UHF FM Transceiver
VX-160EU/-180EU
Service Manual
©2004 VERTEX STANDARD CO., LTD.
EC037U90B
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 EUROPE B.V.
P.O. Box 75525, 1118 ZN Schiphol, The Netherlands
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
VX-160EU VX-180EU
Introduction
This manual provides technical information necessary for servicing the VX-160EU and VX-180EU FM Transceiver.
Servicing this equipment requires expertise in handling 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 circuit board in the transceiver. Each side of is referred
to by the type of the majority of components installed on that side (“leaded” or “chip-only”). 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 technical 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.
Contents
Operating Manual Reprint............................ 2
Cloning .............................................................. 6
Specifications ................................................... 7
Exploded View & Miscellaneous Parts ...... 8
Block Diagram ................................................. 9
Circuit Description ................................ 11
Alignment .................................................13
Board Unit (
MAIN Unit ................................................................ 17
Schematics, Layouts & Parts
)
1
Operating Manual Reprint
Controls & ConnectorsControls & Connectors
Controls & Connectors
Controls & ConnectorsControls & Connectors
LED Indicator
Glows Green Monitor on (except 5-Tone Mode)
Blinking Green Busy Channel (or SQL off)
Glows Red Transmitting
Blinking Red Battery Voltage is low
Blinking Yellow Receiving a Selective Call
Antenna
Push To Talk
(
PTT) Switch
Monitor Button
Microphone
Battery Pack Latch
Display Icons & Indicators (VX-180E Only)Display Icons & Indicators (VX-180E Only)
Display Icons & Indicators (VX-180E Only)
Display Icons & Indicators (VX-180E Only)Display Icons & Indicators (VX-180E Only)
CH (Channel) Selector
VOL/PWR Knob
MIC/SP Jack
(
External Mic/Earphone
Speaker
LCD (VX-180E)
Soft KEY (VX-180E)
Before You BeginBefore You Begin
Before You Begin
Before You BeginBefore You Begin
Battery Pack Installation and Removal
U To install the battery, hold the transceiver with your
left hand, so your palm is over the speaker and your
thumb is on the top of the belt clip. Insert the battery
pack into the battery compartment on the back of the
radio while tilting the Belt Clip outward, then close
the Battery Pack Latch until it locks in place with a
“Click.”
)
U To remove the battery, turn the radio off and remove
any protective cases. Open the Battery Pack latch on
the bottom of the radio, then slide the battery downward and out from the radio while holding the Belt
Clip.
Caution!
Do not attempt to open any of the rechargeable NiCd packs, as they could explode if accidentally shortcircuited.
This indicator confirms that
D
UAL WATCH is active.
This icon is the “Low Battery” indicator, which appears when the
battery voltage becomes too low
for proper operation.
This indicator confirms that 2
or 5-TONE DECODE is active.
8 Character Alpha-numeric Invertible Display
This indicator confirms that
this channel will be skipped
during scan.
This indicator will appears during this "Scan
Pause" condision.
Low Battery Indication
U As the battery discharges during use, the voltage gradu-
ally becomes lower. When the battery voltage becomes
to low, substitute a freshly charged battery and recharge
the depleted pack. The TX/BUSY indicator on the top
of the radio will blink red (on the VX-180, the “
icon will appear on the LCD) when the battery voltage
is low.
U Avoid recharging Ni-Cd batteries often with little use
between charges, as this can degrade the charge capacity. We recommend that you carry an extra, fullycharged pack with you so the operational battery may
be used until depletion (this “deep cycling” technique
promotes better long-term battery capacity).
”
2
OperationOperation
Operation
OperationOperation
Operating Manual Reprint
Preliminary Steps
U Install a charged battery pack onto the transceiver, as
described previously.
U Screw the supplied antenna onto the Antenna jack.
Never attempt to operate this transceiver without an
antenna connected.
U If you have a Speaker/Microphone, we recommend that
it not be connected until you are familiar with the ba-
sic operation of the VX-160E/-180E.
Operation Quick Start
U Turn the top panel’s VOL/
PWR knob clockwise to turn
on the radio on.
U Turn the top panel’s CH selec-
tor knob to choose the desired
operating channel.
U Rotate the VOL/PWR knob to
set the volume level. If no sig-
nal is present, press and hold
in the MONITOR key (the
lower button on the left side)
for more than 1 seconds; back-
ground noise will now be heard, and you may use this
to set the VOL/PWR knob for the desired audio level.
U Press and hold in the MONI-
TOR key for more than 1 sec-
onds (or press the MONITOR
key twice) to quiet the noise
and resume normal (quiet)
monitoring.
U To transmit, press and hold in
the PTT switch. Speak into the
microphone area of the front
panel grille (lower left-hand
corner) in a normal voice level.
To return to the Receive mode,
release the PTT switch.
U If a Speaker/Microphone is available, remove the plas-
tic cap and its two mounting screws from the right side
of the transceiver, then insert the plug from the Speaker/
Microphone into the MIC/SP jack; secure the plug using the screws supplied with the Speaker/Microphone.
Hold the speaker grille up next to your ear while receiving. To transmit, press the PTT switch on the
Speaker/Microphone, just as you would on the main
transceiver’s body.
Note: Save the original plastic cap and its mounting
screws. They should be re-installed when not using the Speaker/Microphone.
Key FunctionsKey Functions
Key Functions
Key FunctionsKey Functions
The VX-180E provides programmable [A], [B], and [C]
function keys, and both the VX-160E and VX-180E provide programmable MONITOR keys. These “Soft” keys
functions can be customized (set to other functions), via
programming by your VERTEX STANDARD dealer, to
meet your communications/network requirements. The
possible Soft key programming features are illustrated at
the right, and their functions are explained in the next chapter. For further details, contact your VERTEX STAN-
DARD dealer.
For future reference, check the box next to each function
that has been assigned to the Soft key on your particular
radio, and keep it handy.
Press
Hold
Soft Key
Press and
Function
None
Monitor
Squelch off
Low Power
Lock*
Lamp*
Channel Up*
Channel Down*
Scan
Follow-me Scan
Dual Watch
Talk Around
Add/Del*
Reset
Speed Dial
TX Save Off
Call 1
Call 2
Call 3
Code Select*
Code Up*
Code Down*
Emergency
Group**
* VX-180E only ** 32 Channel Version only
[A]
Press
Press and
Hold
--
[B]
Press and
--
MONITOR Key
[C]
Press
Hold
--
Press
Press and
Hold
--
3
Operating Manual Reprint
Description of Operating FunctionsDescription of Operating Functions
Description of Operating Functions
Description of Operating FunctionsDescription of Operating Functions
Monitor
Press the assigned Soft key momentarily to override (disable) the Tone squelch (For the 5-Tone mode, please ask
to your nearest Vertex Standard dealers).
Squelch OFF
Press (or Press and hold) the assigned Soft key to hear
background noise (unmute the audio).
Background noise or incoming signals will now be heard
whether or not a matching tone is present on the signal.
Press and hold in the assigned Soft key for more than 1
seconds to override both the Noise and Tone squelch. Again
press and hold in the assigned Soft key for more than 1
seconds (or press the assigned Soft key twice) to resume
normal (quiet) Noise and Tone squelch action.
Low Power
Press (or Press and hold) the assigned Soft key to set the
radio's transmitter to the “Low Power” mode, thus extending battery life. Press the assigned Soft key again to return to “High Power” operation when in difficult terrain.
Lock
Press (or Press and hold) the assigned Soft key to lock
the Soft keys (except Emergency, Lock and Monitor key);
thus, the [A], [B], [C], and MONITOR keys can be disabled to prevent radio settings from being disturbed.
Lamp
Press (or Press and hold) the assigned Soft key to illuminate the LCD for five seconds.
Channel Up
Press (or Press and hold) the assigned Soft key to switch
to a higher operating channel number.
Channel Down
Press (or Press and hold) the assigned Soft key to switch
to a lower operating channel number.
Scan
The Scanning feature is used to monitor multiple channels programmed into the transceiver. While scanning, the
radio will check each channel for the presence of a signal,
and will stop on a channel if a signal is present.
U To activate scanning:
Press (or Press and hold) the assigned Soft key.
The scanner will search the channels, looking for active ones; it will pause each time it finds a channel on
which someone is speaking.
U To stop scanning:
Press (or Press and hold) the assigned Soft key.
Operation will revert to the channel to which the CH
knob is set.
Follow-Me Scan
“Follow-Me” Scan feature checks a User-assigned Priority Channel regularly as you scan the other channels. Thus,
if only Channels 1, 3, and 5 (of the 8 available channels)
are designated for “Scanning,” the user may nonetheless
assign Channel as the “User-assigned” Priority Channel
via the “Follow-Me” feature.
Press the assigned Soft key to activate “Follow-Me” scanning, then turn the CH selector knob to the channel which
you want to designate as the “User-Assigned Priority Channel”. When the scanner stops on an “active” channel, the
User-assigned Priority Channel will automatically be
checked every few seconds.
Dual Watch
The Dual Watch feature is similar to the Scan feature, except that only two channels are monitored: the current
operating channel, and the “Priority” channel.
U To activate Dual Watch:
Press (or Press and hold) the assigned Soft key.
The scanner will search the two channels; it will pause
each time it finds a channel on which someone is speaking.
U To stop Dual Watch:
Press the assigned Soft key.
Operation will revert to the channel to which the CH
knob is set.
Talk Around
Press (or Press and hold) the assigned Soft to activate the
Talk Around feature when you are operating on duplex
channel systems (separate receive and transmit frequencies, utilizing a “repeater” station). The Talk Around feature allows you to bypass the repeater station and talk directly to a station that is nearby. This feature has no effect
when you are operating on “Simplex” channels, where the
receive and transmit frequencies are already the same.
Note that your dealer may have made provision for “Talk
Around” channels by programming “repeater” and “Talk
Around” frequencies on two adjacent channels. If so, the
key may be used for one of the other Pre-Programmed
Functions.
Add/Del
The Add/Del feature allows the user to arrange a custom
Scan.
Press (or Press and hold) the assigned Soft key to delete/
restore the current channel to/from your scanning list.
When you delete a current channel, “SKIP” will appear
on the LCD after pressing the Soft key. When you restore a current channel, “SKIP” indicator on the LCD will
turn off.
4
Operating Manual Reprint
Description of Operating FunctionsDescription of Operating Functions
Description of Operating Functions
Description of Operating FunctionsDescription of Operating Functions
Reset
Press (or Press and hold) the assigned Soft key to reset
the 2-Tone or 5-Tone sequential signaling System.
Speed Dial
Your Dealer may have pre-programmed Auto-Dial telephone number memories into your radio.
To dial a number, just press (or Press and hold) the Dealerassigned Soft key for Speed Dialing. The DTMF tones
sent during the dialing sequence will be heard in the
speaker.
TX Save Off
Press (or Press and hold) the assigned Soft key to disable
the Transmit Battery Saver, if you are operating in a location where high power is almost always needed.
The Transmit Battery Saver helps extend battery life by
reducing transmit power when a very strong signal from
an apparently nearby station is being received. Under some
circumstances, though, your hand-held radio may not be
heard well at the other end of the communication path,
and high power may be necessary at all times.
Call 1
Press (or press and hold) the assigned Soft key to send
the 5-Tone sequential Code which is set to the present channel.
Call 2 / 3
Press (or press and hold) the assigned Soft Key to send
the pre-programmed 5-Tone sequential Code.
Code Select
Press (or press and hold) the assigned Soft Key to engage
the setting of the 5-Tone sequential Code.
While setting the sequential code, press (or press and hold)
this key to move the cursor to the next character.
Code Up
Press (or press and hold) the assigned Soft Key to switch
to a higher paging code number for the 5-Tone sequential
signaling System.
While setting the sequential code, press (or press and hold)
this key to switch to a higher sequential Code number.
Code Down
Press (or ress and hold) the assigned Soft Key to switch
to a lower paging code number for the 5-Tone sequential
signaling System.
While setting the sequential code, press (or press and hold)
this key to switch to a lower sequential Code number.
Emergency
The VX-160E/-180E includes an “Emergency” feature
which may be useful if you have someone monitoring on
the same frequency as your transceiver’s channel. For further details contact your nearest Vertex Standard dealer.
Groupe (32 Channel Version only)
The 32-Channel Version is capable of separating its 32
channels into either of 2 groups (Group-A:CH 1~CH 16,
Group-B:CH 17~CH 32). Press (or press and hold in) the
assigned Soft key to change the between Group-A and
Group-B.
Accessories & OptionsAccessories & Options
Accessories & Options
Accessories & OptionsAccessories & Options
FNB-64 7.2 V 700 mAh Ni-Cd Battery
FNB-V57 7.2 V 1100 mAh Ni-Cd Battery
FBA-25A Alkaline Battery Case
NC-77C 230-240 VAC Overnight Desktop Charger
NC-77U 230 VAC Overnight Desktop Charger
VAC-800 Desktop Rapid Charger
VAC-6800 6-unit Multi Charger
MH-45
MH-37
VC-25 VOX Headset
VCM-1 Mobile Mounting Bracket (for VAC-800)
ATU-6A UHF Antenna, 410~430 MHz
ATU-6C UHF Antenna, 440~470 MHz
CT-42 PC Programming Cable
CT-27 Radio to Radio Programming Cable
CE51 Programming Software
B4B
Speaker/Microphone
A4B
Earpiece Microphone
5
Cloning
The VX-160E/-180E includes a convenient Cloning feature, which allows the programming data from one transceiver
to be transferred to another VX-160E/-180E. Here is the procedure for Cloning one radio's data to another.
1. Turn both transceivers off.
2. Remove the plastic cap and its two mounting screws
from the MIC/SP jack on the right side of the transceiver. Do this for both transceivers.
3. Connect the optional CT-27 cloning cable between the
MIC/SP jacks of the two transceivers.
4. Press and hold in the PTT and MONITOR switches
(just below the PTT switch) while turning the transceiver on. Do this for both transceivers (the order of
the switch-on does not matter). “
on the displays (for the VX-180E) of both transceivers when Clone mode is successfully activated in this
step; in the case of the VX-160E, no change will be
observed at this point.
5. On the Destination transceiver, press the MONITOR
switch. “
180E; for VX-160E, the TX/BUSY indicator on the
top of the radio will glow Green).
LOADINGLOADING
LOADING” will appear on the LCD (for VX-
LOADINGLOADING
CLONECLONE
CLONE” will appear
CLONECLONE
6. Press the PTT switch on the source transceiver; “
INGING
ING” will appear on the Source transceiver (for VX-
INGING
180E; for VX-160E, the TX/BUSY indicator on the
top of the radio will glow Red), and the data will be
transferred.
7. If there is a problem during the cloning process, “
RORROR
ROR” will appear on the LCD (for VX-180E; for VX-
RORROR
160E, the TX/BUSY indicator on the top of the radio
will blink Red); check your cable connections and battery voltage, and try again.
8. If the data transfer is successful, the display will return
CLONECLONE
to “
CLONE” (for VX-180E; for VX-160E, the TX/
CLONECLONE
BUSY indicator on the top of the radio will turn off).
Turn both transceivers off and disconnect the CT-27
cable. You can then turn the transceivers back on, and
begin normal operation.
9. Replace the plastic cap and its two mounting screws.
SEND-SEND-
SEND-
SEND-SEND-
ER-ER-
ER-
ER-ER-
Optional Cloning Cable CT-27
6
GENERAL Specifications
Frequency Range (MHz): 440 - 470 (TYP CS)
400 - 430 (TYP AS1)
420 - 450 (TYP B)
450 - 490 (TYP D)
Number of Channels: 16 channels, 32 channels (32 Channel Version)
Channel Spacing: 12.5 / 25 kHz
PLL Steps 5.0 / 6.25 kHz
Power Supply voltage: 7.5 VDC ± 10%
Operating Temperature Range: –25°C to +55°C
Frequency Stability: ±5.0 ppm
Dimensions (WHD): 58 (W) x 120 (H) x 31 (D) mm
Weight (approx.): 365 g w/FNB-64
RECEIVER Specifications (Measurements made per ETS 300-086)
Sensitivity (ETS 20 dB SINAD) : 0.20 µV
Adjacent channel selectivity: 70 dB (25 kHz) / 60 dB (12.5 kHz)
Intermodulation: 65 dB
Spurious and Image Rejection: 65 dB
Hum & Noise 45 dB
Audio output: 500 mW @4 Ohms, 10% THD
Specifications
TRANSMITTER Specifications (Measurements made per ETS 300-086)
Power output: 5.0 / 1.0 W
Modulation: 16K0F3E, 11K0F3E
Conducted Spurious Emissions: 73 dB Below Carrier
FM Hum & Noise: 43 dB (25 kHz) / 38 dB (12.5 kHz)
Audio distortion (@ 1 kHz): < 5 %
Measurements per EIA standards unless noted above. Specifications subject to change without notice or obligation.
7
Exploded View & Miscellaneous Parts
RA0414400 (Lot. 1-12)
RA041440A (Lot. 13-21)
RA0173500
CAP
RA0296100
VOLUME KNOB
RA0210600
RA0296200
KNOB (CH)
RUBBER PACKING (x 2 pcs)
RA029450A (Lot. 1-38)
RA029450B (Lot. 39-)
LIGHT GUIDE (VX-180E)
RA033490A (VX-180E)
REFLECTOR SHEET
RA041440B (Lot. 22-)
FRONT CASE ASSY (VX-160E)
R6147510
RING NUT (x 2 pcs)
RA0294200
PTT KNOB
RA0438200 (VX-180E)
INSULATOR SHEET
RA0438200 (VX-180E)
LCD HOLDER
G6090139 (VX-180E)
LCD
REF. VXSTD P/N Description Qty.
U44104002 TAPTITE SCREW M2X4NI 10
U44104002
(VX-180E)
TAPTITE SCREW M2X4NI 2
U20206007 BINDING HEAD SCREW M2.6X6B 2
U24110002 TAPTITE SCREW M2X10NI 2
U02206007 SEMS SCREW SM2.6X6B 2
U00103002 PAN HEAD SCREW M2X3NI 1
RA0210900
RA0414600 (Lot. 1-12)
RA041460A (Lot. 13-21)
RA041460B (Lot. 22-)
FRONT CASE ASSY (VX-180E)
WINDOW
RA0294800 (VX-180E)
INTER CONNECTOR
RA0107000
TERMINAL PLATE R
RA010340A (Lot. 1-3)
RA010340B (Lot. 4-)
TERMINAL HOLDER
TERMINAL PLATE L
RA0442300
SPONGE RUBBER
RA0425000 (Lot. 1-4)
RA042500A (Lot. 5-31)
RA042500B (Lot. 32-39)
RA042500C (Lot. 40-)
CONTACT TR25-7X15
RA0110200
HOLDER RUBBER
MAIN Unit
RA0294300
RUBBER PACKING
RA0376900 (Lot. 1-24)
RA0533600 (Lot. 25-)
SHEET
RA0293900
RA0123500
LATCH NAIL B
RA0425100 (Lot. 1-4)
RA042510A (Lot. 5-31)
RA042510B (Lot. 32-39)
RA042510C (Lot. 40-)
CONTACT TR25-10.5X15
RA0293100
REAR CASE ASSY
(w/SMA CONNECTOR, TERMINAL PLATE L,
PAN HEAD SCREW M2X3NI)
RUBBER KNOB
RA0424900 (Lot. 1-4)
RA042490A (Lot. 5-31)
RA042490B (Lot. 32-39)
RA042490C (Lot. 40-)
CONTACT TR25-1815 (2 pcs)
CAUTION
The mic element must be desoldered
and removed from the PCB on order to reinstall its protective rubber cover.
Therefore, be careful not to remove this
cover unless mic element replacement is
necessary.
CP7355001
BELT CLIP ASSY
8
Block Diagram
9
Block Diagram
Note:
10
Circuit Description
Receive Signal Path
Incoming RF from the antenna jack is delivered to the
RF Unit and passes through a low-pass filter consisting of
coils L1001, L1002, and L1003, capacitors C1001, C1002,
C1010, C1011, C1012, C1013, C1014, C1015, and C1016,
and antenna switching diode D1001 (RLS135 TE-11).
Signals within the frequency range of the transceiver
enter a varactor-tuned band-pass filter consisting of coils
L1011 and L1014, capacitors C1043, C1044, C1064,
C1081, and C1082, and diodes D1004, D1005, D1006,
and D1007
(2SC5006-T1) and enter a varactor-tuned band-pass filter consisting of coils L1018, L1019, and L1020, capacitors C1096, C1097, C1098, C1099, C1100, C1101, C1113,
C1114, C1115, C1116, and C1117, and diodes D1014,
D101
mixing by Q1036 (3SK-320 TE85L).
(2SC5005-T1) to provide a pure first local signal between
395.75 and 425.75 MHz for injection to the first mixer.
The 44.25 MHz first mixer product then passes through
monolithic crystal filter XF1001, XF1002 (
HDF0028, 5.5 kHz BW) to strip away unwanted mixer
products, and the IF signal is then amplified by Q1042
(2SC4215Y TE85R).
system IC Q1048 (TA31136FN-EL), which contains the
second mixer, second local oscillator, limiter amplifier,
noise amplifier, and RSSI amplifier.
ence/second local oscillator of 14.60 MHz crystal X1002.
The 14.60 MHz reference signal is tripled by Q1048, capacitor C1191, and coil L1034, and the resulting 43.8 MHz
second local signal is then delivered to the mixer section
of Q1048, which produces the 450 kHz second IF when
mixed with the first IF signal.
(ALFYM450G=K on “Narrow” channels) or CF1002
(ALFYM450F=K on “Wide” channels) to strip away all
but the desired signal, and then is applied to the limiter
amplifier in Q1048, which removes amplitude variations
in the 450 kHz IF, before detection of the speech by the
ceramic discriminator, CD1001 (CDBC450CX24).
pass filter, and then passes via the volume control to the
audio amplifier Q1055 (NJM2070M-TE2), which provides up to 1/2 Watt to the optional headphone jack or a 4ohm loudspeaker.
, and D1019 ( HVC350B TRF), before first
Buffered output from the VCO is amplified by Q1025
The amplified first IF signal is applied to FM IF sub-
The second local signal is produced from the PLL refer-
The second IF then passes through ceramic filter CF1001
Detected audio from Q1048 is applied to the audio high-
HVC350B TRF), then amplified by Q1013
Squelch Control
The squelch circuitry consists of a noise amplifier and
band-pass filter within Q1048 (TA31136FN), and noise
detector D1036 (1SS400 TE-61).
When no carrier is received, noise at the output of the
detector stage in Q1048 is amplified and band-pass filtered by the noise amplifier section of Q1048 and the network between pins 7 and 8, and then is rectified by D1036.
The resulting DC squelch control voltage is passed to
pin 37 of the microprocessor Q1011 (M37516F8HP). If
no carrier is received, this signal causes pin 24 of Q1011
to go low and pin 20 to go high. Pin 24 signals Q1047
(CPH6102) to disable the supply voltage to the audio amplifier Q1055 (NJM2070M), while pin 20 holds the green
(Busy) half of the LED off, when pin 24 is low and pin 20
is high.
Thus, the microprocessor blocks output from the audio
amplifier, and silences the receiver, while no signal is being received (and during transmission, as well).
When a carrier appears at the discriminator, noise is removed from the output, causing pin 37 of Q1011 to go
low and the microprocessor to activate the “Busy” LED
via Q1022 (2SC4154-T11).
The microprocessor then checks for CTCSS or DCS code
squelch information, if enabled. If not transmitting and
CTCSS or DCS is not activated, or if the received tone or
code matches that programmed, audio is allowed to pass
through the audio amplifier Q1055 to the loudspeaker by
the enabling of the supply voltage to it via Q1047.
Transmit Signal Path
Speech input from the microphone is amplified by Q1017
(NJM2902V TE1);
the audio is amplified in another section of Q1017.
The processed audio may then be mixed with a CTCSS
tone generated by Q1011 (M37516F8HP) for frequency
modulation of the PLL carrier (up to ±5 kHz from the
unmodulated carrier) at the transmitting frequency.
If a DCS code is enabled for transmission, the code is
generated by microprocessor Q1011 and delivered to
D1031 (HVC350B TRF) for DCS modulating.
The modulated signal from the VCO Q1040 (2SC4227-
R34) is buffered by Q1025 (2SC5005-T1).
The low-level transmit signal then passes through the
T/R switching diode D1016 (DAN235E-TL) to buffer
amplifier Q1020 (2SC5005-T1), driver amplifiers Q1014
(2SC3357-RF) and Q1009 (2SK2973-T13), then the
amplified transmit signal is applied to the final amplifier
Q1006 (2SK2974-T11), which delivers up to 5 watts of
output power.
The transmit signal then passes through the antenna
switch D1001 (RLS135 TE-11) and is low-pass filtered,
to suppress harmonic spurious radiation, before delivery
to the antenna.
after pre-emphasis by C1059 and R1055,
11
Circuit Description
Automatic Transmit Power Control
Current from the final amplifier is sampled by R1020,
R1039, and R1042, and is rectified by Q1003 (IMZ2A
T108). The resulting DC is fed back through Q1002
(FMW1 T98) to the drive amplifier Q1009 (2SK2973)
and final amplifier Q1006 (2SK2974), for control of the
power output.
The microprocessor selects “High” or “Low” power
levels.
Transmit Inhibit
When the transmit PLL is unlocked, pin 7 of PLL chip
Q1050 (MB15A02PFV1-G-BND-EF) goes to a logic
“Low,” and unlock detector Q1051 (2SA1602A-F) goes
to a logic “High.” The resulting DC unlock control voltage is passed to pin 14 of the microprocessor, Q1011
(M37516F8HP). While the transmit PLL is unlocked, pin
22 of Q1011 remains high, which then turns off Q1023
(CPH6102-TL) to disable the TX 5 V line to Q1014
(2SC3357-T2) and Q1020 (2SC5005-T1), and also Automatic Power Controller Q1002 (FMW1 T98) the controls the bias voltage for Q1006 (2SK2974) and Q1009
(2SK2973-T13), thereby disableing 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, and L1003 plus capacitors C1001, C1002, C1010,
C1012, C1013, C1014, C1015, and C1016, resulting harmonic suppression prior to delivery to the antenna.
PLL Frequency Synthesizer
The PLL circuitry on the Main Unit consists of VCO
Q1037 (2SK508-K52), and Q1040 (2SC4227-R34),
VCO buffer Q1025 (2SC5005), and PLL subsystem IC
Q1050 (MB15A02PFV1-G-BND-EF), which contains
a reference divider, serial-to-parallel data latch, programmable divider, phase comparator, and charge pump.
Frequency stability is maintained by temperature compensating thermistor TH1001. The output from TH1001
is applied to pin 39 of Q1011 (M37516F8HP). Q1011
outputs thermal data to D/A converter Q1004 (M62364FP
600D), which produces a DC voltage corresponding to
the thermal data. The resulting DC voltage is applied to
varactor diode D1031 (HVC350B TRF) to stabilize the
14.60 MHz Reference Frequency.
While receiving, VCO Q1037 oscillates between 395.75
and 425.75 MHz according to the transceiver version and
the programmed receiving frequency. The VCO output is
buffered by Q1025 , then applied to the prescaler section
of Q1050. There the VCO signal is divided by 64 or 65,
according to a control signal from the data latch section of
Q1050, before being sent to the programmable divider
section of Q1050.
The data latch section of Q1050 also receives serial dividing data from the microprocessor, Q1011, 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 5.0 kHz or 6.25 kHz
derivative of the current VCO frequency.
Meanwhile, the reference divider section of Q1050 divides the 14.60 MHz crystal reference (from the reference
oscillator) by 2920 (or 2336) to produce the 5 kHz (or
6.25 kHz) loop references (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 Q1011, which produces a pulsed output with pulse
duration depending on the phase difference between the
input signals.
This pulse train is filtered to DC and returned to the
varactor D1024, D1025, D1026, and D102
HVC350B TRF). Changes in the level of the DC voltage
are applied to the varactor, affecting 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 Q1037, after buffering by
Q1025, is applied to the first mixer as described previously.
For transmission, the VCO Q1040 oscillates between
440 and 470 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. Also, the
VCO is modulated by the speech audio applied to D1020
(HVC350B), as described previously.
Receive and transmit buses select which VCO is made
active, using Q1027, Q1038
and Q1039 (RT1P441U-T11-1).
RT1N441U-T11-1),
Miscellaneous Circuits
Push-To-Talk Transmit Activation
The PTT switch on the microphone is connected to pin
48 of microprocessor Q1011 (M37516F8HP), so that
when the PTT switch is closed, pin 23 of Q1011 goes low.
This signal disables the receiver by disabling the 5 V supply bus at Q1019 (DTB123EK T146) to the front-end,
FM IF subsystem IC Q1048 (TA31136FN), and the re-
ceiver VCO circuitry.
At the same time, Q1024 (FMW1 T98) and Q1023
(CPH6102-TL) activate the transmit 5V supply line to
enable the transmitter.
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