Specifications

Position feedback is often a
standard feature with Agilent
switches, because the construc-
tion of the switch drive signals
can also feed back information-
about the state of the switch.
D-sub socket connectors allow
for the easiest connection to
Y115x distribution boards.
There are other options than can
be purchased or specified for
switches/attenuators. Here are a
few that are worthy of comment:
• TTL/CMOS drive
• Solder lugs
• Current interrupts
The 34945EXT can drive switches
with TTL/CMOS control signals.
However, this option usually
adds cost to the switch, and it
forces all switches connected
to the Y115x to use the same
drive mode. Solder lugs may
appear to be cheaper with
some switches, but you should
consider the labor costs and
reliability. In many cases, the
standard configuration of the
switch is a D-sub connector,
so you may actually pay more
for solder lugs. And, finally,
current interrupts almost
always add cost to the switch.
They allow you to apply a con-
stant voltage to a switch, and
the switch actuates to create
its own pulsed mode to change
states. Current interrupts do
offer the fastest programming
time, because the switch actu-
ates as fast as it can rather
than the timed response of a
pulse-mode control circuit.
The Y115x distribution boards
are the interface between the
34945EXT and the switches/
attenuators. It is the 34945EXT
that actually performs all the
control and sensing operations.
The Y115x boards simply
provide cable headers and/or
screw terminals that interface
a large number of Agilent
switches and attenuators to
the 34945EXT.
Each 34945EXT can drive up
to 64 coils, where each of four
Y115x boards route the control
of relay coils, the position feed-
back, and the drive for external
LEDs for up to 16 coils. Some
devices require two or more coils
and provide varying ways of
indicating position feedback. The
Y115x boards handle all of those
signals for you. You need only
provide a simple ribbon cable
with standard socket connectors.
Let’s take a closer look at one
of the 34945EXT’s distribution
boards, so you can better
understand how to interface
to external switches and
attenuators. The image on the
following page shows a view of
the Y1153A Distribution board.
It is designed to control a wide
range of Agilent attenuators
and supports either a ribbon
cable/connector or screw
terminal connection.
Each LED socket header repre-
sents the state of up to eight
coils, and each vertical lead-pair
connects to the LED, representing
the section position. You can
route a ribbon cable with a
16-pin connector up to your
control panel viewing area.
Or, you can mount LED’s on
a socket connector and plug
them directly into the socket
header on the board.
Relay control and position
feedback is provided in either
a socket header or with screw
terminals for the Y1153A. Most
of the Y115x boards have socket
headers for easy connection to
Agilent switches and attenuators.
Pulse drive, coil voltage, position
feedback, bandwidth, connectors,
and termination represent a
complex set of options in
selecting any switch. However,
this process is made easier by
first matching switches and
attenuators with the correct
Y115x distribution board.
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