Yaesu FT-250R TS Service Manual
FT-250R
Technical Supplement
2009 VERTEX STANDARD CO., LTD. EH038N90A
©
Introduction
This manual provides the technical information necessary for servicing the FT-250R
VHF FM Transceiver.
Servicing this equipment requires expertise in handing surface-mount chip components. Attempts by non-qualified 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 are 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 (surface-mount devices), and the other has either a mixture of both chip
and leaded components (trimmers, coils, electrolytic capacitors, ICs, etc.), or leaded
components only.
VERTEX STANDARD CO., LTD.
4-8-8 Nakameguro, Meguro-Ku, Tokyo 153-8644, Japan
VERTEX STANDARD
US Headquarters
10900 Walker Street, Cypress, CA 90630, U.S.A.
YAESU UK LTD.
Unit 12, Sun Valley Business Park, Winnall Close
Winchester, Hampshire, SO23 0LB, U.K.
VERTEX STANDARD HK LTD.
Unit 5, 20/F., Seaview Centre, 139-141 Hoi Bun Road,
Kwun Tong, Kowloon, Hong Kong
VERTEX STANDARD (AUSTRALIA) PTY., LTD.
Normanby Business Park, Unit 14/45 Normanby Road
Notting Hill 3168, Victoria, Australia
While we believe the information in this manual to be correct, VERTEX STANDARD
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
The transceiver was assembled using Pb (lead) free solder, based on the RoHS
specification.
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 specification,
and any solder with the above alloy composition may be used.
Contents
Specifications ....................................................................................................................................................................2
Exploded View & Miscellaneous Parts .......................................................................................................................3
Block Diagram ..................................................................................................................................................................5
Circuit Description ..........................................................................................................................................................7
Alignment ........................................................................................................................................................................10
Board Units (Schematics, Layouts & Parts)
Main Unit ....................................................................................................................................................................15
VR Unit ....................................................................................................................................................................... 31
SW Unit ....................................................................................................................................................................... 32
DUMMY Unit ............................................................................................................................................................32
Specifications
GENERAL
Frequency coverage (MHz): RX: 136 to 174
TX: 144 to 146 (148)
Channel steps: 5, 10, 12.5, 15, 20, 25 & 50 kHz
Frequency Stability: ±5 ppm @ 14° to 140° F (–10° to +60° C)
Standard repeater shift: 600 kHz
Emission type: F2D, F3E
Supply voltage: Nominal: 7.2 V DC, Negative Ground
Operating: 6.0 to 16.0 VDC, Negative Ground (EXT DC Jack)
Current consumption: Receive: 150 mA;
Standby, Saver off : 38 mA
Standby, Saver on : 23 mA
Auto Power Off : 8 mA
Transmit (HIGH) : 1.3 A;
(MID) : 900 mA;
(LOW) : 500 mA;
Operating Temperature: –4° to 140° F (–20 °C to +60 °C)
Case size (WHD): 2.3" (W) x 4.3" (H) x 1.1" (D) (58 x 108.5 x 26.5 mm) (w/o knob & antenna)
Weight (approx.): 11.5 Oz (325g) w/FNB-83, Antenna and BeltClip
RECEIVER
Circuit type: Double-conversion superheterodyne
Intermediate Frequency: 1st: 21.7 MHz
2nd: 450 kHz
Sensitivity: 0.16 µV for 12 dB SINAD
Adjacent channel selectivity: 65 dB
Intermodulation: 65 dB
Audio output: 0.7 W @16 ohms for 10% THD (@7.4V) Internal Speaker
0.4 W @8 ohms for 10% THD (@7.4V) External Jack
TRANSMITTER
Power output: 5.0 W (High) / 2.0 W (Middle) / 0.5 W (Low) (@7.2 V)
Modulation system: variable reactance
Maximum deviation: ±5 kHz
Spurious emissions: At least 60 dB below
Microphone type: 2-kilohm condenser
Specifications are subject to change without notice, and are guaranteed within the 144 MHz amateur band only. Frequency ranges will vary according to transceiver version; check with your dealer.
2 FT-250R Technical Supplement
Exploded View & Miscellaneous Parts
REF. VXSTD P/N
U07230102
c
U9900101
d
U9900098
e
U9900063
f
U9900068
g
U9900086
h
U02206007
i
PAN HEAD SCREW M2
PAN HEAD SCREW M1.7
TAPTITE SCREW M2
TAPTITE SCREW M2
TAPTITE SCREW M2
TAPTITE SCREW M1.7
SEMS SCREW SM2.6x6B
Description
××
×3NI #1
××
××
×7NI #3
××
××
×3.3Ni
××
××
×4Ni #3
××
××
×2.5B
××
Non-designated parts are available only
as part of a designated assembly.
RA1111800
WINDOW
RA0111400
RA0210600
RUBBER PACKING
RA1112100
KNOB
RA1111900
VOLUME KNOB
RA1112000
ENCODER KNOB
RING NUT
RA0110200
HOLDER RUBBER
××
×14NI #2
××
Qty.
1
1
3
2
9
2
2
RA0211500
RUBBER CAP
CP9485001
FRONT CASE ASS'Y
RA1128200
RUBBER KNOB
RA0210300
RUBBER KNOB
M4090198
SPEAKER
RA0210100
HOLDER
RA020950A
LIGHT GUIDE
RA0211100
INTER CONNECTOR
G6090137
RA010700A
TERMINAL PLATE R
RA0209600
BRACKET
RA0211200
INTER CONNECTOR
LCD
VR Unit
RA010690A
TERMINAL PLATE L
MAIN Unit
RA0210700
TERMINAL PLATE
RA1063600
SPACER
RA021020A
RUBBER PACKING
RA055770C
LATCH NAIL
CP9482001
REAR CASE ASSY
DUMMY Unit
CP9486001
BELT CLIP ASS'Y
3FT-250R Technical Supplement
Exploded View & Miscellaneous Parts
Note
4 FT-250R Technical Supplement
Block Diagram
FT-250R Technical Supplement
5
Block Diagram
Note:
6
FT-250R Technical Supplement
Circuit Description
Receive Signal Path
Incoming RF from the antenna jack is delivered to the RF
Unit and passes through a low-pass filter and high-pass
filter consisting of coils L1001, L1002, L1003, L1004, L1014
& L1015, capacitors C1001, C1002, C1003, C1004, C1006,
C1007, C1042, C1044, C1045, C1046 & C1047, and antenna switching diode D1001 (RLS135).
Signals within the frequency range of the transceiver are
then amplified by Q1011 (2SC5006) and enter a varactor-tuned band-pass filter consisting of coils L1016, L1017
& L1018, capacitors C1049, C1050, C1051, C1052, C1053,
C1054, C1056, C1057, C1058, C1059, C1060, C1061, C1062
& C1063, and diodes D1004, D1005 & D1006 (all
HVC350B) before delivery to the first mixer, Q1013
(3SK296ZQ).
Buffered output from the VCO is amplified by Q1018
(2SC5374) to provide a pure first local signal between
122.3 and 126.3 MHz according to the transceiver version
and the programmed receiving frequency for injection to
the first mixer Q1013. The 21.7 MHz first mixer product
then passes through monolithic crystal filter XF1001
(21R12A4, 6 kHz BW) to strip away unwanted mixer products, and the IF signal is then amplified by Q1014
(2SC4400).
The amplified first IF signal is applied to FM IF subsystem
IC Q1017 (TA31136FN), which contains the second mixer, limiter amplifier, noise amplifier, and S-meter amplifier.
A second local signal is generated by the reference oscillator section of the PLL subsystem IC Q1030
(MB15A01PFV1) using 21.25 MHz crystal X1001; a 450
kHz second IF is produced when this signal is mixed with
the first IF signal within Q1017.
The processed audio passes through the another audio
mute gate Q1041 and Q1042 (both 2SC4081) to the volume control potentiometer VR3001 on the VR Unit, then
is delivered to the audio amplifier Q1053 (DTA2822L),
which provides up to 0.5 Watt to the headphone jack or
an 8-W loudspeaker.
Squelch Control
The squelch circuitry consists of a noise amplifier, bandpass filter, noise detector & noise comparator within
Q1017, audio control gate Q1041, Q1042, Q1044, Q1063
(all 2SC4081), microprocessor Q1035 (M3826AEFGP),
and squelch controller S3001 on the VR Unit.
When no carrier received, noise at the output of the detector stage in Q1017 is amplified and band-pass filtered
by the noise amplifier section of Q1017 and the network
between pins 7 and 8, and then rectified by the noise detector section of Q1017. The resulting DC squelch control
voltage outputs at pin 13 of Q1017, then it is passed to pin
4 of the microprocessor Q1035.
If no carrier is received, this signal causes pins 44 and 47
of Q1035 to go “Low” and pin 54 to go “High.” Pin 47
disables the supply voltage to the audio amplifier Q1053
(TDA2822L), and pin 54 activates the audio control gates
Q1041, Q1042, Q1044, Q1063, Q1049 and Q1050. Thus, the
microprocessor Q1035 blocks output from the audio amplifier, and silences the receiver, while no signal is being
received (and during transmission, as well). Meanwhile,
pin 44 signals Q1056 (2SC4081) to hold the green (Busy)
half of the LED D3001 (BRPY1211F) on the VR Unit off.
When a carrier appears at the discriminator, noise is removed from the output, causing pin 4 of Q1035 to go “low”
and the microprocessor to activate the audio amplifier,
audio mute gate, and “Busy” LED.
The second IF then passes through the main selectivity
element, ceramic filter CF1001 (CFWM450E) to strip away
all but the desired signal; it is then applied to the limiter
amplifier in Q1017, which removes amplitude variations
in the 450kHz IF, before detection of the speech by the
ceramic discriminator CD1001 (JTBM450CX24).
Detected audio from Q1017 is applied to a low-pass filter
consisting of capacitors C1208, C1209 & C1210, resistors
R1320, R1321, R1322, R1323 & R1324, and Q1060
(NJM2902V), then passes through the audio mute gate
Q1044 and Q1063 (both 2SC4081) to the buffer amplifier Q1043 (2SC4617); it is then passed through the deemphasis network consisting of capacitor C1057 and resistor R1208 to a high-pass filter consisting of capacitors
C1058, C1059 & C1060, resistors R1209 & R1210, and
Q1064 (NJM2902V).
The microprocessor then checks for CTCSS or CDCSS code
squelch information, if enabled, or for DTMF data on the
optional DTMF Unit. If not transmitting and CTCSS or
CDCSS is not activated, or if the received tone or code
matches that programmed, the microprocessor stops scanning (if active) and allows audio to pass through the audio amplifier Q1053 to the loudspeaker by enabling the
supply voltage to it via Q1047 (2SB1132Q), Q1048
(UMW1).
7FT-250R Technical Supplement
Circuit Description
Transmit Signal Path
Speech input from the microphone is amplified by Q1064
(NJM2902V), then filtered and sent to any installed optional signaling unit. The audio which returns from the
optional unit then is passed to the pre-emphasis network.
The processed audio may then be mixed with a CTCSS tone
generated by the microprocessor Q1035 (M3826AEFGP);
it is then delivered to D1010 (HSC277) for frequency modulation of the PLL carrier (up to ±5kHz from the unmodulated carrier) at the transmitting frequency.
If an external microphone is used, PTT switching is controlled by Q1054 (UMZ2N), which signals the microprocessor Q1035 when the impedance at the microphone jack
drops.
If a CDCSS code is enabled for transmission, the code is
generated by microprocessor Q1035 and delivered to
D1015 (HVC350B) for CDCSS modulating.
If DTMF is enabled for transmission, the tone is generated by the microprocessor Q1035 and applied to the splatter filter section in place of the speech audio. Also, the
tone is amplified for monitoring in the loudspeaker.
The modulated signal from the VCO Q1023 (2SC5374) is
buffered by Q1022 and Q1018 (both 2SC5374). The lowlevel transmit signal is amplified by Q1010 (2SC5226-5)
and Q1009 (2SK3074); it is then applied to the final amplifier Q1008 (RD07MVS1A), which provides up to 5
watts output power.
The transmit signal then passes through the antenna
switch D1001 (RLS135) and is low-pass filtered to suppress harmonic spurious radiation before delivery to the
antenna.
Automatic Transmit Power Control
Drain current of the final amplifier Q1008 (RD07MVS1A)
is sampled by R1028 and R1035. The resulting DC is fed
back through the APC amplifier Q1003 (NJM2904V) to
the driver amplifier Q1009 (2SK3074) and final amplifier Q1008, for control of the power output.
The microprocessor selects either “High” or “Low” power levels.
Transmit Inhibit
When the PLL is unlocked, pin 7 of PLL subsystem IC
Q1030 (MB15A01PFV1) goes to a logic “Low.” The resulting DC unlock control voltage is passed through the
inversion amplifier Q1032 (2SA1774) to pin 8 of the microprocessor Q1035. While the PLL is unlocked, pin 15 of
Q1035 remains “Low,” disabling the gate voltages of driver amplifier Q1009 (2SK3074) and final amplifier Q1008
(RD07MVS1A), thereby disabling the transmitter.
Spurious Suppression
Generation of spurious products by the transmitter is
minimized by the fundamental carrier frequency being
equal to final transmitting frequency, modulated directly
in the transmit VCO. Additional harmonic suppression is
provided by a low-pass filter consisting of coils L1001,
L1002, L1003, L1006, L1007 & L1008 and capacitors C1001,
C1002, C1003, C1004, C1006, C1007, C1019, C1020, C1021
& C1022, resulting in more than 60 dB of harmonic suppression prior to delivery to the antenna.
PLL Frequency Synthesizer
The PLL circuitry on the Main Unit consists of VCO Q1023
(2SC5374), VCO buffers Q1022 and Q1019 (both
2SC5374), and PLL subsystem IC Q1030
(MB15A01PFV1), which contains a reference divider, serial-to-parallel data latch, programmable divider, phase
comparator, and charge pump.
Stability is maintained by a regulated 3.3 V supply provided via Q1051 (S-812C33AUA) and 21.25 MHz reference frequency crystal X1001, as well as the reference oscillator’s temperature compensating thermistor and capacitors.
While receiving, VCO Q1023 oscillates between 122.3 and
126.3 MHz according to the transceiver version and the
programmed receiving frequency. The VCO output is
buffered by Q1022 and Q1019, then applied to the prescaler section of Q1030. There the VCO signal is divided
by 64 or 65, according to a control signal from the data
latch section of Q1030, before being sent to the programmable divider section of Q1030.
The data latch section of Q1030 also receives serial dividing data from the microprocessor, Q1035, which causes
the pre-divided VCO signal to be further divided in the
programmable divider section, depending upon the desired receive frequency, so as to produce a 5 kHz or 6.25
kHz derivative of the current VCO frequency.
Meanwhile, the reference divider section of Q1030 divides
the 21.25 MHz crystal reference X1001, by 4250 (or 3400)
to produce the 5 kHz (or 6.25 kHz) loop reference (respectively).
The 5 kHz (or 6.25 kHz) signal from the programmable
divider (derived from the VCO) and that derived from
the reference oscillator are applied to the phase detector
section of Q1030, which produces a pulsed output with
pulse duration depending on the phase difference between
the input signals.
8 FT-250R Technical Supplement
This pulse train is filtered to DC and returned to the varactor D1011 (HVC350B). Changes in the level of the DC
voltage applied to the varactor affect the reference in the
tank circuit of the VCO according to the phase difference
between the signals derived from the VCO and the crystal reference oscillator.
The VCO is thus phase-locked to the crystal reference oscillator. The output of the VCO Q1023, after buffering by
Q1022 and amplification by Q1018, is applied to the first
mixer as described previously.
For transmission, the VCO Q1023 oscillates between 144
and 148 MHz according to the model version and programmed transmit frequency. The remainder of the PLL
circuitry is shared with the receiver. However, the dividing data from the microprocessor is such that the VCO
frequency is at the actual transmit frequency (rather than
offset for IFs, as in the receiving case). Also, the VCO is
modulated by the speech audio applied to D1010
(HSC277), as described previously.
Receive and transmit buses select which VCO is made
active by Q1020 (DTA144TE). When the power saving
feature is active, the microprocessor Q1035
(M3826AEFGP) periodically signals switches the Q1033
(DTA114TE) and Q1034 (2SC4081) for the PLL subsystem
IC Q1030 to conserve power and shortens the lock-up time.
Circuit Description
Miscellaneous Circuits
Push-To-Talk Transmit Activation
The PTT switch is connected to pin 28 of microprocessor
Q1035 (M3826AEFGP), so that when the PTT switch is
closed, pin 6 of Q1035 goes “High.” This signals the microprocessor to activate the TX/RX controller Q1028
(UMW1), which then disables the receiver by disabling
the 5 V supply bus at Q1026 (DTA143XE) to the frontend, FM IF subsystem IC Q1017 (TA31136FN).
At the same time, Q1027 (2SA1586Y) activates the transmit 5V supply line to enable the transmitter.
9FT-250R Technical Supplement
Alignment
Introduction
The FT-250R is carefully aligned at the factory for the specified performance across the amateur band. Realignment
should therefore not be necessary except in the event of a
component failure. Only an authorized Vertex Standard
representative should perform all component replacement
and service, or the warranty policy may be void.
The following procedures cover the adjustments that are
not normally required once the transceiver has left the
factory. However, if damage occurs and some parts subsequently are 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 only by authorized Vertex Standard service technicians who are experienced with the circuitry and fully equipped for repair
and alignment. If a fault is suspected, contact the dealer
from whom the transceiver 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 alignments
are cautioned to proceed at their own risk. Problems
caused by unauthorized attempts at realignment are not
covered by the warranty policy. Also, Vertex Standard
reserves the right to change circuits and alignment procedures in the interest of improved performance, without
notifying owners.
Under no circumstances should any alignment be attempted unless the normal function and operation of the transceiver are clearly understood, the cause of the malfunction has been clearly pinpointed and any faulty components replaced, and realignment determined to be absolutely necessary.
Required Test Equipment
The following test equipment (and familiarity with its use)
is necessary for complete realignment. Correction of problems caused by misalignment resulting from use of improper test equipment is not covered 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.
RF Signal Generator with calibrated output level at 200
MHz
Deviation Meter (linear detector)
In-line Wattmeter with 5% accuracy at 200 MHz
50-Ohm 10-W RF Dummy Load
8-Ohm AF Dummy Load
Regulated DC Power Supply adjustable from 3 to 16.5
VDC, 2A
Frequency Counter: 0.2-ppm accuracy at 200 MHz
AF Signal Generator
AC Voltmeter
DC Voltmeter: high impedance
VHF Sampling Coupler
SINAD Meter
Alignment Preparation & Precautions
A 50-Ohm RF load and in-line wattmeter must be connected to the main antenna jack in all procedures that call
for transmission; alignment is not possible with an antenna. After completing one step, read the next step to see if
the same test equipment is required. If not, remove the
test equipment (except dummy load and wattmeter, if
connected) before proceeding.
Correct alignment requires that the ambient temperature
be the same as that of the transceiver and test equipment,
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 some
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.
10 FT-250R Technical Supplement
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