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Rx Tune Up.
Midland 70-066 Receiver Alignment Points Above:
Receiver tune up is straight forward. Reconnect the Receiver Local Oscillator J365 cable to the
synthesizer board.
LO Amplifier Alignment:
Connect multi-meter or DVM to Monitor CM202 pin 1. Note pin 2 is missing key pin). Switch to
center frequency – Channel 49 - 53.250Mhz [center between 53.975Mhz and 52.500Mhz.]
To tune the local oscillator multipliers - Adjust L209 and L210 for maximum reading. A typical
reading is 0.4 V. A common problem with these transceivers is lack of LO injection if they are not
modified and tuned correctly.
RF-IF Alignment:
Tuning the RF front end - On a mid frequency channel (Channel 49 - 53.250Mhz) feed a signal in
from a signal generator to the Midland 70-066 antenna socket. Connect a multi-meter or DVM to
Monitor CM202 pin 2 and peak L201, L202, L204 and L205 for maximum reading while remaining
in the linear range [ie Set signal generator level for positive meter reading before limiting occurs.. Note
the reading at this pin will be negative until sufficient RF input signal is available. Repeat adjustments
for optimum.
An alternative method is to use a Sinad meter or tune for maximum quieting. When correctly aligned
the sensitivity is typically 0.35uV for 12db sinad over the range 52.5 to 54 MHz.
Tests have concluded that the Midland 70-066 should lift the mute at 0.1uV for a reasonable audio
quality.
Quadrature Coil Alignment:
Adjust L252 for maximum audio output.
Tight Squelch Alignment:
Adjust RV251 for the desired tight squelch sensitivity.
Midland 70-066 low Band Conversion to 6 Meters: Receiver Ver 2.1 20-nov-09 Part 3 Page 3.9
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