What requirements do I need to specify when I order a switch from SMI?
1.) Switch type (Waveguide or Coaxial) or both (Dual).
2.) Frequency range.
3.) Operating voltage.
4.) Waveguide flange type or coaxial connector type.
5.) Total quantity of indicator circuits and/or inhibit contacts.
6.) Outdoor or indoor use. (Sealed, Sheltered or Standard)
7.) Any special requirements or options.
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How do I specify a RoHS compliant switch?
List this requirement on the purchase order.
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What is a Sealed Switch?
A sealed switch can be mounted outdoors without any gross protection from atmospheric conditions.
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What is the difference between a Sealed switch and a Sheltered switch?
A sealed switch can be mounted outdoors directly exposed to atmospheric conditions (rain, snow, etc). A sheltered switch is not suitable for unprotected outdoor use. A sheltered switch can be mounted outdoors in a sheltered environment or hub, where the switch is not directly exposed to atmospheric conditions.
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What is the difference between a Latching switch and a Failsafe switch?
A latching switch will maintain a chosen RF path whether or not voltage is continuously applied to the actuator after switching is accomplished. Latching is less expensive, allows for manual override and has a greater MTBF (Mean Time Between Failure). 98% of all commercial switches are latching switches.

A failsafe switch always returns the RF path to the de-energized position when there is no voltage applied to the actuator. Failsafe switches require continuously applied voltage to the actuator in order to maintain the RF path in the energized position. Failsafe is more expensive, does not allow for manual override and has a lesser MTBF (Mean Time Between Failure). SMI provides 2% of all switches to its customers as failsafe switches.
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What are the benefits of a manual override?
The ability to change the switch positions (RF paths) even in the event of a power loss or actuator failure.
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What is the difference between a ‘T’ circuit and a ‘TA’ circuit?
The ‘T’ circuit has two separate TTL lines, one for each switch position.

The ‘TA’ circuit is more common. It has one line with logic. Switch position 1 has logic of ‘1’ and switch position 2 has logic of ‘0’.
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What are the differences between CPRG, CPRF, O-Ring and Plain Flanges?
CPRG flanges have a rectangular groove and a rectangular hole pattern.
CPRF flanges do not have a groove but have a rectangular hole pattern.
O-Ring flanges have a circular groove and a circular or square hole pattern.
Plain flanges do not have a groove but have a circular or square hole pattern.
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What is the frequency limit of a coaxial switch with type N connectors?
The frequency limit of a coaxial switch with type N connectors is 8 GHz.
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What if I have a switch not found on your website?
Contact us. We support all switches made by SMI since 1974.
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What are the typical operating and storage tepmerature ranges of your switches?
Our switches have a typical operating temperature range of -35°C to +65°C and a typical storage temperature range of -50°C to +85°C. We can design switches that exceed these ranges, please
contact SMI for details.
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