Tait TM9100 Service Manual

246 Transmitter Fault Finding (50W/40W Radios) TM9100 Service Manual
© Tait Electronics Limited August 2005
Frequency Bands
Some fault-diagnosis tasks require programming the radio with the lowest,
center or highest frequency in the radio’s frequency band. The relevant
frequencies for the different bands are listed in Table 11.2. Note that the
following frequency ranges are reserved worldwide for use by distress
beacons:
■ B1 band: 156.8MHz ± 375kHz
■ H5 band: 406.0 to 406.1MHz
Do not
program the radio with any frequency in the above ranges.
Can Removal There are five cans shielding the bulk of the transmitter circuitry:
■ PAD TOP
■ PAF TOP
■ DIRC TOP
■ PIN TOP
■ LPF TOP
To remove any can, first remove the main-board assembly from the chassis.
In the case of the
PAD TOP and PAF TOP cans, first detach the heat-transfer
block from the main board. Secure the block again after removing the cans.
Follow the procedures given in “Disassembly and Reassembly” on
page 123.
Can Replacement Replace all cans that have been removed only after repairing the board.
An exception is the B1 band, however, where the
LPF TOP can must be in
place if the transmitter is to operate correctly.
Table 11.2 Lowest, center and highest frequencies in MHz
Band
Lowest
frequency
Center
frequency
Highest
frequency
B1
H5
H7
136
400
450
155
435
485
174
470
520

Tait TM9100 Specifications

General

Brand	Tait
Model	TM9100
Category	Radio
Language	English