3-4
3.6
Multiplexer expansion
3.6.1 Double T configuration
The simplest way to connect the three Model 7038 multi-
plexers together for expansion is to use the double "T" con-
figuration shown in Figure 3-1. Note that this configuration
results in a 1-of-12 multiplexer. Although this configuration
is useful in many applications, the ideal 75
Ω
characteristic
impedance will not be maintained. Consequently, VSWR
will increase, affecting card insertion loss, particularly at
higher frequencies. Also, considerable transmission path re-
flections will occur, an important consideration when
switching pulse signals.
Figure 3-1
"T" connector multiplexer expansion
3.6.2 Matrix expansion
The proper way to connect the three Model 7038 multiplex-
ers together is shown in Figure 3-2. Here, two of the three
outputs are connected together using short coaxial cables,
while the remaining output is connected to one of the other
multiplexer bank inputs. Note that this connection scheme
effectively forms a 4
×
4 matrix with a 4-input multiplexer on
one of the matrix rows. This method provides a convenient
way to connect seven DUTs to four different test instru-
ments. Also, this method maintains the proper 75
Ω
charac-
teristic impedance for optimum bandwidth and minimal
signal loss and reflections. Two jumpers are provided for
bank interconnect (CA-193-1A).
Figure 3-2
4
×
4 matrix/multiplexer connections
IN1
IN2
IN3
IN4
OUTA
IN5
IN6
IN7
IN8
OUTB
IN9
IN10
IN11
IN12
OUTC
Note: This configuration
will not maintain
75
Ω
characteristic
impedance.
Instrument
Model 7038
IN1
IN2
IN3
IN4
OUTA
IN5
IN6
IN7
IN8
OUTB
IN9
IN10
IN11
IN12
OUTC
Model 7038
CA-193-1A
Jumpers
Instrument
Connections
DUT
Connections
A. Connections
B. Matrix/Multiplexer Configuration
1
2
3
4
5
6
7
Power Meter
Spectrum
Counter
Network Analyzer
4x4 Matrix
4-Input Multiplexer
Model 7038
DUTs
Summary of Contents for 7038
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