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Log Ref. Level:
Log/Lin. Switch:
(15)
Adjust the tracking generator for 30 MHz and adjust coils Lll and L12 for-
peak response.
(16)
Set tracking generator to sweep between 0 and 100 MHz. Check that all
frequencies above 56 MHz are at least 20 dB down from a reference level at
30 MHz.
(17)
Disconnect the tracking generator from Pi and the spectrum analyzer from
E3-E5. Reconnect PI of cable W2 to Jl on A2.
(18)
Connect the RF signal generator to PI of A2 and adjust for 2.0000 MHz at -
20 dBm. Adjust the Receiver frequency to 2.00000 MHz. AGC to MAN and
IF GAIN to maximum.
(19)
Connect the spectrum analyzer, using the high impedance probe, to El on A3
(First IF output of A2). Set analyzer to display 40.455 MHz.
(20)
Adjust transformer T3 for maximum output. Ensure that the output level is
not less than -17 dBm.
(21)
Set the RF signal generator frequency to 10.000 MHz and adjust the
Receiver frequency to 10.00000 MHz.
(22)
Ensure that the output level is not less than -17 dBm.
(23)
Set the RF signal generator frequency to 29.999 MHz and adjust the
Receiver frequency to 29.99900 MHz.
(24)
Ensure that the output level is not less than -17 dBm.
(25)
Turn the Receiver off. Disconnect all test equipment and reconnect PI of
cable A2W1 to J5.
d.
Second Mixer, Circuit Card Assembly A3.
The second mixer assembly A3 is located in the bottom portion of the Receiver.
The RF signal generator and RF millivoltmeter, listed in Table 1-2, are required to
align this assembly.
(1)
Disconnect PI of cable A3W2 from J6, located on the Receiver chassis, and
connect PI to the RF mi Hi voltmeter with high impedance probe.
(2)
Connect the RF signal generator to Jl-RF IN on Receiver rear panel.
(3)
Turn the Receiver on and set the MODE to AM, any bandwidth, AGC to
manual and IF GAIN to the maximum clockwise position and Receiver
frequency to 1.5 MHz.
(4)
Adjust the RF signal generator frequency to 1.5 MHz and the output level for
a RF millivoltmeter indication of -10 dBm.
(5)
Adjust coils L8, L7, L6, L5 and Tl, in the order given, for peak output
indication on the RF millivoltmeter. Readjust the RF signal generator level as
required to maintain the -10 dBm output reference.
(6)
After all coils have been adjusted for peak output, check the output level of
the RF signal generator. RF signal generator output level should not be
greater than -53 dBm. If gain is not correct adjust R26 (maintain -10 dBm
reference) and RF signal generator until gain is as specified. If R26 adjusts
to maximum and specified gain cannot be obtained, then slightly adjust C3
for peak output. Readjust R26 for specified gain.
(7)
Turn the Receiver off and disconnect all test equipment. Reconnect PI of
Racal RA6790/GM Alignment & Tuning Manual
-10 dBa
-0 dB Log
Page 6 of 20
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