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170 Frequency Synthesizer Fault Finding TM9100 Service Manual

9.1 Initial Checks

Types of checks There are two different types of initial checks, which are covered in the

following tasks:

■ Task 1: calibration checks

■ Task 2: lock status

Which, if any, of these tasks needs to be carried out depends on the

symptoms of the fault.

Symptoms of Fault The symptoms of the fault may be divided into three categories:

■ radio fails to power up and System error is displayed

■ Out of lock is displayed

■ radio is in lock but exhibits transmit or receive fault

In the first two cases the checks of Task 1 and Task 2 respectively are

required. In the last case there are several symptoms; these are listed below.

Transmit and

Receive Faults

A transmit or receive fault will be implied by one of the following

consequences:

■ radio fails to receive or receive performance is degraded

■ radio fails to enter transmit mode

■ radio exits transmit mode unexpectedly

■ radio enters transmit mode but fails to transmit

■ radio enters transmit mode but transmit performance is degraded

With a fault of this kind, neither of the initial tasks is required.

Fault diagnosis should begin with “Power Supplies” on page 173.

Summary To summarize, given the nature of the fault, proceed to the task or section

indicated below:

■ Task 1: system error

■ Task 2: lock error

■ “Power Supplies”: transmit or receive fault

The checks of Task 1 and Task 2 will indicate the section with which the

fault diagnosis should continue. Note that there are some differences in the

fault-diagnosis procedures, depending on whether the radio is a UHF (H5

and H6 bands) or VHF (B1 band) radio. The product-code label on the

radio body will identify the frequency band as described in “Product

Codes” on page 16.

Tait TM9100 Service Manual

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