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Maverick20
New member
Username: Maverick20
Post Number: 3
Registered: 1-2005
| | Posted on Wednesday, March 09, 2005 - 9:35 pm: | 
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Ok. It works. It looks great. And i need to know where i can download a manual for this bad boy. Any places please let me know. Thanks. |
Kid_vicious
Intermediate Member
Username: Kid_vicious
Post Number: 289
Registered: 9-2004
| | Posted on Friday, March 18, 2005 - 12:28 am: |
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call cobra, or dynascan. they will send you a manual.
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Tech808
Moderator
Username: Tech808
Post Number: 5270
Registered: 8-2002
| | Posted on Friday, March 18, 2005 - 4:03 am: |
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Maverick20,
Cobra Radios and Accessories
Cobra Electronics
6500 W. Cortland Street
Chicago, Il. 60707
1-800-262-7222
Hope this helps,
Lon
Tech808
CEF808
N9OSN
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Racer_x
Intermediate Member
Username: Racer_x
Post Number: 176
Registered: 2-2005
| | Posted on Friday, March 18, 2005 - 7:10 pm: |
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TRC-457 AM/SSB CB Transceiver (210-1580)
Controls and Functions
Microphone - The dynamic microphone must be connected to this jack. To Transmit, press the button on the mic and talk into the mic. To Receive, release the button. When transmitting, hold the microphone at an angle, two or three inches (5-7.5 cm) from your mouth and speak clearly in a normal voice.
PHONES - Plug in communications type headphones for private listening, or in areas where background noise is excessive (factories, at the scene of an accident or fire, etc.). When you plug in the headphones, it automatically disconnects the internal speaker (or an external speaker).
VOLUME with "ON/OFF" Switch - Turn clockwise to apply power to the unit and then adjust for the desired level of sound from the speaker. When using PA it controls the level of the PA output.
SQUELCH - Sets the level of the internal Squelch circuitry to cut out the background noise when no signal is being received. When properly set, it allows signals to come through, but cuts off the receiver sound when no signal is being received, thus eliminating annoying background /atmospheric noise during standby and monitoring conditions. If set too high, you may miss some of the weaker signals. Operating conditions will determine the best setting.
CLARIFIER - Functions as a "fine tuning" (or "delta" tuning) for reception of Single SideBand and AM signals when the Mode switch is set to either LSB or USB. This permits you to tune your receiver to exactly the same frequency of any other station or stations which you are communicating with.
Channel Selector - Use to select any one of the standard 40 CB channels.
PA push-button - Controls the function of the audio amplifier/modulation circuitry when the Microphone button is pressed. When the PA button is in the "out" position, the Microphone button turns the Transmitter on for normal transmissions. When you press the button in, the Transmitter will not function - the Microphone turns on the Public Address Amplifier function. For PA operation you must have a PA speaker connected to the PA jack on the rear chassis.
NB (Noise Blanker) push button - Press in to cut out annoying impulse type noise. Press again to release this function. This is particularly effective for ignition noise on both AM and SSB.
ANL (Automatic Noise Limiter) push button - Press in to cut out annoying hash type noises. Press again to release this function. This will be particularly effective for AM signals.
CAL push button - Press in when using the SWR CAL control to set reference for SWR measurement. Press again to return to normal.
SWR CAL control - Use when setting up the SWR Meter for check Standing Wave Ratio of your antenna system. With an antenna connected, press in CAL button and turn on the Transmitter, then you adjust this control for a meter reading to the red CAL mark. This sets the reference for the SWR function; press CAL button again and you will read SWR on the SWR meter.
RF GAIN - Varies the sensitivity of the RF amplifier stages of the Receiver circuitry. For normal operation, set RF GAIN to maximum and adjust VOLUME for a suitable listening level. Under high signal conditions, you may want to turn RF GAIN down a little and raise VOLUME as required.
AM-USB LSB Mode Switch - Set this switch to the desired mode of operation for both transmit and receive. When in the AM position, both transmitter and receiver sections are operative for AM. When set to the LSB position, the Receiver operates to receive only the lower sideband portion of a signal; the Transmitter will transmit only the lower sideband of the modulated waveform. In the USB position, the Receiver operates only to receive the upper sideband portion of a signal; the Transmitter will transmit only the upper sideband of the modulated waveform. The LED indicators above the Mode Switch will light, reminding you of the mode of operation.
SWR Meter - When used in conjunction with SWR CAL control and CAL push-button will give you an SWR reading for your antenna system.
Signal/Power Meter - Gives visual indication of signal strengths. When receiving, this Meter shows the strength of incoming signals; a change of one "S" unit indicates a change of 6 dB in signal strength. The meter is set up so that a 100 microvolt signal will produce a reading of S-9. When Transmitting, this meter gives a relative indication of output power from the Transmitter.
Digital Clock - Shows the precise time in large, easy to read 7 segment LED displays. A switch on the rear panel will set the clock for either 12 hour or 24 hour time function.
Digital Clock Set Buttons
FAST ....... is to advance the time rapidly for setting the time.
SLOW ....... is to advance the time more slowly as you are setting the time.
HOLD ....... is to hold the time as displayed (so you can wait for the actual time to catch up to the displayed time).
Setting The Digital Clock
Note: The Digital Clock will function only when you are using 120 volt, 60 Hz AC power. It will NOT operate when you are using DC power.
When you plug in the AC power cord, the Clock Display automatically comes on. The Clock, however does not operate until you press either the FAST or SLOW button.
Before you begin, set the CLOCK Slide Switch (on the Rear Panel) for either 12 Hour or 24 Hour operation.
First, determine the exact present time, then press FAST to advance the Clock Display rapidly to the desired hour. Note: If you have selected 12 hour or operation, an LED will light at the left of the Hour Number for AM hours. Be sure to set the Hours properly (AM or PM).
Press SLOW to slowly advance the Clock display to the correct minute. If you advance the display past the actual time, no need to go all the way through the cycle again - just press HOLD: this will hold the Clock at the displayed time (it will show the minutes and 00 seconds). Then, just wait for the actual time to catch up with the displayed time. You should realize that when you press hold, "seconds" are canceled and you hold the minutes in display until you release the button. If you want to reset the Clock to 00:00 (24-Hour time) or 12:00 (12-hour time), just press Hold and SLOW buttons.
When the display shows 00:00 and segments of the first zero pulses, or when the display shows 12:00 with a pulsing AM indicator, this a signal that power has failed for some length of time and the Clock must be reset.
The Rear Panel
PA SPeaKeR Jack - Connect an 8 Ohm Public Address speaker to this jack for PA use.
EXTernal SPeaKeR Jack - If you want to use an external speaker, plug it into this jack. You should use a standard 8 Ohm type. When a standard 1/4" (6.35 mm) phone plug is inserted into this jack, the built in speaker is automatically disconnected.
ANTENNA Coax Connector- Connect your CB antenna to the (SO-239 type, accepts PL-259 connectors)
CLOCK Switch - Set to 12 Hour for 12 Hour clock operation. Use 24 Hour position for 24 hour time.
13.8VDC connector and Power Cable with in line fuse - This cable is to be connected to a source of 12 to 16 volts DC power, negative or positive ground. The Red wire with the in line fuse must be connected to the (+) side and the Black wire to the(-) side.
FUSE - Is for protection of the Transceiver and its source of AC power. If the Transceiver does not operate from AC power, check this fuse - replace only with the same type and value(3 amp.)
120V AC Connector - Plug in the AC power cord when operating from a source of 120 volts, 60 Hz AC power. If you plug in both connectors, AC will be operational, DC will not. For DC operation, use the DC cable only. |
Racer_x
Intermediate Member
Username: Racer_x
Post Number: 177
Registered: 2-2005
| | Posted on Friday, March 18, 2005 - 7:26 pm: |
|
TRC-457 AM/SSB CB Transceiver (210-1580)
Operation
Using Your Transceiver
Note: Do not transmit without an Antenna or suitable load connected. Do not operate the PA function without a speaker connected to the PA SPKR jack.
Your Transceiver can be used either as a base or mobile unit.
For base operation, use the 120 volt AC power cable for connecting between the Power Connector on the rear panel and a source of 120 volts, 60 Hz AC power. Connect coaxial transmission cable from your Antenna to the
ANTENNA coax connector on the rear panel.
For most efficient operation and safety, use a separate ground wire connection between the chassis of your Transceiver and a cold water pipe or ground rod.
You can mount the Mobile Mounting Bracket under the Transceiver. The resultant slightly angled front panel will add to your operating convenience.
For mobile operation, use the 12 volt DC power cable. Also, connect the Antenna, a ground and make all necessary mounting provisions.
To Receive AM
1. Set RF GAIN control maximum clockwise.
2. Set SQUELCH control maximum counterclockwise.
3. Set Mode to AM.
4. Turn power "on" by rotating VOLUME clockwise.
5. Set Channel Selector to the desired channel.
6. Adjust SQUELCH to cut out annoying background noise when no signal is being received. To do this, set Channel Selector to a channel where no signals are present (or wait until signals cease on your channel). Then, rotate SQUELCH in a clockwise direction to the point where the background noise just stops. Now when a signal is present, you will hear it, but will not be disturbed by noise on the channel in between signals.
When properly set, SQUELCH will keep the receiver "dead" until a signal comes in on that channel. Do not set SQUELCH too high, or weak signals will not be able to "open" the Squelch circuit. To receive weak signals, it is best to leave SQUELCH set to the minimum position (maximum counterclockwise).
7. Use CLARIFIER to tune in slightly off frequency stations, or to tune out adjacent channel interference caused by a station on the next channel (which may be too close to your channel).
8. Adjust VOLUME for a suitable listening level.
9. Push NB button in if your reception is disturbed by interference from impulse type noise (ignition noise and other man-made electrical noise). The Noise Blanker Circuitry is most effective with impulse noise.
10. Push ANL button in if your reception is disturbed by interference from hash type noise (fluorescent lights and other types of constant broad frequency type noise). The Automatic Noise Limiter circuit can reduce this type of noise.
NOTE: You can use both NB and ANL in exceptionally high-noise areas.
For most distinct reception, plug communications-type headphones into PHONES jack. This will be particularly helpful when operating in high noise surroundings (factory construction site, etc.).
Often you'll find an external/remote speaker will be most advantageous. We've made provisions for connecting such a speaker - just connect it to the EXT SPKR jack on the back. RadioShack sells a number of fine speakers for this purpose - we recommend Catalog Number 21-549. When you connect a speaker to this jack it automatically disconnects the internal speaker.
To Receive SSB or DSB Signals
1. Set RF Gain maximum clockwise.
2. Set SQUELCH maximum counterclockwise.
3. Set Mode to either LSB (lower sideband) or USB (upper sideband), depending on which sideband is being used by the transmitting station.
Note: When receiving DSB (double sideband) signals, you can use either LSB or USB.
4. Turn power "on" by rotating VOLUME clockwise.
5. Set Channel Selector to the desired channel.
6. Adjust SQUELCH as noted above.
7. Use CLARIFIER to tune in the SSB signal.
SSB tuning takes practice; it is not difficult, it just takes a little experience. When first listening to an SSB signal, it probably will not be understandable; the voice may sound like "Donald Duck", or just a low guttural sound. In either case, very slowly adjust CLARIFIER to bring the signal into its natural voice tonal range. If the signal is Donald Duck type, tune so the signal tones become lower in tone; careful tuning will make the voice sound natural. If the signal is low and guttural, tune for higher tones.
Note: If you try the above procedure and are not able to make the signal intelligible, it may be an SSB signal operating on the other sideband try the other SSB Mode (LSB or USB as the case may be).
8. Adjust VOLUME for a suitable listening level.
Use Noise Blanker (NB) to reduce or eliminate noise interference. With SSB and DSB signals ANL will probably not be as effective as with AM signals. Use the position which results in greatest noise reduction.
Notes on Receiving
An SSB signal will produce a fluttering, unintelligible sound when receiving in the AM mode; in such a case, use either the LSB or USB mode and adjust CLARIFIER for intelligibility.
You can tune AM signals when the Mode switch is in the USB or LSB position; tune CLARIFIER control to eliminate the steady tone caused by the AM carrier ("zero-beat" the tone so it disappears).
Remember that adjustment of CLARIFIER only shifts the Receiving frequency, not the Transmitting frequency.
When receiving an extremely strong SSB signal, you will find it best to use the RF GAIN control to vary the volume (rather than using VOLUME).
Transmitter Operation
1. Be sure PA button is out.
2. Plug the microphone into the MICrophone jack.
3. Set Mode Switch to the desired position.
4. Select the desired channel of operation.
5. Press the push-to-talk button on the side of the Microphone and speak in a normal voice into the Microphone. Best results will be obtained when you hold the mic 1 to 4" (2.5-10 cm) from your mouth and turned at about a 45 degrees angle (not straight on).
6. When transmitting, the meters will turn red. The RF-S Meter will indicate the relative level of output power.
7. To receive, release the push-to-talk button.
The SWR Meter can be used to provide an SWR (standing wave ratio) reading of your entire antenna system. Basically SWR is an indication of the efficiency of your antenna system. The lower the reading, the better the efficiency. An inefficient system will give high SWR readings.
To use the SWR function push in CAL button. Press the mic button for a few seconds and adjust the SWR CAL control to provide a meter reading at the CAL mark. Press CAL again (to release this function) and with the mic button still pressed in, read SWR on SWR Meter. Any reading under 2 is very good. Readings between 2 to 5 are acceptable. If you get a reading of 5 or more, you should carefully evaluate your entire antenna system. Is your antenna mounted correctly? Are you using the correct coaxial cable?
Using The Public Address Amplifier Feature
You can use your Transceiver to provide 4-6 watts of audio power as a Public Address amplifier. To use this function, you must connect an 8 Ohm public address type speaker to the PA SPeaKeR jack on the rear of this unit.
1. Be sure an 8 Ohm speaker is connected to the PA SpeaKeR jack.
2. Push in PA button. You'll notice the Meter lights go out - this will remind you that you can't transmit when you have the PA button pressed in.
3. Turn the Transceiver "on" with the VOLUME control.
4. Connect the microphone and press the push to talk button and talk into the mic. Adjust VOLUME as required for the appropriate level of sound.
5. Even though you have your Transceiver set for PA operation, you can still monitor CB signals - press in both PA and the NB buttons and CB signals will be heard through the PA speaker. This way you won't miss any important calls, even while using PA. To defeat the receiver sound, press NB button again to release it.
6. To return to normal Transceiver operation, press PA button to release it.
SSB (Single SideBand)....What Is It?
We thought you'd be interested in knowing and understanding something about the SSB function and capability of your Transceiver.
To understand SSB, we need to know what an AM (Amplitude Modulated) signal is.
Amplitude Modulation is a form of heterodyning - mixing 2 signals together electrically. In the process of mixing, 3 signals result. Example:
An R.F signal at 27.005 MHz (channel 4 C.B.) is mixed with (modulated by) a 1000 Hz tone.
The resulting signals-
27.005 MHz = original or "carrier" signal.
27.005 MHz - 1000 Hz (27,005,000 minus 1000)= 27.004 MHz, the Lower SideBand.
27.005 MHz + 1000 Hz (27,005,000 plus 1000)= 27.006 MHz, the Upper SideBand.
Notice that the communication or intelligence (the 1000 Hz tone) is contained in each sideband. The Carrier contains no intelligence. This fact is vital!
For the sake of communication, all we need to receive is the 1000 Hz tone. The receiver only needs to recover one signal, and yet we are transmitting 3 signals. Not only are we sending 3 signals, but also we are wasting most of our power in one of them (which carries none of the intelligence, i.e. The carrier, 27.005 MHz) and the other two signals duplicate each other!
Thus, if we can eliminate the carrier (not needed for communication) and can send only one of the sidebands (since they duplicate each other's information anyway), we could concentrate all of the transmitting power into one sideband. This is exactly what Single SideBand accomplishes.
Single SideBand transmissions incorporate only one of the sidebands -i.e. in the example above, only the upper sideband at 27.006 MHz or only the lower sideband at 27.004 MHz. The second sideband and the carrier are eliminated in the early stages of the transmitter circuitry.
When only one sideband is transmitted, we can concentrate all of the available power in this one side band, greatly increasing the effective power of an SSB signal as compared to an AM signal.
See Advantages of SSB Over Normal AM below.
Advantages of SSB Over Normal AM
A theoretically perfect AM transmitter used in Class "D" Citizens Band Radio Service as permitted by the Federal Commission will have the following maximum output power specification:
Carrier - 4 watts with the capability of slightly less than 100 % modulation.
In order to fully Amplitude Modulate a 4 watt carrier, a full 2 watts of audio power is required. In this case, only 1 watt of power can exist in each sideband. Since the carrier contains no intelligence, and the sidebands duplicate each other, really only one sideband is required to transmit the required intelligence.
If we take the above transmitter and convert it to Double SideBand operation (eliminate the carrier power), we can increase the power in the sidebands to 2 watts each, without overloading the circuitry. Further; if we eliminate one of the two sidebands, we can put the full 4-watts of power into remaining sideband. Thus, while an AM transmitter has only 1 watt of power in one sideband, an SSB transmitter can have 4 watts of power in one sideband - or 4 times the power of an AM transmitter.
Thus, effectively an SSB transmitter with the same power limitations is 4 times more powerful than an AM transmitter.
One further advantage, which is not often mentioned. Not only does the SSB signal take up only 1/2 of the frequency spectrum space of an AM signal (only 1 sideband instead of 2), thus permitting twice the number of stations to be in the same amount of band space-but also, at the receiving end, the receiver only picks up 1/2 of the total AM bandwidth. This means that 50% less noise is amplified along with the signal. This results in a 50% improvement in signal-to-noise figures; or, in more technical terms, a 3 dB improvement.
Thus, given equal limitations and conditions, an SSB signal will be 4 times more powerful and will have 2 times the signal to noise advantage of an AM signal - 8 times as effective.
In technical terms, a 9 dB advantage. Thus, for an AM transmitter to be equivalent in effectiveness it would have to be rated at 32 watts!
Enough said! We hope you're enthused. |
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