TM8100/TM8200 Service Manual
Transmitter Fault Finding (25W)
339
© Tait Electronics Limited
June 2006
Task 9 —
Power and Current
Are Skewed
If the RF output power and the supply current are skewed, the output
matching is suspect.
1.
Remove the
DIRC
TOP
can.
2.
Remove the coupling capacitors
C348
,
C349
and
C350
—
see
3.
Solder one terminal of a test capacitor to the PCB at the point shown
in
. Mount the capacitor vertically. Use a test capacitor
of the type GRM111, DLI C17, Murata 1210, or the equivalent.
The value of the capacitor depends on the frequency band of
the radio:
■
A4 — 100pF
■
B1, C0, D1 — 680pF
■
H5, H6 — 82pF.
4.
Solder a 50
Ω
test lead to the PCB. Solder the outer sheath in the
position shown in
, and solder the central wire to the
other terminal of the test capacitor.
5.
Connect the test lead to the test set.
6.
Program the radio with the highest frequency in the radio’s frequency
band: Enter the CCTM command
101
x
x
0
, where
x
is the frequency
in hertz.
7.
Enter the CCTM command
33
to place the radio in transmit mode.
8.
Note the RF output power measured by the test set, and note the
current reading on the DC power supply.
9.
Enter the CCTM command
32
to place the radio in receive mode.
10.
Program the radio with the centre frequency in the band: Enter the
CCTM command
101
x
x
0
, where
x
is the frequency in hertz.
11.
Repeat
12.
Program the radio with the lowest frequency in the band: Enter the
CCTM command
101
x
x
0
, where
x
is the frequency in hertz.
13.
Repeat
14.
If the power and current are still skewed, go to
. If the power
and current are correct, remove the test lead and test capacitor,
resolder the coupling capacitors in position, and go to
— the
PIN switch and LPF require checking.
RF output power: > 35W
current: < 8A (VHF), < 9A (UHF)
Summary of Contents for TM8235
Page 1: ...TM8100 mobiles TM8200 mobiles Service Manual MMA 00005 04 Issue 4 June 2006...
Page 10: ...10 TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 62: ...62 Description TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 148: ...148 Disassembly and Reassembly TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 162: ...162 Servicing Procedures TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 178: ...178 Interface Fault Finding TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 258: ...258 Receiver Fault Finding TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 446: ...446 Spare Parts TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
