Maximizing Antenna Performance with the ATU
© 1999, AXCESS
TM
Inc.
750.001.003
Revised June 1999
75
Adjusting Performance with a Jumper ATU
When you open the ATU, the jumpers will be in the positions shown
in Figure 33. The goal is to set the jumpers so that largest voltage is
produced, as shown by the strength of the five LEDs.
Jumpers can be placed in one of two positions on a header:
Inactive
Active
1
1
Figure 32 Jumper positions on a header. Pin 1 is labeled.
Inactive
– jumper is placed on pins 1 and 2.
Active
- jumper is placed on pins 2 and 3.
The various headers control different types and numbers of
capacitors:
Jp1 through Jp9 – each header adds/removes a small
capacitor (0.01
µ
F) to/from the circuit.
Jp10 – adds/removes one big capacitor (0.1
µ
F) to/from the
circuit.
Jp11 – adds/removes two big capacitors to/from the circuit.
Step 1:
Ensure that all jumpers are placed in the
Inactive
position.
Step 2:
On header Jp1, place the jumper in the
Active
position
and watch the LEDs.
When tuned correctly, LEDs 1 through 4 will be strongly
strobing, and LED 5 will be flickering, showing a strong
signal. Make note of the jumper positions that create this
display.
Step 3:
On header Jp2, place the jumper in the
Active
position
and watch the LEDs for a strong signal.
Step 4:
One at a time, place the jumper in the Active position on
headers Jp3 through Jp9 and watch the LEDs for a strong
signal.
Step 5:
Place all jumpers in the
Inactive
position on all the
headers.
Step 6:
On header Jp10, place the jumper in the Active position.
Step 7:
One at a time, place the jumper in the Active position on
headers Jp1 through Jp9 and watch the LEDs for a strong
signal.