or another switching module in the empty slot.
8. Reconnect the power cord and any other cables.
Connections
The following information describes how to make connections to the switching module and define the channel
designations. A connection log is provided that you can use to record your connections.
Connection and wiring procedures in this document are intended for use by qualified
personnel only, as described by the types of product users in the Safety precautions (on
page 14). Do not perform these procedures unless qualified to do so. Failure to recognize and
observe normal safety precautions could result in personal injury or death.
Wiring procedure
The default closed channels are 1 and 5. At power-up, channels 1 and 5 are always closed. If you are using a
saved setup that calls for another channel to be closed, the switching module is switched to that channel after
the firmware has completed the power-on sequence. Therefore, the lowest channel is closed for at least a brief
time at power-up. You need to verify that nothing is connected to channels 1 and 5 that could be damaged.
The connectors on the switching module are standard SMA connectors. When making or breaking connections,
use a torque wrench to produce mating torque of 0.9 Nm (8 in. lb).
Do not exceed the maximum specifications for the 7712 switching module. Refer to the
specifications provided in the data sheet. Failure to recognize and observe normal safety
precautions could result in personal injury or death.
Do not touch live radio frequency (RF) conductors, even at low voltages. RF behaves
differently than DC or low frequency AC. Low voltage RF can cause severe burns. RF signals
spread out over body areas, generating substantial currents at the points of contact with RF
conductors.
Figure 2: 7712 switching module

Model 7712 3.5 GHz 50 Ohm RF Module Instructions for use with DAQ6510
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Make connections with the correct wire size. If BNC connections are required, use the SMA to BNC adapter
cables available as accessories.
All wiring must be rated for the maximum voltage in the system. For example, if 1000 V is
applied to the front terminals of the instrument, the switching module wiring must be rated
for 1000 V. Failure to recognize and observe normal safety precautions could result in
personal injury or death.
Configuration
The switching module has channels that are grouped into dual 1 ×4 multiplexers. The multiplexer allows one
channel of each set of four to be closed at a time (1 of 4 tree structure). Channels 1 and 5 are normally closed
to OUT A and OUT B, respectively.
Figure 3: Configuration schematic
Refer to Close and open channels (on page 10).
Expansion
One switching module configuration is a dual 1 × 4 multiplexer. A single switching module can also be
configured as a 4 × 4 blocking matrix. The switching module can be combined with additional modules to
further expand its multiplexing and matrix switching capabilities. Specifications may degrade when the
switching module is used in multiple module configurations. Refer to the following table for examples of
multiplexer and blocking matrix expansion.
Matrix and multiplex expansion
Multiplexer
Blocking Matrix
Number of
switching module
1 ×4
1 ×8
1 ×12
4 × 4
4 ×8
1
X
—
—
X
—
2
X
X
X
X
X

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Multiplexer examples
SP8T MUX
This example creates a 1 × 8 SP8T MUX (single-pole eight-throw multiplexer) using two switching modules.
Channels 1 and 2 are connected to OUT A and OUT B of the second switching module in slot two. Terminate
unused channels with a 50 Ω load.
The schematic is shown in the power-up state. Channels 1 and 5 are closed for slots 1 and 2. Grayed channels
are not used.
Figure 4: MUX 1 × 8 expansion

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SP12T MUX
To create a 1 × 12 SP12T MUX (single-pole 12-throw multiplexer) using two switching modules, channels 1
and 2 are connected to OUT A and OUT B of the second switching module in slot 2. Terminate unused
channels with a 50 Ω load.
The schematic is shown in the power-up state. Channels 1 and 5 are closed for slots 1 and 2. Grayed channels
are not used.
Channels 5 to 8 on the switching module in slot 1 correspond to crosspoint channels 9 to 12 of the 1 × 12
SP12T MUX in slot 2.
Figure 5: MUX 1 × 12 expansion
Channels 3 and 4 may also be connected to other banks that will create a 1 × 12 multiplexer.

Model 7712 3.5 GHz 50 Ohm RF Module Instructions for use with DAQ6510
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Single switching module 4 × 4 blocking matrix
This configuration provides a convenient way to connect four DUTs to four different test instruments. In this
configuration, channels 1 to 4 may be routed to channels 5 to 8. Use a short coaxial cable to connect OUT A to
OUT B.
The schematic is shown in the power-up state. Channels 1 and 5 are closed.
Figure 6: Single 4 × 4 blocking matrix
Measurement considerations
Termination of unused connectors
To minimize noise within the system, terminate unused channels with 50 Ω loads. If 50 Ω loads are not
available, terminating unused connectors with a cable may also reduce noise within the system.

Model 7712 3.5 GHz 50 Ohm RF Module Instructions for use with DAQ6510
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Power handling
The graph shows the maximum amount of power per channel that can be routed using the switching module
while maintaining proper digital multimeter accuracy. Power levels of up to 10 watts at frequencies greater than
200 MHz can be used, but this may cause measurement errors. For example, routing 10 watts of power at
1 GHz may cause the switching module to have an additional 6 µV offset uncertainty when measuring DC
voltages. The precision low-level circuitry may cause uncertainty of 30 µV. Move the switching module to slot 2
to reduce uncertainty.
Figure 7: Carry power versus frequency
Operation
This switching module cannot be included in scan lists.
Detailed information on how to close and open switching module channels is provided in the Model DAQ6510
Data Acquisition and Multimeter System Reference Manual. The following summarizes basic operation and
provides operating information specific to the switching module.

Model 7712 3.5 GHz 50 Ohm RF Module Instructions for use with DAQ6510
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Close and open channels
Careless multiple channel operation could create an electric shock hazard that could result in
severe injury or death. Improper operation can also cause damage to the switching modules
and external circuitry. Operating channels independently should be restricted to experienced
test engineers who recognize the dangers associated with multiple independent channel
closures. Do not attempt to perform this procedure unless qualified as described by the types
of product users in the Safety precautions (on page 14). Do not perform these procedures
unless qualified to do so. Failure to recognize and observe normal safety precautions could
result in personal injury or death.
Multiple channel operation provides direct control of the channels of one or two switching modules. OUT A
automatically switches as appropriate for channels 1 to 4 and OUT B automatically switches as appropriate for
channels 5 to 8 for each module. When you close two channels in a single module (one for OUT A and one for
OUT B), the appropriate channels will close; other channels or channels on other switching modules are not
affected by channel closures.
Performance verification
Do not attempt to perform this procedure unless qualified to do so, as described by the types
of product users in the Safety precautions (on page 14). Do not perform these procedures
unless qualified to do so. Failure to recognize and observe normal safety precautions could
result in personal injury or death.
The following tests verify the RF characteristics of the switching module. S-parameters are obtained by
measuring voltage standing wave ratio (VSWR) and insertion loss among the common output and channel.
The following equipment is recommended for the tests in this section:
▪Tektronix TTR506A Vector Network Analyzer (6 GHz)
▪Tektronix test port cables, Type-N(m) to Type-SMA(m), 1 m (012-1770-00)
▪Tektronix 3.5 mm SOLT mechanical calibration kit 0 to 32 GHz, Spinner BN 53 38 54 (CALMECH-35MM)
Prepare for verification
To prepare for verification:
1. Turn on the network analyzer and the DAQ6510 with the switching module installed.
2. Allow the analyzer to warmup for at least one hour.
3. Calibrate the network analyzer from 500 MHz to 3.5 GHz using the appropriate calibration kit. The
calibration routine should include a load, short, open, and pass-through procedure. Use SMA style
connectors in the calibration process.