Transmitter Precautions; Probe Precautions - Codan NGT 2010 RF Technical & Service Manual

Maintenance
Integrated circuit replacement
It is often possible to unsolder and remove components from the board without damage
to the component or the tracks on the board. However, ICs with many connections,
mounted on double-sided or multilayer circuit boards with plated thru-holes, are almost
impossible to remove intact and the operation is likely to damage the circuit boards. To
replace these components, their leads must be cut individually until the body of the
component can be removed. Individual leads must be unsoldered and removed. The
excess solder must be removed before inserting the replacement component (see
page 27,

Transmitter precautions

When making measurements of the low-level stages of the exciter, it is advisable to
remove the drive to the PA PCB. The supply voltage is applied to the PA at all times
when the transceiver is switched on.
CAUTION

Probe precautions

Observe the following when connecting oscilloscope probes to the transceiver:
CAUTION
28
Unsoldering).
Caution should be exercised when connecting probes to avoid incorrect
readings.
• When connecting probes to the PA assembly, the earth clip lead
should be wound around the body of the probe so that the earth clip
just reaches the probe tip. This reduces stray RF pick-up.
• The earth clip should be connected to the ground plane, adjacent to
the point of measurement.
• It is not advisable to connect two probes at the same time, particularly
when one is earthed to the PA ground plane and the other is earthed to
the exciter. This may cause earth loop problems.
• Probes should be connected after power has been applied to the
transceiver and the test equipment. The earth connection should be
made first and disconnected last.
NGT Transceiver System Technical Service Manual