TM8100/TM8200 Service Manual
Receiver Fault Finding
239
© Tait Electronics Limited
June 2006
10
Receiver Fault Finding
Fault Conditions
This section covers the diagnosis of faults in the receiver. The fault-diagnosis
procedures consist of 18 tasks grouped into the following sections.
The symptoms of the fault in the receiver circuitry determine which
sections are relevant:
■
■
“Excessive Loss of Sensitivity”
■
“Moderate or Slight Loss of Sensitivity”
■
■
■
If the receiver sensitivity is low, begin with
“Faulty Receiver Sensitivity” on
to determine the extent of the loss in sensitivity.
CCTM Commands
The CCTM commands required are listed in
. Full details of the
commands are given in
“Computer-Controlled Test Mode (CCTM)” on
Frequency Bands
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’.
The product-code label on the radio body will identify the frequency band
as described in
. A definition of frequency
bands is given in
“Defining Frequency Bands” on page 126
Table 10.1
CCTM commands required for the diagnosis of faults in the receiver
Command
Description
72
Read lock status of RF PLL, FCL and LO2 — displays
xyz
(0=not in lock, 1=in lock)
101
x
y
0
Set transmit frequency (
x
in hertz) and receive frequency (
y
in hertz) to specified values
376
Read tuning voltage for front-end circuitry — displays voltage
x
in millivolts
378
Read signal power at output of channel filter — displays power
x
(square of amplitude
Summary of Contents for TM8235
Page 1: ...TM8100 mobiles TM8200 mobiles Service Manual MMA 00005 04 Issue 4 June 2006...
Page 10: ...10 TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 62: ...62 Description TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 148: ...148 Disassembly and Reassembly TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 162: ...162 Servicing Procedures TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 178: ...178 Interface Fault Finding TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 258: ...258 Receiver Fault Finding TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 446: ...446 Spare Parts TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
