Yaesu FT-51R, Technical Supplement

Page: 15 / 83

The Ff-51R is carefully aligned at the factory for
the specified performance across the amateur band.
Realignment should therefore not be necessary ex­
cept in the event of a component failure. All compo­
nent replacement and service should be performed
only by an authorized Yaesu representative, or the
warranty policy may be void.
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 sub­
sequently 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 Yaesu service technicians who are ex­
perienced with the circuitry and fully equipped for
repair and alignment. Therefore, if a fault is sus­
pected, contact the dealer from whom the transceiver
was purchased for instructions regarding repair.
Authorized Yaesu service technicians realign all cir­
cuits and make complete performance checks to en­
sure 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 re­
alignment are not covered by the warranty policy.
Also, Yaesu reserves the right to change circuits and
alignment procedures in the interest of improved per­
formance, 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 realignment deter­
mined to be absolutely necessary.
The following test equipment (and thorough fa­
miliarity with its correct use) is necessary for com­
plete 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 re­
quire 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
FT-51R Technical Suoolement
beginning, and follow all of the steps in a section in
the order presented.
Required Test Equipment
D RF Signal Generator with calibrated
output level at 500 MHz
D
Deviation Meter (linear detector)
D
In-line Wattmeter with 5% accuracy
at 500 MHz
D
50-n RF Dummy Load
D 8-n AF Dummy Load
D Regulated DC Power Supply adjustable
from 3 to 12 VDC, 2A
D Frequency Counter: 0.2 ppm accuracy
at 500 MHz
D
AF Signal Generator
D
AC Voltmeter
D
DC Voltmeter: high impedance
0 VHF /UHF Sampling Coupler
0
SINAD Meter
Alignment Preparation & Precautions
A 50-Q dummy load and in-line wattmeter must
be connected to the main antenna jack in all proce­
dures that call for transmission, except where speci­
fied otherwise. Correct alignment is not possible with
an antenna.
After completing one step, read the following step
to determine whether the same test equipment will be
required. If not, remove the test equipment (except
dummy load and wattmeter, if connected) before pro­
ceeding.
Correct alignment requires that the ambient tem­
perature be the same as that of the transceiver and test
equipment, and that this temperature be held con­
stant between 20° and 30°C (68° - 86°F). When the
transceiver is brought into the shop from hot or cold
air, it should be allowed some time to come to room
temperature before alignment.
Whenever possible, alignments should be made
with oscillator shields and circuit boards firmly af­
fixed in place. Also, the test equipment must be thor­
oughly warmed up before beginning.
Note: Signal levels in dB referred to in the alignment
procedure are based on
0
dBµ=
0.5
µ
V.
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