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CCP-33D Page 5

CCP-33D\072013\Q3

Series CCP-33D

Low PIM DC–3 GHz

Failsafe SPDT Coaxial Switch

COAX SWITCHES

Actuator

An actuator is the electromechanical mechanism that

transfers the RF contacts from one position to another upon

DC command.

Arc Suppression Diode

A diode is connected in parallel with the coil. This diode

limits the “reverse EMF spike” generated when the coil de-

energizes to 0.7 volts. The diode cathode is connected to

the positive side of the coil and the anode is connected to

the negative side.

Date Code

All switches are marked with either a unique serial number

or a date code. Date codes are in accordance with MIL-

STD-1285 Paragraph 5.2.5 and consist of four digits.

The first two digits define the year and the last two digits

define the week of the year (YYWW). Thus, 1032 identifies

switches that passed through final inspection during the

32nd week of 2010.

Failsafe

A failsafe switch reverts to the default or failsafe position

when actuating voltage is removed. This is realized by a

return spring within the drive mechanism. This type of switch

requires the continuous application of operating voltage to

select and hold any position. (Multi-position switches are

normally open with no voltage applied).

Indicator

Indicators tell the system which position the switch is in.

Other names for indicators are telemetry contacts or tellback

circuit. Indicators are usually a set of internally mounted DC

contacts linked to the actuator. They can be wired to digital

input lines, status lights, or interlocks. Unless otherwise

specified, the maximum indicator contact rating is 30 Vdc,

50 mA, or 1.5 Watts into a resistive load.

Isolation

Isolation is the measure of the power level at the output

connector of an unconnected RF channel as referenced to

the power at the input connector. It is specified in dB below

the input power level.

SPDT Switch

A single-pole double-throw, bi-directional switch that can

be used as having one input and two outputs or two inputs

and one output.

Switching Time

Switching time is the total interval beginning with the arrival

of the leading edge of the command pulse at the switch DC

input and ending with the completion of the switch transfer,

including contact bounce. It consists of three parts: (1)

inductive delay in the coil, (2) transfer time of the physical

movement of the contacts, and (3) the bounce time of the

RF contacts.

TTL Switch Driver Option

As a special option, switch drivers can be provided for both

failsafe and latching switches, which are compatible with

industry-standard low-power Schottky TTL circuits.

Performance Parameters vs Frequency

Generally speaking, the RF performance of coaxial switches

is frequency dependent. With increasing frequency, VSWR

and insertion loss increase while isolation decreases. All

data sheets specify these three parameters as “worst case”

at the highest operating frequency. If the switch is to be

used over a narrow frequency band, better performance

can be achieved.

Actuator Current vs Temperature

The resistance of the actuator coil varies as a function of

temperature. There is an inverse relationship between the

operating temperature of the switch and the actuator drive

current. For switches operating at 28 VDC, the approximate

actuator drive current at temperature, T, can be calculated

using the equation:

Magnetic Sensitivity

An electro-mechanical switch can be sensitive to ferrous

materials and external magnetic fields. Neighboring ferrous

materials should be permitted no closer than 0.5 inches and

adjacent external magnetic fields should be limited to a flux

density of less than 5 Gauss.

GLOSSARY

I

A

[1 + .00385 (T-20)]

Where:

I

T

= Actuator current at temperature, T

I

A

= Room temperature actuator current –

see data sheet

T = Temperature of interest in °C

I

T

=