Icom Ic-910h Vhf/Uhf All Mode Tranciever Service Manual

							SERVICE
MANUAL
VHF/UHF ALL MODE TRANSCEIVER
i910H 
						

							INTRODUCTION
This service manual describes the latest service information
for the IC-910HVHF/UHF ALL MODE TRANSCEIVER at the
time of publication.
VERSION No.
#02
#04
#06
#07VERSION
Europe
Australia
U.S.A.
KoreaSYMBOL
EUR
AUS
USA-1
KOR
To upgrade quality, any electrical or mechanical parts and
internal circuits are subject to change without notice or
obligation.
DANGER
NEVERconnect the transceiver to an AC outlet or to a DC
power supply that uses more than 16 V.  This will ruin the
transceiver.
DO NOTexpose the transceiver to rain, snow or any liquids.
DO NOTreverse the polarities of the power supply when
connecting the transceiver.
DO NOTapply an RF signal of more than 20 dBm (100 mW)
to the antenna connector. This could damage the transceiv-
er’s front end.
ORDERING PARTS
Be sure to include the following four points when ordering
replacement parts:
1. 10-digit order numbers
2. Component part number and name
3. Equipment model name and unit name
4. Quantity required

1110003140 IC LA1150N IC-910H  MAIN UNIT 5 pieces
8810005770 Screw BiH M3´8 ZK IC-910H  Cover 10 pieces
Addresses are provided on the inside back cover for your
convenience.
REPAIR NOTES
1. Make sure a problem is internal before disassembling
the transceiver.
2.DO NOTopen the transceiver until the transceiver is 
disconnected from its power source.
3.DO NOTforce any of the variable components.  Turn
them slowly and smoothly.
4.DO NOTshort any circuits or electronic parts.  An insu-
lated tuning tool MUSTbe used for all adjustments.
5.DO NOTkeep power ON for a long time when the trans-
ceiver is defective.
6.DO NOTtransmit power into a signal generator or a
sweep generator.
7.ALWAYSconnect a 50 dB to 60 dB attenuator between
the transceiver and a deviation meter or spectrum ana-
lyzer when using such test equipment.
8.READthe instructions of test equipment thoroughly
before connecting equipment to the transceiver. 
						

							SECTION 1 SPECIFICATIONS
SECTION 2 INSIDE VIEWS
2 - 1 IC-910H  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 1
2 - 2 UX-910 (OPTIONAL UNIT)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 3
SECTION 3 DISASSEMBLY AND OPTION INSTRUCTIONS
SECTION 4 CIRCUIT DESCRIPTION
SECTION 5 ADJUSTMENT PROCEDURES
SECTION 6 PARTS LIST
SECTION 7 MECHANICAL PARTS
SECTION 8 SEMI-CONDUCTOR INFORMATION
SECTION 9 BOARD LAYOUTS
9 - 1 VR-A BOARD  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 1
9 - 2 VR-B BOARD  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 1
9 - 3 RIT BOARD  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 1
9 - 4 FUNC BOARD  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 3
9 - 5 MIC BOARD  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 3
9 - 6 JACK BOARD  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 3
9 - 7 DRV BOARD  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 3
9 - 8 VARISTOR-A BOARD  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 3
9 - 9 VARISTOR-B BOARD  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 3
9 - 10 VARISTOR-C BOARD  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 3
9 - 11 DISPLAY BOARD  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 5
9 - 12 PA UNIT  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 7
9 - 13 PLL UNIT  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 9
9 - 14 MAIN UNIT  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 11
9 - 15 UX-910 MAIN UNIT  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 13
SECTION 10 BLOCK DIAGRAMS
10 - 1 MAIN UNIT  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 1
10 - 2 PA AND PLL UNITS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 2
10 - 3 FRONT UNIT  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 3
10 - 4 UX-910  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 3
SECTION 11 WIRING DIAGRAM
SECTION 12 VOLTAGE DIAGRAMS
12 - 1 FRONT UNIT  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 1
12 - 2 PLL UNIT  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 2
12 - 3 PA UNIT (1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 3
12 - 4 PA UNIT (2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 4
12 - 5 MAIN UNIT (1)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 5
12 - 6 MAIN UNIT (2)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 6
12 - 7 MAIN UNIT (3)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 6
12 - 8 UX-910 MAIN UNIT (1)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 7
12 - 9 UX-910 MAIN UNIT (2)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 8
TABLE OF CONTENTS 
						

							SECTION 1 SPECIFICATIONS
1 - 1
GENERAL
• Frequency coverage :(Unit: MHz)
*
1Optional UX-910 is installed.
*2Guaranteed range is 144.0–148.0 MHz.
*3Guaranteed range is 430.0–450.0 MHz.
*4Guaranteed range is 1240.0–1300.0 MHz.
• Mode : USB, LSB, CW, FM, FM-N*
*Not available in 1200 MHz band
• No. of memory Ch. : 212 (99 regular, 6 scan edges, 1 calls for each band) plus 10 satellite memories)
• Antenna connector : SO-239 (50Ω; VHF)
Type-N (50Ω; UHF)
• Usable temp. range : –10˚C to +60˚C; +14˚F to +140˚F
• Frequency stability : Less than ±3 ppm (–10 to 60˚C; +14 to +140˚F)
• Frequency resolution : 1 Hz minimum
• Power supply : 13.8 V DC ±15% (negative ground)
• Current drain (at 13.8 V DC) : 
Transmit Max. power 23.0 A
Receive Standby 2.0 A (3.0 A with  UX-910)
Max. audio 2.5 A (3.5 A with UX-910)
• Dimensions : 241(W)×94(H)×239(D) mm
(projections not included) 9
1⁄2(W)×311⁄16(H)×913⁄32(D) in
•Weight (approx.) : 4.5 kg; 10 lb (with UX-910: 5.35 kg; 11 lb 13 oz)
•ACC 1 connector : 8-pin DIN connector
•CI-V connector : 2-conductor 3.5 (d) mm (
1⁄8″)
•DATA connectors : 6-pin mini DIN ×2 (for MAIN and SUB)
TRANSMITTER
•Output power : (continuously adjustable)
144 MHz 5–100 W
430 (440) MHz  5–75 W
1200 MHz 1–10 W (with UX-910)
•Modulation system : SSB Balanced modulation
FM
Variable reactance modulation
•Spurious emission : 144/430 (440) MHz More than 60 dB
1200 MHz More than 50 dB 
•Carrier suppression : More than 40 dB
•Unwanted sideband  : More than 40 dB
suppression
•
Microphone connector: 8-pin connector (600 Ω)
•KEY connector : 3-conductor 3.5(d) mm (
1⁄4″) Version 144 MHz 430 (440) MHz 1200 MHz*
1
U.S.A.Tx: 144.0–148.0 Tx: 430.0–450.0 Tx: 1240.0–1300.0
Rx: 136.0–174.0*2Rx: 420.0–480.0*3Rx: 1240.0–1320.0*4
Europe 144.0–146.0 430.0–440.0 1240.0–1300.0
Australia 144.0–148.0 430.0–450.0 1240.0–1300.0
Korea 144.0–146.0 430.0–440.0 1260.0–1300.0
All stated specifications are subject to change without notice or obligation. 
						

							RECEIVER
•Receive system : 
VHF SSB, CW
Single conversion superheterodyne
FMDouble conversion superheterodyne
UHF SSB, CWDouble conversion superheterodyne
FM Triple conversion superheterodyne
•Intermediate frequencies :
(Unit: MHz)
•Sensitivity : SSB, CW (10 dB S/N)Less than 0.11 µV
FM 
(12 dB SINAD)Less than 0.18 µV 
•Squelch sensitivity : SSB, CW Less than 1.0 µV
(threshold)FM Less than 0.18 µV
•Selectivity : SSB, CW More than 2.3 kHz/–6 dB
Less than 4.2 kHz/–60 dB*
FM  More than 15.0 kHz/–6 dB
Less than 30.0 kHz/–60 dB*
FM-N  More than 6.0 kHz/–6 dB
Less than 18.0 kHz/–36 dB
CW-N  More than 0.5 kHz/–6 dB
(w/FL-132 or FL-133)Less than 1.34 kHz/–60 dB*
*Except 1200 MHz band
•Spurious and image rejection ratio:
144/430 (440) MHz More than 60 dB
1200 MHz More than 50 dB 
•AF output power 
(at 13.8 V DC):
More than 2.0 W at 10% distortion with an 8Ωload
•RIT variable range  : 144/430 (440) MHz ±1.0 kHz 
(SSB, CW)
±5.0 kHz (FM)
1200 MHz ±2.0 kHz (SSB, CW)
±10.0 kHz (FM)
•IF SHIFT variable range: More than ±1.2 kHz
•PHONES connector : 3-conductor 6.35(d) mm (
1⁄4″)
•Ext. SP connectors : 2-conductor 3.5 (d) mm (
1⁄8″) /8Ω×2 (for MAIN and SUB) MAIN BAND SUB BAND
1st 2nd 3rd 1st 2nd 3rd
SSB 10.8500——10.9500——
CW 10.8491——10.9491——
FM 10.8500 0.455—10.9500 0.455—
SSB 71.2500 10.8500—71.3500 10.9500—
CW 71.2491 10.8491—71.3491 10.9491—
FM 71.2500 10.8500 0.455 71.3500 10.9500 0.455
SSB 243.9500 10.8500—243.9500 10.9500—
CW 243.9491 10.8491—243.9491 10.9491—
FM 243.9500 10.8500 0.455 243.9500 10.9500 0.455
144 MHz
430 (440) MHz
1200 MHz
1 - 2 
						

							2 - 1
SECTION 2 INSIDE VIEWS
2-1 IC-910H
• MAIN AND PLL UNITS
DDS IC
(IC701: SC-1287) DDS gate array
(IC131: SC-1246A) DDS gate array
(IC331: SC-1246A) PLL unit
144 MHz band VCO circuit 430 MHz band VCO circuit
Reference oscillator
(X512: CR-452 30.2 MHz) Driver IC
(IC1: BU4094BCF) DDS IC
(IC601: SC-1287)
AF power amplifier
(IC1852: LA4445) MAIN unit * Located under side of the point
FM IF IC
(IC951: TA31136FN)
D/A converter
(IC1521: M62352GP)
Analog master IC*
(IC1701: mPC5023-077)
FM IF IC
(IC401: TA31136FN) Crystal band pass filter
(FI751: FL-129) Crystal band pass filter
(FI151: FL-128)
TX IF amplifier*
(Q1: 3SK131) 
						

							2 - 2
• PA UNIT
TX balanced mixer
 Q501, Q502: 2SK302
 D502: 1SV286 RX balanced mixer
(Q511, Q512: 2SK1740) Pre-amplifier
(Q507: 3SK177)
145 MHz power amplifier
(Q651, Q652: 2SC5152) TX/RX switching relay
(RL700: AE5349)
Varistor-A boardVaristor-C board
440 MHz power amplifier
(Q151, Q152: 2SC3102)
TX balanced mixer*
(Q1, Q2: 2SK302) Pre-amplifier
(Q260: 3SK177)
RX balanced mixer
(Q220, Q221: 2SC3356)
DRV boardDrive amplifier
(Q131: SRFJ7044)
* Located under side of the pointVaristor-B board
TX double balanced mixer
 D190: HSB88WS
 L190, L191: 617DB-1010 
						

							2 - 3
2-2 UX-910 (OPTIONAL UNIT)
• TOP VIEW
• BOTTOM VIEW
Power module IC
(IC21: M57762-02)
1st LO VCO circuit PLL IC
(IC501: TB31242)
DDS IC
(IC661: SC-1246A)RF pre-amplifier
(Q281: NE34018) Power supply circuit
for AG-1200
 Q72: DTC144EU
 Q73, Q74: 2SC2712
RF amplifier
(Q271: 2SC5454)
YGR amplifier
(IC141: mPC1878G)TX 1st mixer
(IC131: mPC8163TB)
RX 1st mixer
(IC241: mPC2721)
TX 1st IF amplifier
(IC111: mPC2709)
RX 2nd mixer
(Q221: 3SK166)
TX 2nd mixer
(D82: HSB88WS)
2nd LO VCO circuit
Power supply circuit for AG-1200
(Q71: 2SD1801)
Pre-drive amplifier
(Q36: 2SK2354)
2nd IF amplifier
(Q81: 2SC2712)
Divider
(IC610: TC7W74FU)
Reference amplifier
(IC601: TC7SU04F)
Drive amplifier
(Q38: 2SK2855) 
						

							SECTION 3 DISASSEMBLY AND OPTION INSTRUCTIONS
• Opening the transceiver’s case
Follow the case and cover opening procedures
shown here when you want to install an optional unit
or adjust the internal units, etc.
qRemove the 5 screws from the top of the trans-
ceiver and  4 screws from the sides, then lift up the
top cover.
wTurn the transceiver upside down.
eRemove 5 screws from the bottom of the trans-
ceiver, then lift up the bottom cover.
CAUTION:DISCONNECT the DC power cable
from the transceiver before performing any work
on the transceiver. Otherwise, there is a danger of
electric shock and/or equipment damage.
• UX-910 1200MHz BAND UNIT
qRemove the bottom cover as shown above.
wRemove the antenna plate from the chassis using a stan-
dard screw driver.
WARNING!
NEVER attempt to remove the antenna plate using
your finger, this may result in injury.
eConnect the FFC (Flexible Flat Cable) of the 
UX-910 to J2 on the MAIN unit, DC power cable to the
power connector (W305) from the PA unit and the coaxi-
al cable to J541 on the PLL unit.
CAUTION
NEVER catch the cables from the optional DSP unit(s)
between chassis and the UX-910, this may damage
the DSP unit(s) and/or transceiver.
J541
J2
UX-910
PLL unit
Power connectorDC power cable Coaxial cable
Flexible flat cable
Disconnect the 
speaker cable.
rPlace the UX-910 using the supplied 4 screws.
BE CAREFULnot to drop the supplied screws inside
the transceiver.
Antenna plate
UX-910
Turn the flexible flat cable up under the UX-910.
J2
MAIN unitFlexible flat cable UX-910
tReturn the bottom cover to its original position.
3 - 1 
						

							• Opening the PA unit cover
qRemove the top cover as shown in the diagram on p. 3-
1.
wRemove 8 screws and grounding plate from the PA unit
cover.
eRemove fastening tape from the inside power cable.
grounding plate
• FL-132/FL-133 CW NARROW FILTER
qRemove the bottom cover as shown in the diagram on 
p. 3-1.
• Remove the UX-910 if you have installed it. (p. 3-1)
wDisconnect the connection cable connectors from J501
and J1051 on the MAIN unit.
eRemove 2 clips.
WARNING!
BE CAREFULnot to pinch your finger with the clip.
rRemove 6 screws from the MAIN unit, then lift up the
MAIN unit.
PLL unit
MAIN unit
J1051 J501
Clips
rSlide the PA unit cover as shown below.
tInstall FL-132 or FL-133 to the specified position on the
MAIN unit.
FL-132
(MAIN)
FL-133
(SUB)
ySolder then cut the leads, keeping 2–3 mm (1/8’’) of the
leads from the bottom of the MAIN unit.
uReturn the MAIN unit and clips to their original positions.
iRe-connect the connection cable connector to J501 and
J1051 on the MAIN unit.
oReturn the bottom cover to the original position.
(MAIN)
(SUB)
3 - 2