Tait TM8100 mobiles Service Manual page 342

Frequency Bands
Emergency
Frequencies
Can Removal
Can Replacement
342 Transmitter Fault Finding (25W)
Where test procedures or figures differ according to the frequency band of
the radio, the frequency band is given in brackets. The frequency band may
be referred to as either 'VHF' (very high frequency) or 'UHF' (ultra high
frequency) or identified by the frequency sub-band, such as 'B1' or 'H7'.
For example:
RF output power: > 35W
current: < 8A (VHF), < 9A (UHF)
A definition of frequency bands is given in
page 131.
Table 12.2 Lowest, centre and highest frequencies in MHz
Lowest
Band
frequency
A4 66
B1 136
C0 174
D1 216
H5 400
H6 450
The following frequency ranges are reserved worldwide for use as maritime
emergency frequencies or by distress beacons:
B1 band: 156.8MHz ± 375kHz
■
D1 band: 243MHz ± 5kHz
■
H5 band: 406.0 to 406.1MHz.
■
Do not program the radio with any frequency in the above ranges.
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 board. In the case of the
cans, first detach the heat-transfer block from the board. Secure the
PAF TOP
block again after removing the cans. Follow the procedures given in
"Disassembly and Reassembly" on page
Replace all cans that have been removed only after repairing the board.
This applies to the A4, B1, C0, D1, H5 and H6 bands. For certain other
bands the transmitter will not operate correctly unless all the cans are fitted.
"Defining Frequency Bands" on
Centre Highest
frequency frequency
77 88
155 174
199.5 225
241 266
435 470
490 530
135.
TM8100/TM8200 Service Manual
© Tait Electronics Limited November 2007
and
PAD TOP