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Midland 70-0671 Alignment Procedure
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Midland 70-0671 Alignment Procedure

Midland 70-0671 Alignment Procedure

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1
Remove the six securing screws from the bottom cover , and the cover itself.
Ω
2
Connect a resistive 50
3
Connect 13.4V DC power to transceiver J505.
Ω
4
Connect a 3.2
, 20W resistor to pins 4 and 6 of the Accessory Plug. The jumper
between pins 5 and 6 must be temporarily removed to make this connection .
The resistor serves as a constant load to replace the speaker's inconsistencies.
CAUTION:Both speaker terminals are LIVE. Never ground either one. Connect grounded receive-audio
measuring -equipment to only one side of the speaker, and chassis ground. Normally, voltage
measurement will be half of true values.
5
Turn the radio on (Push on and Push off switch), set the VOLUME control to
a m i d -position.
Connect the Programmer to Programming Port Mic Jack J302.
Upload the radio programming Data -Packet into the Programmer and
initiate its Remote Control Mode. Refer to the appropriate manual for details.
•
V C O R e s o n a n c e
1
Select the Remote Control Mode of the Programmer and enter the following test
frequencies:
RX Frequency
TX Frequency
2
Adjust Channel RX Tank L713 for 1.5V DC at VC
3 Active transmit mode (using the programmer ) and adjust TX Tank
L702 for 1.5V DC at VC
7 0-0671 Alignment Procedure
SETUP
RF load and wattmeter to Antenna Connector J502.
SYNTHESIZER ALIGNMENT
A -B a n d
3 0 . 0 0
3 0 . 0 0
(VCO Steering) .
(VCO Steering) .
B -B a n d
C -B an d
3 6 . 00
42.00
3 6 . 00
42.00
MHz
MHz

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Summary of Contents for Midland 70-0671

  • Page 1 7 0-0671 Alignment Procedure SETUP Remove the six securing screws from the bottom cover , and the cover itself. Ω Connect a resistive 50 RF load and wattmeter to Antenna Connector J502. Connect 13.4V DC power to transceiver J505. Ω Connect a 3.2 , 20W resistor to pins 4 and 6 of the Accessory Plug.
  • Page 2 • Reference Oscillator 4 Initiate transmit on any channel. Measure transmitted RF carrier frequency without modulation and, if necessary, adjust REFERENCE OSCILLATOR X701 ± for carrier frequency to within 3 0 H z o f c h a n n e l f r e q u e n c y . P A M O D U L E A L IG N M E N T The 70 -0671 should be adjusted to have a 6 MHz channel spread (8 MHz C-B a n d ) at 110W.
  • Page 3 ± ± ± ± Adjust RV401 for 750 Hz 100 Hz (wide) or 375 Hz 100 Hz (narrow) deviation. C h a n g e the transmit DCS code +023 to the transmit test by testing frequency using the programmer. 10 Adjust RV401 so that modulation waveform from modulation analyzer matches the correct waveform shown in Figure 2-1 .

  • Page 4: Receiver Alignment

    RECEIVER ALIGNMENT Change the RX test frequency to 33.0 MHz for A-Band radios, 39.0 MHz for B -Band , 46.0 MHz for C-B a n d . • First Injection 2 No adjustment for first injection is required. • Preselector Alignment No adjust ment for the preselector (L201, L202, L203, L204, L205, L206, L207,and L208 ) is required.

  • Page 5: Test Instrument

    Temporarily disable the pulse generator. 8 Using coax cable of minimum convenient length, connect the pulse generator, the RF signal generator, and the radio to the two-way power divider. 9 Disable the noise blanker by placing SW801 to the OFF position. 10 Apply an on -channel signal to obtain12dB SINAD, then increase the RF generator output by 40dB.
  • Page 6 • Tight Squelch Squelch level set maximum ( 80 ). by using the front UP / DN switch Ω Apply 0.95 uV of modulated standard deviation on -c h a n n e l R F signal to the 50 antenna connector.

  • Page 7: Instrument Capabilities

    C O M P L E T E R E A L I G N M E N T Complete realignment is only needed when a component that affects alignment h a s b e e n r e p l a c e d . R A D I O R E P R O G R A M M I N G W I T H T E S T F R E Q U E N C I E S I S R E Q U I R E D .