User Manual

November ’00 Chapter 5. Installation and Use

5.1 Mechanical Mounting

To protect the RF module from strong mechanical shock and vibration, grommets are

inserted into the mounting hole of the PCB as shown in Figure 9. Because the grom-

mets are made of soft material, eyelets or spacers must be inserted into them when

the RF module is mounted with screws.

Figure 9: PCB Mounting Proposal

5.2 Supply Voltage

The module uses two different supply lines each with a separate ground line. The re-

ceiver and the logic are supplied via the VSRL and GNDL pins from a voltage regu-

lated power supply. The transmitter power stage with its relatively high current

consumption is supplied via the VSP and GNDP pins. The supply voltage range for

VSP is wider than for VSL. This allows the direct connection of VSP to a four cell

NiCd battery, if the variation of the power pulse field strength caused by the variation

of the battery voltage is acceptable.

Both ground lines GNDL and GNDP are decoupled inside the RFM with the resistor

R_GND and the capacitor C_GND and have to be connected together externally as

shown in Figure 10 or Figure 11 (depending on your power supply). This technique

allows the power ground level GNDP to float in a certain range against the logic

ground level GNDL without creating adverse effects to the control signals from and

to the control unit. Floating GNDP can happen during transmit time if you are using

a long supply line between the RF module and a control module.

Note:

Take care when disconnecting ST1 that you pull the plug straight out

and do not apply any sideways strain to the plastic guides.