Yaesu FT-227RB User manual

INSTRUCTION
MANUAL
FT-227RB
YAESU MUSEN CO ,LTD.
TOKYO JAPAN.

TABLE OF CONTENTS
(Page)
INTRODUCTION

1
SPECIFICATIONS

2
CONTROLS AND SWITCHES 
3
REAR APRON
 5
INSTALLATION 
7
OPERATION
9
BLOCK DIAGRAM

11
THEORY OF OPERATION 
12
MAINTENANCE AND ALIGNMENT

19
PARTS LIST

26

Ato
FT-227RB SCANNING MEMORIZER
2 METER FM TRANSCEIVER
The FT-227RB is a PLL synthesized FM trans-
ceiver, designed to provide high performance for
the discriminating 2 meter operator.
Channel selection is by means of a photo-inter-
rupter scheme, providing selection of as many as
800 PLL channels between 144 and 148 MHz.
This optical coupling system eliminates noisy, un-
reliable rotary switches used in other makes of
equipment. Digital display of the last four digits
of the operating frequency is provided.
A memory circuit allows storage and recall of two
simplex and four repeater channels, with the press
of a switch. The memorized frequency may be
held when the power switch is turned off, via the
backup circuitry.
For repeater operation, ± 600 kHz split is provided,
and auxiliary splits may be programmed using the
memory system. Tone burst generation is provided,
and a subaudible tone squelch (CTCSS) encoder/
decoder is an available option for your FT-227RB.
Superb operating convenience is provided by the
PLL scanner, allowing up/down scanning control
from the microphone, without rotation of the
main tuning dial..
Your FT-227RB, represents the latest develop-
ments in solid-state technology. With proper care,
and if the directions to follow are observed with-
out fail, your FT-227RB. will provide many years
of trouble-free operation. The owner is encouraged
to read this manual in its entirety, so as to become
better acquainted with the exciting new FT-227RB,
the latest development from the hams at YAESU.
1

SPECIFICATIONS
GENERAL
Frequency Converage
144
to 148
MHz
Number of Channels
800 channels
Speaker
Internal 3" dynamic speaker with provision
for connecting an external 8 ohm dynamic
speaker.
Microphone
Dynamic push-to-talk microphone with re-
tractable coiled cord. Impedance is 600
ohms.
Deviation
±5 kHz.
Audio Response
+1,
—3 dB of 6 dB/Octave pre-emphasis
characteristic from 300 to 2500 Hz.
Spurious Emissions
60 dB below carrier minimum
Tone Burst.
Nominally one second at 1800 H
Repeater Split.
±600
kHz or any frequency in 5 kHz
increments
Power Requirement 
RECEIVER
13.8 Volts DC, ±10%.
Current Consumption
0.5 Amps Receive.
2.5 Amps Transmit.
Metering
Illuminated front panel meter indicates
relative received signal strength and trans-
mitter power output.
Type
Double conversion super-heterodyne
Intermediate Frequency
10.7 MHz
first IF; 455 kHz second IF
Sensitivity
0'.3 µV for 20 dB quieting.
Selectivity
Dimensions

±6
kHz at 6 dB: ±12 kHz at 60 dB
180 (W) x 60
(H)
x 220 (D) mm
Audio Output
Weight

1.5 Watts at 8 ohms
2.7 kg.
TRANSMITTER
RF Output
10
Watts into 50 ohm load at 13.8 Volts DC
Frequency Stability
±0.002%.
Modulation
F3.
SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE
2

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13
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CONTROLS & SWITCHES
- VW
The FT-227RB has been designed for ease of

modern computer technology. Be sure you
operation. However, the operator may not be

throughly understand the function of each control
familiar with some controls, since it utilizes

and indicator before operating the equipment.
(1) Vol inner control
The VOLUME control adjusts the receiver audio
output level and turns power off when rotated to
and extreme CCW position.
(2) SQL Outer control
The SQUELCH control adjusts the receiver squelch
threshold sensitivity.
(3)
FUNCTION switch
This switch selects the transmit frequency. Positions
M l and M2 (SIMP) can be used for simplex oper-
ation. Positions Ml—M3 can be used for ±600 kHz
split, for repeater operation. M4 is used for pro-
gramming an auxiliary split of up to 4 MHz. Refer
to the section on operation for details.
(4) Channel Selector
Endless optical coupling selects 800 channels.
(5)
DIAL Display
The digital display indicates the operating frequency.
(6) METER
The meter indicates the signal strength on receiver
and the relative power output on transmit.
(7)
MIC receptacle
Four pin connector is used for microphone input
and push-to-talk relay actuation.
(8)
MEMORY switch
When pressed, the frequency on the dial is
memorized, and the M lamp lights up. To release
the memorized frequency, press the switch a
second time.
(9)
5UP switch
The channel frequency shifts 5 kHz up, and the
5UP lamp lights up.

MIC
le
PTT
UP C
DN 111
0 
PIN No
1 UP
2 COM
3 DOWN
4 PTT
5 GND
6 MIC
(10)
+TX
This switch is used to select the direction of the
repeater split. When the switch is not pushed,
repeater split of —600 kHz is selected. With the
switch pushed, repeater split of +600 kHz is
selected. Refer to the section on repeater oper-
ation.
(11)
MEMORY RECALL switch
When switch is pressed, the memorized frequency
is recalled, and the MR lamp lights up.
(12)
BUSY indicator
The lamp lights up when a signal is received.
(13)
ON AIR indicator
The lamp lights up when in the transmit mode.
Figure
1
Microphone Connections
CABINET BOTTOM
(1) BURST
When this switch is in the ON position, a short
duration audio tone of 1800 Hz will be super-
imposed on the transmitted signal. This is normally
used only with repeaters requiring tone access.
(2)
BUSY/MAN/CLEAR
This switch selects the mode of the PLL scanner.
In the BUSY position, the scanner will search until
it finds an occupied channel (one containing a
signal strong enough to trip the FT-227R13
squelch). In the MAN position, scanner stop
commands come exclusively from the microphone.
In the CLEAR position, the scanner will search
until it finds a channel which has no signal present.

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REAR PANEL
(1) ANT receptacle
UHF type coaxial receptacle for connection of
antenna.
(2)
TONE SQUELCH switch
An optional TONE SQUELCH circuit is activated
when switch is placed in ON position.
(3) ACC socket
The ACCESSORY socket is used for external
control of the transceiver.
(4) SP receptacle
Audio output is provided at this receptacle for
an external speaker. (Output impedance is 8 ohms,
and the internal speaker will be disabled when a
plug is inserted.)
(5)
POWER receptacle
A two-pin connector is used for connection to
13.8 Volt DC (negative ground) power source,
vehicle battery, or AC power supply.
ACCESSORIES
The following accessories are included with this
transceiver:
1.
Dynamic microphone with retractable, coiled
cord.
2.
Mobile mounting bracket with hardware.
3.
DC power cable.
4.
Cigarette lighter adapter.
5.
Spare fuses.
6.
Microphone hanger.
7.
Miniature phone plug for external speaker.
8.
Accessory plug (must be inserted in rear of
transceiver at all times).
9.
Tap connector.
CAUTION
IMPROPER FUSE REPLACEMENT CAN CAUSE
PERMANENT DAMAGE IN THE EVENT OF
UNUSUAL OPERATING CONDITIONS. OUR
WARRANTY DOES NOT COVER DAMAGE
CAUSED BY IMPROPER FUSE REPLACEMENT.
USE ONLY A 3 AMPERE FUSE.

BLACK
 1 i 
RED
RUBBER TUBE
POWER PLUS
FUSE HOLDER
FUSE
SOLDER
3A
vcca
BLACK
 Cr\.0 
RED 3 A
Figure 2
.
POWER CABLE CONNECTIONS
PIN No.
I
2 MIC IN I
3 PTT

JUMPER
4 SP-
5 I3.8V
4
Figure 3.
ACC (TONE IN) PLUG CONNECTIONS
6

INSTALLATION
The FT-227RB transceiver is designed primarily
for mobile service, requiring only an antenna and
13.8 volt DC power source for operation. The
transceiver has been pre-tuned at the factory, and
requires no further adjustment for normal oper-
ation into a 50 ohm load.
Under no circumstances should the power cable
ever be connected to AC power. OUR WAR-
RANTY DOES NOT COVER DAMAGE CAUSED
BY APPLICATION OF AC POWER TO THE
POWER JACK ON THE REAR APRON OF THE
TRANSCEIVER.
ANTENNA CONSIDERATIONS
In antenna installations, it is desirable that the
antenna be located as high and in the clear as
possible. In addition, be certain that the SWR on
the feedline is less than 1.5 : 1. A higher SWR may
cause a reduction in power output, because of the
protective circuitry incorporated in design. As well,
high SWR will increase the feedline losses.
In all installations, do not economize on coaxial
cable. For mobile applications, in which the feed-
line length is 20 feet or less, type RG-58A/U cable
is satisfactory, and the foam types are preferred,
because of their lower loss. For base station
systems, type RG8A/U may be used for moderate
lengths; for very long cable installations, we recom-
mend the use of type RG-17A/U, air-dielectric
"heliax" cable, or aluminum-jacketed "foamflex"
coax. Beware of "bargain" coax, as the shield
coverage may be very poor, and this can seriously
degrade system performance.
BASE STATION INSTALLATION
As base station, the FT-227RB requires a power
source of 13.8 volts DC at 2.5 amperes. A base
station stand is included with your transceiver,
for easy viewing.
MOBILE INSTALLATION
For mobile service, the FT-227RB may be installed
where the controls, indicators, and microphone are
easily visible and accessible for operation. The unit
may be mounted in any position without loss of
performance. Suitable locations are atop the trans-
mission tunnel, under the dash, etc. A universal
bracket is supplied with the transceiver for this
purpose. Install the FT-227RB as follows (refer to
Figure 4):
Use the universal mounting bracket as a
template to locate the mounting holes. Use
a 3/16" diameter drill bit for these holes, and
allow clearance for the transceiver, its
controls, and all connecting cables. Secure
the mounting bracket with the screws,
washers, and nuts supplied, as shown in
Figure 4A.
2.
Install the transceiver in the mounting
bracket, sliding it into the guide rail of the
bracket. Tighten the screws on both sides.
3. The microphone hanger may be affixed in any
convenient place for handling the micro-
phone.
Figure 4 A.

Figure 4 B.

4.
The supplied power cable may be plugged
directly into the vehicle's cigarette lighter
receptacle, for casual use. For permanent
installation, the lighter plug may be removed,
and the leads routed directly to the battery
(red to positive, black to negative or ground).
Alternatively, the power leads may be routed
to the nearest power terminal, e.g. ignition
switch, fuse block, etc. If it is necessary to
extend the power leads, use the shortest
length possible, and use only #16 AWG in-
sulated copper wire (or larger) to avoid
excessive voltage drop.
CAUTION
BEFORE CONNECTING THE POWER CON-
NECTOR TO THE TRANSCEIVER, CHECK
THE BATTERY VOLTAGE WITH THE ENGINE
RUNNING (BATTERY CHARGING). IF THE
VOLTAGE EXCEEDS 15 VOLTS DC, THE
VEHICLE VOLTAGE REGULATOR SHOULD
BE ADJUSTED TO PROVIDE A MAXIMUM
CHARGING RATE OF LESS THAN 15 VOLTS
DC. ALSO, BE CERTAIN TO OBSERVE PROPER
POLARITY WHEN MAKING BATTERY CON-
NECTIONS. THE RED LEAD IS CONNECTED
TO THE POSITIVE BATTERY TERMINAL,
WHILE THE BLACK LEAD IS CONNECTED TO
THE NEGATIVE TERMINAL. REVERSED
POLARITY WILL NOT DAMAGE THE FT-
227RA, BECAUSE OF THE PROTECTIVE
CIRCUITRY INCORPORATED; HOWEVER,
THE TRANSCEIVER WILL NOT OPERATE
UNDER THESE CONDITIONS.
5.
Connect the power cable to the POWER
receptacle on the rear panel of the transceiver.
6.
Connect the 50 ohm antenna cable to the
ANT receptacle on the rear apron of the
transceiver.
HOW TO USE THE TAP CONNECTOR
(a)
Do NOT strip insulation from wires.
(b) The tap connector will handle most wire sizes
used in automotive instrument panels.
(c) Slice the "hot" lead into tap connector as
shown.
(d)
Insert transceiver power lead 3/4 of the way
into connector (just past metal connector
element).
(e) Using pliers, press the metal connector
element until it is FLUSH.
(f)
Fold the hinged cover over the connector
element and snap firmly in place.
Plastic Insulator with
hinged "snap-in" cover
Lft
° 45 g3t* ------ Power to
transceiver
•
Slot for side entry
41*
of "hot" wire
Connection made with
pliers or similar tool by
driving element over
wires
Self-stripping "U" type
spring pressure connector
element
wires
Figure 5
7.
Connect the microphone cable to the 6-pin
microphone receptacle on the front panel of
the transceiver.
RED
8.
An external 8 ohm speaker may be connected
at the SP receptacle on the rear panel, if
desired. This will automatically disconnect
the internal speaker. Use the external speaker
plug supplied.
BLACK
Figure
6
8

OPERATION
INITIAL CHECK
1. Rotate the VOLUME control in a clock-
wise direction to apply power. The meter
will become illuminated, and the digital
display will indicate "7.000" initially
("5000" on models limited to 144-146
MHz). With the 5 UP button pressed, the
display will indicate

"7. 1 005" ("5.005").
2.
Rotate the SQUELCH control fully counter-
wise.
3.
Adust the VOLUME control for a normal
listening level on an incoming signal or the
background noise.
4. Rotate the main tuning dial to find a clear
channel (background noise only). Advance
the SQUELCH control clockwise until the
receiver is just silenced and the BUSY lamp
turns off. Perform this step carefully so as
not to go beyond the threshold point; if
you do, the receiver will not respond to
weak signals.
FREQUENCY SELECTION
The channel selection knob selects the operating
frequency in 10 kHz steps. Clockwise rotation of
the main dial increases the frequency up to
148.000 MHz, while counterclockwise rotation
lowers the frequency to 143.990 MHz. On
143.990 and 148.000 MHz, the transmitter is
disabled, preventing out-of-range operation.
This protection applies, as well, to memorized
frequencies, in addition to dial frequencies.
CAUTION
CHANNEL SELECTION MUST NOT BE MADE
WHILE THE PUSH-TO-TALK SWITCH IS
ACTIVATED FOR TRANSMISSION.
SCANNER OPERATION
The PLL scanner will allow remote scanning for
easy frequency change. Set the BUSY/MAN/
CLEAR switch to MAN. Now, pressing the UP
switch on the microphone for an instant will shift
the operating frequency up 10 kHz. Pressing the
DN switch will, likewise, lower the operating fre-
quency 10 kHz.
Now, press the UP switch, and hold it in the de-
pressed position. After an initial shift of 10 kHz,
and a delay of approximately 1 second, the scanner
will be activated, and the frequency will be shifted
rapidly upward until the UP or DN switch is
pressed again, at which time the scan will be
halted. When the upper band edge is reached, the
scan will reverse itself, and will begin scanning in
a lower direction.
The same relations apply when the DN switch is
pressed, except that when the lower band edge is
reached, the scanner will reverse itself and begin
scanning upward.
To set the scanner for searching for an occupied
channel, set the BUSY/MAN/CLEAR switch to
BUSY. Now, when the scanner is activated, the
scan will be halted whenever the squelch is acti-
vated by an incoming signal. If the squelch is not
adjusted to silence the receiver (with no signal
present), the scanner will advance only 10 kHz
per press, thinking that an occupied channel has
been found.
To set the scanner for searching for a clear channel,
set the BUSY/MAN/CLEAR switch to CLEAR.
Now, the scanner will halt when the squelch is
silenced (no signal present).
Whether in the BUSY, MAN, or CLEAR modes,
the scan may be halted at any time by pressing
either the UP or DN switches while scanning. If
the PTT switch is pressed while scanning, the scan
will be halted and transmission will occur on the
frequency on which the scan was halted.
9

MEMORY OPERATION
Select the channel desired with the main dial or
scanner controls. Set the FUNCTION switch to
M1 (SIMP), and press the M (Memory) switch.
Now the frequency on the dial is memorized, and
both TX and RX will occur on the memorized
frequency. For instant recall to the memorized
frequency, press MR (Memory Recall). In like
fashion, another frequency may be memorized
for simplex operation, by setting the FUNCTION
switch to M2 (SIMP), and pressing the M button.
Rotation of the FUNCTION switch to positions
Ml—M3 (600 kHz RPT) automatically shifts the
transmit frequency 600 kHz down from the memo-
rized frequency. For example, if you memorize
146.940 MHz in the M1 (SIMP) position, you will
be operating transceive on that frequency. Now,
rotate the FUNCTION switch to M1 (600 kHz
RPT). You will be transmitting on 146.340 MHz,
while receiving on 146.940 MHz. By pressing the
+TX button, you will be transmitting 600 kHz
above
the receiving frequency, i.e. 147.540 MHz.
The M4 position may be used for split frequency
operation, with a split of up to 4 MHz possible.
Rotate the main dial or scan to the desired trans-
mit frequency, and press the M button. Now rotate
the dial or scan to the desired receive frequency.
You will transmit on the memory frequency, while
receiving on the dial frequency. The position of
the MR button is not important in the case of
the MR position of the FUNCTION switch.
REPEATER OPERATION
A frequency shift of 600 kHz will be applied to
the dial frequency when the FUNCTION switch
is placed in the 600 kHz RPT position.
When the FUNCTION switch is set to positions
Ml—M3 (600 kHz RPT), and the MR switch is not
pushed, automatic split of —600 kHz will be
applied to the dial frequency. With the FUNCTION
switch set to Ml—M3 (600 kHz RPT), and the MR
switch pushed,
the —600 kHz split will be applied
to the memorized frequency.
When operating in the repeater mode, the repeater
shift may be made +600 kHz, by pressing the +TX
button.
Be careful not to transmit outside the amateur
band when using the repeater shift feature.
Remember: placing the FUNCTION switch in the
Ml—M2 (SIMP) position will provide simplex
operation.
When the BURST switch on the bottom of the
transceiver is placed in the ON position, a tone of
1800 Hz of approximately 1 second duration will
be superimposed on the speech signal. This tone is
normally used only with "tone access" repeaters,
and the BURST switch should be turned OFF
when using repeaters not requiring this access tone.
OPTIONAL TONE SQUELCH OPERATION
The tone squelch option allows silent monitoring
of busy channels. When the tone squelch unit is
installed, and the TONE SQ button pushed, a sub-
audible tone will be superimposed on the transmit-
ted signal. On receive, the squelch will not open
unless a subaudible tone is superimposed on the
transmitted signal of the other station. The tone
frequency can be set to any frequency between
70 and 250 Hz, as shown in the Alignment section
of this manual.
To install the tone squelch option, remove the
transceiver from its case. Locate the space provided
for the tone squelch circuit board, and align the
board so that it fits down over the pins, as shown.
Solder the connections shown, and remove the red
jumper wire shown in the illustration.
With the tone squelch option installed, the BUSY
lamp will light up when
any
signal is received, but
the squelch will open only when a subaudible tone
is received on an incoming signal. The operator
should check the BUSY lamp before transmitting,
out of courtesy to other operators who may be
using the channel. The tone squelch system is
designed to allow silent monitoring of busy chan-
nels; it is not
designed to allow two operators
-
so
equipped to have priority use of a channel.

FT
-
227RB MEMORIZER BLOCK DIAGRAM

THEORY OF OPERATION
The block diagram, as well as the following circuit
description, will provide you with a better under-
standing of this transceiver. Refer to the schematic
diagram for circuit details.
The FT-227RB transceiver consists of a transmitter
and a double conversion superheterodyne receiver.
A digital phase lock loop synthesizer provides
operation on any of the 800 channels within the
frequency range of 144-148 MHz. Solid state
circuitry is employed throughout, and computer
theory is utilized for frequency selection. The
transceiver is designed for use from a 13.8 volt
DC power source.
TRANSMITTER
The transmitter produces a Frequency Modulated
(FM) signal. The audio signal from the microphone
is set to the proper level
by VR201 ,
and is ampli-
fied by
Q201, Q202 ,
and Q203 (2SC372Y). The
audio output from
Q
2
02
is coupled to the Instan-
taneous Deviation Control (IDC) circuit, where
both positive and negative peaks are clipped by
diodes
D
2 0
1
and
D202
(1S1555). The output from
the last amplifier
(Q 203
)
is fed through a low-pass
filter, which attenuates frequencies above the
speech range caused by clipping at the IDC; the
deviation level is set by VR
202
. This control is
normally set for a deviation of ± 5 kHz. The speech
signal is then applied to the phase modulator
varactor diode,
D
401
(1SV50), which varies the
frequency of the 10.7 MHz crystal controlled oscil-
lator,
Q401
(2SC372Y). The frequency modulated
10.7 MHz signal is then amplified by a buffer
amplifier,
Q402
(2SC372Y), and fed to the balanced
mixer,
Q403
and
Q404
(2SK19GR), where the
signal is converted up to 144-148 MHz by mixing
with the 133.3-137.3 MHz signal delivered from
the Voltage Controlled Oscillator (VCO). The out-
put from the balanced mixer is fed through the
tuned circuits, consisting of
T404 —T407 ,
to a
MOSFET amplifier,
Q405
(3 SK51-03).
T404 —T407
are tuned to the transmitting frequency by varactor
diodes
D403 —D406 ,
whose capacitances are varied
in accordance with the DC output voltage from
the PLL unit. The 144-148 MHz signal is then
amplified by amplifier stages
Q204
(2SC535A),
Q206
(2SC2053),
Q207
(2SC730), and
Q208
(MRF212), which deliver 10 watts of RF energy,
through a diode switch and low pass filter, to the
antenna.
Diodes
D205
and
D
2 11
(1S188FM) rectify a small
portion of the RF output and apply the resultant
DC voltage to the meter, which indicates relative
transmitter power output.
The DC output from
D
20 5
is also delivered to the
lamp driver,
Q209 —Q210
(2SC372Y), turning the
ON AIR lamp on during transmission.
If the transmitter is keyed without an antenna
being connected, or if a high SWR exists in the
antenna system, the reflected power is detected
through
T202
and a diode, D
2 0
8
(1S188FM),
which produces a DC voltage.
Q211
(2SC372Y)
conducts with the application of the DC voltage
through VR20
5
, causing a decrease in the collector
current of
Q212
(2SC372Y).
Thus, the collector voltage of
Q213
(2SA496)
drops, causing Qi (2SD235) to decrease current
and supply voltage to the PA amplifier, preventing
damage to the transistor. The threshold level is set
by VR2os •
The antenna changeover circuit consists of switch-
ing diodes
D206
and
D207
(MI1301).
The tone burst circuit consists of a timing
generator and a gated multivibrator. With the
BURST switch in the ON position, a DC voltage
is applied to the tone burst current. When the
transmitter is keyed,
Q214
(2SC372Y) conducts,
triggering the one-shot multivibrator,
Q215
(MC14011
B).
The other half of
Q 215 generates
a tone signal, which is amplified by buffer
Q216
(2SC372Y), and applied to the microphone circuit
of the transmitter.
The tone frequency is adjusted by VR
2 0 7
, while
the output level of the burst signal is adjusted by
VR
2 0
9
. The burst duration is set by VR2os .

RECEIVER
The input signal from the antenna is fed through
the low-pass filter, consisting of L
1 ,
L213 , L214 ,
C 1 ,
and
C243 —C245 ,
the diode changeover switch
D 206 —D207 ,
and L
212 ,
to the RF amplifier, Qi o
(3SK51). The amplified signal is then applied,
through a four-stage high-Q coaxial resonator
system, to the first mixer, Q10 2
(3SK51). The use
of MOSFET components, in conjunction with the
high-Q resonator, minimizes the effects of inter-
modulation, as well as other spurious responses;
a low noise figure is also secured for the receiver
system.
The 144-148 MHz signal is heterodyned with the
local oscillator signal from the VCO circuit, pro-
ducing a 10.7 MHz first IF signal. The first IF
signal is fed through crystal filter XF101, which has
a passband of ± 7.5 kHz, to the second mixer,
Q103
(3SK4OM), resulting in a second IF of
455 kHz. The second local oscillator signal of
10.245 kHz is generated by
Q104
(2SC372Y).
Qios (25A564) works as a switch which dis-
connects the supply voltage to Q104
when the
PLL circuit is unlocked.
The IF signal is amplified by
Q106 , Q107 ,
and
Q108
(2SC372Y), and Q109 (RC577H). Cascade-
connected ceramic filters
CF101
and
CF
I 02
provide
narrow band selectivity for the receiver, and the
limiting action of
Q109
removes any amplitude
variation in the IF signal, which is subsequently
fed to the discriminator, CD 101, D106 ,
and
D107
(15188FM).
The discriminator produces an audio output in
response to a corresponding frequency shift in
the IF signal. The output audio signal is amplified
by Q
113 and Q
114
(2SC372Y), and applied across
volume control VR
1
to the input of audio ampli-
fier Q
116
(µPC575C2). The output from
Q 116 in
series through the ACC socket to the internal
speaker. The low-pass filter between
Q 113
and
Q114
attenuates the audio spectrum above 3 kHz,
to increase readability of the incoming signal.
A portion of the 455 kHz IF signal is rectified by
D 103
and
D104 (1S188FM)
for S-meter indication.
VR101 is used to set the meter sensitivity.
When no carrier is present in the 455 kHz IF, the
high frequency noise at the discriminator output
is amplified by Quo and Qi (25C372Y), and
then detected by
D108
and
D
109
(15188FM),
producing a DC voltage. This voltage is then
applied to turn
Q1 12
(2SC372Y) ON. With the
conduction of Q112, the base of Q
11
3 is grounded,
squelching the audio amplifier. When a carrier is
present in the 455 kHz IF, the noise is removed
from the discriminator output, and the audio
amplifier recovers normal operation.
The opening of the squelch circuit causes
Q
113
to
conduct, causing lamp driver Q
115
(2SC372Y) to
draw current, lighting up the BUSY lamp. The
squelch controls, VR
2
and VR
1 0 2
, set the squelch
threshold level.
HETERODYNE OSCILLATOR
The heterodyne signal is generated by a Phase
Locked Loop (PLL) circuit, comprised of a VCO,
reference crystal oscillator, programmable divider,
and phase comparator.
The VCO transistor,
Q 301
(2SK19GR), generates
a signal of 133.3-137.3 MHz. The oscillator fre-
quency is controlled by varactor diode
D301
(1S2209), which varies the capacitance of a tuned
circuit consisting of
L301
5
TC301 ,
and
C
30
4 ,
in
accordance with a DC voltage supplied from phase
comparator
Q 309
(TC5081P).
The output signal from
Q3 0 1
is amplified by buffer
amplifier
Q302
(35K51-03). The signal is further
amplified by
Q303
(2SC535A), and fed through
diode switches
D302
and
D3 0 3
(151555), to the
transmitter and receiver mixers.
A portion of the output from
Q303
is fed through
buffer amplifier
Q304
(35K51-03) to PLL mixer
Q305
(25C535A), producing a 1-5 MHz PLL IF
signal, through mixing with the PLL heterodyne
signal. The latter signal is generated by an over-
tone crystal-controlled oscillator,
Q310
(25C372Y).
The amplified signal, is then fed to a programmable
divider,
Q308
(.11
3
C857C).
Crystal oscillator
Q312
(25C373) generates a
10.24 MHz signal, and its output is fed to scaler/
divider
Q308
(µPC857C), where the 10.24 MHz
signal is divided into a 10 kHz reference signal.

SQ IN
0 
1
0713 0714
DC AMP
0702 1/6
DELAY
0701 1/2
0701 1/2
D.
F/F(CK)
0707 2 / 6
1 STEP GATE
0704 i/4
...I
0707 1/6
DELAY
0704 2/4
UPO-ci
- a a
d 0707 2/6
D N

SCHMITT
...L:
02 1/6
DELAY
D.F/F (U/D)
M. PLEXER
M. VIBRATOR
0
0703 1/6
0709-0711
U/DCCUNTER
CK 0
u/DO
INV
0703 1/6
Q704
1/4
ER
0708 2/4
B W CONT INV
M PLEX
0702. 703. 707. HEX INVERTER
0704. QUAD 21NPUT NAND GATE
0708. QUAD 2INPUT AND GATE
0703 1/6
DE
LAY
ir! ',11-0- •
BCD
1
0705.0706
RAM
M. CH
Q712
BCD -
DECIMAL
DECODER
0715
RELAY DR I V
0702
TX CONT
The digital phase comparator,
Q309
(TC5081P),
compares the phase of the PLL IF signal with that
of the reference signal, and any difference is con-
verted into an error-correcting voltage. This error-
correcting voltage is fed to varactor diode D301 ,
which changes the output signal phase to lock with
that of the reference signal.
PLL CONTROL UNIT
Please refer to the PLL Control Unit logic diagram
for questions regarding the operation of this cir-
cuitry. A complete treatment of every logic state
is beyond the scope of this manual.
When the VCO is locked, the constant voltage at
pin 4 of
Q309
is applied to
Q316 (MPSA13), caus-
ing it to conduct; in turn,
Q315
(2SC372Y) cuts
off. The H voltage at the collector of
Q315
causes
Q205
(2SC372Y) to conduct, supplying DC voltage
to exciter stages
Q204
and
Q206 .
When the VCO is
unlocked, the DC voltage at the emitter of
Q205
drops, preventing normal operation of
Q204
and
Q206 •
The output voltage from Q31 . 5 is reversed in
polarity by Q314 (2SC372Y), and applied to
Q606
(2SC372Y), keeping the collector of
Q606
at the
H level, in order to drive
Q601
-
Q603
(MSM561)
for the display of the channel frequency. The volt-
age is also applied to
Q105
(2SA564), which
supplies DC voltage to the second heterodyne
oscillator,
Q104
(2SC372Y).
When the VCO is unlocked, the collector of DC
voltage drops, causing the LEDs to turn off.
Simultaneously, the second heterodyne oscillator
ceases to oscillate. The receiver is thus muted until
VCO lock occurs.
Crystal Frequency
PLL Het. Freq.
Remarks
X301
44.10000 MHz
132.300 MHz
Simplex
X302
43.90000
/'
131.700
//
TX —600 kHz shift
X303
44.30000
-
132.900
/-
TX +600 kHz shift
X304
44.10166
••
132.305
,
Simplex 5 kHz up
X305
43.90166
',
131.705 ,
TX —600 kHz 5 kHz up
X306
44.30166
,
132.905 ,
TX +600 kHz 5 kHz up

(E 7
-
)
ti
oc
)
, C
''

'o(AF OUT)
(TONE (

OUT)
0523 2 5o
(AF IN)
 G-0(l3.5 V )

c5( EARTH )
—
0503
2SKI9GR/
JF1033
®66
0502
NE 567
0504
2SC372
47K
4.7K
( TONE SQ SWITCH)
TONE SQUELCH
(PB-1555A)
OPTION
( Sw
777
7.47-
POWER SUPPLY
A 13.8 volt DC supply, is used for the audio power
amplifier,
Q116 ,
as well as the relay and lamps. The
supply voltage for the final amplifier is fed through
voltage regulator Q
i
(2SD235D), which is con-
trolled by the automatic final protection unit.
Voltage regulator
Q605
(RC14305) regulates the
supply voltage at 5 volts, to supply
Q308
and the
display unit.
Q313
(2SC372Y) and D301(RD6„8EB)
regulates the supply voltage at 6 volts for the VCO
and phase comparator. The 5 volt supply for the
PLL control unit is regulated by zener diode D 3
(WZ050), and is connected directly (not via the
power switch) for memory backup purposes.
A regulated 8 volt circuit using
Q 117
(RC14308)
is used for all other circuits.
When the transceiver is used in the memory mode,
D 4 and D
5
(WZ050) supply 5 volts to the receiver
and transmitter, respectively.
* * *
C 516  R 516 
R 513  R 514  R 524
21  *
70Hz
t 
0.15pF  39Kn 
15Kn 
470Kn 
15Kfl
160Hz
160Hz
/

0.1uF  33Kn  8.2Kn  270K0  8.2Kn
250Hz
TONE SQUELCH UNIT (OPTION)
The tone squelch circuit disables the audio circuit
of the receiver until a preset, subaudible tone is
received. On transmit, a subaudible tone is super-
imposed on the output audio signal. The frequency
of this tone can be set to any frequency between
70 Hz and 250 Hz.
The tone signal is generated by
Q
5 02
(NE567), and
its frequency is set by
R516 , VR
502
,
and
C516 .
The
level of the tone signal is set by VR
504
, and the
signal is subsequently fed through buffer amplifier
Q503
(2SK19GR) to a low pass filter on unit "d"
of operational amplifier Q 501 (MC3403). The tone
signal is then superimposed on the speech signal at
Q202.
The constants for setting the subaudible
tone frequency are shown in Table 2.
The audio output signal from the receiver dis-
criminator is fed to unit "a" of
Q501 .
Unit "a" of
Q
501
acts as a high-pass filter, while unit "b" acts
as a T-notch filter. These filters remove the sub-
audible tone from the audio signal, which is -then
fed through audio amplifier
Q505
(2SC372Y) to
amplifier Q113
•
The subaudible tone then passes through a low-pass
filter at unit "c" of
Q 501 ,
and is fed to
Q50
2 .
When
the tone frequency is the same as that preset for
transmission, the voltage at pin 8 of
Q502
becomes
low, causing
Q504 (2SC372Y) to turn off. In turn,
proper bias voltage is applied to
Q 119
,
allowing
normal operation.
When the proper tone signal is not present,
Q504
conducts, removing the bias from
Q 119
,
thus dis-
abling the audio circuit.
As the conventional carrier-controlled squelch is
still in operation, irrespective of the condition of
the tone squelch, the BUSY lamp will light up
when any carrier is received. This feature alerts
the operator that the channel is occupied, though
no signal may be heard.
Table 2

PLL CONTROL UNIT PB-18
93

Q304
3SK4OM
BUFF
Q302
3SK4OM
BUFF
Q301
2SKI9BL
VCO
Q309
TC508IP
P. DET
Q 310
2SC373
OS C
133.3MHz —137 3MHz
 TX MIX ,Q403,404
--S RX 1st MIX, Q102
D302,303
1SS53
X 2
SW
133.3MHz-137.3MHz
Q303
2SC535A
AMP
10kHz
Q308
u PD8 57C_
1/ 1024
P. DIV
X3
0311
2SC7I0
MULTI
0305
2SC535A
PLL MIX
I MHz — 4.9 Ni-lz
0306
2SC372Y
IF AMP
D3I5-320
ISS 53 x 6
SW
Q307
2SC372Y
IF AMP
CRYSTAL DATA FT-227RB
FUNCTION HOLDER
RANGE
(MHz)
MODE
LOAD C
SERIES R
DRIVE
LEVEL
REFERENCE (X4
07 )
HC-18/U
10.240
Fundamental 30 pF 25 2
2 mW
2nd Local 
(X 101 )
HC-18/U 10.245
Fundamental
30 pF 25 2 2 mW
Carrier
 (X
401
)
HC-18/U
*10.700
Fundamental
30 pF
20 2 2 mW
(X301)
44.100
(X 302)
43.900
PLL Local 
(X
303 )
HC-18/U
44.300
3rd overtone
20 pF 40 2 2 mW
(X304)
44.10166
(X305)
43.90166
(X306)
44.30166
*ACTUAL FREQUENCY: 10.740 MHz
Load Capacitor: 30 pF, 40 kHz UP (Decided by circuit)
PLL CIRCUIT FREQUENCY RELATIONS
- SIMP: 
44.10000MHZ(132.300MHz)

HOF--
600: 
43.90000MHz(131.700MHz)

-
HOF
-4
600:

4 4.30000MHz (132.900MHz)
H
al— 5UP

44.10166MHz(132.305MHz)
—
101
--
600
. 5UP: 43.901 6 6MHz( 131.705MHz)
H
OF
-1-
600.5UP: 44.30166 MHz (132.905 MHz)
10.240MHz
Q312
2SC373

01 —
OSC 
10240MHz
133.3MHz — I37. 3MHz

10kHz
PROGRAM DATA I/ 100 — 1/499

Q308 ,uPD857C) PROGRAMMABLE DIVIDER CODE
Q 308 PROGRAMMABLE INPUT PIN -, 1
2 3
4
5 6
7 8 9 10 11
P /J305
4
5
6
7 8 9 10 11 12 13 14
P /J304
11 10 9 8 7 6 5 4 3 2 1
FREQUENCY
I
DIAL
DISPLAY
,i,
PROGRAMMABLE
DIVIDER RATIO
1
P,
P2
P 3 P 4
P 5
P
6
000000
00
O
o
o
O
o
P 9
P10
P
11
144.00
4.000
1/100 0 0 0 0 0
0
1
0
4.01
4.010
1/101
1 0 0 0 0 0 1 0
0
4.02
4.020
1/102
0 1 0
0 0 0 1 0
0
4.03
4.030
1/103
1 1 0 0 0 0 1
0 0
4.04
4.040
1/104 0 0 1 0 0 0
1 0
0
4.05
4.050
1/105
1 0 1 0 0 0
1
0 0
4.06
4.060
1/106 0 1 1 0
0 0
1 0 0
4.07
4.070
1/107
1 1 1 0 0 0
1 0
0
4.08
4.080
1/108 0 0
0 1 0 0 1
0 0
4.09
4.090
1/109
1 0 0 1 0 0
1
0 0
144.10
4.100
1/110
0 0
0 0
1
C)
C
) 0
0 0
C
)
0
0
0
0 0 0
0 0
0 0
0 1
0 0
4.11
4.110
1/111
1 0 0 0 1
0 1 0 0
4.12
4.120
1/112
0
1 0
0
1
0 1
0 0
4.13
4.130 1 /
1 13 1 1
0 0 1
0 1 0 0
4.14
4.140
1/114
0
0 1
0
1 0 1
0 0
4.15
4.150
1/115
1 0
1 0 1 0 1 0 0
4.16
4.160 1/116 0 1
1
0 1 0 1
0 0
4.17
4.170
1/117 1 1 1
0 1 0 1
0 0
4.18
4.180
1/118
0
0
0
1 1 0
1 0 0
4.19
4.190
1/119 1
0 0
1
1 0 1 0 0
144.20
4.200
1/120 0
0 0 0 0
1 0 0
1 0
0
4.30
4.300
1/130
0 0 0 0
1 1 0 0 1
0 0
4.40
4.400 1/140
0 0 0 0
0 0 1
0 1 0 0
4.50
4.500
1/150
0
0 0
0
1
0
1
0 1 0 0
4.60
4.600
1/160
0 0
0 0 0
1 1 0
1 0 0
4.70
4.700
1/170 0
0 0 0
1 1
1
0 1 0
0
4.80
4.800 1/180
0 0 0
0 0 0
0
1
1 0 0
4.90
4.900
1/190
0 0 0 1 0 0
1 1
0 0
145.00
5.000
1/200
0 0 0
0
0 0
O
C
)
O 0
40
0
O C)
O C
)
0
C
D O O O O O
O
O
C
)
0 1
0
145.01
5.010
1/201
1
0
0
0 0 0
0 1 0
145.02
5.020
1/202
0
1 0
0 0
0
0
1 0
145.03
5.030
1/203
1 1 0 0 0 0 0
1 0
145.04
5.040
1/204
0 0
1
0 0 0 0
1 0
145.05
5.050
1/205
1 0 1
0 0 0 0
1
0
145.06
5.060
1/206
0 1 1
0
0 0 0
1 0
' 
145.07
5.070
1/207
1 1 1 0 0 0
0 1
0
145.08
5.080
1/208
0 0 0
1
0
0 0
1
0
145.09
5.090
1/209 1
0 0
1
0
0
0
1 0
145.10
5.100
1/210
0
0
0
0
0
0
0
0
0
0
0
0
0
0 0
0
1 0
0
1-
1
1-
1
0 0
0 0
0
0
0
0
0
0
0
0 0
0 0 0
1
0
145.20
5.200
1/220
0
0
0
1
0
1 0
145.30
5.300
1/230
0 0
1
1 0
1 0
145.40
5.400
1 /
2
40
0
0
0
0
1 1 0
145.50
5.500
1
/
2
50
0 0
1
0
1 1 0
145.60
5.600
1 /
2
60
0 0
0 1 1 1
0
145.70
5.700
1 /
2 70
0
0
1
1 1 1
0
145.80
5.800
1 /
2
80
0
0 0
0
0
1
0
145.90
5.900
1
/
2
90
0 0
1
0
0
1
0
146.00
6.000
1/300

f 0
0
0
0 0 0 0 0
1
1 0
147.00
7.000
1/400
0
0 0
0 0
0
0
0
0
0
1
147.99
7.990
1/499
1
0 0
1
1
1 HIGH LEVEL ( 5V)
- 18 -

0
LOW LEVEL
(OV)