Pearce Simpson ST901 User manual

PEARCE-SIMPSON ®
ST901
40-CHANNEL AM/SSB CB RADIO
Owner's Manual
HATADI ELECTRONICS CORPORATION PTY. LTD.
SYDNEY AUSTRALIA

SPECIFICATIONS
TRANSMITIER SECT IO N
RF Power Output @I3.8V DC
RECEIVER SECTION
Sensitivity at IOdB S+N/N
Adjacent Chan nel Selectivity
Cross Modulation
Audio Output .
Audio Bandwidth (IKHz / OdB) 3dB down
"S" Meter Sensitivity for a reading of 59
Clalificr Frequency Range
Pow er Source
AM:4.0W
SSB: Up to 12 W PEP
± JOO o/o
26.965 through 27.405 MHz
Better than -60dB
.. AM: 0.4~V
SSB: 0.2,V
SOd B
Threshold: 0.2JtV
Maximum(stop): SOOJ!V
Better than 70dB
60dB
450 to 2000Hz
JOO~V
±2.5KHz
Operates from nominal
13.8Volts DC.
,--------- WARNING - -- ------,
The citizens Band (CB) Radio Service is under the jurisdiction of the Department
of Transport & Communications. Any adjustment or alternations which would alter
the performance
of transceiver's or iginal D.O.T .C. type acceptance or would change
the frequency determining method are strictly prohibited.

DESCRIPTION
This mode l is an all-transistor 2-way radio transceiver for mobile operation. A fre-
quency synthesizer ci rcuit provides 40 crysla.l contro lled PL L uansmit and receive
channels in the 27M
Hz Band, engineered for trouble-free performance. Your tran-
sceiver u ses heat r es istant transistors in all critical areas. Cu rr ent drain on 12 vo lt s
DC is exceptionally low. Operatio n over long periods is feasible even with yo ur en-
gi ne turned off. Th e tr an sceiver may also be operated from A .C. when u sed with
an optional Power Supp ly.
RECEIVER
The receiver i sase nsili veand highlyselecti vedual-conversions uperheter odyne type
providing crystal-contro ll ed PLL operation on a1140 CB channels. Th e ci rcuit incor-
porat es an effective fu ll time Automatic Noise Li m it er in the aud io stages. A ceramic
filterprovidessharpselectivityand high adjaccmchannelrcjcction. As a result, tran s-
missions on adjacent channels cau se minimum interference.
A vari
ab le squelch con trol is incorporated to "silenc e" the receiver when no signals
are being received.
Thesquelchci rcui ti sa dju stableprov idin gva rying d egreesofse n-
sitivity to in
co ming signals.
TRANSMITTER
Th e transmiuer offe rs crystal-controlled ope rati on on all 40 CB channels, providing
small DC power input to the final
RF with average modulati on capabilities is possi-
ble by the use of high-efficency Tr ansistors and low loss components, wiring, and
moum ing board s, Th e legal limit of power f or this service is provided.
POWER SUPPLY
The transceiver is ready for co nnection to a 12 volt DC , negative gr ound system.
DC power is provided to the transceiver by means of a fused power lead.

OPERATING CONTROL AND FEATURES
PASPEAKER
JACK
MICROPHONE
JACK
VOLUME SQUE LCH
CON TR OL CON TROL
POWER ON /OF F SWITCH (on Volume Conl rol)
CHANNEL
SELECTOR
Thi s switch !Urns the transceiver power ON and OFF. power is observed to be
ON when the Channel Selector Dial and the Meter li ghts glow, and OFF when
the lights are not illuminated and the tran sce iv er fails to operate
BLANKER & NOISE LIMITER ON/ OFF SWITCH
Excessive electrical noise, ignition and other atmospheric disturbances will be great ly
reduced when this control is in the ON position. For normal conditions set the switch
in the
OFF position.
This switch selects the mode of operation. When set in the CB position, the tran-
sce iv er will function as a Clitizens Band Radio. When set in the PA (Public Ad-
dress) position, and an EXTERNAL PA SPEAKER is connected to the PA jack
on the rear panel, the unit operates as a public address amplifier.
RF GAIN CONTROL
This control is used to in crease the sensitivity of the recei ve r so that distant sta-
tions may be received more deary, or to decrease the sensitivity so that very strong
stations may be received more clearly.

SQUELCH CONTROL
The word "squelc h" means to silence; therefor, the function of the control is
tosilencetheatmosphericnoise(hash)usuallypresentinallhighfrcquencyAM
radio communication. The maximum "squelch" is obtained when the contro l is
in full CLOCKWISE position, minimum "squelch" when in the COUNTER-
CLOCKWISE position
This control provides an adjustment for TUNING -IN stations which are s li ght ly
OFF frequency, to optimize the AM and SSB reception.
RECEIVER VOLUME CONTROL
This control provides the proper or desired listening volume for the receiver
The Channel Selector sets the channel frequencies simultaneously for the receiv-
ing
and transmitting modes
This selector
enab le s the operator to select the mode of operation, upper or lower
sideband
or AM. Th e sw it ch changes both the transmitter and the receiver.
This
jack accomodates the microphone connector, and is wired to provide trans-
mit when microphone switch
is keyed.

TRANSCEIVER INSTALLATION
Always mount where contro ls are readily accessible, Unit may be mounted to the
underside of the dashboard of a car, truck, etc., utilizing special bracket includ-
ed with transceiver.
Attach bracket
to the underside of dashboard using the se lf-tapping screws sup-
plied. Atta ch the transceiver to the bracket using the two knurled securing screws
at the side.
Tilt the unit to the most convenient angle before tightening securing screws.
With regard to the connection of the power cords, it may be possible or desirable
to connect the red lead (for negative ground systems) or the black lead (for posi-
tive ground systems) to the ignition switch accessory terminal so that the radio
is automatically turned off when the ignition switch (key) is turned off.
Alternately, the power lead may be connected to an available
t~rminal on the fuse
block
or even to a point in the wiring harness. Care must be taken, however, to
guard against a short circuit condition. When in doubt, please contact y our vehi-
cle dealer for specific information for your vehicle.
GROUND INFORMATION
Most newer U.S. and foreign made cars and small trucks use a negative ground
system, while some older cars and some newer, larger trucks may use a positive
ground system. A negative ground system is generally identified by the"-" bat-
tery terminal being connected to the vehicle motor block, but if you cannot de-
termine the polarity of your vehicle, consult your vehicle dealer for information.
NOTE: This radio may be installed and used in 12 -v olt DC negative ground system.
NEGATIVE GORUND SYSTEM
Connect the red DC power cord from the radio to the positive "+" battery ter-
minal or other convenient point and connect the black power lead to the chassis
or vehcile frame, or the negative"·" terminal of the battery.

To Negative( - )
T erminal
~
F use To Positive(+ )
FI GU RE 4. CONNECTING DC POW ER CO RD
The lead-in cable from the CB antenna must be terminated with a PL- 259 type
male connector. Attach to the matchi ng antenna input connector at the rear or
the transceiver.
Attach the microphone bracket provided to any convenient location
MICROPHONE CONNECTION
Insert the 4 pin plug at the end or the coiled cord into the microphone socket.
DO NOT TRANSMIT WITHOUT AN AN TENN A
CONNECTED TO THE TR A NSCEI V ER.
Normally the suppression on modern automoti ve eng i nes is adequate to prevent
annoying interference to your CB transceiver. If it does not, consult your dealer
who w ill recommend addi1ional suppression measurements.
I. Select desired channel using the channel Selec10r Switch.
2. Rotate
"squelch" control to the extre me counter-clockwise position
3 Rotate the "VOLUME / ON-OFF" switch clockwi se, to apply power. Oper-
at i on will be instantaneous.
4. Set the "VOLUME/ON-OFF" switch clockwise to a comfortable listening
level (approximately 1
/3 setting). The receiver is now ready to operate.

SQUELCH ADJUSTMENT
The Squelch control eliminate annoying background noise in the absence of sig-
nals.
To adjust the SQUELCH control properly turn up VOLUME until back-
ground noise
is heard. Rotate the SQUELCH slowly clockwise until the background
noise
just disappe ar. At this point the receiver will be quiet under "no-signal"
conditions, however a reasonable strength incoming signal will overcome the
squelch action
and be heard. As the cont rol is advanced the squelch action is
progressively increased and stronger incoming signals are needed to overcome it.
To receive weak signals or to disable the squelch circuit turn the control fully counter
clockwise
EXTERNAL SPEAKER JACK
Recommended plug for the EXT SPEAKER jack is a "MINIPLUG" subminia-
ture phone plug. The impedance of earphones or speakers connected should be
8·16 ohms. Insertion of a plug automatically silences the transceives internal
speaker.
SIGNAL STRENGTH LEVEL METER
When receiving, the S/RF POWER LEVEL METER provides a relative indica-
tion of signal strength.
TRANSMITTING
To transmit, depress the push-to-talk button on the microphone. The S/ TX power
LEVEL
METER indicates the relative transmit power level. Use the microphone
like a telephone speaking several inches from
the face. Do not shout, use a nor -
mal speaking voice.
When you are transmitting, the receiver is silenced and reception is , therefore,
impossible. In the same way, your signal cannot be heard by another station when
he
is transmitting-each must take turns. To receive aga in , simply release the micro-
phone push·tO·talk button.
S/TX POWER LEVEL METER
In transmit position the S/ TXPOWER LEVEL METER gives a relative indica-
tion of antenna RF power.
TX MODE LED INDICATOR
This lamp light on TX mode.
USE AS PUBLIC ADDRESS SYSTEM
Provision ha s been made for Public Address (PA) op eration utilizing the micro-
phone and audio stages in the transceiver. For PA operation, use an external high-
efficiency pu.blic addr ess hornt ype speaker with an impedance range of 8 to 16
ohms. Connect to the PA jack on the rear panel of the transceiver. The required
plug is a subminiature
phone plug. For Public Address (PA) operation, switch
CB / PA SWITCH to PA position

AVAILABLE CITIZEN BAND FREQUENCIES
Your transceiver provides operation on all available C iti zens Band channels. Fre-
quencies are listed in accompanying tab le.
Ch anne l Frequen cy C hann el Frequency
I 26.965 21 27.215
2 26.975
22
27.225
3 26.985 23 27.255
4 27.005 24 27.235
5
27 .015 25 27 .245
6 27.025 26 27.265
7
27.0 35 27 27.275
8 27.055 28 27.285
9 27.065 29 27.295
10 27.075 30 27.305
II 27.085 31 27.315
12 27.105 32 27.325
13 27.115 33 27.335
14 27.125 34 27.345
15 27.135
35
27.355
16 27 .1 55 36 27.365
17 27 .1 65 37 27.375
18 27. 175 38 27.385
19 27 .1 85
39 27.395
20 27.205 40 27.405
TRANSCEIVER SERVICING
Trans ce i ve r ha s been full ytested prtor to shipment and will not normally require
fur ther a dju s tm ems

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