TM9100 Service Manual
Transmitter Fault Finding (25W Radios)
337
© Tait Electronics Limited
August 2005
Task 13 —
Check Biasing
of First PA
Check the biasing of the first PA (Q310).
Important
Ensure that the current limit on the DC supply is 2 A.
And, when entering the CCTM command
331 x
, do not
specify a value
x
higher than that recorded in
Task 12
.
Failure to do so might result in the destruction of the PAs.
1.
Use a multimeter to measure the voltage at pin 14 of IC301
(see
Figure 12.9
). The voltage should be:
2.
Note the current reading on the DC power supply. As mentioned in
Step 7
of
Task 12
, this will be less than 500mA.
3.
Enter the CCTM command
331 x
(where
x
was recorded in
Task 12
).
4.
Check that the voltage changes to:
5.
Also note the current reading. This should increase by an amount
approximately equal to the offset given in
Table 12.6
.
6.
If the voltage and current are both correct, go to
Step 7
. If the voltage
is correct but not the current, go to
Task 14
. If neither the current
nor the voltage is correct, go to
Task 15
.
7.
Enter the CCTM command
331 1
to switch off final bias 1, and go to
Task 16
.
pin 14 of IC301: < 100mV (initially)
pin 14 of IC301: 2 to 5V (after entry of CCTM 331
x
)
Table 12.6
Gate biases for the PAs and PA driver at high power
Frequency band
Offset currents in mA
First PA
Second PA
PA driver
B1
750
750
300
H5
1000
1000
450
H6
1000
1000
450
Summary of Contents for TM9100
Page 1: ...TM9100 mobiles Service Manual MMA 00017 01 Issue 1 August 2005 ...
Page 4: ...4 TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 10: ...10 TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 22: ...22 Introduction TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 62: ...62 Description TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 96: ...96 TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 138: ...138 Disassembly and Reassembly TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 152: ...152 Servicing Procedures TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 168: ...168 Interface Fault Finding TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 244: ...244 Receiver Fault Finding TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 396: ...396 CODEC and Audio Fault Finding TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 420: ...420 Fault Finding of Control Head TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 426: ...426 Spare Parts TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 430: ...430 TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 444: ...444 TMAA04 05 Ignition Sense Kit TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 448: ...448 TMAA10 01 Desktop Microphone TM9100 Service Manual Tait Electronics Limited August 2005 ...