Introduction And Precautions; Alignment Preparation & Precautions; Required Test Equipment - Yaesu FT-991A Technical Supplement

Introduction and Precautions

Realignment may be required after the components
have been replaced.
We recommend that authorized Yaesu Technicians,
who are experienced with the circuitry and fully
equipped to align our products, perform aligns.
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 poli-
cy.
The need for realignment should be determined to
be absolutely necessary.
The following test equipment (and a thorough fa-
miliarity with its correct use) is necessary for cor-
rect realignment. Most steps do not require all of
the equipment listed. The interactions of some ad-
justments may require that more complex adjust-
ments be performed in a sequence. Do not attempt
to perform only a single step unless it is clearly iso-
lated electrically from all other steps. Have all test
equipment ready before beginning, and follow all
of the steps in a section in the order they are pre-
sented.

Required Test Equipment

 RF Signal Generator
 AF Signal Generator
 Spectrum Analyzer good to at least 1 GHz.
 Frequency Counter
 SINAD Meter
 RF Millivoltmeter
 Electronic Load
 Digital DC Voltmeter (high-Z, 1 M-Ohm/V)
 DC Voltmeter
 DC Ammeter (23 A)
 Ohmmeter
 50-Ohm Dummy Load (100/200 watts)
 In-Line Wattmeter (150/300 watts, 50-Ohm)
 Linear Detector
 RF Coupler
 4-Ohm AF Dummy Load (3 watts)
 1/4-inch 3-contact Plug
Important Notice
Do not adjust the alignment menus that are not
mentioned in this manual.
Alignment Preparation & Precautions
A 50-ohm RF Dummy load and in-line wattmeter
must be connected to the ANT jack in all proce-
dures that call for transmission, except where spec-
ified 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 unneeded test
equipment before proceeding. (except the dummy
load and wattmeter).
Correct alignment requires that the ambient tem-
perature be maintained constant between 68 °F ~ 86
°F (20 °C ~ 30 °C). When the transceiver is brought
into the shop from a hot or cold environment, it
should be allowed time to come to room tempera-
ture before alignment. Also, the test equipment
must be thoroughly warmed up before beginning.
Whenever possible, alignments should be made
with oscillator shields and circuit boards firmly af-
fixed in place.
Note: Signal levels in dB referred to in this proce-
dure are based on 0 dBµ = 0.5 µV (closed cir-
cuit).
ALIGNMENT-1
Alignment
FT-99 Technical Supplement
1