DX 949
SOLID STATE CITIZENS BAND
AM/SSB MOBILE TRANSCEIVER
OWNER’S MANUAL
Printed In Malaysia
AT0949011A
MIC980508
TABLE OF CONTENTS |
|
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
2 |
Installation |
|
Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
3 |
Mounting The Radio . . . . . . . . . . . . . . . . . . . . . . . . . . |
3 |
Ignition Noise Interference . . . . . . . . . . . . . . . . . . . . . |
4 |
Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
4 |
Tuning The Antenna For Optimum SWR . . . . . . . . . . |
5 |
External Speaker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
6 |
Operation |
|
Control Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
7 |
Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
7 |
Rear Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
10 |
Frequency List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
11 |
Procedure To Receive And Transmit . . . . . . . . . . . . . |
12 |
Receiving SSB Signals . . . . . . . . . . . . . . . . . . . . . . . . |
13 |
Alternate Microphones And Installation . . . . . . . . . . . |
15 |
Maintenance And Adjustment . . . . . . . . . . . . . . . . . . . |
18 |
A Few Rules That Should Be Obeyed . . . . . . . . . . . . |
19 |
How Your CB Can Serve You . . . . . . . . . . . . . . . . . . |
19 |
Use Channel 9 For Emergency Messages Only . . . . . |
20 |
Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
21 |
- 1 -
SPECIFICATIONS
GENERAL
Channels |
40 |
Frequency Range |
26.965 ~ 27.405 MHz |
Emission |
AM/USB/LSB |
Frequency Control |
Phase-Lock-loop (PLL) Synthesizer |
Frequency Stability |
0.001% |
Temperature Range |
-30°C to +50°C |
Input Voltage |
13.8 VDC |
Antenna Impedance |
50 Ohms |
Speaker Impedance |
8 Ohms |
Size |
7 7/8” (W) x 9 1/4” (D) x 2 1/8” (H) |
Weight |
5.5 lbs. |
TRANSMITTER
RF Power Output |
AM : 4W ; USB/LSB : 12W PEP |
Frequency Response |
300 to 2500 Hz |
Frequency Tolerance |
0.005% |
Spurious Emission |
Better Than -55 dB |
Unwanted Sideband |
Better Than -55 dB |
RECEIVER
Sensitivity for 10 dB (S+N)/N |
AM : 0.5 uV ; USB/LSB : 0.25 uV |
Squelch Sensitivity |
Less Than 0.5 uV |
Audio Power Output |
2W @ 10% Distortion |
Image Rejection Ratio |
-65 dB |
AGC Figure of Merit |
100 mV for 10dB Change in Audio Output |
Audio Response |
300 to 2500 Hz |
Clarifier Range |
± 1.0 KHz |
(SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE)
- 2 -
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 automobiles, the transceiver is usually mounted 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 grounding 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 with the installation of the mounting bolts.
2.Connect the antenna cable plug to the standard receptacle on the rear panel. Most transceiver antennas are terminated with a type PL-259 plug and mate with the ANT receptacle.
3.Connect the red DC power input wire (with the fuse) to +13.8V DC. This wire extends from the rear panel. In automobile installation, +13.8V DC is usually obtained from the accessory contact on the ignition switch. This prevent 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 broadcast receiver in the car.
4.Connect the black lead to –13.8V DC. 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 that microphone is readily accessible.
IGNITION NOISE INTERFERENCE
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 installation is from the generator and ignition system in the vehicle. Under most operating conditions, when signal level is adequate, the background noise does not present a serious problem. Also, when extremely low level signals are being received, the transceiver may be operated with vehicle engine turned off. The unit requires very little current and therefore will not significantly discharge the vehicle battery.
Even though the transceiver has ANL and NB controls, 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 as variations between vehicles require different solutions to reduce the noise.
ANTENNA
A vertically polarized, quarter-wavelength whip antenna provides the most reliable operation and greatest range. Shorter, loaded-type whip antennas are more attractive, compact and adequate for applications where the maximum possible distance is not required. Also, loaded whips do not present the problems of height imposed by a full quarter-wavelength whip.
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 practical purpose, 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 good metal electrical ground in the vehicle. When installed in a boat, the transceiver will not operate at maximum efficiency 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.
- 3 - |
- 4 - |
TUNING THE ANTENNA FOR OPTIMUM S.W.R
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 on all channels of the transceiver. Channel 1 requires a longer antenna than Channel 40 because it is a lower frequency.
Due to the various methods of adjusting antennas for proper S.W.R., we have chosen what we think is the optimum method:
A. Antenna with adjustment screws (set screws).
1.Start with the antenna extended and tighten the set screw lightly enough so that the antenna can be lightly tapped with your finger for easy adjustment.
2.Set your transceiver to Channel 20. Press the PTT (push-to-talk) switch, and tap the antenna (making it shorter). The S.W.R meter will show a lower reading each time the antenna is tapped. By continuing to shorten the antenna, you will notice the S.W.R 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. When the lowest point has been reached, switch to Channel 1 and then to Channel 40 and compare S.W.R readings. They should be almost equal.
NOTE
The proper setting is achieved when the SWR is 1.5 or below, and when it has the same reading for channels 1 and 40.
B. Antennas which must be cut to proper length
1.Follow the same procedure as above, but adjust the length by cutting in 1/8” increments until a good match is obtained.
2.Be very careful not to cut too much at one 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.
-5 -
If you’re 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 in 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 or lamp post, fences, etc.)
NOTE
The transceiver will operate into an SWR of 2 to 1 indefinitely and sustain an SWR of 20 : 1 for a maximum of 5 minutes at rated operating conditions.
EXTERNAL SPEAKER
The external speaker jack (EXT SP.) 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.
PUBLIC ADDRESS
To use the transceiver as a public address system, connect an external 8 ohms speaker (4 watts minimum) to the PA. SP. jack located on the rear panel. Direct speaker away from the microphone to prevent acoustic feedback. Physical separation or isolation of the microphone and speaker is important when operating the PA at high output levels.
- 6 -
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