Icom IC-730 User manual

....... '.
•
HF ALL BAND TRANSCEIVER
IC-73D
MAINTENANCE MANUAL
DIICOMI
ICOM INCORPORATED
1-6-19. Kamikurazukuri Hirano-ku. Osaka. Japan
Phone: (oo1793~1
Telex: ICOM TR J63649
ICOM a.oPE G.M.B.H.
Himmelgeister Stress 100
4000 Duesseldorf 1
Weat Germany
Phone:[phone]
Telex:41-8688082
ICOM AMaleA, Ie.
2112 116th Mnue N.E.
Bellevue. WA 90004
Phone:t2(6)454-8165
Telex:230-162210 !COM AMER BVUE
3331 TowelWOOd Dr .• Suite 307
Dalla•• T_ 76234
Phone:[phone]
ICOM CANADA LTD.
810 S.W. Marina Oriw
Val'lCOU\ler. BC Canada
Phone:I8(4)321-1833
Telex:21-464315
ICOM AUS1RALIA, PlY. Ltd.
7 Duke Street. Windsor 3181
Victoria Australia
Phone:[phone]
Telex:71-35621 ICOMAS AA36621
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TABLE OF CONTENTS
SECTION
1. SPECIFICATIONS ............................................. 1-1
SECTION 2. OPERATING CONTROLS ....................................... 2 - 1 -- 4
SECTION 3. CIRCUIT DESCRIPTION ........................................ 3 - 1 -- 8
SECTION
SECTION
SECTION
SECTION
SECTION
SECTION
3 - 1 RECEIVING CIRCUITS ............. "". . . . . . . . . . . . . . . . . . . . .. 3 - 1
3 - 2 TRANSMITTING CIRCUITS... ... . .. . ...... .... . . ... . .. ... 3 - 3
3 -
31ST LOCAL OSCILLATOR CIRCUITS ...................... 3-6
3 - 4 DISPLAY UNIT ......................................... 3-8
4. INSIDE VIEWS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4 - 1 -- 4
5. BLOCK DIAGRAM ............................................ 5 - 1
6. OPTIONS INSTALLATION ...................................... 6 -1 -- 9
7. MECHANICAL PARTS AND DISASSEMBLY ....................... 7 - 1 -- 23
8. MAINTENANCE AND ADJUSTMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8 -1 -- 19
8 - 1 MEASURING INSTRUMENTS REQUIRED
FOR ADJUSTMENT
8-1
8 - 2 PLL ADJUSTMENT ........ , ........ '" .. , ... ... . . .. .. ... 8 - 2
8 - 3 RECEIVER ADJUSTMENT
................................ 8 - 11
8 - 4 TRANSMITTER ADJUSTMENT ............................ 8 - 13
9. VOLTAGE (CIRCUIT) DIAGRAMS ............................... 9 - 1-- 14
SECTION 10. PARTS LIST .................................................. 10 - 1 -- 20
SECTION 11. SCHEMATIC DIAGRAM
......................................... 11 - 1
SECTION 12. BOARD LAYOUT .............................................. SEPARATE
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SECTION 1 SPECIFICATIONS
GENERAL
Number of Semiconductors:
Transistors
71
FET 15
IC (Includes CPU) 25
Diodes 212
Frequency
Coverage:
3.5MHz -4.0 MHz
7.0MHz -7.3 MHz
10.0MHz -10.5 MHz (Receive Only)
14.0MHz
-14.35MHz
18.0MHz -18.5 MHz (Receive Only)
21.0MHz -21.45MHz
24.5MHz -25.0 MHz (Receive Only)
28.0MHz -29.7 MHz
Frequency Control:
CPU based 10Hz step Pre-mixed synthesizer.
Independent Transmit-Receive Frequency Available on
same band.
Frequency Readout:
6 digit 100Hz readout.
Frequency Stability:
Less than 500Hz after switch on 1 min to 60 mins, and
less than 100Hz after 1 hour. Less than 1KHz in the
range of -10° C to +60° C.
Power Supply. Requirements:
DC 13.8V ±15% Negative ground Current drain lOA
max. (at 200W input)
AC power supply
is available for AC operation.
Antenna Impedance:
50 ohms Unbalanced
Weight:
6.4
Kg
Dimensions:
94mm(H) x 241mm(W) x 275mm(D)
TRANSMITTER
RF Power:
SSB (A3J) 200 Watts PEP input
CW (AI) 200 Watts input
Continuously Adjustable Output power 10Watts -Max.
AM (A
3)
40 Watts output
Continuously Adjustable Output power 10 Watts -
40
Watts .
Emission Mode:
A3J
SSB (Upper sideband and Lower sideband)
Al CW
A3 AM
Harmonic Output:
More than 50dB below peak power output
Spurious Output:
More than 50dB below peak power output
Carrier Suppression:
More than 50dB below
peak power output
Unwanted Sideband:
More than 55dB down at 1000Hz AF input
Microphone:
Impedance 1300 ohms
Input Level 120 millivolts typical
Dynam1c : or Electret Condenser Microphone with
Preamplifier
RECEIVER
Receiving System:
Quadruple Conversion Superheterodyne
with continuous
Pass-Band Shift Control.
Receiving Mode:
AI, A3J (USB, LSB), A3
IF Frequencies:
1st 39.7315MHz
2nd 9.0115MHz
3rd 455KHz
4th 9.0115MHz
with continuous Pass-Band Shift Control.
Sensitivity: .
SSB,CW
AM
Selectivity:
SSB,CW
AM
CW-N
Less than 0.3 microvolts for 10dB S+N/N
Less than 0.6 microvolts for 10dB S+N/N
2.4KHz at -SdB
4.8KHz at -6OdB
6.0KHz at -SdB
18.0KHz at -SOdB
(when optional crystal
filter installed)
600Hz at
-6dB
1.5KHz at '-SOdB
(when optional AF filter installed)
150Hz at
-SdB
1100Hz at -4OdB
Spurious
Response Rejection Ratio:
More than
SOdB
Audio Output:
More than 2 Watts
Audio Output Impedance:
8 ohms
Specifications
are approximate and are subject to change without notice or obligation.
1 - 1
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SECTION 2 OPERATING CONTROLS
2 -, FRONT PANEL
O TRANSMIT IN ' oICATOA------------ -----
@METER 5./lT(;H,---------- -------- ~
®MOOE 5.IIT ' CH-----------
, MIC co,m"CTOA ---
(4 PHONES JA,CK -------
5 MIC GAIN CCIN1'AelL---------------~
re RF POWER CClN1'ACIL----------------
Il NB (Noi$8 BI.nker) 5."TC;H---------------~
1 AF GA IN CONTROL--------------------'
8 RF GAIN CONTAOL-----------------------'
It AGC 5WITC: H ----------------------------'
~ l PREAMP SWITCH ___________________________ ..J
2-2
~1 AN TI · VOX CCIN1'AelL---
l1 CW MONITOR
~ N . B . WIDTH 5WITCH---
!l FREOUENCY SET
2 -3 REAR PANEL CONNECTIONS
(4 ~ ANTENNA CCIN"EC:Ta'A--I~
(gIGROUNO TERMINAL
@POWER 50 ' CK'" -------I-~
DISPLAY
SW I TCH
SW IT CH
SWITCH
1---- - 7T' RIT INDI CATOR
CONTROL
SW ITCH
L _____________ 14 DIAL LOCK SW ITCH
L ___________ 2! TUNING RATE SW ITCH ES
CONTROL KNOB
L __________________ ~ MEM ORYIVFO WRITE BUTTON
2- 1
3~VOX DELAY CONTROL
PROCESSOR
SWITCH
I------ -- - ill SWR SWITCH
SET CONTROL
GA IN CONTROL
SWITCH
BACK UP
TERMINAL
(4 ~, EXTERNAL ALC
~1= ====~~~:: lT ERMINAL
I SPEAKEA
JACK
HI- ---------- ,' ~ ,:ev JACK
1!~~I_--- ~ I A(:CE '5 5'OAV SOCKET
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FRONT PANEL
1. MODE SWITCH
This switch selects the mode of operation for both transmit
and receive.
USB Upper Sideband, mainly for 10, 14, 18,21,24 and
28M Hz bands.
LSB Lower Sideband, mainly for 3.5 and 7MHz bands.
ON Continuous Wave, for CW operation on all bands.
CW-N Narrow ON. The narrow crystal filter is auto-
matically turned
ON in this position to improve
selectivity when receiving.
(When optional crystal
filter
is installed).
AM Amplitude Modulation.
2.
POWER SWITCH
The POWER SWITCH is a push-lock type switch which
controls the input
DC power to the IC-730. When the
external
AC power supply (lC-PS15) is used, the switch also
acts
as the AC power supply switch. When the switch is
pushed in and locked, power is supplied to the set. When
the switch
is pushed again and released, power is cut to all
circuits except the PA unit. (When the BC-10A is used,
power
will also be supplied to the CPU.
3. MIC CONNECTOR
Connect the supplied microphone or optional microphone,
IC-SM5 or IC-HM10 to this jack. If you wish to use a dif-
ferent microphone.
4. PHONES JACK
Accepts a standard
1/4 inch headphone plug forheadphones
'of 4 - 16 ohms. Stereo phones can be used without modi-
fication.
5.
MIC GAIN CONTROL
Adjusts the level of modulation according to the input of
the microphone. Oockwise rotation increases the micro-
phones gain. As the input will vary with different micro-
phones and different voices, the knob should beturned until
the Meter needle, in the ALC mode, begins to move slightly
within the ALC zone.
In SSB and AM modes, when the
speech processor is in use, the MIC GAIN CONTROL sets
the clipping limits, while
the RF POWER CONTROL sets
the RF drive level to the maximum power level, where ALC
starts
at the saturation point of the amplifiers.
6. RF
POWER CONTROL
Controls the RF output power 10 Watts to maximum (SSB:
100 Watts PEP, CW: 100 Watts, AM: 40 Watts). Clockwise
rotation increases
the output power.
7. AF GAIN CONTROL
Controls the audio output level in the receive mode. Clock-.
wise rotation increases
the level.
8. RF GAIN CONTROL
Controls the gain of the RF section in the receive mode.
Clockwise rotation gives the maximum gain. As the control
is rotated counterclockwise, the needle of the METER rises,
and only signals stronger than the
level indicated by the
needle
will be heard.
2-2
9. T/R (TRANSMIT/RECEIVE) SWITCH
This switch is for manually switching from transmit to
receive and vice versa. Set the switch to RECEIVE (out)
and
the IC-730 is in the receive mode. Set the switch to
TRANSMIT (in) and it switches to transmit. When switch-
ing with the PTT switch on the microphone or with the
VOX switch set to ON, the T/R switch must be in the
R
ECE IV E position.
10. VOX SWITCH
This switches the VOX circuit ON and OFF. When it is in
the ON (in) position, in SSB, T/R switching is accomplished
by means
qf a voice signal. In CW operation, semi-break-in
switching by means
of keying is possible.
11.
NB (NOISE BLANKER) SWITCH
When pulse type noise such as automobile ignition noise is
present, set this switch to the ON (in) position. The noise
will be reduced to provide comfortable reception.
The blanking time can be selected NARROW and WIDE,
by the NB WIDTH switch under the access cover. It will be
effective against any type noises.
12. AGC (AUTOMATIC GAIN CONTROL)
SWITCH
For changing the time-constant of the AGC circuit. With
the switch in the AGC position (out) the AGC voltage is
released slowly, and thus is suitable for SSB reception.
With the switch
in the FAST (in) position, the AGC voltage
is released faster, and the AGC is suitable for stationssuffer-
ing from fast fading or when operating in the CW mode.
13. PREAMP SWITCH
Switches the preamplifier for the receiver.
14. MEMORYNFO WRITE BUTTON
By pushing this button, A VFO's frequency is written into
Memory,
or one VFO's frequency is transferred to the
other VFO.
15. MEMORY SWITCH
Push this switch when you wish to write a frequency into
memory,
or to call a memorized frequency.
16. TUNING CONTROL
KNOB
Rotating the TUNING CONTROL KNOB clockwise in-
creases the frequency, while rotating it counterclockwise
decreases the frequency. The frequency
is changed in 10Hz,
100Hz
or 1KHz steps which is according to the TUNING
RATE switches. One complete rotation of the tuning
knob results
in a 1 KHz frequency increase or decrease in
10Hz steps, 10KHz in 100Hz steps and 100KHz in 1KHz
steps.
17. METER
When
in the receive mode the meter acts as an S meter
regardless
of the position of the meter select switch. Signal
strength
is indicated on a scale of S1-S9, and S9 to
S9+6OdB.
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In the transmit mode the meter has two functions which
are selected by the Meter Switch (18). They are
as follows:
Po; Indicates the relative
output power. SWR can be
measured by placing
the switch located inside the top cover
to the SWR position.
ALC;
In this position the meter functions when the RF
output reaches a certain level.
18. METER SWITCH
Selects meter function in the transmit mode.
19. TRANSMIT INDICATOR
Illuminates when the transceiver
is in the transmit mode.
20. FREQUENCY DISPLAY
The frequency of the IC-730 is displayed on a luminescent
display tube. Since the 1
MHz and 1 KHz decimal points are
displayed, the frequency can easily be read. The frequencies
indicated are the carrier frequencies
of each mode in AM,
USB, LSB and CW.
Remember, if you turn the R IT SWITCH ON to change the
receive frequency and rotate the RIT CONTROL knob, the
frequency displayed will not change.
21. NORMAL/SPLIT (TRANSCEIVE/SPLIT) SWITCH
Selects the relationship of the two VFO's. In the NORM
(out) position, one VFO is for both transmit and receive.
In the SPT (in) position, one VFO is for transmit and
the other
is for receive.
22. VFO
SWITCH
You can select either of the built-in two VFO's with this
switch.
It also selects the relationship of the two VFO's
with the NORMAL/SPLIT switch. The switch performs the
following operations according
to its position.
A. (NORMAL) Selects the "A" VFO for both transmit and
receive.
A. (SPLIT) Selects
"A" VFO for receive and "B" VFO
for transmit.
B. (NORMAL) Selects the "B" VFO in both transmit and
receive.
B. (SPLIT) Selects
"B" VFO for receive and "A" VFO
for transmit.
23. TUNING RATE SWITCHES
The small vernier marks on the tuning knob are changed to
correspond to 10Hz, 100Hz or 1KHz steps which is selected
by pushing
the switch either 10Hz, 100Hz or 1 KHz.
2-3
24. DIAL LOCK SWITCH
After the IC-730 is set to a certain frequency for rag
chewing, mobile operation, etc., push the DIAL
LOCK
switch the VFO is electronically locked at the displayed
frequency, thus inactivating the operation
of the tuning
knob. To change frequency, the dial lock must first be
disengaged by pushing and releasing the DIAL
LOCK switch
again.
25. RIT SWITCH
Switches the RIT circuit ON and OFF.
26. RIT CONTROL
Shifts the receive frequency ±800Hz either side of thetrans-
mit frequency. When the RIT is ON, the RIT INDICATOR
is illuminated. Rotating the control to the (+) side raises
the receive frequency, and rotating to the (-) side lowers
the receive frequency. The frequency shifted by turning
the RIT Control
is not indicated on the frequency display.
27. RIT INDICATOR
Illuminates when R
IT is turned ON.
28. BAND SWITCH
The BAND SWITCH is an 11 position rotary switch used for
selecting one of the 500KHz segments. The selectable bands
are 3.5KHz, 7MHz, 10MHz, 14MHz, 18MHz,
21 MHz,
24MHz and 28MHz. (28MHz band is separated to four
500KHz segments.)
29. PASS-BAND SHIFT (TUNING) CONTROL
Allows continuous shifting of the pass-band from upper or
lower side
in SSB and CWo This will reduce interference by
a nearby signal. When the optional crystal filter F
L-3O is
installed, this control allows continuous tuning of the
pass-band selectivity by moving
the filter up to 800Hz from
the upper or lower side in SSB and CWo Not only improves
selectivity, but also can improve the audio tone. Normal
position
is in the center position and is 2.4KHz wide in
SSB.
CONTROLS UNDER THE ACCESS COVER
30. SPEECH PROCESSOR SWITCH
Switches the speech processor circuit ON and OFF. This
circuit enables greater talk power and better results
in DX
operation.
31.
SWR SWITCH
When measuring SWR, calibration SET and SWR reading
functions are selected with this switch. When reading
SWR
make sure the METER switch on the front panel is in the
RF position.
32.
SWR SET CONTROL
This control calibrates the meter needle to the SWR SET
position when you want to determine the value of SWR.
The METER switch must be in the RF position and the set
must be transmitting a carrier.
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33. VOX GAIN CONTROL
This control adjusts input signal level via the microphone to
the VOX circuit. For VOX operation in SSB, adjust the .
control so that the VOX circuit will operate with normal
speech.
34. VOX DELAY (VOX time constant) CONTROL
This controls the transmit to receive switching time. Ad-
just it so transmit to receive switching will not occur during
short pauses in normal speech.
35. ANTI-VOX CONTROL
In VOX (SSB) operation, the VOX circuit may be operated
by sound from the speaker causing a switch to transmit.
This trouble can be prevented by adjusting the input level
of the ANTI-VOX circuit with this control along with the
VOX gain control so that the VOX circuit only operates
from the operator's voice, not by .sound from the speaker.
36. N.B. WIDTH SWITCH
Switches the blanking action time of the noise blanker
NARROW (short) and WIDE (long). Set the switch in the
NARROW or WIDE position according to incoming noise.
37. CW MONITOR (MONn CONTROL
This control adjusts the audio volume of the side tone
(monitor) audio during ON transmit operation. Adjust it to
your desired level for easy listening.
38. FREQUENCY SET CONTROL
This control is for fine adjustment of the reference fre-
quency of the PLL unit, which is local oscillator frequency.
Do
not turn it unless you want to change the frequency.
REAR PANEL CONNECTIONS
39. MEMORY BACKUP (RL) TERMINAL
For connection of a 9 - 12V DC power supply. Formobile
installation connection to the vehicle's battery can be made
'. the current drain is low, for fixed installation use of the
BC·10A is recommended.
By changing an internal connector, this terminal can be
used for Transmit/Receive relay control terminal. This
terminal can be used
to switch 24V 1A DC. Don't exceed
this limit.
40. EXTERNAL ALC TERMINAL
This terminal can be used for input terminal of external
ALC signal
from a linear amplifier or transverter.
By using optional adapter, IC-EX205 and changing internal
connectors, this terminal can be used for TRANSVERTER
terminal.
VHF and UHF
operation using a suitable transverter with
the IC-730 is possible. This terminal is for Transverter
connection. The output is a few milliwatts.
41. EXTERNAL SPEAKER JACK
When an external speaker is used, connect it to this jack.
2-4
Use a speaker with an impedance of 8 ohms. When the
external speaker is connected, the built-in speaker does
not function.
42_ KEY JACK
For ON operation, connect the key here. For electronic
keying
the terminal v.oltage must be less than 0.4V DC.
43. ACCESSORY (ACC) SOCKET
Various functions are available through the accessory socket
such as modulation output, receiver output, T /R change-
over, and so forth. The table below shows those terminals.
ACC SOCKET CONNECTIONS
PIN No.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.-24.
0®@@@@
00@@@@
Q)@@@@@
CD 0 ® @@ @ Outside view
FUNCTION
NC (no connection)
13.8 Volts DC in conjunction with the power
switch operation.
Connected to Push-to-talk, T /R change-over
switch. When
grounded, the set operates in
the transmit mode.
Output from the receive detector stage. Fixed
output regardless of AF output or AF gain.
Output from Transmitter MIC amplifier stage.
(Input for MIC gain control stage.)
8 Volts DC available
when transmitting. (relay
can not be directly actuated. Max. 5mA).
Input for external ALC voltage.
Ground
NC
8 Volts DC available
when the 28MHz band is
selected.
Input for TRANSVERTER control. When 8
Volts DC
is applied, set can operate with a
transverter.
Output reference voltage for band switching.
Output for external band switching.
NC
44. ANTENNA (ANT) CONNECTOR
This is used to connect an antenna to the set. Its imped-
ance is 50 ohms and connect with a PL-259 connector.
45. GROUND TERMINAL
To prevent electrical shock, TVI, BCI and other problems,
be sure
to ground the equipment through the GROUND
TERMINAL.
For best results use as heavy a gauge wire or
strap as possible and make the connection as short as
possible, even in mobile installations.
46. POWER SOCKET
For connection of the IC-PS15's DC power cord, or other
suitable power supply.
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SECTION 3 CIRCUIT DESCRIPTION
3·1 RECEIVING CIRCUITS
3·' • 1 RF CIRCUITS
The receiving signal from the antenna is fed from P3 of the
LPF
unit to J2·1, where frequencies less than 3.5MHz are
attenuated about 4Od8 by a High-Pass filter. This filter
reduces intermodulation by strong BC signals.
The signal is usually fed to 03 directly through the contacts
of RLl.
The set employs the OFM (Direct Feed Mixer) system at
the
front end, to get wide dynamic range.
When the PREAMP switch on the front panel is in the ON
position, the signal is fed to the preamplifier. The pre-
amplifier, consisting of 01 and 02, is designed to provide
the gain
of about 10dB and the intercept point of 26dBm
on the entire band.
To the preamplifier, power source (13.8V)
is always applied
regardless if the preamplifier is turned on or off. When the
PREAMP switch
is pushed in, the emitter of 03 is grounded
through the switch
and RL1 is actuated in the receive mode,
as R8V is applied to the base of 03 through R4. In the
transmit mode
or when 08 is turned on as the TRV signal
is applied to its base, the bias voltage is not applied to 03
and RL1 is not actuated even if the PREAMP switch is
pushed in.
05 is turned on in the transmit mode and shunts the re-
ceiver input line to ground to prevent RF feedback.
The
signal passed 03 is fed to a band-pass filter which is
selected by the band switching signal sent from the BAND
switch through the PRE·MIX
unit.
The band-pass filters are provided for each band, and one
is selected for the band of operation by turning ON the
diodes located at the
input and output circuits of the
filter.
These filters have about 2dB insertion loss res-
pectively.
The
signal passed the band-pass filter is fed to the 1st mixer
consisting
of 04 • 07 (Doubly Balanced Mixer). This OBM
has a+18dBm intercept point and 6dB insertion loss.
The 1st Local Oscillator functions at the operating fre-
quency plus 1st IF (39.7315MHz) frequency. It is fed from
the
BPF unit through J6.
This
1st LO is changed with 1kHz steps and its frequency
range for each band is as follows;
BAND
3.5MHz
7.0MHz
10.0MHz
14.0MHz
18.0MHz
1st LO FREOUENCY
43.1319MHz "" 43.8315MHz
46.6315MHz
"" 47.3315MHz
49.6315MHz"" SO.3315MHz
53.6315MHz "" 54.3315MHz
57.6315MHz
"" 58.3315MHz
3-1
21.0MHz
24.5MHz
28.0MHz
28.5MHz
29.0MHz
29.5MHz
60.6315MHz "" 61.3315MHz
64.1315MHz "" 64.8315MHz
67.6315MHz
"" 68.3315MHz
68.1315MHz
"" 68.8315MHz
68.6315MHz
"" 69.3315MHz
69.1315MHz
"" 69.8315MHz
The center frequency
of the 1st IF is varied 39.7305MHz-
39.7315MHz due to the 10Hz step tuning.
The 1st IF
signal converted at the 1st mixer is fed to the
monolithic crystal
filter FI2 through 020 transmit/receive
switching diode, then fed
to the 1st IF amplifier 06. FI2
has a pass band of 15kHz at -3dB points.
The 1 st IF amplifier 06 is aMOS FET, and an AGC voltage
is applied to its 2nd gate. The attack time constant is
determined by R36 and C67. C81 prevents VHF parasitic
oscillation.
The amplified 1
st IF signal is fed to F 11 through 021
transmit/receive switching diode. Fll is the same as F12,
and totally the 2nd image rejection ratio is more than SOdB.
The 1st IF signal passed Fll is then fed to the 2nd IF unit.
3 -1 - 2 SECOND IF CIRCUITS
The 2nd IF signal fed from the RF unit is input to J2 and
fed
to the Noise Amplifier and Noise Blanker gate circuits.
The
signal (39.7315MHz) is amplified with 01 and 02, dual
gate MOS FETs, and IC1, high gain amplifier with AGC.
The amplified signal is detected by 014 and then fed to
IC2, voltage comparator and noise pulses are detected.
016 genarates the reference voltage, 1.2V, for IC2. 015
shunts over-voltage to prevent long delay-times.
A part
of the detected signal from 014 is used for the AGC
of IC2. The detected signal is fed to the base of 07 through
R42.
When the detectedvoltage exceeds 0.6V, 07 is turned
ON which turns 08 ON as well. 2.5V is usually applied to
pin 3 of IC2. This voltage is increased when 08 turns ON,
with time constant of R34 and C42 (attack-time), This
provides the AGC function. This time constant (attack·
time)
can be changed by the NB WIDTH switch (S4 on the
MAl N unit). When it is set at the WI DE position, the time
constant
is determined by R46 and C42. The release-time
of the AGC is determined by R34, R38, R47 and C42.
Average voltage at pin 2 of IC2 will be 0.6V due to the
AGC function. Only when the detected voltage exceeds
1.2V caused by a noise pulse, pin 3 output terminal of IC2
puts out lV pulse, and it turns ON the NB gate switch 03.
The NB gate circuit is composed of 020, 021 and 024,
and usually 020 and 021 are turned ON and 024 is OFF
by the reverse voltage (6.6V) applied to the cathode. When
OJ is turned ON by a noise pulse, 024 is turned ON and
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shunts the RF signals to ground. This grounds the anodes
of
020 and 021, and turns them OFF. Thus the noise
pulse
is not fed to the following circuits.
The signal which passes the NB gate circuit is then fed to
the 2nd mixer consisting of 01 - 04 diode OBM.
The 2nd local oscillator consisting of Q9 and X1 oscillates
at 30.71901MHz . 30.720MHz with 10Hz steps. 019
varactor diode provides this frequency variation. A control
voltage generated in the LOGIC unit and ~C-amplified in
the MAIN unit is applied to 019. The oscillation frequency
can be adjusted by L1 and the voltage applied to 019. The
2nd local oscillator signal is about +2dBm and is fed to the
L6 center tap in the 2nd mixer circuit to convert the 1st
IF signal to 2nd IF (9.0115MHz) signal.
elf
O----------------ill~--~~
416
J3
88~----------~~
J4
eWH 0- ....... _.+----;-0
csw O-+- ...... f-..,
J3
Df
R8~----------------------~
The voltage CSW is fed to the filter selection pins consisting
of P3, J7 and JS, through pin 1 of J4 and 017. P3 is con-
nected to J7 when the set has been shipped. When the
optional SSB crystal filter (this provides PBT function) is
installed, P3 should be connected to JS.
The voltage CWN is fed to the filter selection pin~ consisting
of P2, J5 and J6, through pin 2 of J4 and O1S. P2 is con-
nected to J5 when the set has been shipped. When the
optional CW crystal filter is installed, P2 should be con·
nected to J6.
When any optional filters are
not installed (the filter se-
lection pins are original connections), the bases of 04 and
05 are not applied with any bias voltages, so 04 and 05
are turned OFF and both emitters are OV. Thus 09 and
013 are turned OFF and 06 is turned ON, and 010 and
011 are turned ON and FI1 is selected in any modes.
When
the optional SSB crystal filter is installed and P3 is
connected to JS, 05 is turned ON and RSV is applied to
07 and OS, and 07 and OS are turned ON. Thus the SSB
3-2
The 2nd IF signal is fed to FI1 monolithic crystal filter
installed as standard. When optional
SSB crystal filter,
FL-30, and/or CW crystal filter, FL-45 is installed, the
suitable crystal filter is selected by the MODE switch.
FI1 has 3kohm input/output impedance, so LS and L9
work as step-up and step-down matching transformers
respectively.
FI1 has lower insertion loss than other
optional filters, so R15 and R2S are inserted as an at-
tenuator. L9 is tuned by 012 varactor diode, which gives
more isolation when other filters are selected. The filtered
2nd IF signal is then fed to the MAIN unit through P1.
Filter selection
is made by voltages CWN (applied in CW-N
mode) and pSW (applied in other modes) from the MODE
switch through J4.
Itl!;
..
II<
DIO
D2J
crystal filter is selected. At the same time, RSV is applied
to the base of 06 through 013 and turns OFF 06, thus FI1
is isolated from the circuit.
When the optional
CW crystal filter is installed and P2 is
connected to J6, 04 is turned ON and RSV is applied to
05 and 023, and 05 and 023 are turned ON. Thus the
CW crystal filter is selected. At the same time, RSV is
applied to the base of 06 through 09 and turns OFF 06,
thus FI1 is isolated from the circuit the same as when SSB
crystal filter is installed.
06 is turned ON when the optional CW filter is selected,
and it shunts to ground the optional SSB filter input
terminal to prevent signal leakage in the pass band of the
SSB filter.
These optional filters are selected only when the set is in
the receive mode.
3-1-3 MAIN UNIT
The receive signal from the 2nd IF unit P1 is fed to J16 on
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the MAIN unit. In the receive mode, 01 is turned ON and
010 is turned OFF by the RSV, and the signal is fed to the
1st
gate of IF amplifier 01, dual gate MOS FET. To the
2nd
gate, AGC voltage is applied. Its attack time is de-
termined by R4 and C4.
The amplified 2nd IF signal is fed to the 1st gate of the 3rd
mixer
03, dual gate MOS FETthrough 02, which is turned
ON in the receive mode. To the 2nd gate, 9.4665MHz local
oscillator signal
for IF TUNE or PST is applied, and the
2nd IF
signal is converted into 455kHz 3rd IF signal.
In SSS or CW mode, the 3rd IF signal is passed through FI1
mechanical filter through 04 and 06, which are turned ON.
MF-455-11 AZ or MF-455-11GZ is employed for F Ilo
11 AZ has 1.5kohm and 240pF input/output impedance
and 11GZ
has 1.5kohm and 20pF. Thus, C75 through
C7S are not used for the 11GZ.
In AM mode, the 3rd
IF signal is passed through FI2
ceramic filter through 05 and 07.
The output from the 455kHz filters is fed to a balanced
mixer consisting
of 04 and 05, and converted into a
9.0115MHz 4th IF signal again. The local oscillator signal
is the same one for the 3rd mixer, and fed to the center tap
of the input tuned circuit. The 4th IF signal is fed to IF
amplifier 06 through a switching diode OS, then amplifier
07. Soth amplifiers employ dual gate MOS FET res-
pectively. To the 1st gate, the IF signal is fed and to the
2nd gate, AGC voltage
is applied respectively. The amplified
signal is fed to the OET UNIT through J6, Pin 5.
The source voltage
of OS is varied according to AGC voltage
i.e., incoming signal level. This voltage
is amplified by 07,
then fed to the S-meter. R42 is for meter zero-point ad-
justment and R41 is for full-scale adjustment.
3 - 1- 4 IF TUNE AND PBT CIRCUITS
The VXO circuit consisting of 011 and X1 oscillates at
9.4665MHz, and this frequency
can be changed by ±1.5kHz
by changing the voltage applied
to 013 varactor diode.
This voltage is varied
by R13, PASS BAND SHIFT
CONTROL on the front panel, and applied to 013 through
012 in the receive mode. In the transmit mode, a voltage
adjusted
by R66 is applied to 013 through 011, and the
oscillation frequency
is fixed at the center frequency,
9.4665MHz. This signal
is fed to the 2nd gate of 03, 3rd
mixer,
and 4th mixer 04 and 05 through a.buffer am-
plifier 012.
When the Pass-Band Shift Control is set at the center po-
sition, the VXO oscillates at 9.4665MHz, and 9.0115MHz,
the center frequency
of the 2nd IF signal is converted into
455kHz, the center frequency of 3rd IF signal: This
455kHz signal
is converted into 9.0115MHz signal again
with the 9.4665MHz VXO signal. This is the normal con-
dition of the Pass-Band Shift system and incoming signals
pass through both pass-bands of the filters, 9.0115MHz and
455kHz.
When the PB Shift Control is slid toward the right side, the
VXO frequency is increased, as an example; 9.4675MHz
3-3
(9.4665MHz+1kHz), 9.0115MHz, the center frequency of
the 2nd IF signal is converted into 456kHz, 3rd IF signal.
This 456kHz signal
is converted into 9.0115MHz signal
again with the 9.4675MHz VXO signal. However, the
456kHz, 3rd IF signal
is off from the center frequency of
the 455kHz filter. In other words, the pass-band of the
455kHz
filter is shifted toward the lower side, and the total
pass-band is also shifted toward the lower side. At this
time,
if the optional SSB filter FL-30 is installed, the total
band
width is narrowed from the upper side. Thus the
center position
of the control is the widest bandwidth and
is equivalent to the normal SSB bandwidth, and theband-
width is narrowed electrically from either the upper or
lower side continuously by up to SOOHz.
3 -1 - 5 DETECTOR CIRCUITS
In the
SSB and CW modes, a 9.0115MHz, 4th IF signal is
fed to IC2, product detector in the OET unit. To the other
port of IC2, a BFO signal is applied and an AF signal is
put out from pin 3. The BFO is composed of OS, X1,
C39, C40, L2 through L4, etc. C39, C40 and L2 through
L4 are connected in series with X1, and L2 through L4 are
shunted to ground respectively according to the selected
mode
to get proper BFO frequency.
The detected
AF signal is fed to pin 5 of IC1 operational
amplifier. The amplified
AF signal is put out from pin 7
and fed
to 07, low-pass filter, then to the VOLUME control
on the
front panel.
IntheAM mode, the 4th IF signal is fed to 01, IF amplifier.
A part
of the amplified signal is then fed to AM detector
05.
Toe detected AF signal is fed to pin 3 of IC1, operational
amplifier. The amplified
AF signal is put out from pin 1
and then fed
to low-pass filter 07.
As an AGC voltage, a part of the 4th IF signal at 01 col-
lector is fed to AGC detector 01. The detected DC signal
is then fed to the base of 02. When the applied voltage is
over the threshold voltage, 02 is turned ON and a negative
voltage connected
to the emitter, charges C6 through R9.
When the applied voltage becomes less than threshold
voltage,
or zero, 02 is turned OFF and the voltage of C6
is discharged through RS (high value resistor). This provides
fast attack/slow
release AGC. AGC voltage is taken from
the collector of 02 and supplied to each 2nd gate of the
IF amplifiers. On the AGC line, the RF gain control voltage
from the RF GAIN control is superimposed.
When the AGC switch on the front panel is pushed in, 010
is turned ON, and R13 and C10 (in series) are connected
in parallel
with RS and the AGC time constant becomes
shorter.
3 - 1 -6 AF POWER AMPLIFIER CIRCUIT
AF signal from the VOLUME control, RS-2, on the front
panel is fed to pin 1 of IC1 AF povver amplifier on the
MAIN unit. The signal is amplified with IC1 to get 2 watts
output power in an Sohm load. The output signal is fed to
the internal speaker through the PHONES jack and EX-
TERNAL SPEAKER jack. This IC is activated in the
transmit mode
to produce the CW side-tone.
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3 -2 TRANSMITTING CIRCUITS
3 - 2 -1 AF CIRCUITS
The audio signal from the microphone is fed to pin 3 of
IC4, operational amplifier on the MAIN unit, through the
MIC GAIN control R14-2 on the front panel. The amplified
AF signal is put out from pin 1, then fed to pin 5 of the
balanced modulator, IC2 in the OET unit, which is the
same one for the receiver product detector. To pin 7, the
BFa signal is fed and mixed with the audio signal, and a
9.013MHz or 9.010MHz modulated OSB (carrier suppressed
double side band) signal
is put out from pin 3.
In the receive mode and SSB transmit mode, bias voltages
adjusted
by R44 and R45 are applied to pins 5 and 7 res-
pectively to place IC2 in a carrier null condition. In the
·AM and CW transmit modes, 06 is turned OFF and an off-
set voltage is applied to pin 5 through 04. Thus IC2 is in
an unbalanced condition and a 9.0115MHz AM signal or
carrier is put out from pin 3. In the other modes, 06 is
turned ON and the offset voltage is shunted to the ground
and IC2 is in a balanced condition.
In the receive mode and CW transmit mode, 05 is turned
ON and shunts the AF signal from the microphone to
ground to prevent the AF signal is applied to IC2.
3 - 2 - 2 IF CIRCUITS
The signal output from IC2 in the OET unit is fed to the
1st gate of 03, mixer, the same one for receive 3rd mixer,
through 03 in the MAIN unit to be converted into a
455kHz signal. The local oscillator for this mixer is also the
same one for the receive. However, the oscillation fre-
quency is fixed at 9.4665MHz.
In the receive mode, 02 is turned ON and shunts the signal
fed
from the OET unit to ground to prevent the signal
from leaking into the receiver IF circuits.
In the SSB and CW modes, the 455kHz signal is fed to Fll,
MF-455-11GZ (or -llAZ), mechanical filter which has a
2.4kHz bandwidth, to remove unwanted sideband signal.
In the
AM mode, the 455kHz AM signal is fed to FI2,
CWF455HT, ceramic filter which has a 6kHz bandwidth,
and the signal passes through the filter unchanged.
The
output from the selected filter is then fed to the
balanced mixer consisting of 04 and 05 which is the same
one used in the receiver's 4th mixer. The mixer's porpuse is
to convert the incoming signal to 9.0115MHz. The 9.0115
MHz signal is then fed to the IF amplifier 09.
In the CW mode and key-up condition, a positive voltage is
applied to the source of 09 through 019, and 09 is turned
off and the signal is not fed to the next stages. In key-
down condition, 010 is turned ON and the positive voltage
applied
to the source is shunted to ground through 010.
Thus the positive voltage is not applied, 09 functions in
normal
condition and the signal is amplified then fed to the
next stages.
The
amplified IF signal is then fed to F 11, 9M lOA 9.0115
3-4
MHz crystal filter (or installed optional crystal filter) in
the 2NO IF unit.
Then the signal is fed to the doubly balanced mixer con-
sisting of 01 through 04, which is the same one used in the
receiver's
2nd mixer. In this case, the mixer's purpose is
to convert the incoming signal to 39.7315MHz.
The 39.7315MHz signal is fed to the amplifier 07, then the
mixer consisting of 04 through 07, which is the same one
for receiver 1st mixer, for conversion to the desired ope-
rating frequency.
When 10MHz, 18MHz or 24.5MHz band is selected, a po-
sitive voltage is applied to the source of 07 through 027,
026 or 025 respectively. This turns 07 OFF and mutes
transmission on these bands.
To transmit on these bands,
cut lead of the diode for the desired band.
The desired operating frequency signal is fed to the band-
pass filter to produce a clean output. The appropriate
filter is selected with the BANO switch. The signal is then
amplified by 04 and fed to the PA unit.
3 - 2 - 3 RF POWER AMPLIFIER CIRCUITS
The transmit signal fed to the PA unit is amplified by 01
up to about 1 watt. 01 is a class A amplifier and maintains
high
linearity.
L2 gives the correct phase signals (180 degrees apart) for
the push-pull amplifier 02 and 03. 02 and 03 are class
AB amplifiers and amplify the signals up to about 6 watts.
The
bases of 02 and 03 are biased by means of the barrier
voltage set
by 01. 01 functions as temperature com-
pensator for 02 and 03, and is attached to the case of 02.
Negative feedback by Rand C applied across each collector
and base of 02 and 03, provides stablility and broadband
characteristics.
L4, a broadband transformer provides balanced OC feed to
the collectors of 02 and 03, and for matching the collector-
to-{;ollector impedance.
Then the signal
is fed to each base of 04 and 05 through
L4 secondary for impedance matching and correct phasing_
04 and 05 are class AB push-pull amplifiers which produce
100 watts output.
The bases of 04 and 05 are biased for class AB operation
by the emitter voltage of 06 which is controlled by the
bamer voltage of 02. 02 voltage is adjusted by R21 to
give proper idling current.
02 also functions as a temperature compensator to prevent
runaway caused
by heating, and is attached to the case of
04.
R17 and R18 are resistors which provide negative feedback
from L7. L7 samples the output and provides stablility and
broadband characteristics.
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The signal amplified by 04 and 05 is fed to the FI L (low-
pass filter) unit throu{ll L8 impedance matching trans-
former.
A thermal switch
is mounted on the case of 04 and turns
ON when the case temperature exceeds 70 degrees C. This
changes the speed of the cooling fan from low to high. This
cooling fan rotates at
low speed during transmit in the
normal condition.
At this time, 8 volts is supplied to the
fan
motor through R22, R23 and 07. When the thermal
switch
is turned ON, 13.8 volts is supplied to the fan motor
through R22 only, and the cooling fan rotates at high speed
not only in the transmit mode but also in the receive mode.
The transmit signal which has passed the low-pass filter is
fed to the ANT (antenna) connector on the rear panel
through the SWR detectorcoil L15 in the FIL unit.
3 - 2 - 4 ALC CIRCUITS
The foward power voltage, SWF and reflected power
voltage, SW8, detected at the FIL
unit, are fed to the
MAIN unit through J20. The foward power voltage, SWF,
is fed to the negative input terminal of IC28and amplified
as an ALC voltage. This ALC voltage is fed to the 2nd gates
of 09 in the MAIN unit and 07 in the RF unit.
In the SS8 or CW mode, the attack time of the ALC
voltage
is determined by R70, C43 and R169 and the release
time is determined by C43 and R88, and a peak voltage is
put out. -
In the AM mode,
013 and 014 are turned ON, and the
attack time
is determined by R70 and C42, and the release
time by R68 and C42, and an average voltage is put out.
To the positive terminal
of IC28, a voltage from the RF
POWER control on the front panel is applied to control
the
ALC voltage and the output power can be adjusted
between 10 watts and 100 watts by adjusting the RF
POWER control.
The
ALC voltage is also fed to the negative terminal of
IC38 through R88 and amplified to indicate ALC level on
the meter. The swing
of the meter is adjusted by R91.
The voltage applied
to the negative terminal of IC28 is
controlled by the RF POWER control on the front panel.
When the control is turned fully counterclockwise, the
voltage
is minimum and the output power is also miminum
(10 watts). This voltage (output power) can be adjusted
by R149.
When the control is turned fully clockwise, the voltage is
the maximum and the output power is also the maximum
(SSB and CW: 100 watts, AM:4O watts). This voltage is
divided from 8 volts by R147 and R150, and can be ad-
justed by R150.
In the AM mode,
019 is turned ON and R151 is connected
with R150 in parallel, and the maximum power is reduced
to 40 watts.
3-5
S3 is a switch to reduce the maximum power toOO watts.
When S3 is switched ON, a voltage is applied to the base
of 019 through 028 and R153 and 019 is turned ON the
same as in the AM mode. In addition, a voltage is applied
to the RF POWE R control through R168 and 029, and the
maximum power
is adjusted to 50 watts by R168. In the
AM mode,
020 is turned ON and R168 is shunted to
ground and the maximum power is 40 watts as usual.
3 - 2 - 5
VOX CIRCUITS
Audio signal from the microphone is fed to pin 5 (positive
input terminal) of IC6, comparator, through J3 and R137,
VOX GAIN control. To pin 5, a bias voltage which is
divided by R132 and R135, and R136 is applied through
R137.
To_ pin 6 (negative input terminal), a reference
voltage which
is divided by R132, and R135 and R136 is
applied. The difference voltage between the two terminals
is only the voltage across R135. Thus the sensitivity of the
comparator
is very high and the VOX circuit actuates with
asmall input level.
When a voice signal presents, the output
terminal (pin 7) of IC6B becomes at High level and this
voltage
charges C63. The charged voltage is discharged
through R128 and R129 and
it decides the VOX holding
time. The
VOX holding time can be adjusted by R129.
This High level voltage
is applied to pin 5 (positive input
terminal)
of IC5B, VOX control.
In the CW mode, IC5A is used as a break-in control.
In the key-up condition, the same bias voltage is applied to
both pin 2 (negative input terminal) and pin 3 (positive
input terminal), and pin 1 (output terminal) is low level.
In the key-down condition, pin 2 is grounded through
R117 and pin 1
becomes at high level. This voltage charges
C62 and is applied to pin 5 of IC5B. The holding time is
decided by C62, and R128 and R129.
To pin 6 of IC5B, abias voltage divided by R125 and R139
is applied as a reference voltage. When the voltage at pin 5
becomes higher than that one at pin 6, pin 7 (output
terminal) puts out high level voltage. This turns on 017
and 018, and grounds the SEND line, when the VOX
switch is turned on, to set the radio in the transmit mode.
3 - 2 -6
ANTI VOX CIRCUITS
A part of the receiver audio signal put out from IC1 is fed
to pin 3 (positive input terminal) of IC6A, comparator,
through the
ANTI VOX level control, R142. When a re-
ceiver audio is present, pin 1 of IC6A puts out high level
voltage. This voltage
is applied to pin 6 of IC5B, and in-
creases the reference voltage and cuts off IC5B. Thus the
VOX circuit does not function with an audio from the
speaker.
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3 - 31ST LOCAL OSCILLATOR CIRCUITS
The 1st local oscillator employs a premix system consist-
ing of a PLL and a crystal oscillator for each band.
1. PLL (PHASE LOCKED LOOP) CIRCUITS
The PLL employs a mixed down type, and is locked in
10kHz steps. This output is divided into 1/10, as a result,
1kHz steps is obtained.
The local oscillator, 01 oscillates at 13. 666MHz with the
crystal unit X2. This signal is tripled at 02 and 03, thus
the local oscillator output, 123MHz is obtained. A varactor
diode, 01 is connected in series with X2, and voltages from
the RIT control and FREOUENCY SET control are applied
to the cathode and anode respectively. This varies the local
oscillator frequency slightly to provide the RIT function
and frequency Cillibration.
06 is the VCO (Voltage Controlled Oscillator), and oscil-
lates at a frequency between 132MHz and 139MHz. The
Address Data Address Data
output signal is fed to the base of 04, PLL mixer, through
buffer amplifiers 07 and 08. To the emitter of 04, the
local oscillator signal is fed and mixed with the VCO signal
to mix down the VCO frequency.
The output signal from the mixer is fed to the low·pass
filter consisting of C23, L6 and C24, to filter out only the
signal below 15MHz. Then the signal is amplified to the
proper level (more than 3V poP) of the programmable
divider, IC1, by
05.
IC1, PLL IC, consists of the programmable divider, re-
ference frequency oscillator, fixed divider, phase detector,
etc. The reference frequency oscillator oscillates at 9.000
MHz, and its signal is divided into 10kHz and fed to the
phase detector as the reference frequency.
The signal from 05 is divided into 1IN at the programmable
divider. The N data is sent from the CPU in the LOGIC
unit in sequence as shown in the illustration.
Data
\~ _____ ....JI\,," ______ JI\,," ______ ..JI\~ _____ ....JI\ ....... ______ J
KHz 10KHz 100KHz
The divided signal is fed to the phase detector internally.
The phase detector detects the phase difference between
the 10kHz reference signal and the output signal from the
programmable divider, and proportionately puts out
positive/nagative pulse signal at pin 14.
This pulse signal
is fed to the loop filter consisting of R28
through R30 and C34 through C36, then fed to the varactor
diode, 02, to lock the VCO frequency.
The locked VCO signal is fed to the buffer amplifier, 07,
and a part of this signal is fed to the 1/10 divider, IC2.
Then the divided signal, between 13.2MHz and 13.9MHz
with 1kHz steps,
is fed to the mixer in the PREMIX unit
through low-pass filter consisting of C53 through C57, L10
and L11, and attenuator consisting of R41 through R43.
2. PREMIX CIRCUITS
The premix circuits are composed of offset frequency
oscillator for each band, mixer and band·pass filter for each
band.
01 through 011 are offset frequency oscillators. One of
them is selected by the band signal from the band switch
3-6
MHz Mode
and oscillates at the frequency shown in the table for each
band.
BAND OFFSET FREOUENCY
--
3.5 29.9315MHz
.-
7.0 33.4315MHz
10.0 36.4315MHz
14.0 40.4315MHz
----
18.0 44.4315MHz
21.0 47.4315MHz
24.0 5O.9315MHz
28.0 54.4315MHz
28.5 54.9315MHz
29.0 55.4315MHz
---
29.5 55.9315MHz
The offset frequency signal
is fed to the doubly balanced
mixer consisting of 01 through 04, and L12 and L13.
To the other port
of the mixer, the PLL output signal is
applied to convert into the 1st local oscillator signal.
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012 through 033 are matrix diodes to convert the band
signal into hexadecimal
code for the CPU.
The
output signal from the mixer is then fed to the BPF
unit. The BPF unit is composed of a high-pass filter, low-
pass filter and band-pass filter for each band, and buffer
amplifiers.
The high-pass filter
is composed of C1 through C5, and
L1 and L2.
The low-pass filter
is composed of C6 through C13 and
L3 through L5.
The band-pass filters are provided for each band and
selected one of them by
the band signal from the band
switch.
The signal passed through the high-pass filter, low-pass
filter and a band-pass filter
is then fed to the buffer am-
plifiers, 01, 02 and 03. The output of 03 is then fed to
the mixer consisting of 04 through 07 in the RF unit as
the 1st local oscillator signal.
3. LOGIC CIRCUITS
The logic circuits control operating frequency, band, mode,
PLL, display etc., and are designed for low power con-
sumption and high speed operation using a CMOS 4-bit
CPU.
The CPU,
IC1 is a plastic package with 42 pins. CLO and
CL1
of pins 1 and 42 are the clock terminals for this CPU,
oscillating at about 400kHz with X1 ceramic oscillation
unit.
The
CPU has a total of 9 input and output ports, each
sharing its own function:
Port A - 4 bit
input
Decodes the port E output as shown in the matrix table to
expand input functions with time sharing.
Port B- 4
bit input
Used as an input port for the sensor (tuning control).
Port C - 4 bit
output
Outputs the 2nd local oscillator 100Hz steps 0/ A convert-
ing signal.
Port 0 - 4 bit
output
Outputs the 2nd local oscillator 10Hz steps O/A converting
signal.
Port E - 4
bit output
Outputs various data as a general purpose output terminals.
Port F - 3 bit
output
FO ; Strobe signal output for display.
F1 : Load signal
output for PLL above 1kHz digit.
F2 : Reset signal
output for display.
Ports G and H are
not used.
3-7
Port I - 1 bit output
10 : Reset signal output for sensor counter.
When
the power switch is turned on, 13. av DC is applied
to IC9, voltage regulator, through R2 and 01. ICg puts out
regulated 5V. At the same time, 02 is turned on and
supplies
the regulated 5V as the power source of the
LOGIC unit. When a memory backup power source is con-
nected, the power is applied to ICg through R1, and re-
gulated 5V is supplied to IC1, the CPU to maintain the
operating frequency, memorized frequency, etc. At this
time,
02 is turned off and 5V is not supplied for the other
circuits.
At the moment of the power switch has been turned on,
a pulse is fecfto pin 3 of Ica through C3. After the pulse
has been waveform-shaped, it
is fed to the reset terminal
(pin 7)
of IC1, to initialize the CPU.
The matrix circuit
is designed as follow:
I
I I
",1
~NOR
I'\0B I'\OHZ
EO El E2 E3
AO
",2
~EV ~E~
~z
Al
~4
~sPLIT
A2
1'\8
~WRITE
~~ON
CPU
1.3
L
eo
Sensor Bl
input
B2
B3
BA 1 through BAa are band data which is fed from the
PREMIX unit.
This data
is processed by the CPU and the CPU puts out
signals to control the display and PLL.
In the SSB operation, the selected sideband (LSB or USB)
is reversed automatically when changing the operating band
from 10MHz to the lower band or from 7MHz to the upper
band. For this function, the band data and mode data
(LSB or. USB) from the mode switch are fed to exclusive
OR gates, IC7, and their outputs are fed to AO and A1
input terminals
of the CPU.
The two signals from
the rotary encoder connected to the
tuning control are input to SENS1 and SENS2 terminals of
the LOGIC unit, and waveform-shaped by the respective
Schmitt triggers, consisting
of IC2 and R11 through R14.
One of the waveform-shaped signal is fed to pin5 of IC7.
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•
inverter, then Pin6 of 1C3 as a switching signal. The other
waveform-shaped signal
is output from pin3 of IC2 and
differentiated by C12 and Rl0, then fed to pinl of IC3,
inverter. The output signal from pin3 of IC3 is also dif-
ferentiated by Cll and R9, then fed to pins 5 and 12 of
1C3. To the other gates of 1C3, the switching signal is
applied and controlled the differentiated signals. The
output signals from pins 4 and 11 of 1C3 are fed to 2-
input NOR gate of IC3 and combined as the UP signal.
This UP signal is fed to CP terminal of IC5, flip-flop, and
it holds the output terminal, pin 13, H-Ievel when the UP
signal is present. This H-Ievel signal is then fed to B3
terminal of the CPU, and the CPU processes to increase
the operating frequency. When the tuning control is
turned counterclockwise, the B3 terminal is maintained in
the .L-Ievel.
Two differentiated signals at C12 and Cll are fed to pins
5 and 6 of IC2, OR gate, and combined signal is ~utPut
from pin4. The rotary encoder outputs 50 pulses per
revolution, while pin4 of IC2 outputs both leading edge
and trailing edge, resulting in an output of 100 pulses per
revolution. This output signal is fed to a counter of 3-bit,
consisting of 1C4 and a half of IC5.
This counter is capable of counting a maximum of 7
pulses, and serves as a timing buffer between the encoder
and the display in relation to reading by the CPU. If there
is any output at the counter, the output of the diode OR
gate, consisting of 05 throug, 07, becomes H-Ievel, input
to inverter, IC8, then input to the INT terminal of the CPU
with its level inverted to L-Ievel. This terminal is a priority
terminal which
gives priority to sensor processing by
stopping other operations. In the priority routine, counter
data and up-down data fed to BO throug, B3 terminals
are read by the CPU, performing in this way all operations
related to sensor processing.
Immediately after the sensor data have been read, a reset
pulse is put out from IlJ terminal, and the pulse is differ-
entiated by C5 and R46, then fed to clear terminals of
the counter and up-down latch to clear them.
The up-down control circuit consisting of 03, 04, R16
through R21, C17
throug, C21, etc., provides frequency
control from the up-down switches on the microphone.
When the UP or DOWN button is depressed, the multi-
vibrator, 03, oscillates and pulses are fed to pin6 of IC4,
and the 3-bit counter counts the pulses the same as the
pulses from the rotary encoder.
After processing, the CPU outputs frequency data for the
PLL from the port E. This data is a 4-bit parallel data and
it is output in sequence according to its digits. The port E
also output frequency data for the display with time
sharing. This data is 4-bit parallel and 8-digit data. FO and
F2 terminals output clock pulses for the display and Fl
terminal outputs clock pulse for the PLl. Data for 1kHz
and lower digits are output from the ports C and 0, and fed
to DIA converter consisting of R35 through R43 to convert
into a analog signal. This analog signal is fed to the 2nd
3-8
local oscillator in the 2nd IF unit to get 10Hz step fre-
quency resolution.
3 - 4 DISPLAY UNIT
This unit is composed of DS1 display tube, ICl driver IC
and DC-DC converter for the display tube and negative
voltage source.
The frequency data is fed to pins 2 through 5, input port S,
and timing control pulse is fed to pin 15. After processing,
segment data is put out from pins 16 throug, 22 with digit
control signal put out from pins 6 through 11. These signals
are fed to the display tube and light the tube with dynamic
lighting.
The DC-DC converter is composed of 01, L1, Rl through
R3, Cl through C4, 01 through 04, etc. This converter
generates a negative voltage and filament voltage for the
display tube, and -5V for the AGC circuit and operational
ampl ifiers.
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..
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TOP VIEW
RJ OF Shih wI dth "".1 .-- __
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MIC
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DISPLAY UNIT
LPF UNIT and ACC BOARD
LPF U.'T---------------_
Lll . L12 (1S ..... 21MHz LPFI --- iii
L13 , LI4j24 .... 28MHz LPFI---
51 (BAND
L15 jSWA D.teetiOf\ eo",----
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PA UNIT
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LOGIC UNIT
Ie.. (TC4013C CO,"",I--------
ICS h,P04013C Cour",r' Up/Down CO"' '' ''' jr--
P2 10 PLL Jl---------,:- .
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2nd IF UNIT
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4 - 4
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