Midland 79-290 Transceiver Manual

							 
2 TABLE OF CONTENTS
 
Specifications 
Installation 
Location 
Mounting the Radio 
Ignition Noise Interference 
Antenna 
Tuning the Antenna for Optimum SWR 
External Speaker
    
Operation 
Control and Indicators 
Front Panel 
Real Panel 
Operating Procedure to Receive 
Operating Procedure to Transmit 
Receiving SSB signals 
 
SPECIFICATIONS (CB) 
GENERAL 
Channels  40 CH/AM//USB/LSB (120 ch. total) 
  
Frequency Range  26.965 + 27.405 CB 
  
Frequency Control  Phase Lock Loop (PLL) synthesizer  
                           
Frequency Tolerance  0.005% 
 
Frequency Stability  0.001% 
 
Operating Temperature    
Range       -20° C to + 50° C               
 
Microphone  Plug-in dynamic; with push-to-talk switch   and co
i
 
Input Voltage  13.8 V DC nominal, 15.9 max., 
                        11.2 V min ( negative ground) 
 
 
  
						

							 
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TRANSMITTER 
Power Output    AM 4 Watts 
  SSB 12 Watts PEP 
 
Modulation  AM/SSB                         
                           
Intermodulation SSB 3
rd order, more than -25 dB 
Distortion        5th order, more than -35 dB     
                          
SSB Carrier Suppression  55 dB 
 
Unwanted Sideband  50 dB 
Frequency Response    AM 350 to 2500 Hz 
RECEIVER 
Sensitivity         .50 uv AM 
         .25 uv SSB 
 
 
IF Frequency  AM/FM: 10.695 MHz 1st IF,  455 kHZ 2nd 
IF  SSB: 10.695 MHz 
 
Adjacent-Channel 
Rejection  60 dB AM/SSB 
 
Automatic Gain Control  Less than 10 dB change in audio  
 
(AGC)                 output for inputs from 10 to 100.000 microvolts 
 
Squelch Adjustable;      threshold 
						

							 
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Your new Midland model 79-290  represents cutting edge technology  in the 
communications field. From its high tech detachable control panel  to finned  cast 
almuinum transmitter heatsink  it incorporates features found on no other CB. 
These features include full surface mount technoloy, fiberglass printed circuit 
board, dual power output stage, and a digital  information screen using a black 
matrix LCD (liquid crystal display).  All the features are under microprocessor 
control for increased function and reliability.  Your Midland 79-290 assures you 
of having the ultimate technology in a CB radio.
 
 
INSTALLATION
 
LOCATION 
Plan the location of the transceiver and microphone bracket before starting the 
installation. Select a location that is convenient for operation and does not 
interfere with the driver or passengers in the vehicle. The units location must not 
interfere with airbag operation. In automobiles, the transceiver is usually mounted 
below the dash panel, with the microphone bracket beside it.
  
MOUNTING THE RADIO 
The transceiver is supplied with a universal mounting bracket. When mounting 
the bracket and radio to your car, make sure it is mechanically strong. Also 
provide a good electrical connection to the chassis of the vehicle. Proceed as 
follows to mount the transceiver: 
1.  After you have determined the most convenient location in your vehicle, 
hold the transceiver with mounting bracket in the exact location desired. If 
nothing will interfere with mounting it in the desired position, remove the 
mounting bolts. Before drilling the holes, make sure nothing will interfere or 
be damaged by the installation of the mounting bolts. 
 
2.  Connect the antenna cable plug to the standard receptacle on the rear panel. 
Most CB antennas are terminated with a type PL 259 plug and mate with the 
receptacle. 
 
3.  Connect the red DC power input wire (with the fuse) to +13.8 Vdc. This 
wire extends from the rear panel. In automobile installation, +13.8 Vdc is 
usually obtained from the accessory contact on the ignition switch. This 
prevents the set being left on accidentally when the driver leaves the car, and 
also permits operating the unit without the engine running. Locate the 
accessory contact on most ignition switches by tracing the power wire from 
the AM/FM radio in the car. The AM/FM radio power circuit generally has 
noise filtering built-in, making it a good place to connect your CB.  
 
4.  Connect the black lead to +13.8 Vdc. This is usually the chassis of the car. 
Any convenient location with good electrical contact (remove paint) may be 
used. 
 
5.  Mount the microphone bracket on the right side of the transceiver or near the 
transceiver, using two screws supplied. When mounting in an automobile, 
place the bracket under the dash so the microphone is readily accessible. 
IGNITION NOISE INTERFERENCE  
						

							 
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Use of a mobile receiver at low signal levels is normally limited by the presence 
of electrical noise. The primary source of noise in automobile installations is from 
the vehicle itself. If the CB operates quietly with the car motor turned off it’s 
most likely that the car electrical system is generating noise. In some installations 
ignition interference may be high enough to make good communications 
impossible. The electrical noise may come from several sources. Many 
possibilities exist and variations between vehicles require different solutions to 
reduce the noise. 
ANTENNA 
Mobile whip antennas utilize the metal body of the vehicle as a ground plane. 
When mounted at a corner of the vehicle they are slightly directional, in the 
direction of the body of the vehicle. For all pratical purposes, however, the 
radiation pattern is nondirectional. The slight directional characteristic will be 
observed only at extreme distances. A standard antenna connector (type SO 239) 
is provided on the transceiver for easy connection to a standard PL 259 cable 
termination. 
If the transceiver is not mounted on a metal surface, it is necessary to run a 
separate ground wire from the unit to a good metal electrical ground in the 
vehicle. When installed in a boat, the transceiver will not operate at maximum 
efficiently without a ground plate, unless the vessel has a steel hull. 
Before installing the transceiver in a boat, consult your dealer for information 
regarding an adequate grounding system and prevention of electrolysis between 
fittings in the hull and water
. 
TUNING THE ANTENNA FOR OPTIMUM SWR 
Since there is such a wide variety of base and mobile antennas, this section will 
strictly concern itself to the various types of mobile adjustable antennas. 
Because the antenna length is directly related to the channel frequency, it must be 
tuned to resonate optimally all 40 channels of the transceiver. Channel 1 requires 
a longer antenna than Channel 40 because it is lower in frequency. 
Due to the various methods of adjusting antennas for proper SWR we have 
chosen what we think is the optimum method: 
 
A.  Antennas with adjustment screws (set screws). 
 
 
 
 
1.Start with the antenna extended and tighten the set screw lightly enough so that 
the antenna can be easily shortened by hand for easy adjustment. 
 
2.  Set your transceiver to Channel 20. Press the PTT (push-to-talk) switch, and 
move the antenna down. The SWR meter will show a lower reading each time the  
						

							 
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antenna is shortened. By continuing to shorten the antenna you will notice the 
SWR reading will reach a low point and then start rising again. This means that 
you have passed the optimum point for Channel
 20. Extend the antenna a short 
distance and again follow the procedure above. 
 
B.  Antennas which must be cut to proper length. 
1.  Follow the same procedure as above, but adjust the length by cutting 1/4 in. 
increments until a good match is obtained. 
2.  Be very careful not to cut too much at a time, as once it is cut, it can no 
longer be lengthened. 
3.  The whip is easily cut by filing a notch all the way around and breaking the 
piece off with pliers. 
 
If you are having difficulties in adjusting your antenna, check the following: 
A.  All doors must be closed when adjusting the antenna. 
B.  Make sure the antenna base is grounded. 
C.  Check your coaxial cable routing (it may be pinched when routed into the 
car). 
D.  Try a different location on your car (keeping in mind the radiation pattern 
you wish). 
E.  Is the antenna perfectly vertical? 
F.  Try a different location in your neighborhood. Stay away from large metal 
objects when adjusting (metal telephone posts, buildings, or fences).
 
 
WARNING: The transmitter may be damaged if operated into a bad antenna 
system. When adjusting antenna only operate the transmitter as short a time as 
possible. 
External Speaker 
The external speaker jack (EXT. SPK.) 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 disabled.
  
 
 
 
  
						

							 
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FRONT PANEL DRAWING 
 1. ON/OFF VOLUME (inner dual concentric). Turn clockwise to apply 
power to the unit and to set the desired listening level. During normal CB 
operation, the VOLUME control is used to adjust the output level obtained 
either at the transceiver speaker or the external speaker, if used. 
 
2. SQUELCH (outer dual concentric). This control is used to cut off or 
eliminate receiver background noise in absence of an incoming signal. For 
maximum receiver sensitivity it is desired that the control be adjusted only 
to the point where the receiver background noise or ambient background 
noise is eliminated. Turn fully counterclock-wise then slowly clockwise until 
the receiver noise disappears (wtih car engine running). Any signal to be 
received must now be slightly stronger than the average received noise. 
Further clockwise 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. 
3. MIC BUTTON: Adjusts the microphone power in the transmit mode. 
This is a push on-push off switch. When the MIC symbol is visible in the 
LCD screen it indicates a reduced microphone power level. This mode is 
useful when operating in a high noise enviroment. 
  4. LOC BUTTON. To be used to reduce the gain of the RF amplifier under 
strong signal conditions. This is a push-push switch. When the “LOC” 
indicator is visible in the LCD screen the receiver is in the local mode (short 
range). Normally the unit would be operated in the distant mode (long range) 
with the “LOC” disabled. 
  
  5. CH 19 BUTTON. Press this button for instant selection of highway 
channel 19. The channel or frequency display flashes channel 19 when 
instant channel 19 is selected. The rotary channel selector is bypassed when 
the CH19 button is activated. Press the CH 19 button again to return to 
normal channel selection. 
  
						

							 
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 6. WX BUTTON. Press this button for instant selection of the NOAA 
weather bureau or Canadian receiver. Select the proper channel, with the 
rotary channel selector, for your area. It is normal to hear the same 
information on more than one channel, select the channel with best sound. 
To return to CB operation, push the WX button again. 
   
 7. MEMORY CHANNEL INDICATOR. LCD indicator showing which 
memory channel has been selected (1 - 4). 
 
  8. TX INDICATOR. This indicator on the LCD screen will be illuminated 
when the unit has been set in TX mode. 
  
  9. CHANNEL SELECTOR. This switch selects any one of the forty 
Citizens Band channels desired. The selected channel or frequency appears 
on the LCD readout. The channel selector is bypassed and will not operate 
when instant channel 9 or 19 has been selected. 
    
 10. M1-M4 BUTTONS. These 4 buttons are used to enter and select the 4 
memory channels. To set channels in the memory ,select the desired channel 
for M1, press and hold the “M1” button until a second beep is heard and the 
memory channel indicator lights. Your selected channel is now entered at 
M1. Repeat the above operation for M2 through M4. To recall a  memory 
channel just press the the “M” button. 
 
  11. BD BUTTON (Band Button). This button is used to select the LSB, 
USB, AM,  mode of operation. Unless the station with which 
communication is desired is equipped with SSB, the AM mode is normally 
used. The band “BD” button changes the mode of operation of both 
transmitter and receiver simultaneously. Turn to ‘’Receiving SSB signals’’ 
for a further explanation of single sideband. Continued pressing of the band 
button causes the unit to keep switching between AM/LSB/USB as indicated 
by the LCD screen. 
 
12. CLARIFIER. This control allows variation of the receiver operating 
frequencies above and below the assigned frequency. Although this control 
is intended primarily to tune in SSB signals, it may be used to optimize AM 
and WX signals as described in the Operating Procedure paragraphs.  
  13. BAND INDICATOR. LCD indication of the band selected by using the 
band switch button. 
  
   14. SC INDICATOR. LCD indicator showing when the scan mode has    
   been activated. 
  
15. WX INDICATOR. LCD indicator showing when the weather receive 
mode has been selected. 
 
  
  
						

							 
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  16. SC INDICATOR.  LCD indicator showing when the scan mode is 
activated. 
 
 17. MIC INDICATOR. LCD indicator showing when the low power 
microphone mode has been selected. 
 
 18. LOC INDICATOR. Indicates the local mode of receive has been 
selected.  
  
  19. FRQ BUTTON. Pressing this button causes the LCD to switch between 
channel and 5 digit frequency display. 
 
  20. CH 9 BUTTON. Pressing this button causes instant selection of 
emergency channel 9. The LCD display of channel/frequency will flash 
when instant channel 9 is activated. Other keypad and selectors are disabled 
when instant channel 9  is selected.  
 
  21. CHANNEL/FREQUENCY INDICATOR. Displays either the selected 
channel (CB or weather)or frequency in Mhz (CB only). The indicator is 
toggled between channel number or frequency by pressing the “FRQ” 
button. 
 
 22. DW BUTTON. Pressing this button allows you to monitor 2 channels at 
the same time. To use this feature select the first channel you wish to 
receive, adjust the squelch until background noise is muted, and press the 
DW (dual watch) button. While the DW is still flashing on the LCD screen 
select the second channel you wish to monitor and press the DW button 
again. Your radio now toggles between the 2 selected channels until a signal 
is heard. When a signal is heard the radio will stop on the channel to allow 
you to listen, and will remain on the channel 10 seconds after the signal 
disappears to allow answering of the received call. To exit the dual watch 
mode press the “DW” button again.  
 
 23. SRF METER DISPLAY. In the receive mode the LCD indicator shows 
the relative incoming signal strength (“s” units). The stronger the received 
signal the more segments will light. In the transmit mode the display will 
activate according to the transmitter power. If the meter activates less than 
half scale it can indicate an antenna problem. 
 
24. SC BUTTON. This button activates the scan operation. To operate scan 
adjust the squelch until the background noise is muted. Presss the “SC” 
button, the unit will begin rapidly scrolling through the channels until a 
signal is heard. The unit will remain stoppped on the last active channel 10 
seconds after the signal disappears to allow time for the user to answer the 
message. To exit scan press the “SC” button again. 
  
  25. MICROPHONE CONNECTOR. Connection for the microphone. Plug  
  the microphone into the connector and securely tighten the outer threaded  
 sleeve. 
  
						

							 
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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 2 in. from the mouth and 
speak clearly in a normal ‘’voice’’. The radio comes complete with a low-
impedance (500 ohm) dynamic microphone. 
 NOTE: The receiver audio will not function unless the microphone is  
 connected 
  
  26. LCR BUTTON. Pressing this button causes the unit to revert to the  
  previously selected channel. 
 
  27. TX INDICATOR. This lamp glows red when the transmitter has been  
 activated. 
 
  28. CONTROL PANEL RELEASE BUTTON. Pressing this button causes  
  the front panel to unlock for removal. Always use care when removing or  
  replacing the control panel. NOTE: Before removing the front panel turn the  
  power off.  To replace the panel insert the left edge first and slowly push the  
  panel in place until locked. Due to the microprocessor control, at rare times  
  errors may occur in the display or the display may become blank. Usually  
  these errors can be cleared by removing and replacing the control panel. If  
  necessary the display may be manually reset by removing the control panel  
  and shorting the pins as indicated on the back of the control panel. The pins  
  may be shorted by using a  jumper wire or   tweezers. 
POWER JACK. Accepts 13.8 VDC power cable with built-in fuse. 
EXT SP. Accepts 4 to 8 ohm, 5 watt external speaker. When an external 
speaker is connected to this jack, the built-in speaker is automatically dis-
connected. 
 ANTENNA. Accepts 50 ohm coaxial cable with a type PL-259  plug.
 
 
 
 
 
 
 
OPERATING PROCEDURE TO RECEIVE