Transmit Tests; Secure Main-Board Asssembly; Ensure Proper Antenna Load; Limit Duration Of Transmit Tests - Tait TM9100 Service Manual

The following points need to be borne in mind when carrying out transmit

Transmit Tests

tests:
These points are discussed in more detail below.
Before conducting any transmit tests, ensure that the main-board assembly
Secure Main-Board
Assembly
is adequately secured in the chassis. This is essential if overheating of the
radio is to be avoided. (As mentioned earlier, the heat-transfer block must
already be secured to the main board of the assembly.) It is good practice to
secure the assembly by at least the two external screws and one of the
internal screws. The screws are labelled
There is no need, however, to secure the lid of the radio body.
The radio has been designed to operate with a 50Ω termination impedance,
Ensure Proper
Antenna Load
but will tolerate a wide range of antenna loading conditions. Nevertheless,
care should be exercised. Normally the RF connector on the main-board
assembly will be connected to the RF communications test set as shown in
Figure 4.2 on page
necessary, a 50Ω load may be used instead. Do not operate the transmitter
without such a load or without a connection to the test set. Failure to do so
might result in damage to the power output stage of the transmitter.
After setting the frequency and power level (if necessary), enter the CCTM
Limit Duration of
Transmit Tests
command 33 to perform a transmit test. This command places the radio in
transmit mode. After completing the measurement or check required,
immediately enter the CCTM command 32. This command returns the
radio to the receive mode. Restricting the duration of transmit tests in this
way will further limit the danger of overheating. The reason for this
precaution is that the transmit timers do not function in the CCTM mode.
Under certain circumstances the microprocessor can key on the transmitter.
Protect Against
Accidental
Ensure that all instruments are protected at all times from such accidental
Transmissions
transmissions.
Avoid thermal burns. Do not touch the cooling fins or underside of the
Avoid Thermal
and RF Burns
radio body when the transmitter is or has been operating. Avoid RF burns.
Do not touch the antenna or the RF signal path on the circuit board while
the transmitter is operating.
TM9100 Service Manual
© Tait Electronics Limited August 2005
secure main-board assembly

ensure proper antenna load

limit duration of transmit tests

protect against accidental transmissions
avoid thermal and RF burns
106. But for those tests where this connection is not
Transmitter Fault Finding (50W/40W Radios)
I E
and in Figure 5.3 on page 127.
247