JRC NDR-91 User manual

2 REV.
INSTRUCTION
MANUAL
RECEIVER
o+
O*
@ flrytnadioCo.,Ild.

MODEL
NRD-91
RECEIVER
OUTSIDE
VIEW
(DESK-MOUNT
TYPE)
#
û
o
o
ôffiË
MODELNRD-91RECEIVER
OUTSIDEVIEW
(CONSOLE
OR RACKTYPE)
ô

CONTENTS
CAUTION
1. GENERAL
DESCRIPTION
1.1 FEATURES
1.2 SPEC|F|CAT|ONS
. . . . . .
2. COMPOSTTTON
2.1 STANDARDCOMPOSITION
2.2 oPTtONS
2
2
2
5
5
5
3. INSTALLATION
3.1 INSTALLATION
3.2 ANTI-INDUCTION
OFTHE
TRANSMITTING
WAVE
3.3 CONNECTION
OFEXTERNAL
LINES
3.4 HOW TO
MOUNT
AUX CRYSTAL
OPERATION
4.1 OPERATIONPANEL
4.2 OPERATINGPROCEDURES
4.2.1 Basic
Operation
of SSBReception
4.2.2 BasicOperation
of CW
Reception
4.2.3 Operation
of DSB
Reception
4.2.4 Operation
of FSK Reception
4.2.5 Operation
of FAX Reception
. . .
4.2.6 FurtherOperation
CIRCUITDESCRIPTION
5.1 RECEIVINGSECTION
5.2 LOCALSIGANL
GENERATOR
SECTION
5.3 PANEL
SECTION
5.4 POWER SUPPLY
SECTION
MAINTENANCE
6.1 GENERAL
6.2 GENERALMAINTENANCE
ANDCHECK
.
6.3 TROUBLESHOOTING
6.3.1 Declineof the Sensitivity
6
6
6
6
9
l0
l0
t2
l3
l3
l3
t4
t4
l5
t6
t6
l6
t7
l8
t9
t9
t9
20
20
4.
5.
6.
-l-

6.3
.2 No Sound. .. 2L
6.3.3 NoiseandBeat .... .21
6.3.4 Interferenceby theTransmitter
of Your Station 22
6.3.5 Intermodulation 23
AppendixedDrawings PartsArrangements
BlockDiagram
OutlineDrawing
Circuit Diagrams
Speaker
Unit
-ll-

CAUTION
l. Read
this instruction manualthoroughly beforeturning on this receiver.
2. When connecting
the BK cableand
othercables,referto Fig.3.3of Paragraph
3.3.
3. Whenthe transmitting wavesarestronglyinducedin the receivingantenna,take the counter-
measure
described
in Paragraph3.2.
4. Do not turn semifixed resistors,high frequency transformers, trimmer capacitors, etc.
mounted on the printed circuit board unlessabsolutely necessary,
because
they are all
preadjusted
at the factory.
5. If the MHz knob is setat inadequate
position,the receiveris muted. Therefore,the MHz
knob mustbeset correctlv.
6. This receiver
haslow-voltage-operable
ICs andtransistors.Be sureto turn off both power
switohes when connecting or removing the printed circuit board and cablesto external
equipments.
1. If the AUX mode is selectedat a condition where
additional
crystal
is not provided,the
receiveroperates
actually
in the DSB mode eventhoughtheAUX modeisindicatedon the
front panel.
8. The illumination of LEDS (Receivingfrequency, Mode and Bandwidth indicators) is
gradually reducedas turning f-DlMMEil knob counterclockwise.
Finally they fade out
completely
at theminimum position.
(). When the ntode is except SSB and Frequency
Display shows
the tiequency between
000.0kH2 and001.4kH2,
MHz LED displaysthe frequerlcy
obtainedby addinglMHz to
the display
of MHz Selector
Switch. In such
a case,Receiver
receivesthe frequencydis-
played
by LED.
10. When
the rnode
isexceptSSB,
the upper
limit of the received
fiequency
to be displayed
is
3000
|.4kHzand
the
lowerlimit is 001
.5
kHz.
-l-

1. GENERAL
DESCRIPTION
The model NRD-91 Receiveris a highly reliable receiverwith the simple circuit com-
position, developed
by JRC based
on our many year'sexperimentand technicalresults.
PLL
syuthesizeris equipped in the first local oscillator to prvode the high accuracy of frequency
setting,so that this receiver
hasenoughperformances
for usein the SSBmode as a back-up
receiver.
1.1 FEATURES
I
) Provided
with digital
synthesizer
of PLL type
The reference
oscillator
with the highstability(t5 x l0-6ppm) ensures
highstabilityof
fiequencies
overa wide frequencyrange
for reception.
2) Wide
receivingfrequencyrange
Thisreceiver
covers
the wide receiving
frequencyrange
from 90 kHz to 29.9999MHz.
3) Digital
indication
of receiving
frequencies
This receiver is provided with light emitting diodes for a numerical display of the
receiving
frequency
from 100
Hz digit to l0 MHz digit.
Therefore,
the frequencycanbesetcorrectly.
4) BCband
rejector
BC bandrejector
reduces
theinterferences
such
as
cross-modulation
andintermodulation
due to the strong radio waveof the broadcasting
wavegenerating
during receivingthe
MHF radiowave.
5) Directlyconnected
to Teleprinter
andFAX
The line output terminal,
600St
0 dBm,isprovided.
By addingtheoptional crystal,FSk
or FAX canbereceived
in the AUX mode.
At thistime, the center
frequency
of the line
output is 1.7
kHz and l.9 kHz respectively.
6) Entirely modular
construction
The circuits are accomodated
in the plug-in type printed circuit boards(excluding the
panel
section
andpower
supply
unit). Thus,maintenance
andcheckare
facilitated.
1) Operable
on either
AC or DC power
The receiver
canbe operated
on AC or DC power
by changing
the powerswitch
on the
panel.
1.2 SPECIFICATIONS
I
) Receivingfrequency
range
9OkHz to 29.9999
MHz
2) Circuitsystem
Double superheterodyne with up-conversion
system using a phase-locked
digital
frequency
synthesizer.
Ist
lF- : 70.45
5 MHz
2ndIF : 455kHz
3) Reception
mode
CW(AlA), MCW(A2A,
HzA), DSB(A3E),
SSB(R3E,H3E, J3E) andFSK(FlB) or FAX
(F3C)
,2-

1)
But FSK andFAX are
option.
4) Receiving
frequency
indication {
Light emitting diode for six-digitnumericaldisplay(
I0 MHz- to 100Hz- digit)
5) Tuningmethod
Continuous tuning with MHz knob, UP/DOWN switch and TUNE knob of l}kHzl
rotation
(minimum
steP: 100Hz)
6) Sensitivity
------_-_ Mode
Receivùg -----
frequency AIA A3E J3E
90- 199.9 kHz 2O
pY or less 60
pV orless
200- 1599.9 kHz l0 pV or less 30pV or less
1.6-29.9999
MHz 2 pY or less 6 pV or less 3 pV or less
15çt standard signal
generator
is directly connected
to the antenna
terminalS/N 20 dB,
Output 100
rnW,
Bandwidth
3 kHz,400Hz 30%
modulation.
Selectivity
-\!tenuation
BandwidÈ=--=- 6 dB bandwidth 60 dB bandwidth
6 kHz 4.4 kHz or more l0 kHz or less
3 kHz 2-2.6 kHz 6 kHz or less
0.5
kHz 0.5-
1.0
kHz 3 kHz or less
8) Frequency
stability
I hour after l5-1rilute preheating
t 10
x l0-6 or less,
but under
the condition where
the receiving
frequency
is 1.6
MHz or morein the SSB
mode.
9) Image
rejection
ratio
60 dB or more )
l0) IF rejection
ratio
60 dB or n-lore
I l) Spurious
response
60dB or more
12) Blocking
The input level
of the unwanted
signal
is more than l0 mV which suppress
the output
level of the wanted signal
by 3 dB, under a condition where the unwanted signal
is
separated
by 2OkHz or more from the wanted
signal
of l0pV. (SSB
mode,3kHz,
AGC
ON)
! 't '.
1
-'"
r û''1 i._;-
\ .'J '!."1
.
! I.
d'l
o,t t,g 1,'i:
-3-

l3) Cross-modulation
The cross-modulation
output, which is generated
when the 20kHz detunedunwanted
signal
of 90 dB is added
at the wantedsignal
of 60 dB, is 30 dB or lessfbr the wanted
signal
or"rtput.
I4) Interrnodulation
The secondor third intermodulation output, which is generated
when the two 80 dB
interference
wavesof 20 kHz detuned
are
added,
isbelow
the wanted
signal
output.
l5) AGC characteristic
The variation
of the AF or-rtput
is l0 dB or less
for the antenna
input levelof 3 pV to
100
rnV.
l6) AF characteristics
Speakeroutput
Lineoutput
Headphone
output
Frequency
response
Distortionfactor
l1) Radiation
I x lO-eW
orless
l8) Norninalinput impedance
50-75 ohrns
l9) Variablerange
of BFO
!2 kRz or more
20) Variablerange
of Clarifier
t50 Hz ormore
2l) Power
supply
AC power
supply 100/110/200
l220Ytl0% 50160
Hzapprox.30vA
DC power
supply 24V!10'/o
(negative
grounded)
approx.25W
22) Temparaturerange
and
relative
humidity
-10"C to
+50oC,
9s%
at
+35oC
23) Dimensions
andweight
Without the cabinetcase
149(H)x 480(W)x 294(D)excluding protuberence Approx. j ke
With thecabinetcase
190(H)
x 489(w)x 305(D)excluding
protuberence Approx.I1.5
kg
lW or more
(6000)
lmWor more(6004)
lOmW
or more
(6004)
3 dB or lessat the frequency
range
of 300 to 3000Hz
Speakeroutput3%or less
at500mW
Lineoutput 3%
or less
at I mW
-
4-

2. COMPOS|TION
2.1 STANDARD COMPOSITION
The composition
of this receiver
depends
on its type, that is, desk-mount
type or rack
type.
* Spare
parts
include: One each
of BK relay, andfuses.
2.2 OPTIONS
Remarks
Provided
for only the desk-mount
type
600alw
Provided
for only the desk-mount
type
t
NRD-9
I
MPBXI
0832
NVA-92
'ZCJDOOOO5
MPKCO3
I08
M-P_7
6ZXJD5IO43
Receiver
Cabinetcase
Speaker
Powercable
BK cable
Instructionmanuâl
ANT Connector
Spare
parts
Testdata
Item Model or code Remarks
Headphones I ST-3 | 600ohms
DCpower
cable MPKCOI74I I ForDC24V
Extensioncard
fbr maintenance I CMH-330 | Usedfor checking
each
PC
boad
| | in operation
Additional cr1'stal | | Crystalto bemountedin the
AUX position
In caseof FSK 456.7kHz
In case of FAX 456.9kHz
-5--

3. INSTALLATION
3.1 INSTALLATION
(I
) Wheninstallingthe receiver
on the l9-inch standard
rack,
place
theguide
bolt provided
on the side of the chassis
on the rails,
and pushthe receiver
to the inside
of the rack.
Then, flx the receiver
in positionby screwing
the 5-rnmscrews
through the mounting
holes
at two positions
of both left andright sides
of the front panel.
(2) Wheninstalling
the receiver
on the desk,
Llse
the special
cabinet
(optionally available
on
separateorder).
Attaclt the sliderails
(supplied
with the cabinet
case)onto left andright sides
of chassis
of thereceiver
andmount thereceiver
in the cabinet
case.
Fix thereceiver
to the cabinet
case
by screwing
the 5-mmscrews
through
four mountingholes
on the front panel.
3.2 ANTI-INDUCTION
OF THE TRANSMITTING
WAVE
Whenthe receiver
is operated
with a paired
transmitter,
it sometimes
happens
that the
transmitting
waveof own stationis
induced
in thereceiving
antenna.
When
the induction currentof the transmitting
wavesis I ampere
or less,
thereceiver
is
protectedby the built-in input protectivecircuit. But if the induction currentexceeds
I
anlpere,theinputcircuit of thereceiver
maybe
burntout.
When
the receiving
antennasuf-fers
fiom such
an excessive
induction current,move
the
receiving
antenna
as
far as
possible
trom thetransmitting
antenna,or insert
the anti-inducer
in series betweetr
thereceiving
autenna
and
antennainput connector
asshownin Fig.3.l.
Receiving
antenna
l00v 60w 100v I
60w I
PL1
01 PL1
02 |
l/\l
i- ç?(e}
-{çf-'-_----_--.. a-f - #to' Q - to tne[Àtrtrlconnecter
rl
ll
L_ __J
AW-01
'18
Anti-inducer
Fig.3.1 Protection of the Receiver
by the Anti-inducer
3.3 CONNECTION
OF EXTERNAL LINES
(l) This
receiveris
operable
in either
ACl00tlO% (50/60
Hz)or DC24V!lO%.
For AC operation,conrlectthe AC power cableto [nC tO()Vl located
on the rear panel
of the nrair-t
tratne. For DCI operation,
connect
the DC power cable
MPKCQ|74I
(option) to LO_.9_?4located
on therear
panel
of themainframe.
-
6,

o
When changing the power voltage at the installation place, change the terminal
connection
of the powertransformer
located
inside
the chassisasshown
in Fig.3.2. For
the location of the transformer,
seethe annexedpart arrangement
drawing.
Fis.3.2
(2) Connectthe antenna
cableto the |,ANT-I
connectorprovidedat the rearpanel.
(3) Connect
the grounded
wireto theterminal H on the rear
panel.
(4) If the break-in
relay
circuitisto beused,
connectthe special
cable
(MPKCO3
108)to the
tBK & Lin[Êl connector.
TheAF output
signal
(600S,
unbalanced
speaker
output,
and
600O balanced
line output) canbe alsotaken out from thisconnector.
SeeFig. 3.3 for
details.
AC power Headphones
ST*3 (Option)
DCpower
I
I
I
I
I
I
rT1
I
I
I
I
I
I
I
I
1Oo/o
I
II
I
I
20vAC2
o
Externa
I
Speaker
NVA-92
Line
output (600f,l balanced,0 dBm)
To FAX. Tape recorder,
FSdemodulator,
etc.
Fis.3.3
-7 -,
AC200Vr l Oolo
NRD-91
Rear
panel
?lt- rr
9ilL5t I
\

Item Indication Cable
andconnector Pin Color Explanation
IACIOOV,
r
t0v
200v,
220V
Connector
HSl6P-2
Cable6ZCJDO0005
IWhite For AC power input
Thecable
isattached
with the
receiver,
only whenthe receiver
ismountedin the cabinet
and
shipped.
2Black
2DCz4V Connector
HSl2P-2
Cable
MPKCO
17
4l
IWhite +24V For DC power
input
Cableis
option.
2Black OV
(grounded)
3ANT M-P-3ls
17 Antenna
input
4BK&
LINE Connector
S- 13
I2-CEA
Cable
MPKCO3l08
IWhite -BK (key signal)
2Red +BK
(BKpower+24Y)
3Black E600s}
unbalanced
lW output
4Green Speaker
5Silver Shielded
(commonground)
6Not used
7White Line 600s,
balanced,0 dBm
AF output
8Red Line
9Black Centertap
l0 Green Not used
ll Silver Shield.ed
(common
ground)
t2 Not used
-8-

3.4 HOW TO MOUNT AUX CRYSTAL
By adding the crystal to the AUX mode position, the center frequency of the line
output canbe 1.7kHz in caseof FSK reception
and I.9
kHz in FAX reception
whensetting
the frequency indication on the panel to the wanted receiving frequency, and this line
output can be connectedto FS demodulator or FAX. The frequency of the crystal is
456.7
kHz in FSK reception
and 456.9kH2 in FAX reception.
Since
this receiver
hasone
AUX crystal
space,
one of FSK, FAX or otherdesirable
modeisavailable. Please
inform us
of your desirable modeor the frequencyof the crystalwhen ordering.
Mount the crystalaccordingto the following procedures.
I. Insertthe crystalinto AUX (X3) on CMH
-379 IF 2ndunit andsolderit.
2. Connect two holes(AUX) positionednear the connector(PlO) on the sameunit by
meansof the leadingwire.
3. Connect the speakerand
turn on thepower.
If the beat sound comesout through the speakerwhen setting the mode to AUX, the
crystalismounted correctly.
Note) The beat sound can be easily known by comparing the noisein AUX mode
with the noise in DSB mode, becausethe noiseincreaseswhen changingthe
mode from DSBto AUX.
-9-

4. OPERATION
4.1 OPERATION
PANEL
[Jmll
runo-sr
lnecrtven
| | | rr^hr
i:i !:,,='11k-3,-- - |
r MH, '- '-rH, BANDW'FT"
J
BFO& CLARIFIER ON REJECT
0t
OFF OFF
RF
GAIN AF GAIN AGC I pOWER
PEAKER sr-ow$
/orlg
OFF/ T
DC
No. Control Function
IMeter Indicating
the strength
of thereceiving
waves
or level
of the
AF output(line
output)
2DIMMERknob Used
for adjusting
thebrightness
of allLE,Ds.
Adjust the
brightness
by thisknob according
to the circumstance.
LEDsfade
out if thisknob isturnedfully counterclockwise.
Keep
this
in your mind whenusing
thisreceiver.
3Receiving
frequency
indicator Displaying
thereceiving
numbers.
In caseof SSB
displayed
and
in caseof
frequency
isdisplayed.
frequency
by 6-digit
numerical
mode,
the carrierfrequency
is
modes
otherthanSSB,the assigned
4BANDWIDTH
indicator Displaying
the
bandwidth
of the IF filter specified
by the
BANDWIDTH A selector
switch
(one
of 0.5 kIHz,3klHz
and
6 kHz)
5MODE
indicator Displaying
the mode
specified
by the MODE switch@
(one
of SSB,CW,
DSB
and
AUX)
- l0
-

No. Control Function
6MODEselector Usedfor selectingthe reception*oà. (oneof SSB,CW,DSB
andAUX). When
changingthe mode from oneof AUX,
DSBandCWto SSB,
the frequencyobtained by subtracting
1.5kHz from the originalfrequencyis displayed
on the
frequencyindicatorO .This isbecausethat the carrier
frequency
is displayedin caseof SSB
reception.SinceAUX
isoption, makea specialorder if necessary.
If this AUX
modeis specifiedwhen the optional crystalis not mounted,
actualreceptionmode isDSB eventhough the AUX mode
isindicatedby the MODE indicator.
1BANDWIDTH
selector Selectingthe bandwidth of the IF filter (intermediate
frequency)
(one
of 0.5 kHz,3 kHz and6 kHz).
8METER selector
switch Selecting
the content to beindicatedfor the meter(D. When
settingthis switch to S,turning RF GAIN @ fully clock-
wise,andsetting the AGC switch
@ to FAST or SLOW,
the meterpointer indicatesthe relativesignal strengthof
the HF input of the receiver.
Whensetting this switch to
LINE, the meterindicates
the lineoutput level
(6000
balanced).
9SPEAKER
jack Used
for connecting the specialspeaker, NVA-92 or the
speaker
of 600C1impedance.
l0 PHONES
jack Usedfor connecting
headphone
of 600C2the optionalheadphones,
ST-3 or the
impedance.
ll MHz selector Usedfor settingthe MHz digit of the receiving
frequency.
The full rotation of thisknob covers30 bands
(
I MHz step).
t2 BFO
& CLARIFIER
knob Serving
asBFO adjustment knob in caseof CWmode.
This
knob canvary the frequencyof 455 kHz beat oscillator
(BFO) by more than t2 kIIz. Therefore,the tone of the
telegraphsignal
canbeadjusted.
This knob alsoserves
asa fine adjustmentknob (CLARI-
FIER) of thereceivingtiequency in SSB
andAUX modes.
This canvary the centerfrequencyof the oscillating
fiequencyby morethan t50 Hz.
l3 RFGAIN
knob is Gain controller for the RF amplifier andIF amplifier. It
recommended
to adjustaccordingto the strength
of the
receiving
signalfor obtainingthe optimum volume.
t4 TUNE knob Usedfor settingthereceivingfrequencyin 100Hz steps.
The full rotation changesthe receivingfrequencyby l0 kHz.
l5 UP/DOWN switch Fastforward switch of the receivingfrequency.While
pressing
UP (or DOWN), the fiequency increases
(or
decreases)at aspeed
of approx. 125kHz/second.
- ll -

No. Control Function
t6 LOCK switch Usedfor locking the setfrequencyelectricallysoasnot to
be changed
by carelessmisoperation.
By setting
this switch
to the locked condition (pressed),
the receiving
frequency
will not bechanged
even
though operating
the TUNE knob
@ and UP/DOWN switch@ .f'or releasing
the locked
condition, press
this switchagain.
l1 AF GAIN knob This is avolume adjustment
knob for the speaker
or
headphones.
And this knob does not af'fectthe levelof the
lineoutput (600O balanced)on the rear panel
of the
receiver.
t8 Attenuator switch Usedfor selecting
the ON or OFF conditionof the 20 dB
HF attenuatorfor thereceiver
input. Setthisswitch
to ON
for the better receptionwhen the signalisreceived
at the
neardistance
andthe desired
signalisinterfered due to the
strongneighboring
signals
etc.But usually,setthis switch
to the OFF position.
t9 AGC
switch Usedfor selecting
the ON or OFF condition of the AGC
circuit andselecting
the discharging
time constant.
TheFAST position
isfor the reception
of DSBsignals,
andthe SLOIV
position
isnormally f
or thereception
of
CWor SSB
signal
affected
by fading. By setting
thisswitch
to OFF, the AGC circuitremains
inoperative
andsignals
aresaturated.
Thus,
control thegain
by the RF GAIN
knob @ for the best
receiving
condition.
20 BCBAND
REJECTOR Setthisswitch
to ON for the betterreception
whenthe
cross-modulation
or intermodulation dueto the strong
radiowave
of thebroadcasting
wave
(525 to 1605
kHz)
interferes
theMHF reception.
2l POWER
switch Usedfor turning ON or OFF the power.Also usedfor
selecting
AC or DC power supply.
4.2 OPERATING
PROCEDURES
Beforeturning on the power switch,checkthe following items.
(I) Power
voltagecheck
The label, which showsthe nominal power voltage,
is placed
abovethe power connector
located on the rear panel of the receiver.
Check that the power voltageto be usedis
within the rangeof the nominal value
!lO%.
(2) Antenna systemcheck
Check that eachconnectingpart of the antennacableto be connected
to this receiver
is
firmly connected.When the antenna coupler and antennachangerare used,checkthat
they arecorrectly set
*-t2-

(3) Check
of the connectors
on the rear
panel
Check that each connector and grounded wire on the rear iranel of the receiverare
surely
connected.
(4)Connect
thespeaker
or
heaclphone
to lspeaKf nl or IFHONES-I
jack.
4.2.1 BasicOperation
of SSB
Reception
(l) Setthe tAF GÀlN I knob to the position
wherethe knob isturned clockwise
by 4 or 5
graduations
fiom the mininlum position.
(2) Setthr FQ@ switch
to [Ac] in caseof theACpower
supply,orto E in case
ofthe DC
power
supply.
(3) PressttrelSSe-l
button
amons
the ltvtôOfl switches.
(4) Setthe desired
receiving
fiequency
by usingthe IMHil knob, I-UPIDôW-NI switchand
FÙnel
knob.
(5) Set the
t
slow
I
(6) After hearing
the desiredsignal,turn the tAFGÀiNl knob and setit for anoptimum
sound
volume.
(7)Adjustthe BFO& CLARIFIERknob soasto setthe tone the most natural to hear.
knob to the maximum position and turn the AGC switch to
(8) Whenthereceivedradiowaveisnot strongly
affectedby fading, turn the FF GAINI
knob slightlycounterclockwiseand IAF GAIN-l knob slightly
clockwiseso
asto obtain
thebestS/N of thereception voice.
4.2.2 Basic
Operationof CWReception
(Morse
Telegraph)
(
I
) Settn. [11tQA|Nl knob to 4 or 5 graduations.
(2)
Pressthe
ltw I button
amonsilre
lrvrooe
Iswitches.
(3)
Setthe
desiredreceiving
frequency
byusing
thelMHll knob,
ttre
IÙP/DOWN-I
switch
utro
lîulrtr I knob.
(4)
Press
ttre
lo.s
kHl button
among
th. M switches.
(5) Setthe FFGAINI knob almost
to the center
position
andthe trGôl switch to
desiredsignal,set the volume to the optimum level by adjusting the
BFO
& CLARIFIERknob, setthe tone the mostpleasant to hear.
(8) Adjurt Inf Gatwl nn6
[RF CÀitrtlsothat
S/N
of the receivingsignal
willbe
thebest.
(9) When the receivingwave is affected by fading or the strong waveand weak wave are
received reciprocally, set the tÀGC-l switch to I-SLôWI or |FÀST I and turn the
f
RFGAINl knobslightlyclockwise.
4.2.3 Operationof DSB Reception
(l) Pressthe IDSBI button amonsI MODTI switches,and i6 kHtl button amons
BANDWIDTH
I switches.
(2)Setthe l-RF GÂlNl knob to themaximum
position
andset
the tAGC-l switch
to
(3) Setthe desired
receivingfrequencyby usingthe f
MHI knob,IUF/DOWN lswitch and
(6) When hearingthe
Erc4l$ knob
(7) BV
adjusting
the
knob.
- t3
-

(a) Bvadjustingthe
IAF GAINI knob,
set
thevolume
to theoptimum
level.
(5) In caseof stronginterference,
press
theF kHA button among BANDWIDTHswitches.
4.2.4 Operationof FSKReception
A teleprinterand FSdemodulator
areadaptative
to thisreceiver
to receive
a FSK signal.
Receive
the FSK signalin the following procedures.
But thismodeisoption.
(l) Press
tn. I nuXl buttonamons
f
MoDEl
switches.
(2) Selectthe proper BANDWIDTHbutton in accordance
with the frequency shift width
signal under reception. In caseof the narrow band and modulation speedof an FSK
directprintingtelegraph,select
W andthe f
RFCÂiN-l knobto themaximum
position
(4) Setthe desired
receivingfrequency
by using
th. [@ knob,trFDôWNl switch
and
truNEl
knob.
(5) After receiving
the siganl,
adjust tne [-Âf GÂt[l knob so as to obtain the desired
volume,
as
required.
SetthetMEaER-l
switchlocated
on
Adjust the BFO
& CLARIFIER
demodulator deflects
maximumly and LEDs of both MARK and SPACE
blink in the
sarne
brightness.
Note) When perfbrming the teletype communication by connecting this receiver
to the narrow band direct printing terminal, be sure not to changethe
BANDWIDÏHafter the circuit is connectedonce. Otherwise,it may happen
that thephase isout dueto thedifferenceof the delay time of the filter.
4.2.5 Operation
of FAX Reception
A radio facsimileequipment is alsoadaptative
to this receiver
to receive
the FAX signal.
Receive
the FAX signalin the following procedures.
But this mode isalsooption.
(l) Press
ttre
I
nUX I button
amons
IMODEI switches.
(2) Selectthe proper BANDWIDTH
button in accordance
with themodulationspeedand
frequency shift width of the FAX signal under reception. In case
of the broad band
facsimilesuchasweatherfacsimile,
etc.,
press
F kHtl
(3)
Setthe
I
AGCIswitch
to tFÂST-l
and
the FF GAIN
Iknob
tothe
maximum
position
(fully clockwise).
(4) Setthe desiredreceiving
frequency
by using
the IMHz
I knob,IUffiôWN Iswitch
and
tTut\i-trI
knob.
(5) After receiving
the signal,
adjust 11s
l-Af Celw Tknob so as to obtain the desired
volume,
as
required.
(6)AdjusttheknobsothatLEDsfortuning,locatedonthefront
panel
of the facsimilerecorder,
[îU NFTI utO
fîulUF2l wiil lightthemostbrilliantly
(3) Setthe fÀcC-l switchto
(fullyclockwise).
(6)
(7) thefrontpanel
of theFS
demodulator
to fTUNtrl.
knob so that the FUruEt meterof the FS
in thesamebrightness.
-14 -

4.2.6 FurtherOperation
(
I
) Operation
of ATT.
The receivingantennacatches
many kinds of radio wave from the strong one to weak
one. If many strong waves arrive at the high frequency stage of the receiver,
interferencessuch as intermodulation, blocking, cross-modulationand so on arise,so
that sometimes
the desiredradio wavescannot bereceived
well. Also, when the partner
station is located very closeto your station, the sound is distorted because
the AGC
circuit cannot control such a strong radio wave. In sucha case,by setting J
,Â1T I to
N, the receiving
condition is greatly improved. If p meter deflects, the desired
radio wave can be received even though l-AT1-l is set to trt. Especially, when
receivingthe radio wavebelow 1.6MHz, it is recommendedto alwaysset IATTI to
@ except
at the stand-bycondition.
(2) Operation
of BCBAND REJECT
While receiving
the MHF band (below 3 MHz), many other radio wavesmay bereceived
besidesthe radio wave of the desiredstation. Theseare called cross-modulationand
intermodulation interferencesdue to the strong radio wave of the broadcastingwave
(525 to 1605
kHz). In such a condition, by setting BC BANDREJECT switch to
@, aneliminator
filter locatedatthe
ANT inputcircuit
operatesso
as
to rejectsuch
interferences,
so that the receivingconditionwill be remarkablyimproved.Whenthe
desiredwave
is comparatively
strong,
usethe above-described
IATT-I
togetherwith
BCBAND
REJECT
(3) Operation
of AGC switch
Thedischarging
time constant
at the position
of AGC tSLôVln is setto 3 sec.
so
asto
suppress
the noise between communications in SSB mode enough for the pleasant
communication. When receiving the radio wave affected by moderate fading, the
ISLOW Iposition
seems
to give better
result.
However,
the weak signal
promptly after that the strong signal
is receivedmay not be
ableto hearsince
the gain
is not recovered
yet. Therefbre,when communicating
with
the shipat a far distance
and the one at aneardistance
by turns,set
the l-ÂGClswitch
tofF-Àsr-]. €5?*rl
ïeû4_
lri,.rb
i;
f ||,r''h'{3
#\
i7
Ëi
s
6\fsff
't *\:$f
'!:
.r il i | *.
^ 4 ir if
| 5'li lr t- . *r
t-
- t5 -

5. CIRCUIT
DESCRIPTION
Refer to the annexed blockdiagram for the circuit composition of the receiver. This
receiver
is composed
of receiving,
localsignal
generator,
panel
andpower supply sections.
5.1 RECEIVING
SECTION
The receiving system is an up-conversiontype double-superheterodyne
with a first
intermediate frequency of 70.455MHz and a second
intermediate frequency of 455 kHz.
A signal frequency of 90 kHz to 29.9999MHz is supplied to the RF input filter after
passing
through the BK relay and the input protection circuit. The signalthus supplied
passes
through the 35 MHz LPF andis supplied
to oneof the sevenfilter circuits,depending
on the operatingfrequency.The signal
is then fed into the lst Mix. in whichthereceiving
signal is mixed with the first local signal of 70.545 to 100.4549
MHz and is thereby
convertedinto the first IF of 70.455MHz. The convertedoutput passes
through the crystal
filter with a center frequency of 70.455
MHz and a bandwidth of l2kHz, and then is
amplified by the lst IF AMP. Then the siganlis supplied to the 2nd IF in which the
amplified signalis mixed with the 2nd local frequency signalof 70 MHz and is thereby
convertedinto a 2nd IF of 455 kHz. The converted
output passes
through oneselected
out
of three filters with bandwidth of 6 kHz, 3 kHz and 0.5 kHz and the filtered signalis
amplified
by the455 kHz IF AMP. 2r'J
The amplifed receivingsignalis supplied to the AGC circuit and demodulator circuit
respectively.The AGC voltage for automatic gain control is applied to the lst IF AMP
(70.455
kHz) and 2nd IF AMP (455 kHz.). In caseof DSB detection, the demodulator
circuit takesout the carriercomponent from the receivingfrequencysignal
andoperates
as
a synchronousdetector.
In case of otherthanDSBdetection,
the BFO signalsupplied
from
the BFO circuitandthedemodulator
circuitoperates
as
aproductdetector.
The demodulatedoutput is supplied
to AF AMP andLINE AMP respectively.
AF AMP
is a AF power amplifier for speaker and headphones.
The gain is adjusted by IC for
electronic volume placed on the fbrmer stage
of AF AMP according to the DC voltage
suppliedfiom AF GAIN controller on the front panel.
The LINE AMP output is supplied
to [BRE- LINEI connector
on therear
panel
and
usedfor connectingto the tape recorder,
FAX, FSK demodulator,etc. The LINE AMP
output is approx. 0 dBm which is not affected by the AF GAIN controller on the front
panel.
The BK circuit is provitled for protecting from burning due to the inducation of own
station'stransmitting radio wave.
This BK circuit is controlled by the external
+BK and-BK
(keying signal).When-BK line becomes0V (keyed), the BK circuit operatesfor grounding
the antennaterminal. At the sametime, since
the AGC circuit is controlled, the gainof the
receiver
isreduced
andthe speaker output doesnot appear
(muting condition).
5.2 LOCAL SIGANL GENERATOR
SECTION
The local signalgenerator section is composed
of the lst local oscillator,2nd local
oscillatorand BFO circuit.
-16-