Alinco DJ269T User Guide

CIRCUIT DESCRIPTION DJ-296T

1) Receiver System The receiver system is a double superheterodyne system with a 30.85 MHz first IF and a 455 kHz second IF.

1. Front End The received signal at any frequency in the 216.00 to 249.995 MHz range is passed through the low-pass filter (L2, L3, L8, C2, C9, C10, C11, C62 and C189), high-pass filter (C56, C57, C58, C61, L22, L25 and D15), and amplified by the RF amplifier (Q9). The signal from Q9 is then passed through the tuning circuit (C12, C14, C65, C66, L19, L20, L21, D12, D1 3 and D14) and converted into 30.85 MHz by the mixer (Q 10). The tuning circuit is controlled by the tracking voltage from the CPU (IC9) so that it is optimized for the reception frequency. The local signal from the VCO is passed through the buffer (Q11), and supplied to the source of the mixer (Q10). The radio uses the lower side of the superheterodyne system.

2. IF Circuit The mixer mixes the received signal with the local signal to obtain the sum of and difference between them. The crystal filter (XF1) selects 30.85 MHz frequency from the results and eliminates the signals of the unwanted frequencies. The first IF amplifier (Q8) then amplifies the signal of the selected frequency.

3. Demodulator Circuit After the signal is amplified by the first IF amplifier (Q 8), it is input to pin 16 of the demodulator IC (IC4). The second local signal of 30.395 MHz , which is oscillated by the internal oscillation circuit in IC4 and crystal (X2). Then, these two signals are mixed by the internal mixer in IC4 and the result is converted into the second IF signal with a frequency of 455kHz. The second IF signal is output from pin 3 of IC4 to the ceramic filter (FL1), where the unwanted frequency band of that signal is eliminated, and the resulting signal is sent back to the IC4 through pin 5.

The second IF signal input via pin 5 is demodulated by the internal limiter amplifier and quadrature detection circuit in IC4, and output as an audio signal through pin 10.

4. Audio Circuit The audio signal from pin 10 of IC 4 is compensated to the audio frequency characteristics in the

ADJUSTMENT DJ296T

1) Required Test Equipment The following items are required to adjust radio parameters :

1. Regulated power supply Supply voltage: 5 - 14 VDC

Current: 3A or more

2. Digital multimeter Voltage range: FS = Approx. 20V

Current: 10A or more Input resistance: High impedance

3. Oscilloscope Measurable frequency: Audio frequency

4. Audio dummy load Impedance: 8 ohm

Dissipation: 1W or more Jack: 3.5 mm

5. SSG Output frequency: 500MHz or more

Output level: -20dBu/0.1uV - 120dBu/1V Modulation: AM / FM

6. Spectrum Analyzer Measuring range: Up to 2 GHz or more

7. Power meter Measurable frequency: Up to 500MHz

Impedance: 50 ohm, unbalanced Measuring range: 0.1W - 10W

8. Audio voltmeter Measurable frequency: Up to 100kHz

Sensitivity: 1mV to 10V

9. Audio generator Output frequency: 67Hz to 10kHz

Output impedance: 600ohm, unbalanced

10. Distortion / SINAD meter Measurable frequency: 1kHz

Input level: Up to 40dB Distortion: 1% - 100%

11. Frequency counter Measurable frequency: Up to 500MHz

Measurable stability: Approx. +/- 0.1 ppm

12. Linear detector Measurable frequency: Up to 500MHz

Characteristics: Flat CN: 60dB or more Note

• Standard modulation : 1 kHz +/- 3.5kHz / DEV

• Reference sensitivity 12dB SINAD

• Specified audio output level: 200mW at 8 ohm

• Standard audio output level: 50mW at 8 ohm

• Use an RF cable (3D2W: 1m) for test equipment.

• Attach a fuse to the RF test equipment.

• All SSG outputs are indicated by EMF.

• Supply voltage for the transceiver: 13.8VDC

2) Adjustment Mode

The DJ -296 does not require a serviceperson to manipula te the components on the printed-circuit board, except the trimmer when adjusting reference frequency and deviation. Most of the adjustments for the transceiver are made by using the keys on it while the unit is in the adjustment mode. Because the adjustment mode temporarily uses the channels, frequency must be set on each channel before adjustments can be made. For instructions on how to program the channels, see the “DJ-296 INSTRUCTION MANUAL” which came with the product. In consideration of the radio environment, the frequency on each channel must be near the value (+/- 1 MHz) listed in the table below. To enter the adjustment mode, set key lock and input 490217. Decimal point at 100MHz and 10MHz appears in LCD. (To release the mode, set key lock an d input 490217.)

Channel frequencies used in the adjustment mode Memory Channel Channel function Frequency 1 Reference frequency adjustment 223.5 MHz 2 High power adjustment 223.5 MHz 3 Low power adjustment 223.5 MHz 4 Minimum frequency sensitivity adjustment 215 MHz 5 Medium frequency sensitivity adjustment 223 .5 MHz 6 Maximum frequency sensitivity adjustment 240 MHz 7 S-meter ( 1 ) adjustment 223.5 MHz 8 S-meter ( FULL ) adjustment 223.5 MHz 9 Deviation 223.5 MHz

10 DTMF ( 1 ) test 223.5 MHz

11 DTMF ( D ) test 223.5 MHz 13 Tone 88.5Hz test 223.5 MHz 15 DCS code 255 test 223.5 MHz 16 Tone burst test 223.5 MHz

17 Aging (Not required to use ) 223.5 MHz

Reference Frequency Adjustment

1. In the adjustment mode, select channel 1 by rotating the main tuning dial.

2. Press the PTT key to start transmission.

3. Rotate TC1 on the Main board until the value on the frequency counter matches the one displayed on the LCD.

High Power Adjustment

1. In the adjustment mode, select channel 2 by rotating the main tuning dial. ( “L” at the upper-left of the display disappears).

2. Hold down the PTT key to start transmission.

3. While watching the reading of the TX power meter, set the output power to the value closest to 5 W by rotating VR3 on Main board.

Low Power Adjustment

1. In the adjustment mode, select channel 3 by rotating the main tuning dial. (“L” appears at the upper-left of the display).

2. Hold down the PTT key to start transmission.

3. While watching the reading of the TX power meter, set the output power to the value closest to 0.8 W by rotating the main tuning dial.

4. When the PTT key is released, the output power at that time will be stored as the low power setting.

Minimum Frequency Sensitivity Adjustment

1. In the adjustment mode, select channel 4 by rotating the main tuning dial.

2. Adjust the minimum frequency sensitivity to the best tuning by rotating the main tuning dial, while F appears after the FUNC key is pressed.

Medium Frequency Sensitivity Adjustment

1. In the adjustment mode, select channel 5 by rotating the main tuning dial.

2. Adjust the medium frequency sensitivity to the best tuning by rotating the main tuning dial, while F appears after the FUNC key is pressed.

Maximum Frequency Sensitivity Adjustment

1. In the adjustment mode, select channel 6 by rotating the main tuning dial.

2. Adjust the maximum frequency sensitivity to the best tuning by rotating the main tuning dial, while F appears after the FUNC key is pressed.

S-meter (1) Adjustment

1. In the adjustment mode, select channel 7 by rotating the main tuning dial. The S-meter will show a single star.

2. Enter “0” dBu (EMF) with the transceiver tester.

3. Press the F key . The transceiver beeps indicating the new setting has been stored successfully.

S-meter (FULL)

1.In the adjustment mode, select channel 8 by rotating the main tuning dial.

The S -meter will show all six stars.

2. Enter “+20”dBu (EMF) with the transceiv er tester.

3. Press the F key. The transceiver beeps indicating the new setting has been stored successfully.

Deviation

1. In the adjustment mode, select channel 9 by rotating the main tuning dial.

2. Input a 50mVrms, 1KMz signal with your transceiver tester through the external microphone jack.

3. With the tester, put the transceiver in the transmission mode.

4. Rotate the VR1 on the printed-circuit board of the transceiver until the deviation is set to 4.5KHz.

DTMF (1) Test

This function is only for checking the DTMF code, not adjusting it.

1. In the adjustment mode, select channel 10 by rotating the main tuning dial.

2. Press the PTT key. DTMF code “1” is automatically sent and you will hear the monitoring tone from the speaker.