C&M Systems

1:1 Downlink controller

Switch Operation:

The DNL-4 contains one coax switch. Its designation is S2 on the front panel.

Note that coax switches with manual override OR coax switches without manual override may be purchased. All Coax switches are Latching type with position indicators. Coax switches without manual override are less expensive.

The wave guide switch (not normally included) is external to the controller.
The S1 S2 combination of input and output switches are electrically ganged. This means that the position commands are sent out to the 2 switches at the same time, from the same source. Whenever the controller switches S1 to a position, the input coax switch that is internal to the controller will receive the same position command. That is why it is necessary for the wave guide switch and the coax switch to have the same switching voltage and polarity.

For most applications it is assumed that the operating voltage of the switches is between 20-30Vdc, with the switch common being “Negative”. That means that the command voltage is “positive”. The DNL-4 uses a 28Vdc supply for switch operation to reduce the effects of cable losses due to length and gauge of the switch cables being used.

Position Indicators are different.
Each of the 2 switches in the system have two position indicators (position 1 and position 2 indicators). Each of these indicators are independently displayed on the front panel. Under normal operation, both the input and output switches will always be in the same position. It should be noted that for automatic switching purposes, the position indicators from the waveguide switch are used by the controller to determine switching commands.

Should the input wave guide switch and output coax switch be in different positions, those positions will be displayed on the front panel.

All coax switches used are of the “Latching” type. This means that the switches maintain their position in the event of the controller being turned off.

All commands out to the switches are of a momentary nature. A command only exists for about 0.5 seconds. This facilitates the use of the mechanical override knobs that may be present on the switches.

All switches are 4 port devices. When a switch has a position, then two diagonally opposite leds should be lit on the front panel at the same time. A front panel switch display (the 4 leds), should always have 2 opposite leds lit. Of course if the switch is not connected, then all leds should be “off”.