Low Pass Filter And Directional Coupler Board - Tait TB8100 Service Manual

8.12

Low Pass Filter and Directional Coupler Board

Task 1 —
Visual Inspection
Task 2 —
Check Voltage
Levels
TB8100 Service Manual
© Tait Electronics Limited September 2006
These checks will verify that:
components are correctly placed and soldered
the correct voltage levels are present at selected test points.
Figure 8.14 on page 166
directional coupler board. Refer also to
test points and their associated voltage levels.
1. Check that the bridging links are correctly fitted to SK100.
2. Desolder the two tabs and remove the shield lid.
3. Check the board for any faulty solder joints, including the N-type
connector joint.
4. Check that the RF input coupling components are placed in the
correct location(s) on the board. These components are:
B, C, H and K bands
L band
Important
These components must be correctly placed, or the PA
may be damaged when it is keyed.
Figure 8.14 on page 166
and Table 8.4 on page 167
nents are correctly placed, go to
correctly as shown in
1. Set up the test equipment as shown in
PA) or Figure 8.9 on page 150
2. Power up the PA and check that the 10V regulated supply is present
at TP103 (or pin 3 of SK100). If it is, go to
to Step 3.
3. Check that the 10V regulated supply is present at pin 3 of SK108 on
the control board. If it is not, replace the control board. If it is, check
the continuity of the connector, and replace if necessary. Then repeat
Step 2.
4. Run the Service Kit and connect to the base station.
5. Put the base station in Run Mode and key the PA using the TX KEY
switch on the CTU.
6. Measure the forward power analogue voltage at TP101 (or pin 1 of
SK100). The voltage should be greater than 0.27V. If it is, go to
Step 7. If it is not, replace the LPF/directional coupler board.
shows the location of the test points on the LPF/
Table 8.5 on page 167
C109 or C110
R138/R139 or R145/R146.
shows the location of these components,
lists when they are fitted. If the compo-
Task 2. If they are not, place them
Figure 8.14 and go to
Figure 8.8 on page 149
(12V PA).
Power Amplifier Fault Finding
for a list of
Task 2.
(28V
Step 5. If it is not, got
165