Cobra 148 GTL 148GTLE_Eng-Spa - Page 7

Section IV Operation (Continued) 4. SWR CAL CONTROL (outer dual concentric). 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 and 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 1 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. 5. DYNAMIKE. Adjusts the microphone gain in the transmit and PA modes. This controls the gain to the extent that full talk power is available several inches away from the microphone. In the Public Address (PA) mode the control functions as the volume control. 6. VOICE LOCK. 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 also be used to optimize AM signals as described in the Operating Procedure paragraphs. 7. DIM/NOR/BRT SWITCH. Controls the brightness of the meter and LED channel indicator for optimum intensity for day or night-time driving. 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. 0FF/ANL/NB + ANL SWITCH. In the ANL position only the automatic noise limiter in the audio circuits is activated. When the switch is placed in the ANL + NB position, the RF noise blanker also is activated. The RF noise blanker is very effective for repetitive impulse noise such as ignition interference. Section IV Operation (Continued) 10. PA/CB SWITCH. Selects the mode of operation. In the CB position, the PA function is disabled and the unit will transmit and receive on the speaker that is connected. In the PA mode, incoming CB transmission will be heard through the PA speaker. This allows you to monitor messages while outside of your vehicle. To use the PA feature, a speaker having a voice coil impedance of 8 ohms and a power handling capability of at least three watts should be used. This speaker must be plugged into the PA SPKR jack at the rear of the transceiver. If the public address feature is to be used primarily for outdoor applications, the use of a weatherproof horn type public address speaker is recommended. The durability of this type speaker plus the inherent efficiency of such a speaker will provide more than adequate results when combined with the high audio output level available from the COBRA 148GTL. 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 too close to the microphone, acoustic feedback will result when the public address system is operated at high volume. A directional type outdoor speaker reduces the amount of isolation required. 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. S-RF/CAL/SWR SWITCH. When in the S-RF position, the meter swings proportionally to the strength of the received signal. When transmitting, the meter indicates relative RF output power. When in the "CAL" position, the SWR meter can be calibrated by adjusting the "SWR" control to the "CAL" mark on the meter face. When in "SWR" position, the standing wave ratio is measured. 12. MODE (LSB/AM/USB) SWITCH. This switch is used to select AM, LSB or USB mode of operation. Unless the station with which communication is desired is equipped with SSB, the AM mode is normally used. The mode selector switch changes the mode of operation of both transmitter and receiver simultaneously. Turn to "Receiving SSB signals" for a further explanation of single sideband. 13. TONE SWITCH-HI/NOR/LOW. This switch is used to shape the audio response to the operator's preference. Bass is increased in the LOW position and treble is increased in the HI position. 10 11