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5.4.4
PA Current Limit
Since it may not be practical to increase the PA current to set the PA Current
Limit control, you may use this indirect method.
With the carrier turned off, look at the DC voltage at the right end of R413 on the
Metering board. The current limit, in amperes, will be 0.35 amps higher than ten
times this voltage. For example, for a current limit of 7.35 amps, adjust the PA
Current Limit control for 0.7 volts at R413 ; or 0.565 volts for 6.0 amps. Set the
current limit for 3 amps (FM30), 6 amps (FM100), or 8.5 amps (FM250).
5.5
Motherboard Adjustments
See page 6-14 for motherboard jumper configuration.
5.6
Display Modulation Calibration
The Modulation Calibrate trim pot sets the sensitivity of the front panel
Modulation bar graph display.
This adjustment may be made only after the Output trim pot on the Stereo
Generator board has been set. (See section 5.2.4.)
1.
Set the Stereo-Mono switch to Mono.
2.
Feed a sine wave source of about 2.5 kHz into the left channel at a level
sufficient to put the wideband gain-reduction indicator somewhere in the
middle of its range.
3.
Set the Modulation Calibrate trim pot so that the "90" light on the front
panel Modulation display just begins to light.
5.7
Voltage Regulator Adjustments
JP701, a 10–pin header on the Voltage Regulator board, sets the time between
program failure and carrier turnoff. Pins 1 and 2 are the two pins closest to the
edge of the board. The times are approximate. Sections 2.11, 2.12, and 4.8
contain further information.
1.
Short pins 1 and 2 for a 30–second delay.
2.
Short pins 3 and 4 for a 2–minute delay.
3.
Short pins 5 and 6 for a 4–minute delay.
4.
Short pins 7 and 8 for an 8–minute delay.
You may select other times by changing the value of R721. The time is
proportional to the resistance.
5–6
FM30/FM100/FM250 User's Manual
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