Yaesu VR-120D, Техническое дополнение

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7
Alignment
Introduction
The VR-120D has been carefully aligned at the
factory for the specified performance across the
amateur band. Realignment should therefore not
be necessary except in the event of a component
failure. All component replacement and service
should be performed only by an authorized Vertex
Standard representative, or the warranty policy may
be voided.
The following procedures cover the sometimes
critical and tedious adjustments that are not
normally required once the transceiver has left the
factory. However, if damage occurs and some parts
are replaced, realignment may be required. If a
sudden problem occurs during normal operation,
it is likely due to component failure; realignment
should not be done until after the faulty component
has been replaced.
We recommend that servicing be performed only
by authorized Vertex Standard service technicians
who are experienced with the circuitry and fully
equipped for repair and alignment. Therefore, if a
fault is suspected, contact the dealer from whom
the transceiver was purchased for instructions
regarding repair. Authorized Vertex Standard
service technicians realign all circuits and make
complete performance checks to ensure compliance
with factory specifications after replacing any faulty
components. Those who do undertake any of the
following alignments are cautioned to proceed at
their own risk. Problems caused by unauthorized
attempts at realignment are not covered by the
warranty policy. Also, Vertex Standard must reserve
the right to change circuits and alignment
procedures in the interest of improved performance,
without notifying owners. Under no circumstances
should any alignment be attempted unless the
normal function and operation of the transceiver
are clearly understood, the cause of the malfunction
has been clearly pinpointed and any faulty
components replaced, and the need for realignment
determined to be absolutely necessary.
Required Test Equipment
The following test equipment (and thorough
familiarity with its correct use) is necessary for
complete realignment. Correction of problems
caused by misalignment resulting from use of
improper test equipment is not covered under the
warranty policy. While most steps do not require
all of the equipment listed, the interactions of some
adjustments may require that more complex
adjustments be performed afterwards. Do not
attempt to perform only a single step unless it is
clearly isolated electrically from all other steps. Have
all test equipment ready before beginning, and
follow all of the steps in a section in the order
presented.
r RF Signal Generator with calibrated output level
at 1300 MHz
r Deviation Meter
r Frequency Counter: ±0.1 ppm accuracy at 500
MHz
r
DC Voltmeter: high impedance
r AF Dummy Load: 8-Ohms, 1W
Note: Signal levels in dB referred to in this procedure
are based on 0 dBµ = 0.5 µV (closed circuit).
Alignment Preparation & Precautions
Correct alignment requires that the ambient
temperature in the repair shop be the same as that
of the receiver and test equipment, and that this
temperature be held constant between 20 °C and
30 °C (68° ~ 86° F). When the receiver is brought
into the shop from hot or cold air it should be
allowed some time for thermal equalization with
the environment before alignment. If possible,
alignments should be made with oscillator shields
and circuit boards firmly affixed in place. Also, the
test equipment must be thoroughly warmed up
before beginning.