Frequently Asked Questions

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Switch Notes:

Power Handling

Please refer to power chart. (INSERT LINK TO POWER CHART HERE) Please note that the power chart is representative of average power handling at sea level and ambient temperature. For applications that require operation at altitude or extended temperature, please contact factory for power deratings.


The “S” option is epoxy seal. The epoxy seal is rated to 95% non-condensing humidity.

The “T” option is tested at DKM over the -55⁰C & +85⁰C; if the units are used in the lab or controlled area then the T option is not required. The “T” option includes the epoxy “S” seal.

The “I” immersion seal is rated to 100% non-condensing humidity. Immersion proof switches shall be tested in accordance with method 104 of MIL-STD-202.


“TTL” stands for Transistor-Transistor Logic. This is basically a way of interfacing using electrical levels. There is TTL low logic, and TTL high logic. The most common for our customers is “TTL HI”, the “A” option. This option is different from a normal switch in that there are terminals on the enclosure for the high level voltage input and the low level voltage input, along with a separate terminal to apply the nominal voltage to the switch. As far as function, the “high level” requires an input of 2.4V-5V, and the “low level” has an input of 0V-0.8V. For example, applying 5V to terminal 1 closes the switch, and applying no voltage keeps the position open. (Non-TTL switches have the nominal voltage applied to the position for actuation) TTL is the easiest and most common logic method to control our switches.

“BCD” stands for Binary Coded Decimal. This logic is coded in binary according to the below table.

The number of bits determines the number of controls available. For example, the “0000” control may indicate position 1 open, while “0001” controls closing position 1, and so on.

TTL is not offered with Pulse Latching switches, Latching Self Cut-off is offered instead.

BCD is not offered with Pulse Latching switches, Latching Self Cut-off is offered instead.

Power Consumption

Current draw is dependent on nominal voltage and environment. The current draw at ambient temperature is listed on the sales drawing. For extended temperature values, please contact the factory for deratings.

Current draw from TTL line (A or S):

401, 411, 521: 400µA

Up to SP6T: 1.3mA

Up to SP12T: 2.6mA

Mechanical Indicators

Mechanical indicators let the user know if the switch is open or closed beyond the evidence that it is open or closed. Operationally it’s its own switch, so when the switch opens it opens the indicator, closed switch will indicate closed indicator.

Suggested Indicator Voltage: 5Vdc, 100mA max.

Hot Switching

Dow-Key commercial switches are not designed for hot switching, the contacts will degrade from the heat and losses/poor RF connection will result. Our Reliant product line is rated for hot switching up to 2W CW. For applications that require hot switching, contact the factory for a custom solution.


SPDT     5,000,000 hrs

DPDT    2,000,000 hrs

SP4T      500,000 hrs

SP8T      100,000 hrs

SP10T   50,000 hrs

SP12T    30,000 hrs

ESD Sensitivity Class: 3A

Suggested switch mounting spacing

DKM switches: 1/16 in

Transco Switches: 1/8 in