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 Frequency Range Frequency Control Frequency Tolerance Frequency Stability 40 CH/AM//USB/LSB (120 ch. total) 26.965 + 27.405 CB Phase Lock Loop (PLL) synthesizer 0.005% 0.001% Operating Temperature Range Microphone Input Voltage -20° C to + 50° C Plug-in dynamic; with push-to-talk switch 13.8 V DC nominal, 15.9 max., 11.2 V min ( negative ground) and coi 2 TRANSMITTER Power Output AM 4 Watts SSB 12 Watts PEP AM/SSB SSB 3rd order, more than -25 dB 5th order, more than -35 dB 55 dB 50 dB AM 350 to 2500 Hz Modulation Intermodulation Distortion SSB Carrier Suppression Unwanted Sideband Frequency Response RECEIVER Sensitivity .50 uv AM .25 uv SSB AM/FM: 10.695 MHz 1st IF, 455 kHZ 2nd SSB: 10.695 MHz IF Frequency IF Adjacent-Channel Rejection Automatic Gain Control (AGC) Squelch Adjustable; 60 dB AM/SSB Less than 10 dB change in audio output for inputs from 10 to 100.000 microvolts threshold <.50 uv tight 1000 uv 4 watts into 8 ohms Audio Output Power WEATHER RECEIVER Channels 1 162.550 5 162.450 8 161.550 2 162.400 6 162.500 9 161.775 3 162.475 7 162.525 10 163.275 4 162.425 *All specifications subject to change without notice 3 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. 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. 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. 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. 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. 2. 3. 4. 5. IGNITION NOISE INTERFERENCE 4 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 5 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. B. C. D. E. F. All doors must be closed when adjusting the antenna. Make sure the antenna base is grounded. Check your coaxial cable routing (it may be pinched when routed into the car). Try a different location on your car (keeping in mind the radiation pattern you wish). Is the antenna perfectly vertical? 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. 6 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. 7 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. 8 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 s ...