Motorola VRS750 Service Manual page 74

VCO Attenuation
VCO Attn. 25 kHz
VCO Attn. 20 kHz
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7. Program the warp value into the radio by pressing the Program
button.
8. Exit the Reference Oscillator Warp function.
NOTE: The Transmit Deviation Limit softpot sets the
maximum deviation of the carrier. Tuning is
performed for 12.5 kHz, 20 kHz, and 25 kHz channel
spacing. Tuning for 25 kHz channel must be done first
for all frequency points. Tuning for 12.5 kHz and 20
kHz channel spacing determines only the offset to the
previously tuned deviation for 25 kHz tuning channel
spacing. For (12.5, 20 kHz) channel spacing, only the
last non 0 transmit frequency point (normally F7) will
be used for tuning.
1. Under the Tx Align menu, select VCO Attn. 25 kHz.
2. Begin with the lowest frequency. Select the thumb of the slider at
the lowest frequency point and then press the PTT Toggle button
to key up the radio at the corresponding frequency point. The
spin control can also be toggled via its up/down arrow buttons.
The softpot value can also be typed into the edit control (press
ENTER to confirm selection/send a softpot value).
3. Inject a 1 kHz at 80 mVrms signal into the external mic connector
on the test box (VRS750 input).
4. Note down the deviation obtained.
5. Adjust the slider, adjust the spin control or key in softpot values
(press ENTER to confirm) for the frequency point until the
deviation is within range as defined in Table 12.
6. Dekey radio (press the PTT Toggle button). Choose the next
frequency, key up and repeat steps 3 to 6 until all seven tuning
points are done.
7. Program the softpot value by pressing the Program button.
8. Exit the VCO Attn. 25 kHz function.
NOTE: Tuning of Modulation Balance Attn. and VCO Attn. for
25 kHz channel spacing must be done first.
1. Under the Tx Align menu, select VCO Attn. 20 kHz.
2. Press PTT Toggle to key up the radio at the last non 0 transmit
frequency point (normally F7).
3. Inject a 1 kHz at 80 mVrms signal into the external mic connector
on the test box (VRS750 input).
4. Note down the deviation obtained.
5. Adjust the slider, adjust the spin control or key in softpot values
(press ENTER to confirm) for the frequency point until the
deviation is within range as defined in Table 12.
6. Press PTT Toggle to dekey the radio.
7. Program the softpot value by pressing the Program button.