Alignment - Vertex Standard VXR-7000 Service Manual

Alignment

The VXR-7000 is carefully aligned at the factory for
the specified performance across the entire operating fre-
quency range. Realignment should therefore not be nec-
essary except in the event of a component failure. All com-
ponent replacement and service should be performed only
by an authorized Vertex Standard 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 repeater has left the factory. However, if damage oc-
curs and some parts subsequently are placed, realignment
may be required. If a sudden problem occurs during nor-
mal operation, it is likely due to component failure; re-
alignment should not be done until after the faulty com-
ponent 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 re-
pair and alignment. Therefore, if a fault is suspected, con-
tact the dealer from whom the repeater 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 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 Stan-
dard reserves 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
repeater 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.
The following test equipment (and thorough familiari-
ty with its correct use) is necessary for complete realign-
ment. Correction of problems caused by misalignment re-
sulting from use of improper test equipment is not cov-
ered 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.
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Required Test Equipment
RF Signal Generator with calibrated output level at
1,000 MHz
Deviation Meter (linear detector)
In-line Wattmeter with 5% accuracy at 1,000 MHz
50 Ω RF Dummy Load with power rating 100W at
1,000MHz
4 Ω AF Dummy Load
Frequency Counter with 0.2ppm accuracy at
1,000MHz
AF Signal Generator
AC Voltmeter
DC Voltmeter: High input impedance
VHF Sampling Coupler
SINAD Meter
IBM PC/compatible Computer with MS-DOS or lat-
er operating system
Yaesu VPL-1 Connection Cable & CE27 Channel/
Alignment Diskette
Alignment Preparation & Precautions
A 50 Ω RF Dummy Load and in-line wattmeter must
be connected to the TX antenna jack in all procedures that
call for transmission, except where specified 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 re-
quired. If not, remove the test equipment (except dummy
load and wattmeter, in connected) before proceeding.
Correct alignment requires that the ambient tempera-
ture be the same as that of the repeater and test equipment,
and that this temperature be held constant between 68° ~
86 °F (20° ~ 30 °C). When the repeater 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 the alignment pro-
cedure are based on 0dBµ = 0.5µV. (closed circuit)