Cobra 89XLR User manual

Cobra 89XLR
40-Channel
Solid
State Citizens Band
2-Way Radio Base Station
Cobra Communications Product Group
6460 W. Cortland Street
Chicago,
Illinois 60635

INSTRUCTION MANUAL
for
Cobra 89XLR
40-Channel
Citizens Band Solid State
2-Way Radio
Base Station
Cobra Communications Product Group
DYNASCAN CORPORATION
6460 W. Cortland Street
Chicago, Illinois 60635
--------

TABLE OF CONTENTS
Page
Section
I: Introduction
Frequency Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
FCC Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Section II: Specifications
Section III: Installation
Location ................................................ .
Base Station Antenna ...................................... .
Mobile Operation/Emergency Power Operation
.................. .
Public Address ........................................... .
Remote Speaker
.......................................... .
Alternate Microphones and Installation
........................ .
Section IV: Operation
A. Control Functions
B. Indicator Functions ..................................... .
C. Operating Procedure to Receive ............................ .
D. Operating Procedure to Transmit ........................... .
Section V: Maintenance and Adjustment
......................... .
Appendix
6
8
8
9
9
9
lO
14
17
17
18
19
Ten Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
A Few Rules That Should
Be Obeyed . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
How Your CB Can Serve You . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Use Channel 9 for Emergency Messages Only . . . . . . . . . . . . . . . . . . . . . 23
Warranty Service Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Limited 90-Day Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2

THE CB STORY
The Citizens Band lies between the shortwave broadcast and 10-meter
amateur radio bands, and was established by law in 1949. The Class D two-way
communications service was opened in 1959. (CB also includes a Class A
business band and Class C remote control frequencies.) Acquiring the Class D
license requires no detailed technical or Morse-code knowledge that
is required
for a
"Ham" license.
In March, 1975, the FCC reduced the cost
of a CB license from $20 to $4.
One license can
be good for any number of sets used by a given family or
business. Once you receive your Class D license for
your equipment, anyone may
use it.
For example, though the equipment must be licensed to someone over 18
years
of age, a child can use the equipment to talk to another child, or an
employee can use the equipment as part of his or her routine services. However,
final responsibility
of legal operation rests with the CB licensee.
NOTE
FCC regulations permit only "transmissions" (one party to another)
rather than "broadcasts"
(to a wide audience). Thus, advertising is
not allowed on C'B channels because it is broadcasting.
HAVE
A GOOD DAY
TODAY
AND
A BETTER DAY
TOMORROW!
3

Section I
Introduction
FREQUENCY RANGE
The COBRA 89XLR provides high level trouble-free performance in the
Citizens Radio Service which
is comprised of the following frequency
assignments: Channel Frequency Channel Frequency
Channel
in MHz
Channel
in MHz
1 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 27.035 27 27.275
8 27.055 28 27.285
9 27.065 29 27.295
10 27.075 30 27.305
11 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 27.155 36 27.365
17 27.165 37 27.375
18 27.175 38 27.385
19
27.185 39 27.395
20 27.205
40
27.405
To obtain maximum performance from your COBRA 89XLR, please read
carefully the following descriptions and operation instructions.
These frequencies are generated and accurately controlled by a phase lock
loop (PLL) circuit, comprised
of the latest state-of-the-art integrated circuit
technology, thereby ensuring high reliability and excellent frequency stability on
the above channels.
4

FCC WARNING*
1. Operation of this equipment requires a valid Station License issued by the
Federal Communications Commission. Do
not transmit with your equipment
until
you have received your License. Illegal operation can result in severe
penalties.
Be certain you have read Part 95 of the FCC Rules and Regulations.
before operating your station.
2. License applications are to be made on FCC Form 505, available from
your
nearest field office. (A copy of this form is included with your new COBRA
transceiver.)
3. You are required
to maintain a current copy of Part 95 of the FCC Rules, as
part of your Station records. Copies of Part 95 are available from the
Superintendent
of Documents, GPO, Washington. D.C. 20402.
4. Your Station License
is to be posted in accordance with paragraph 95.101 of
the Rules and an executed Transmitter Identification Card (FCC Form
452-C)
is to be attached to each transmitter. (A copy of this form also is
included with your new COBRA transceiver.)
5. FCC Rules require
that ALL transmitter adjustments other than those
supplied
by the manufacturer as front panel operating controls, be made by,
or under the supervision of, the holder of an FCC-issued lst or 2nd Class
Radio Operator License.
6. Replacement or substitution,
of crystals. transistors, regular diodes or any
other part of a unique nature. with parts other than those recommended by
Dynascan, may cause violation of the technical regulations of Part 95 of the
FCC Rules,
or violation of the Type Acceptance requirements of Part 2 of the
Rules.
*Excerpted from Part 95 of the FCC Rules and Regulations.
5

Section II
Specifications
GENERAL
Channels 40.
Frequency Range 26.965 to 27.405 MHz.
Frequency Control Phase
Locked Loop (PLL) synthesizer.
Frequency Tolerance 0.005%.
Operating
Temperature Range -30°C to +50°C.
Microphone Plug-in
type; dynamic.
Power Source 117 VAC nominal;
13 .8 VDC nominal.
Power
Consumption
(117 VAC)
Current Drain (13.8 VDC)
Size
Weight
Antenna Connector
Semiconductors
Meter I
Meter 2
(Positive
or negative ground.)
Transmir: AM full mod., 55 watts.
Receive: Squelched, 25 watts.
Full audio,
25 watts.
Transmit: AM full mod., l.5A DC (nominal).
Transmit: AM full mod., 60VA AC (nominal).
Receive: Full audio output, l .2A DC
(nominal; no signal 0.5 A DC
(nominal).
534
11
Hx 13-3/8"Wx 12-5 /8"0.
10 pounds.
UHF, S0239.
24 transistors, 30 diodes, 6 integrated
circuits.
Illuminated; indicates relative
power output
and received signal strength.
Illuminated, indicates standing wave ratio
and level of modulation.
6

TRANSMITTER
Power Output
Modulation
Frequency Response
Output Impedance
Output Indicators
RECEIVER
Sensitivity
Selectivity
Image Rejection
IF Frequencies
Adjacent Channel Rejection
RF Gain Control
Automatic Gain Control
(AGC)
Delta Tune Range
Squelch
Audio
Output Power
Frequency Response
Distortion
Built-in Speaker
External Speaker
(Not Supplied)
PA SYSTEM
Power Output
External Speaker for PA
(Not Supplied)
4 watts.
High- and low-level Class B amplitude
modulation.
300 to 3000Hz.
50 ohms, unbalanced.
Meter indicates relative
RF output power,
standing wave ratio and level
of modulation.
Less
than lµV for 10 dB (S+N)/N.
6 dB @.: 7KHz, 60 dB @: 1OKHz.
50 dB.
Double conversion, 1st: 10.695MHz.
2nd:45SKHz.
-
70 dB.
Variable
type.
Less than 10 dB change in audio output for
inputs from 10
to 500,000 microvolts.
±l .5KHz continuously adjustable.
Adjustable, threshold less than
lµV.
4 watts.
300 to 3000Hz.
Less and 10%
ca 3 watts @1 OOOHz.
8 ohms, round.
8 ohms; disables internal speaker when
connected.
4 watts into external speaker.
8 ohms; when PA-CB switch is in PA, the PA
speaker also monitors the receiver, separate
jack provided.
7

Section Ill
Installation
LOCATION
Prior to beginning operation of the transceiver, a basic installation must be
prepared. Installation
of the transceiver itseif is a rather simple procedure.
In selecting the location for
the unit, two basic factors must be considered.
1. Access to a 120V, 60 Hz power source.
2. The location must be convenient for running the antenna lead-in cable
if an outside antenna installation is proposed.
BASE STATION ANTENNA
Since the maximum allowable power output of the transmitter is limited by
the FCC, the antenna is the most important factor affecting transmission
distance. Only a properly matched antenna system will allow maximum power
transfer from
the 50-ohm transmission line to the radiating element.
The recommended method
of antenna tuning is to use an in-iine watt-meter
or VSWR bridge
to adjust the antenna tuning for minimum reflected power on
channel 21.
The radio may be used with any type
of 50-ohm base station antenna. A
ground plane vertical antenna will provide the most uniform horizontal coverage.
This type
of antenna is best suited for communication with a mobile unit. For
point-to-point operation where both stations are fixed, a directional beam will
usually increase communicating range since this type
of antenna concentrates
transmitted energy in one direction. The beam antenna also allows the receiver
to "hsten" in only one direct10n thus reducmg interfering signals.
Antenna height
is an important factor when maximum range is desired.
Keep the antenna clear
of surrounding structures or foliage. FCC regulations for
base station antenna height are:
8

1. Omni-directional antennas may not be higher than 60 feet above the
groun<l when using a tower, mast or pole, and no higher than
20 feet
above an existing structure.
2. Beam antennas may
not be higher than 20 feet above the ground when
using a tower, mast, pole,
or an existing structure.
These are only general regulations applicable
to most but not all parts of the
nation. Locations near airports and some military installations are subject to
different rules; therefore, it
is best to contact your nearest Federal Communica-
tions Commission office for information regarding
your specific area.
MOBILE OPERA TI ON/EMERGENCY POWER OPERATION
lt is possible to operate the COBRA 89XLR from an external 13.8 VDC
power supply for emergency power conditions or from an automobile battery
for mobile operation. The COBRA 89XLR
is supplied with a polarized plug for
operation
on an external DC supply.
The negative lead
is black.
The positive lead
is red and has an in-line fuse holder as an integral part of
the positive lead.
PUBLIC ADDRESS
An external 8-ohm, 4-watt speaker may be connected to the PA speaker
jack located
on the rear panel when the transceiver is used as a public address
system. The speaker should be directed away from
the microphone to prevent
acoustic feed-back. Physical separation or isolation of the microphone and
speaker must be used when operating the PA at high-output levels.
REMOTE SPEAKER
The external speaker jack (EXT. SPKR.) on the rear panel is used for
remote receiver monitoring. The external speaker should have 8 ohms impedance
and be able
to handle at least 4 watts.
When the external speaker
is plugged in, the internal speaker is
disconnected.
9

ALTERNATE MICROPHONES AND INSTALLATION
For best results, the user should select a low-impedance dynamic type
microphone
or a transistorized microphone. Transistorized type microphones
have a low
output impedance characteristic. The microphones must be provided
with a four-lead cable. The audio conductor and its shielded lead comprise
two
of the leads. The third lead is for transmit/receive control and the fourth lead is
the speaker return lead which disables the speaker during transmit. The
microphone should provide the functions shown in schematic below.
4-Wire Mic Cable
Pin Number
2
3
4
Mic Cable Lead
Audio Shield
Audio Lead
Transmit Control
Receive Control
1/8" STRIP
a TIN
Fig. l . Microphone cable preparation.
If the microphone to be used is provided with pre-cut leads, they must be
revised
as follows:
1. Cut leads so that they extend 7I16" beyond the plastic insulating jacket
of the microphone cable. (See Fig. 1.)
10

2. All leads should be cut to the same length. Strip the ends of each wire
I /8" and tin the exposed wire.
Before beginning the actual wiring, read carefully
the circuit and wiring
information provided with the microphone you select. Use the minimum head
required in soldering the connections. Keep the exposed wire lengths
to a
minimum
to avoid shorting when the microphone plug is reassembled.
To wire the microphone cable to the plug provided, proceed as follows (see
Fig. 2):
1. Remove the retaining screw.
2. Unscrew the housing from the pin receptacle body.
3. Loosen the
two cable clamp retainer screws.
4. Feed the microphone cable through the housing, knurled ring and
washer
as sll\)wn in Fig. 2B.
KNURLED
RING HOUSING
~ \
PIN CABLE CLAMP
RECEPTACLE RETAINER SCREW
(2)
RETAINING
SCREW
A. MICROPHONE CONNECTOR ASSEMBLY
WASHER
I
~
B. MICROPHONE CONNECTOR DISASSEMBLED FOR WIRING
Fig. 2. Microphone plug wiring.
11

5. The wires must now be soldered to the pins as indicated in the above
wiring tables.
If a vise or clamping tool is available it should be used to
hold the pin receptacle body during the soldering operation, so that
both hands are free to perform the soldering. If a vise or clamping tool
is not available, the pin receptacle body can be held in a stationary
position by inserting it into the microphone jack
of the front panel.
The numbers
of the pins of the microphone plug are shown in Fig. 3, as
viewed from the back of the plug. Before soldering the wire to the pins,
pre-
tin the wire receptacle of each pin of the plug.
3 2
.. ')!?(
·· ~~~ ··
. ~ . ·
4: . . .. : ·: .,
Fig . 3. Microphone plug pin numbers viewed from rear of pin receptacle.
Be sure that the housing and the knurled ring of Fig. 2 are pushed back
onto the microphone cable before starting to solder. If the washer is
not captive to the pin receptacle body, make sure that it is placed on
the threaded portion
of the pin receptacle body before soldering.
If the microphone jack is used to hold the pin receptacle during the
soldering operation, best results are obtained when the connections
to
pins 1 and 4 are made first and then the connections to pins 2 and 3.
Use a minimum amount of solder and be careful to prevent excessive
solder accumulation on pins, which could cause a short between the pin
and the microphone plug housing.
6.
When all soldering connections to the pins of the microphone plug are
complete, push the knurled ring and the housing forward and screw the
housing onto the threaded portion
of the pin receptacle body. Note the
location
of the screw clearance hole in the plug housing with respect to
the threaded hole in the pin receptacle body. When the housing is
completely threaded onto the pin receptacle body, a final fraction of a
turn either clockwise or counterclockwise may be required to align the
12

screw hole with the threaded hole in the pin receptacle body. When
these are aligned, the retaining screw
is then screwed into place to
secure
the housing to the pin receptacle body.
7. The two cable clamp retainer screws should now be tightened to secure
the housing to the microphone cord.
If the cutting directions have been
carefully followed, the cable clamp should secure to the insulating
jacket
of the microphone cable.
8. Upon completion
of the microphone plug wiring, connect and secure
the microphone plug in the transceiver.
13

Section IV
Operation
L
I @
A. CONTROL FUNCTIONS
1. DYNAMIKE. Adjusts the microphone gain in the transmit and PA
modes. This controls the gain to the extent that fu ll talk power is
available several inches away from the microphone. In the Public
Address (PA) mode the control functions
as the volume control.
2.
OFF /ON VOLUME. Tum clockwise to apply power to the unit and to
set the desired listening level.
3.
SQUELCH. This control is used to cut off or eliminate receiver/
background noise in the absence
of an incoming signal. For maximum
receiver sensitivity the control should be adjusted only
to the point
where the receiver background noise or ambient background noise
is
eliminated. Tum fully counterclockwise then slowly clockwise until
receiver noise disappears. Any signal
to be received must now be
slightly stronger than the average received noise. Further clockwise
14

rotation will increase the threshold level which a signal must overcome
in order
to be heard. Only strong signals will be heard at a maximum
clockwise setting.
4. TONE. This control
is used to shape the audio response to the
operators preference.
Base is increased by counterclockwise rotation
and trebel
is increased by clockwise rotation.
S. RF GAIN. Adjust as required to optimize the signal. This control is
used primarily to optimize reception in strong signal areas. Gain is
reduced by counterclockwise rotation of the control.
6. DELTA TUNE. For normal operation set the control
to the center
position. This feature has several uses and can greatly enhance receiver
operation. First,
if a received signal is slightly off frequency, the
Delta-Tune control can be operated as required
to optimize the received
signal level. The effectiveness of the Delta-Tune feature under these
conditions can be observed either
by listening for a more readable signal
at the speaker
or by noting the S-meter reading when the Delta-Tune
control
is operated. Another effective application of this control is in
eliminating adjacent channel interference. If it is verified that an
exceptionally
high level signal from an adjacent channel is creating
interference
on the channel being used, the Delta-Tune can be used to
minimize
or eliminate the interference. Operate the control as required
to obtain minimum adjacent channel interference.
7.
SWR CAL CONTROL. In order for you to achieve maximum radiated
power and the longest range,
it is important that your antenna be in
good condition, properly adjusted and matched to your transceiver.
The built-in SWR (standing wave ratio) meter lets you easily measure
your antenna condition. To operate this function, connect your
antenna
to the transceiver antenna output connector. Select a channel
near the middle
of the band such as 21, or the channel you plan to use
most frequently. Turn the power
on and set the meter function switch
to the CAL position. Press and hold the microphone push-to-talk
button; using the SWR CAL control, adjust the meter to read the CAL
position indicated on the meter face. Then, without releasing the
microphone
button, switch the meter function switch to the SWR
position and read the SWR indicated. The lower the figure, the better,
with l being ideal. Generally speaking, readings up
to 3 are acceptable,
but over 3 indicates that you are losing radiated power and antenna
adjustment may be advisable.
15

8. CHANNEL SELECTOR. This switch selects any one of the forty
Citizens
Band channels desired. The selected channel appears on the
LED readout directly above the Channel Selector knob. Channel 9 has
been reserved by the FCC for emergency communications involving the
immediate safety of
life of individuals or immediate protection of
property. Channel 9
may also be used to render assistance to a
motorist.
9. OFF/ANL SWITCH. In the ANL position, the noise reduction circuits
of the Automatic
Noise Limiter are activated.
IO. PA/CB SWITCH . Selects the mode of operation. Jn the CB position. the
PA function is disabled and the unit will transmit and r eceive on the
selected frequency.
The PA function should not be used unless a PA
speaker is connected.
To use this PA feature. a speaker having a voice coil impedance of
8 ohms and a po
wer handlingcapability ofat least four watts should be
used. This speaker must be plugged into the PA SPKR jack at the rear
of the transceiver. With the PA speaker connected as outlined
previously,
be sure that there is physical separation between the
microphone and the speaker itself. If the speaker
is located close to the
microphone, acoustic feedback
will result when the public address
system
is operated at high volume. Some experimentation will
determine the minimum amount of isolation required for a given sound
level from the public address system.
NOTE
PA volume is controlled by adjusting the DYNAMIKE KNOB to the
desired volume.
11. SWR/SWR CAL/RF-MOD SWITCH. In the RF-MOD position, the S-RF
and
MOD meters are activated. When in the SWR or SWR CAL
positions the SWR meter is activated. In the latter two cases, the
operation
is described in the above SWR CAL CONTROL description.
12.
PRESS-TO -TALK MICROPHONE. The receiver and transmitter are
controlled by the press-to-talk switch on the microphone. Press the
switch and the transmitter
is activated; release switch to receive. When
transmitting, hold the microphone two inches from the mouth and
16

speak clearly in a normal "voice". The radios come complete with a
low-impedance 500-
ohm dynamic microphone. For installation instruc-
tions on
other microphones, see next section, "ALTERNATE MICRO-
PHONES AND INSTALLATION.''
B. INDICATOR FUNCTIONS
S-METER. Swings proportionally to the strength of the incoming signal.
RF METER. Swings proportionally to the RF output power. When
transmitting, the RF -% MOD switch must be in the
"RF" position and the
OFF-CAL-SWR switch must be in the
"OFF" position.
MODULATION METER. Swings proportionally to the degree of modula-
tion. When transmitting, the RF -%
MOD switch must be in the % MOD
position, and the OFF-CAL-SWR switch must be in the "OFF" position.
SWR METER. Measures the ratio of standing wave voltage of the antenna
system. Used to properly adjust the length
of the antenna, and to monitor
the quality of the coaxial cable and all RF electrical connections. If there is
any degradation whatsoever in any of the above, due to humidity, salt
spray, vibration or corrosion. the SWR meter reading will rise, thereby
indicating
that a problem exists.
To calibrate, switch
to the "CAL" position transmit by pressing the mike
switch, and adjust the SWR control to the
"CAL" mark on the meter then
switch
to "SWR" position for the SWR measurement.
CHANNEL INDICATOR. The selected channel appears on the LED readout
directly above the channel selector knob.
C. OPERATING PROCEDURE TO RECEIVE
1. Place the CB/PA switch in the CB position.
2. Turn the set ON by turning the VOLUME control clockwise, until a
click
is heard.
3. Set the VOLUME for a comfortable listening level.
17

4. Set the Channel selector switch to the desired channel.
5. Set the RF GAIN fully clockwise.
6. Set the DELTA TUNE control to the center position.
7. Listen to the background noise from the speaker. Turn the SQUELCH
control slowly clockwise, until the noise JUST disappears. (No signal
should be present.) Leave the control at this setting. The SQUELCH is
now properly adjusted. The receiver will remain quiet until a signal is
actually received. Do not advance the control too far, or some of the
weaker
signals will not be heard.
D. OPERATING PROCEDURE TO TRANSMIT
1. Select the desired channel of transmission.
2'. Set the DYNAMIKE control fully clockwise.
3. If the channel is clear, depress the push-to-talk switch on the
microphone and speak
in a normal voice.
The S-RF meter will indicate relative power output and the modulation
meter
will indicate percentage of modulation as you speak into the
microphone.
CAUTION
Be sure the antenna is properly connected to the radio before
transmitting. ProlongeJ transmitting without
an antenna or a poorly
matched antenna could
cause damage to the transmitter.
18

Section V
Maintenance and Adjustment
i ne LU.ijKA ~~A.LK lransce1ver is aes1gneo spe~mcauy ror use a~ a oase
station and may also be used in mobile installations. The use of all solid circuitry
f~:SUlU> 111 llE;iil Wl::lf;ill aHU lug;1 l<;;;luuii.i.l}'. 3l1vuJ.~ a ;.;;_:1 .. rn .. u'-'-u1, ''-l-'~"'-" t'"«-'
only with identical parts. Do not substitute. Refer to the schematic diagram and
parts list.
NOTE
If the perform~ncf' cif'~crihNi in thf' OPERATION and MATNTEN ANCE
AND ADJUSTMENT section is not obtained, review the operating
instrudiom to insure that pruper procedures were followed. If a
problem still exists, refer to WARRANTY SERVICE INSTRUCTIONS
on the last page of this manual.
FCC WARNING
Federal law requires that adjustment of the radio frequency section of
this transceiver may nut be made by a CitiLem Band 0pcrat0r. Only a
United States licensed First
or Second Class commercial license holder
may tune the transmitter section of this transceiver, per FCC part 95
section 95.97d
..
19