User Manual

30
Mini-RFM - Reference Guide November ’00
5.6.4 Tuning Procedure
Ensure that the reader is switched OFF.
Connect the antenna to the RF Module.
Remove all jumpers from the tuning connector ST2 and connect the “Switch Box”
with all six switches in the OFF position.
Switch the RF module transmitter ON (continuous or fast reading mode).
While watching the current meter, increase tuning capacity with the “Switch Box”
step-by-step until you find a peak.
When you find a peak continue with two more steps and check in case you find an-
other, higher peak. Looking for a possible second peak is necessary because the ca-
pacitors of the tuning network have overlapping capacitance, which causes
discontinuous capacitance steps.
Check if the power stage supply current or the field strength has the correct value for
that application.
Switch the transmitter OFF, disconnect the switch box and then plug-in jumpers at
all the places where the switches are in the ON position.
Switch ON the equipment again and check if the current or field strength are almost
the same as they were with the switch box connected.
Switch OFF the transmitter or reading unit. Tuning is completed.
WARNING:
C
ARE MUST BE TAKEN WHEN HANDLING THE
M
INI
-RFM. H
IGH
VOLTAGE
ACROSS THE ANTENNA TERMINALS AND TUNING CONNEC
-
TORS COULD BE HARMFUL TO YOUR HEALTH
. I
F THE ANTENNA
INSULATION
IS DAMAGED IT MUST NOT BE CONNECTED TO THE
M
INI
-RFM.
Note:
If you are using a switch box, do not forget that the capacitors
attached to the jumpers are binary weighted, and that you should set
the switches in a binary way:
Switch 1 ON
Switch 1 OFF Switch 2 ON
Switch 1 ON Switch 2 ON
Switch 1 OFF Switch 2 OFF Switch 3 ON
and so on.