Power And Current Are Skewed - Tait TM9100 Service Manual

If the RF output power and the supply current are skewed, the output
Task 9 —
Power and Current
matching is suspect.
Are Skewed
1.
2.
3.
4.
5.
6.
7.
8.
9.
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13.
14.
266 Transmitter Fault Finding (50W/40W Radios)
Remove the can.
DIRC TOP
Remove the coupling capacitors C348, C349 and C350 —
see Figure 11.8 (B1) and
Solder one terminal of an 82 pF (H5, H7 bands) or 680 pF (B1) test
capacitor to the PCB at the point shown in
Figure 11.9. Mount the capacitor vertically. Use a test capacitor of
the type GRM111, DLI C17, Murata 1210, or the equivalent.
Solder a 50 Ω test lead to the PCB. Solder the outer sheath to the test
pad shown in Figure 11.8
wire to the other terminal of the test capacitor.
Connect the test lead to the test set.
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.
Enter the CCTM command 33 to place the radio in transmit mode.
Note the RF output power measured by the test set, and note the
current reading on the DC power supply.
RF output power: > 70W (VHF), > 60W (UHF)
current: < 15A (VHF), < 12A (UHF)
Enter the CCTM command 32 to place the radio in receive mode.
Program the radio with the center frequency in the band: Enter the
CCTM command 101 x x 0, where x is the frequency in hertz.
Repeat Step 7 to Step 9.
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.
Repeat Step 7 to Step 9.
If the power and current are still skewed, go to
and current are correct, remove the test lead and test capacitor,
resolder the coupling capacitors in position, and go to
PIN switch and LPF require checking.
Figure 11.9 (H5, H7).
Figure 11.8
and Figure 11.9, and solder the central
Task
TM9100 Service Manual
© Tait Electronics Limited August 2005
and
10. If the power
Task 33 — the