Alignment - Yaesu FT-897 Technical Supplement

Alignment

Introduction and Precautions
The following procedures cover adjustments that are
not normally required once the transceiver has left the fac-
tory. However, if damage occurs and some parts subse-
quently be 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 by autho-
rized Vertex Standard service technicians, experienced with
the circuitry and fully equipped for repair and alignment.
If a fault is suspected, contact the selling dealer for in-
structions regarding repair. Authorized Vertex Standard
service technicians have the latest configuration informa-
tion, and realign all circuits and make complete perfor-
mance checks to ensure compliance with factory specifi-
cations after repairs.
Those who do undertake any of the following align-
ments are cautioned to proceed at their own risk. Prob-
lems 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, with-
out notifying owners.
Under no circumstances should any alignment be at-
tempted unless the normal function and operation of the
transceiver are clearly understood, the cause of the mal-
function has been clearly pinpointed and any faulty com-
ponents replaced, and the need for realignment determined
to be absolutely necessary.
The following test equipment (and thorough familiar-
ity with its correct use) is necessary for complete realign-
ment. Most steps do not require all of the equipment listed,
but the interactions of some adjustments may require that
more complex adjustments be performed in a sequence.
Do not attempt to perform only a single step unless it is
clearly isolated electrically from all other steps. Rather,
have all test equipment ready before beginning, and fol-
low all of the steps in a section in the order they are pre-
sented.
10
Required Test Equipment
Digital DC Voltmeter (high-Z, 1 M-Ohm/V)
DC Ammeter
RF Millivoltmeter
AC Voltmeter
RF Standard Signal Generator w/calibrated output and
dB scale, 0 dBμ = 0.5μV
Signal Generator with calibrated output
Spectrum Analyzer good to at least 1 GHz.
Frequency Counter
50-Ohm Dummy Load (200 watts)
100-Ohm Dummy Load (200 watts)
150-Ohm Dummy Load (200 watts)
In-Line Wattmeter (200 watts, 50-Ohm)
Linear Detector
RF Coupler
Alignment Preparation & Precautions
A 50-ohm RF Dummy load and in-line wattmeter must
be connected to the main antenna jack in all procedures
that call for transmission, except where specified other-
wise. 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 re-
quired. If not, remove the test equipment (except dummy
load and wattmeter, if connected) before proceeding.
Correct alignment requires that the ambient tempera-
ture be the same as that of the transceiver and test equip-
ment, 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
time to come to room temperature before alignment.
Whenever 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.
Note:Signal levels in dB referred to in this procedure are
based on 0 dBμ = 0.5 μV (closed circuit).