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panel.
(3)
Tune the Receiver to 5.0 MHz. Adjust RF signal generator to 5.0 MHz with a
+3 dBm output level.
(4)
Set vector impedance meter frequency range to 4.5-14 MHz and magnitude
range to 100.
(5)
Note reading on vector impedance meter.
and 55 ohms and in phase (0 degrees).
(6)
Repeat steps 3, 4 and 5 for both 15 and 25 MHz.
(7)
Vector impedance meter shall be between 45 and 55 ohms and in phase at
both 15 and 25 MHz.
n.
Phase Jitter.
This test requires the RF signal generator, signal filter assembly and spectrum
analyzer listed in Table 1-2.
(1)
Connect the RF signal generator output to the input of the signal filter
assembly. Connect the output of the signal filter assembly to Jl on Receiver
rear panel.
(2)
Connect spectrum analyzer with 600 ohm load to J2 on Receiver rear
panel.
(3)
Tune the Receiver to 1.400000 MHz, select 6.8 kHz bandwidth, manual
AGC, CW mode and tune BFO to +8.00 kHz.
(4)
Adjust the RF signal generator for 1.400000 MHz at -40 dBm output level.
All modulation off.
(5)
Set the spectrum analyzer as follows:
Frequency
Bandwidth
Sweepwidth
Scan Time
Input Attenuator
IF Attenuator
(6)
Adjust the spectrum analyzer for a symmetrical response about the center
frequency and adjust the Receiver IF gain control for peak response at 0 dB.
(7)
Observe trace and note noise levels are down at least 21 dB at +100 Hz and
at least 27 dB down at +200 Hz.
(8)
Set the spectrum analyzer sweepwidth to 1 kHz/div and bandwidth to 30 Hz.
(9)
Adjust the spectrum analyzer for a symmetrical response about the center
frequency and adjust the Receiver IF gain control for peak response at 0 dB.
(10)
Observe trace and note noise levels are down at least 42 dB at j ^ l kHz and
51 dB down at ^2 kHz.
o.
Filter Delay Characteristics.
This test requires the 50 ohm adapter and network analyzer listed in Table 1-2.
(1)
Connect the network analyzer channel B output to connector A4J1 on circuit
card A4 with the cable to circuit card A3 disconnected.
(2)
Connect the input of Channel B of the network analyzer to J2 on Receiver
rear panel through the 50 ohm adapter.
(3)
Be sure filters are installed in the filter slot as shown in Table 3-3.
Racal RA6790/GM Alignment & Tuning Manual
8 kHz
10 Hz
100 Hz/div
2 secs/div
-10 dBm
+20 dB
Reading shall be between 45
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