TK-8108H
33
If normal power is not obtained, please follow the
step below
Open the shielding cover (upper), and screw 3 locations
around ANT pin.
1. Switch off the transceiver.
Impedance of Final FET (Q504) and Drive FET (Q503) can
be measured easily using DVM
Ω
mode.
Normal condition – Gate : 20k
Ω
~50k
Ω
, Drain : 1M
Ω
~2M
Ω
The above impedance values are rough estimations.
2. Switch on the transceiver. Check the voltage at R823 out-
put point.
The voltage is around 13.6V in receiving condition. The
voltage will be 12.6V~ in transmitting condition.
3. Remove R525.
4. Connect 50
Ω
load at the ANT location.
Transmit and check current drain at High power mode.
If the current drain is less than 1A, then Final FET is bro-
ken.
If the current drain is less than 5.0A, short the Drive FET
gate to ground, and check the current drain.
If the current drain is not 0.1A less than the original value,
then the Drive FET is broken.
5. Check input power level at Drive FET gate location.
Connect the wire to [RF] location.
Transmit and check for power to be within the range of
0.7W~1W.
If power found is less than 0.5W, check the circuit before
the Drive FET.
Item
Condition
Test equipment
Terminal
Parts
Method
Specifications/
Remarks
Measurement
Adjustment
ADJUSTMENT
5. DQT
1) CH : TX low (Wide)
Modulation analyzer
ANT
PC key
Adjust the waveform as below
balance
CH : TC center (Wide/Narrow)
or Linear detector
CH : TX high (Wide)
(LPF : 3kHz)
2) Transmit
Oscilloscope
6. MAX
1) CH : TX low (Wide)
Modulation analyzer
ANT
±
4.0kHz (Wide)
±
50Hz
balance
CH : TC center (Wide/Narrow)
or Linear detector
MIC
±
2.0kHz (Narrow)
CH : TX high (Wide)
(LPF : 15kHz)
According to the large +, –
2) AG : 1kHz/50mV
Oscilloscope
3) Transmit
AG
AF V.M
7. MIC
1) CH : TX center (Wide/Narrow)
Check
±
3kHz
±
0.2kHz
sensitivity 2) AG : 1kHz/5mV
(Wide)
3) Transmit
±
1.5kHz
±
0.1kHz
(Narrow)
8. DQT
1) CH : TX low (Wide)
Modulation analyzer
±
0.75kHz (Wide)
±
0.05kHz
deviation
CH : TX center (Wide/Narrow)
or Linear detector
±
0.35kHz (Narrow)
CH : TX high (Wide)
(LPF : 3kHz)
2) Transmit
Oscilloscope
9. QT
1) CH : TX low (Wide)
±
0.75kHz (Wide)
±
0.05kHz
deviation
CH : TX center (Wide/Narrow)
±
0.35kHz (Narrow)
CH : TX high (Wide)
2) Transmit
10. DTMF
1) CH : TX center (Wide/Narrow)
±
3.0kHz (Wide)
±
0.2kHz
/MSK
2) Transmit
±
1.5kHz (Narrow)
deviation