Racal Instruments RA6790/GM, Техническое руководство

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Racal RA6790/GM Alignment & Tuning Manual
Page 15 of 20
standard is 5 MHz +1 Hz.
(3) Disconnect digital frequency counter and reconnect PI of cable W4 to J2 and
A3.
d. RF Gain Control.
This test requires the distortion analyzer and RF signal generator listed in Table 1-2.
(1) Using a 600 ohm termination connect distortion analyzer to AF LINE output.
(2) Set the Receiver controls as follows:
Power
ON
Gain Mode Manual
Detection Mode CW
BW 3.24 kHz (or closest bandwidth available)
(3) Set the RF signal generator for an output of 1.5 MHz at –110 dBm (1.0
uVolts), CW. Connect RF signal generator to RF IN connector Jl on rear
panel.
(4) Adjust the manual IF GAIN control on the Receiver front panel fully clockwise
(maximum gain) and adjust the line level control for 1 mW output on
distortion analyzer with analyzer in voltmeter mode.
(5) Adjust the IF GAIN control counterclockwise from maximum and ensure level
changes indicated on the distortion analyzer are continuous.
(6) Increase RF signal generator level to -10 dBm (70 millivolts) and set IF GAIN
control to maximum.
(7) Decrease the RF signal generator output to restore the 1 mW reference and
note the RF signal generator level. This should be less than -100 dBm.
e. Final IF Frequency.
This test requires the RF signal generator, 50 ohm adapter, digital frequency
counter, and RF millivoltmeter listed in Table 1 -2.
(1)
Set up the equipment as follows:
(2) Set the Receiver controls as follows;
Power
ON
Gain Mode AGC-SHORT
BW 3.0 kHz (or closest bandwidth available)
Receiver Tuned Frequency 1.5 MHz
Detection Mode
CW
(3) Set the RF signal generator for an output of 1.5 MHz, CW at a level of -10
dBm. Connect the 50 ohm adapter (load) with the RF millivoltmeter to IF
OUTPUT connector J2.
(4) Note the IF output level indicated on the RF mi Hi voltmeter.
(5) Remove the 50 ohm adapter (load) from the IF output and observe that the
indicated output voltage increases by 6 dB ^1 dB.
(6) (Connect the digital frequency counter to IF output jack J2 and measure the
IF frequency. This should be 455.000 kHz.
f. Fixed and Variable BFO Operation.
This test requires the 50 ohm adapter and digital frequency counter listed in Table
1-2.