HP 33304, 33305 schematic

Agilent
33304/5
Programmable
Step Attenuators

Data Sheet

Features and description

•

Rapid switching (less than 0.05 second)

•

High repeatability (0.05 dB typical)

•

Broadband (DC to 18 GHz)

•

Two ranges and step sizes

Discontinued Product Information

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2

The 33300 Programmable Step Attenuators provide a fast and precise means
for electrically controlling the level of signal attenuation in automatic test
systems, receivers, and other RF equipment. They provide attenuation up
to 110 dB in 1 or 10 dB steps over a frequency range of dc to 18 GHz.

The products are defined as:

Model no. Total attenuation Step size

dB dB
33304 11 1
33305 110 10

The 33300 series attenuators utilize a unique operating principle. Magnetic
latching solenoids are used to switch individual attenuation elements
(tantalum resistive films on sapphire substrates) into and out of contact
with a 50-ohm transmission line. Each unit is comprised of three or
four attenuation sections. By energizing the appropriate solenoid, any
combination of these sections may be put across the 50-ohm transmission
line to give the desired levels of attenuation.

The extreme stability of the sapphire tantalum attenuator pads, combined
with the elimination of sliding contacts, gives rise to a product that has as
number of important operational features. Among these are fast switching
speed, excellent repeatability, compact size, long life, and high stability.

Magnetic latching solenoids move the transmission line into and out of
contact with the sapphire attenuator elements. These solenoids are supplied
with coils for 24-volt operation. The 24-volt coil can be run at up to 30 volts.

Because the solenoids are of the latching type, power need not be
continuously maintained to keep the solenoid in either the in or the out
position. It is sufficient to pulse the solenoid for 30 milliseconds at its rated
voltage to change states. To change states the polarity across the terminals
must be reversed. However, both terminals are “floating,” so either can
be grounded. Thus, unipolar power supplies are sufficient for controlling
these units.

For switching speeds faster than 30 ms, this pulse voltage can be increased.
A maximum of double the rated voltage may be put across the solenoids
in such cases, but pulse width should be limited to keep average solenoid
power below 3.3 watts per section.

Indicator contacts, which allow the user to determine whether a given
section is engaged or not, can be included. These contacts are in their
open position when the appropriate attenuator cards are not engaged.
The contacts close, and remain closed, when the appropriate card moves
into contact with the transmission line.

The 33300 series is available with any combination of 3 mm, 7 mm or
Type N connectors. A three-digit code specifies these options. The first
digit is always 0. The second digit calls out port 1, the third, port 2.
See figure 2 for details.

Description