Yaesu FT-250R, Техническое дополнение

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10
FT-250R Technical Supplement
Alignment
Introduction
The
FT-250R
is carefully aligned at the factory for the spec-
ified performance across the amateur band. Realignment
should therefore not be necessary except in the event of a
component failure. Only an authorized Vertex Standard
representative should perform all component replacement
and service, or the warranty policy may be void.
The following procedures cover the 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 like-
ly 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 au-
thorized Vertex Standard service technicians who are ex-
perienced with the circuitry and fully equipped for repair
and alignment. If a fault is suspected, contact the dealer
from whom the transceiver was purchased for instruc-
tions regarding repair. Authorized Vertex Standard ser-
vice technicians realign all circuits and make complete per-
formance checks to ensure compliance with factory spec-
ifications 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
reserves the right to change circuits and alignment proce-
dures in the interest of improved performance, without
notifying owners.
Under no circumstances should any alignment be attempt-
ed unless the normal function and operation of the trans-
ceiver are clearly understood, the cause of the malfunc-
tion has been clearly pinpointed and any faulty compo-
nents replaced, and realignment determined to be abso-
lutely necessary.
Required Test Equipment
The following test equipment (and familiarity with its use)
is necessary for complete realignment. Correction of prob-
lems caused by misalignment resulting from use of im-
proper test equipment is not covered under the warranty
policy. While most steps do not require all of the equip-
ment listed, the interactions of some adjustments may re-
quire that more complex adjustments be performed after-
wards.
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.
ˆ
RF Signal Generator with calibrated output level at 200
MHz
ˆ
Deviation Meter (linear detector)
ˆ
In-line Wattmeter with 5% accuracy at 200 MHz
ˆ
50-Ohm 10-W RF Dummy Load
ˆ
8-Ohm AF Dummy Load
ˆ
Regulated DC Power Supply adjustable from 3 to 16.5
VDC, 2A
ˆ
Frequency Counter: 0.2-ppm accuracy at 200 MHz
ˆ
AF Signal Generator
ˆ
AC Voltmeter
ˆ
DC Voltmeter: high impedance
ˆ
VHF Sampling Coupler
ˆ
SINAD Meter
Alignment Preparation & Precautions
A 50-Ohm RF load and in-line wattmeter must be con-
nected to the main antenna jack in all procedures that call
for transmission; alignment is not possible with an anten-
na. After completing one step, read the next step to see if
the same test equipment is required. If not, remove the
test equipment (except dummy load and wattmeter, if
connected) before proceeding.
Correct alignment requires that the ambient temperature
be the same as that of the transceiver and test equipment,
and that this temperature be held constant between 68 ~
86° F (20° ~ 30° C). 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 os-
cillator shields and circuit boards firmly affixed in place.
Also, the test equipment must be thoroughly warmed up
before beginning.
Note : Signal levels in dB referred to in the alignment pro-
cedure are based on 0dBµ = 0.5µV.