Yaesu FT-991A Manual

HF/VHF/UHF ALL MODE TRANSCEIVER
FT-991
Introduction
This manual provides the technical information necessary
for servicing the FT-991A HF/VHF/UHF ALL MODE
TRANSCEIVER.
Servicing this equipment requires expertise in hand-
ing surface-mount chip components. Attempts by non-
qualied persons to service this equipment may result
in permanent damage not covered by the warranty, and
may be illegal in some countries.
Two PCB layout diagrams provided for each double-
sided board in this transceiver. Each side of the board
is referred to by the type of the majority of components
installed on that side ("Side A" or "Side B"). In most
cases one side has only chip components, and the other
has either a mixture of both chip and leaded components
(trimmers, coils, electrolytic capacitors, ICs, etc.), or
leaded components only.
While we believe the information in this manual to be
correct, YAESU assumes no liability for damage that
may occur as a result of typographical or other errors
that may be present. Your cooperation in pointing out
any inconsistencies in the technical information would
be appreciated.
Important Note
This transceiver was assembled using Pb (lead) free solder, based on the RoHS specication.
Only lead-free solder (Alloy Composition: Sn-3.0Ag-0.5Cu) should be used for repairs performed on this apparatus. The solder stated
above utilizes the alloy composition required for compliance with the lead-free specication, and any solder with the above alloy com-
position may be used.
Caution
Risk of explosion if battery is replaced by an incorrect type. Dispose of used batteries according to the instructions.
Technical Supplement
EH067M90B
©2017 YAESU MUSEN CO., LTD.
Contents
Specications
Exploded View & Miscellaneous Parts
Block Diagram
Connection Diagram
Alignment
Board Unit (Schematics, Layouts & Parts)
MAIN Unit
PLL Unit
EDSP Unit
CNTL Unit
HF-PA Unit
V_U-PA Unit
PANEL Unit
TUNER Unit
JACK Unit
SCP Unit
DSP Unit

FT-991 Technical Supplement
Specications
SPECIFICATIONS-1
General
Rx Frequency Range: 30 kHz - 56 MHz, 118 MHz - 164 MHz, 420 MHz - 470 MHz (operating)
1.8 MHz - 54 MHz, 144 MHz - 148 MHz, 430 MHz - 450 MHz (specied
performance, Amateur bands only)
Tx Frequency Ranges: 1.8 MHz - 54 MHz, 144 MHz - 148 MHz, 430 MHz - 450 MHz (Amateur
bands only)
Frequency Stability: ±0.5 ppm (after 1 minute @+14 °F to +122 °F [–10 °C to +50 °C])
Operating Temperature Range: +14 °F to +122 °F (–10 °C to +50 °C)
Emission Modes: A1A (CW), A3E (AM), J3E (LSB, USB), F3E (FM), F7W (C4FM), F2D
Frequency Steps: 5/10 Hz (SSB, CW, & AM), 100 Hz (FM, C4FM)
Antenna Impedance: 50 Ohms, unbalanced
16.7 - 150 Ohms, unbalanced (Tuner ON, 1.8 MHz - 30 MHz Amateur
bands)
25 - 100 Ohms, unbalanced (Tuner ON, 50 MHz Amateur band)
Power Consumption (Approx.): Rx (no signal) 1.8 A
Rx (signal present) 2.2 A
Tx 23 A (HF/50 MHz 100 W)
15 A (144/430 MHz 50 W)
Supply Voltage: DC 13.8 V ± 15% (Negative Ground)
Dimensions (WxHxD): 9.0” x 3.2” x 10.0” (229 x 80 x 253 mm)
Weight (Approx.): 9.5 lbs (4.3 kg)
Transmier
Power Output: 5 - 100 was (2 - 25 was AM carrier)
Modulation Types: J3E (SSB): Balanced,
A3E (AM): Low-Level (Early Stage),
F3E (FM): Variable Reactance
F7W (C4FM): 4-level FSK
Maximum FM Deviation: ±5.0 kHz/±2.5 kHz
Harmonic Radiation: Beer than –50 dB (1.8 MHz - 30 MHz Amateur bands)
Beer than –63 dB (30 MHz Amateur band)
Beer than –60 dB (144 MHz, 430 MHz Amateur bands)
SSB Carrier Suppression: At least 50 dB below peak output
Undesired Sideband Suppression: At least 50 dB below peak output
Bandwidth: 3 kHz (LSB/USB), 500 Hz (CW), 6 kHz (AM), 16 kHz (FM/C4FM)
Audio Response (SSB): Not more than –6 dB from 300 to 2700 Hz
Microphone Impedance: 600 Ohms (200 to 10 kOhms)

FT-991 Technical Supplement
Specications
SPECIFICATIONS-2
Receiver
Circuit Type: SSB/CW/AM: Triple-conversion Superheterodyne
FM/C4FM: Double-conversion Superheterodyne
Intermediate Frequencies: 40.455 MHz
SSB/CW/AM: 69.450 MHz/9.000 MHz/24 kHz
FM/C4FM: 69.450 MHz/450 kHz
Sensitivity: SSB/CW (BW: 2.4 kHz, 10 dB S+N/N)
0.158 µV (1.8 - 30 MHz) (AMP 2 “ON”)
0.125 µV (50 - 54 MHz) (AMP 2 “ON”)
0.11 µV (144 - 148 MHz)
0.11 µV (430 - 450 MHz)
AM (BW: 6 kHz, 10 dB S+N/N, 30 % modulation @400 Hz)
5 µV (0.5 - 1.8 MHz) (AMP 2 “ON”)
1.6 µV (1.8 - 30 MHz) (AMP 2 “ON”)
1.25 µV (50 - 54 MHz) (AMP 2 “ON”)
FM (BW: 15 kHz, 12 dB SINAD)
0.35 µV (28 - 30 MHz) (AMP 2 “ON”)
0.35 µV (50 - 54 MHz) (AMP 2 “ON”)
0.18 µV (144 - 148 MHz)
0.18 µV (430 - 440 MHz)
There is no specication for frequency ranges not listed.
Squelch Sensitivity (TYP.): SSB/CW/AM
1.0 µV (1.8 - 30 MHz, 50 - 54 MHz) (AMP 2 “ON”)
1.0 µV (144 - 148 MHz, 430 - 450 MHz)
FM
0.35 µV (28 - 30 MHz, 50 - 54 MHz) (AMP 2 “ON”)
0.125 µV (144 - 148 MHz, 430 - 450 MHz)
There is no specication for frequency ranges not listed.
Selectivity: Mode –6 dB –60 dB
CW/RTTY/PKT 0.5 kHz or beer 750 Hz or less
SSB 2.4 kHz or beer 3.6 kHz or less
AM 6 kHz or beer 15 kHz or less
FM 12 kHz or beer 30 kHz or less (–50 dB)
Image Rejection: 70 dB or beer (1.8 MHz - 50 MHz Amateur bands)
60 dB or beer (144/430 MHz Amateur band)
Maximum Audio Output: 2.5 W into 4 Ohms with 10% THD
Audio Output Impedance: 4 to 8 Ohms (4 Ohms: nominal)
Conducted Radiation: Less than 4 nW
Specications are subject to change, in the interest of technical improvement, without notice or obligation,
and are guaranteed only within the amateur bands.

EXPLODED VIEW-1 FT-991 Technical Supplement
Exploded View
RA600120A
TOP CASE
R4150130
HANDLE END
R3520660A
HANDLE
RA089840A
SP NET
①
①
①
REF. YAESU P/N Description Qty.
①U31306007 OVAL HEAD SCREW M3X6B 8
②U24206001 BIND HEAD TAPTITE-B M2.6X6 12
③U31206007 OVAL HEAD SCREW M2.6X6B 4
④U31415007 OVAL HEAD SCREW M4X15B 2
Non-designated parts are available only as psrt of a designated assembly.
①
①
③
③
②
④
④
R7153663
HIMERON
RA6024400
PORON SHEET(6x25)
M4090229
SP 66S-A3627
RA131710A
SPONGE RUBBER(SP-CE)
RA0994000
PORON SHEET(151505)
RA6017300
SPONGE RUBBER(10x98)
RA6000700
SHIELD CASE COVER
RA1550600
SP HOLDER(H034M)
③
③
②
②②
②
②
②
②
②
②
①
①
①
②
RA6032500
DOUBLE FACE (19x9)
②
S5000260
LEAD CLAMP
RA6032300
HEATSINK
RA6046900
BLIND SHEET (0715)
RA6033500
GASKET (10x20)
RA6033500
GASKET (10x20)
RA123330A
SHEEET
RA0471500
ELEC. COND TAPE(C)

EXPLODED VIEW-2 FT-991 Technical Supplement
Exploded View
REF. YAESU P/N Description Qty.
①U31306007 OVAL HEAD SCREW M3X6B 9
②U20406007 BINDING HEAD SCREW M4X6B 2
③U30305002 FLAT HEAD SCREW M3X5NI 4
Non-designated parts are available only as psrt of a designated assembly.
RA600110A
BOTTOM CASE
S4000052
CASE LEG FF-004-AR791
R3100700A
FOOT
①
①
①
①
①
①
①
①①
②
②
R7153663
HIMERON
RA1236600
PORON SHEET(10X10t3)
RA6101700
GASKET(70x40)
RA6024400
PORON SHEET(6x25)
RA6000800
SHIELD CASE COVER
③
③
③
③
RA0423200
LOCK PLATE
RA6033500
GASKET (10x20)
RA089560A
GASKETW9H4L40
R0145630
STAND

EXPLODED VIEW-3 FT-991 Technical Supplement
Exploded View
①
①
RA6003400
LCD SPACER(57B)
JACK-UNIT
RA6025300
BLIND SHEET(9x28)
RA6025300
BLIND SHEET(9x28)
RA6107900
FRONT PANEL(PRT)
RA6018200
NAME PLATE
RA6003200
WINDOW(LED)
RA6003600
RUBBER KNOB(H057)
RA6003500
RUBBER KNOB(PWR)
RA1340000
LCD SPACER (A)
Q7000653
LCD MODULE
①
①
①
①
REF. YAESU P/N Description Qty.
①U24108001 BIND HEAD TAPTITE-B M2X8(3) 13
②U24206001 BIND HEAD TAPTITE-B M2.6X6 2
Non-designated parts are available only as psrt of a designated assembly.
PANEL-UNIT
①
①①
①
①
①
①
RA6004500
RUBBER RING(MAIN)
RA6004200
KNOB MAIN ASSY
RA152820A
WASHER(FELT)
RA1528400
WASHER(PE)
RA0979300
HOLDER(SPRING)
U9900211
WAVE WASHER WW-16011(SUS)
RA6004600
KNOB SKIRT
②
②
U70015001
PLAIN WASHER FW9X14X0.5
U62009001
VOLUME NUT 9X12X2
Q9001000
ROTARY ENCODER
RA6003700
KNOB ASSY(VOL)
RA6004000
KNOB ASSY (ENC)
ø1
ø2
ø1
ø2
ø1
ø2
ø1
ø2
J60800322
POT (w/ ø1, ø2)
Q9000996
ROTARY ENCODER (w/ ø1, ø2)
Q9000758
ROTARY ENCODER (w/ ø1, ø2)
RA6030000
GASKET(8x10)
RA6054500
PORON SHEET(10x3.5) (2 pcs)
RA6035100
LEAF SPRING

EXPLODED VIEW-4 FT-991 Technical Supplement
Exploded View
RA602550A
PORON SHEET (10x85)
RA602540A
PORON SHEET (10x115)
RA600030A
CHASSIS
RA1558800
GASKET(60x12)
RA6015300
GASKET(120x10)
EDSP-UNIT
CNTL-UNIT
DSP-UNIT
RA6001000
RUBBER PACKING
RA1391800
SPACER(DSP)
RA6000900
SHIELD CASE COVER
RA1499500
PORON SHEET(25x35)
①
①
②
②
③
①
①
①
①
REF. YAESU P/N Description Qty.
①U34206001 FLAT HEAD TAPTITE-B M2.6X6 6
②U24206001 BIND HEAD TAPTITE-B M2.6X6 10
③U24208007 BIND HEAD TAPTITE-B M2.6X8B 1
Non-designated parts are available only as psrt of a designated assembly.
②
②
②
②
②
②
②
②
RA0060200
SHIELD CASE
RA1559100
GASKET(5x12) (3 pcs)

EXPLODED VIEW-5 FT-991 Technical Supplement
Exploded View
RA6000400
DISPLAY PANEL
RA6049000
Thermal Conductive Pad
P1091158A (CE OFF)
P1090547 (CE ON)
CONNECTOR
P1091158A
CONNECTOR
S5000236 (CE ON)
LUG WASHER FOR MDR-2
RA0415200
GROUND PLATE (4 pcs)
RA6035100
LEAF SPRING
⑤
⑤
④
④
⑥
⑥
⑦
①
①
②
②
③
③
①
①
①
①
①
①
①
①
REF. YAESU P/N Description Qty.
①U24206001 BIND HEAD TAPTITE-B M2.6X6 26
②U24208007 BIND HEAD TAPTITE-B M2.6X8B 3
③U03310002 SEMS SCREW ASM3X10NI 8
④U03306002 PAN HEAD SCREW ASM3X6NI 4
⑤U04333007 SEMS SCREW HSM3X33B 4
⑥U24306001 BIND HEAD TAPTITE-B M3X6 4
⑦U04410002 SEMS SCREW HSM4X10NI 1
Non-designated parts are available only as psrt of a designated assembly.
②
③
③
S5000331
TERMINAL
④
④
③
③
③
③
①
①
①
①
①
①
①
①
①①
①
①①
①
①
①
⑤
⑤
S5000320
FAN GUARD
M2090052
FAN
⑥
⑥
RA6032400
Thermal Conductive Pad
HF-PA-UNIT
V_U-PA-UNIT
R0131680
SHIELD COVER
R0131670A
SHIELD CASE

EXPLODED VIEW-6 FT-991 Technical Supplement
Exploded View
RA6015400
GASKET(80x10)
MAIN-UNIT
RA1152200
SHIELD CASE(28x15)
RA0830300
SHIELD CASE(21X25)
RA0659300
SHIELD CASE
RA6002100
SHIELD PLATE
PLL-UNIT
RA6001700
SHIELD CASE COVER
REF. YAESU P/N Description Qty.
①U03306002 PAN HEAD SCREW ASM3X6NI 4
②U24206001 BIND HEAD TAPTITE-B M2.6X6 9
③U24306001 BIND HEAD TAPTITE-B M3X6 5
④U20205001 BINDING HEAD SCREW M2.6X5 3
⑤S5000414 SPACER QBSB2613E 3
Non-designated parts are available only as psrt of a designated assembly.
①
①
②
②
③
③
①
①
RA1152400
SHIELD CASE COVER
RA0830400
SHIELD CASE COVER
RA1152300
SHIELD CASE COVER
②
②
②
②
②
②
②
RA6025200
Thermal Conductive Pad
RA6025100
Thermal Conductive Pad
③
③
③
S5000260
LEAD CLAMP CC-1002
RA6032400
Thermal Conductive Pad
TUNER-UNIT
RA6110000
SHIELD CASE(21X25.5)
④
④④
⑤
⑤
⑤
SCP-UNIT
RA6108900
GASKET
RA6115000
GASKET

BLOCK DIAGRAM-1 FT-991 Technical Supplement
Block Diagram

CONNECTION DIAGRAM-1 FT-991 Technical Supplement
Connection Diagram

Alignment
ALIGNMENT-1 FT-991Technical 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 aempts 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 aempt
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 was)
 In-Line Wameter (150/300 was, 50-Ohm)
Linear Detector
RF Coupler
 4-Ohm AF Dummy Load (3 was)
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 wameter
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 wameter).
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 rmly af-
xed 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
ALIGNMENT-2 FT-991Technical Supplement
VDD Meter Adjustment
Connect the DC voltmeter to J4006 on the HF-
PA-Unit.
Press and hold in the [A=B], [A/B], and [FAST]
keys, while turning the radio on, to enter the
alignment mode.
Rotate the [MULTI] dial knob to select the
alignment menu item “01-01 VDD MTR”.
Press the [F(M-LIST)] key, then rotate the
[CLAR/VFO-B] knob so the VDD meter reading
is the same as the reading on the DC voltmeter
(13.8 V).
Press the [F(M-LIST)] key.
 Press and hold in the [MENU(SETUP)] buon
for one second to save the new seing and exit
the alignment mode.
COMP Meter Adjustment
Press and hold in the [A=B], [A/B], and [FAST]
keys, while turning the radio on, to enter the
alignment mode.
Rotate the [MULTI] Dial knob to select the
alignment menu item “22-02 COMP MTR
10dB”, then rotate the [CLAR/VFO-B] knob for
"10 dB" on the COMP meter.
Rotate the [MULTI] Dial knob to select the
alignment menu item “22-03 COMP MTR
20dB”, then rotate the [CLAR/VFO-B] knob for
"20 dB" on the COMP meter.
Rotate the [MULTI] Dial knob to select the
alignment menu item “22-04 COMP MTR
30dB”, then rotate the [CLAR/VFO-B] knob so
the COMP meter deects to full scale.
 Press and hold in the [MENU(SETUP)] buon
for one second to save the new seings and exit
the alignment mode.
J4006

Alignment
ALIGNMENT-3 FT-991Technical Supplement
VCO Adjustment
Connect the Digital DC voltmeter (high-Z) to
TP2002 on the PLL Unit.
Disconnect the coaxial cable from J2001 on the
PLL Unit, then connect the RF millivoltmeter to
pin 13 of J2001.
Press and hold in the [A=B], [A/B], and [FAST]
keys, while turning the radio on, to enter the
alignment mode.
Referring to the table below, select the ap-
propriate “Alignment menu item” using the
[MULTI] Dial knob per the chart right, and
adjust the listed components for the required
voltage, or confirm that the correct voltage is
present on each alignment menu item.
Alignment
Menu Item
Adjust /
Conrm DC voltmeter RF millivoltmeter
01-05 VCO1-HIGH
(TXI)
Adjust
L2004 5.1 V ±0.1 V At least 3 dBm
01-06 VCO1-LOW Conrm At least 0.3 V At least 3 dBm
01-07 VCO2-HIGH Adjust
L2005 5.1 V ±0.1 V At least 3 dBm
01-08 VCO2-LOW Conrm At least 0.6 V At least 3 dBm
01-09 VCO3-HIGH Adjust
L2006 4.1 V ±0.1 V At least 3 dBm
01-10 VCO3-LOW Conrm At least 0.4 V At least 3 dBm
01-11 VCO4-HIGH Adjust
TC2001 5.0 V ±0.1 V At least 3 dBm
01-12 VCO4-LOW Conrm At least 0.5 V At least 3 dBm
01-13 VCO5-HIGH Adjust
TC2002 5.0 V ±0.1 V At least 3 dBm
01-14 VCO5-LOW Conrm At least 0.8 V At least 3 dBm
Disconnect the RF millivoltmeter from J2001,
then re-connect the coaxial cable to J2001.
 Press and hold in the [MENU(SETUP)] buon
for one second to save the new seing and exit
the alignment mode.
TP2002
J2001
TC2001 TC2002L2006L2005L2004

Alignment
ALIGNMENT-4 FT-991Technical Supplement
2nd/3rd Local Oscillator Adjustment
Set the VFO-A frequency to 14.200 MHz in the
CW-USB mode.
Set the following controls as indicated:
[IPO] : AMP1
[ATT] : OFF
[NB] : OFF
[AGC] : AUTO
[RF GAIN] : Fully clockwise
3rd Local Level Adjustment
Connect the RF millivoltmeter to TP1024 on the
MAIN Unit.
Adjust T1029 on the MAIN Unit for maximum
deection on the RF millivoltmeter.
2nd Local Level Adjustment
Connect the RF millivoltmeter to TP1025 on the
MAIN Unit.
Adjust T1027, T1028, T1030, and T1033 on the
MAIN Unit for maximum deection on the RF
millivoltmeter.
TP1025
T1033
TC1006
TP1008
T1027
T1030
T1028
TP1005
TP1024
T1029

Alignment
ALIGNMENT-5 FT-991Technical Supplement
REF OSC Adjustment
Connect the frequency counter to TP1025.
Press and hold in the [A=B], [A/B], and [FAST]
keys, while turning the radio on, to enter the
alignment mode.
Rotate the [MULTI] Dial knob to select the
alignment menu item “01-04 REF FREQ”.
Rotate the [CLAR/VFO-B] knob so that the
frequency counter reading is “60.450000 ±4
Hz”.
Disconnect the frequency counter from TP1025.
 Press and hold in the [MENU(SETUP)] buon
for one second to save the new seing and exit
the alignment mode.
FM Local Oscillator Adjustment
Set the FM mode.
Connect the Digital DC voltmeter (high-Z)
TP1008 on the MAIN Unit.
Adjust TC1006 on the MAIN Unit for 3.6 V ±0.1
V on the Digital DC voltmeter.
Set the CW mode.
TP1008
TC1006
TP1025

Alignment
ALIGNMENT-6 FT-991Technical Supplement
1st Local Oscillator Adjustment
Connect the RF millivoltmeter to TP1005 on the
MAIN Unit.
Press and hold in the [A=B], [A/B], and [FAST]
keys, while turning the radio on, to enter the
alignment mode.
Rotate the [MULTI] Dial knob to select the
alignment menu item “02-01 Local 1.8”.
 Press and hold the PTT buon, then rotate the
[CLAR/VFO-B] knob so that the RF millivolt-
meter reading is “+10 dBm ±1 dBm”.
 Release the PTT buon.
Rotate the [MULTI] Dial knob to select the
alignment menu item “02-02 Local HFL”.
 Press and hold the PTT buon, then rotate the
[CLAR/VFO-B] knob so that the RF millivolt-
meter reading is “+10 dBm ±1 dBm”.
 Release the PTT buon.
Rotate the [MULTI] Dial knob to select the
alignment menu item “02-03 Local HFM”.
 Press and hold the PTT buon, then rotate the
[CLAR/VFO-B] knob so that the RF millivolt-
meter reading is “+10 dBm ±1 dBm”.
 Release the PTT buon.
Rotate the [MULTI] Dial knob to select the
alignment menu item “02-04 Local HFH”.
 Press and hold the PTT buon, then rotate the
[CLAR/VFO-B] knob so that the RF millivolt-
meter reading is “+10 dBm ±1 dBm”.
 Release the PTT buon.
Rotate the [MULTI] Dial knob to select the
alignment menu item “02-05 Local 50”.
 Press and hold the PTT buon, then rotate the
[CLAR/VFO-B] knob so that the RF millivolt-
meter reading is “+11.5 dBm ±0.5 dBm”.
 Release the PTT buon.
Rotate the [MULTI] Dial knob to select the
alignment menu item “02-06 Local 144”.
 Press and hold the PTT buon, then rotate the
[CLAR/VFO-B] knob so that the RF millivolt-
meter reading is “+10 dBm ±1 dBm”.
 Release the PTT buon.
Rotate the [MULTI] Dial knob to select the
alignment menu item “02-07 Local 430”.
 Press and hold the PTT buon, then rotate the
[CLAR/VFO-B] knob so that the RF millivolt-
meter reading is “+10 dBm ±1 dBm”.
 Release the PTT buon.
 Press and hold in the [MENU(SETUP)] buon
for one second to save the new seings and exit
the alignment mode.
Alignment
Menu Item RF millivoltmeter
02-01 Local 1.8 +10 dBm ±1 dBm
02-02 Local HFL +10 dBm ±1 dBm
02-03 Local HFM +10 dBm ±1 dBm
02-04 Local HFH +10 dBm ±1 dBm
02-05 Local 50 +11.5 dBm ±0.5 dBm
02-06 Local 144 +10 dBm ±1 dBm
02-07 Local 430 +10 dBm ±1 dBm
TP1005

Alignment
ALIGNMENT-7 FT-991Technical Supplement
MCF Adjustment (1)
Set the VFO-A frequency to 145.900 MHz in the
CW-USB mode.
Set the following controls as indicated:
[AGC] : AUTO
[RF GAIN] : Fully clockwise
Connect the AF millivoltmeter and 4 Ohm
dummy load to the EXT SP jack.
Connect the RF Signal Generator to the “144/430
MHz” ANT jack, then set the output level to +0
dBµ at the 145.900 MHz.
Adjust T1001, T1003 and T1025, T1026 on the
MAIN Unit in succession several times for
maximum deection on the AF millivoltmeter.
Note: If the S-meter deflects while adjusting,
reduce the RF Signal Generator output so
that the S-meter does not deect.
Set the FM mode.
Connect the SINAD meter and 4 Ohm dummy
load to the EXT SP jack.
Connect the RF Signal Generator to the “144/430
MHz” ANT jack, then set the output level to –9
dBµ at the 145.900 MHz with ±3.5 kHz devia-
tion FM modulation of a 1 kHz audio signal.
Adjust T1025 on the MAIN Unit in succession
several times for maximum deflection on the
SINAD meter.
Note: Do not adjust T1025 more than 180 degrees
rotation.
MCF Adjustment (2)
Set the VFO-A frequency to 439.900 MHz in the
CW-USB mode.
Set the following controls as indicated:
[AGC] : AUTO
[RF GAIN] : Fully clockwise
Connect the AF millivoltmeter and 4 Ohm
dummy load to the EXT SP jack.
Connect the RF Signal Generator to the “144/430
MHz” ANT jack, then set the output level to +0
dBµ at the 439.900 MHz.
Adjust TC1001 and TC1007 on the MAIN
Unit in succession several times for maximum
deection on the AF millivoltmeter.
Note: If the S-meter deflects while adjusting,
reduce the RF Signal Generator output so
that the S-meter does not deect.
T1025
T1026
T1001
T1003
TC1001
TC1007

Alignment
ALIGNMENT-8 FT-991Technical Supplement
IF Trap Adjustment
Set the VFO-A frequency to 51.900 MHz in the
CW-USB mode.
Set the following controls as indicated:
[IPO] : AMP2
[ATT] : OFF
[AGC] : AUTO
[RF GAIN] : Fully clockwise
Connect the AF millivoltmeter and 4 Ohm
dummy load to the EXT SP jack.
Connect the RF Signal Generator to the “HF/50
MHz” ANT jack, then set the output level to
+70 dBµ at the 69.450000 MHz.
Adjust T1017 on the MAIN Unit for minimum
deection on the AF millivoltmeter.
Note: If the S-meter deflects while adjusting,
reduce the RF Signal Generator output so
that the S-meter does not deect.
RF AGC Adjustment
Set the VFO-A frequency to 14.200 MHz in the
CW-USB mode.
Set the following controls as indicated:
[IPO] : AMP1
[ATT] : OFF
[AGC] : AUTO
[RF GAIN] : Fully clockwise
Connect the RF Signal Generator to the "HF/50
MHz" ANT jack, then set the output level to
+76dBµ at the 14.200 MHz.
Connect the Digital DC voltmeter (high-Z) to
TP1016 on the MAIN Unit.
Press and hold in the [A=B], [A/B], and [FAST]
keys, while turning the radio on, to enter the
alignment mode.
Rotate the [MULTI] Dial knob to select the
alignment menu item “03-03 RF-AGC HFM”.
Adjusting the [CLAR/VFO-B] knob so the Digi-
tal DC voltmeter reading is "2.6 V ±0.2 V".
Set to the same parameter of the alignment
menu item “03-03 RF-AGC HFM” for the Align-
ment Menu items “03-01 RF-AGC 1.8”, “03-02
RF-AGC HFL”, “03-04 RF-AGC HFH”, “03-05
RF-AGC 50”, “03-06 RF-AGC 144” and “03-07
RF-AGC 430”
 Press and hold in the [MENU(SETUP)] buon
for one second to save the new seing and exit
the alignment mode.
T1017
TP1016

Alignment
ALIGNMENT-9 FT-991Technical Supplement
IF Gain Adjustment
Set the following controls as indicated:
[IPO] : AMP1
[ATT] : OFF
[AGC] : AUTO
[RF GAIN] : Fully clockwise
Connect the AF millivoltmeter and 4 Ohm
dummy load to the EXT SP jack.
Connect the RF Signal Generator to the “HF/50
MHz” ANT jack, then set the output level to
+36 dBµ at 1.900 MHz.
Set the VFO-A frequency to 1.900 MHz in the
USB mode.
Press and hold in the [A=B], [A/B], and [FAST]
keys, while turning the radio on, to enter the
alignment mode.
Adjust the [AF GAIN] knob so that the AF mil-
livoltmeter reading is “0 dB”.
Set the RF Signal Generator output level to +10
dBµ.
Adjust the [CLAR/VFO-B] knob so that the AF
millivoltmeter reading is “-1.5 ± 0.5 dB”.
Select the appropriate “Alignment menu item”
using the [MULTI] Dial knob per the chart be-
low, then set the RF Signal Generator output to
each frequency & level, and adjust the [CLAR/
VFO-B] knob for the corresponding AF milli-
voltmeter reading at each frequency.
 Press and hold in the [MENU(SETUP)] buon
for one second to save the new seings and exit
the alignment mode.
Alignment
menu item
VFO-A
Frequency
RF Signal
Generator Adjust AF millivoltmeter
04-01 IGC 1.8 1.900 MHz 1.900 MHz, +36 dBµ [AF GAIN] knob 0 dB
1.900 MHz, +10 dBµ [CLAR/VFO-B] knob -1.5 dB (±0.5 dB)
04-02 IGC HFL 7.100 MHz 7.100 MHz, +36 dBµ [AF GAIN] knob 0 dB
7.100 MHz, +10 dBµ [CLAR/VFO-B] knob -1.5 dB (±0.5 dB)
04-03 IGC HFM 14.200 MHz 14.200 MHz, +36 dBµ [AF GAIN] knob 0 dB
14.200 MHz, +10 dBµ [CLAR/VFO-B] knob -1.5 dB (±0.5 dB)
04-04 IGC HFH 21.230 MHz 21.230 MHz, +36 dBµ [AF GAIN] knob 0 dB
21.230 MHz, +10 dBµ [CLAR/VFO-B] knob -1.5 dB (±0.5 dB)
04-05 IGC 50 51.900 MHz 51.900 MHz, +36 dBµ [AF GAIN] knob 0 dB
51.900 MHz, +7 dBµ [CLAR/VFO-B] knob -1.5 dB (±0.5 dB)
04-06 IGC 144 145.900 MHz 145.900 MHz, +30 dBµ [AF GAIN] knob 0 dB
145.900 MHz, -3 dBµ [CLAR/VFO-B] knob -1.5 dB (±0.5 dB)
04-07 IGC 430 439.900 MHz 439.900 MHz, +30 dBµ [AF GAIN] knob 0 dB
439.900 MHz, -3dBµ [CLAR/VFO-B] knob -1.5 dB (±0.5 dB)