Racal ra6790/gm alignment and tuning manual from maxhdrm2@comcast.Net february 2003.
Racal ra6790/gm alignment & tuning manual page 2 of 20 chapter 3 assembled receiver alignment and test 3-1. Introduction. This chapter provides both alignment procedures and an end -to-end check for an assembled receiver. The information is presented in two sections with alignment procedures contain...
Racal ra6790/gm alignment & tuning manual page 3 of 20 a10a1 (refer to table 2-28 in chapter 2). Do not disconnect power output connector j3 during these measurements, as this will unload the power supply and could result in erroneous readings. B. Low pass filter, assembly al. Test equipment require...
Racal ra6790/gm alignment & tuning manual page 4 of 20 45 mhz relative lev el>20db 0.5mhz 40.453mhz each graticule = 10 mhz figure 3-2. Alignment waveforms 45 mhz relative level > 20 d b each graticule lodb each graticule = 10 mhz figure 3-2. Alignment waveforms.
Racal ra6790/gm alignment & tuning manual page 5 of 20 c. First mixer, circuit card assembly a2. The first mixer assembly a2 is located in the bottom portion of the receiver. The spectrum analyzer, rf signal generator, rf millivoltmeter and digital multimeter, listed in table 1-2, are required to al...
Racal ra6790/gm alignment & tuning manual page 6 of 20 log ref. Level: -10 dba log/lin. Switch: -0 db log (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...
Racal ra6790/gm alignment & tuning manual page 7 of 20 cable a3w2 to j6. E. Main if /af, circuit card assembly a4. This assembly is located in the top portion of the receiver. The test equipment required to align the assembly includes the spectrum analyzer, am/fm signal generator, digital multimeter...
Racal ra6790/gm alignment & tuning manual page 8 of 20 generator to .5 uv. Note reading of rf millivoltmeter. Increase output of am/fm signal generator +120 db in 10 db steps and assure that reading on rf millivoltmeter remains within 3 db of that obtained at the .5 uv rf input level. (12) remove th...
Racal ra6790/gm alignment & tuning manual page 9 of 20 and the meter range to +10 db (1 mw). (18) select the fm mode, adjust the am/fm signal generator frequency for 1.5 mhz with an output of -40 dbm and modulate the signal at 1 khz with a peak deviation of +4 khz. Check the audio output indication ...
Racal ra6790/gm alignment & tuning manual page 10 of 20 table 3-1. Bandpass filter characteristics pas sband *3 db max i mum - hz attenuation stopband 60 db minimum - hz attenuation bandpass filter from to below above 400 hz -200 +200 -1240 +1240 1.2 kh z -600 +600 -3600 +3600 6.8 khz -3400 +3400 -1...
Racal ra6790/gm alignment & tuning manual page 11 of 20 (3) adjust r19 and r23 to the full clockwise positions. Cancel man agc and note the indication of the rf millivoltmeter. Rf millivoltmeter should read 70 +10 millivolts. (4) reduce the am/fm signal generator output to -113 dbm (0.5 uvolts). Sel...
Racal ra6790/gm alignment & tuning manual page 12 of 20 h. First lo synthesizer, circuit card assembly a7. This circuit card assembly is located in the bottom portion of the receiver. The test equipment required to align the assembly includes the spectrum analyzer, digital multimeter, digital freque...
Racal ra6790/gm alignment & tuning manual page 13 of 20 counter to p2 (bfo output). Connect the digital multimeter between tp8, and ground and set on the 10 volt dc range. Note with the probe of the digital multimeter on tp8 a fault may be indicated on the front panel. This is normal and alignment p...
Racal ra6790/gm alignment & tuning manual page 14 of 20 section ii. Assembled receiver test 3-3. General. This section prov i des procedures to check the receiver's operation after repairs and/or alignment have been made. The test procedures are designed to provide an overall operational check of th...
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 termina...
Racal ra6790/gm alignment & tuning manual page 16 of 20 (1) set the receiver controls as follows: power on gain mode agc-short detection mode cw bw 3 khz (or closest bandwidth available) bfo on (word bfo displayed in mode lcd) (2) disconnect w6p2 from j5 on the a4 module. (3) using the 50 ohm adapte...
Racal ra6790/gm alignment & tuning manual page 17 of 20 khz +50 hz as indicated on the digital frequency counter. (5) set the af output level to 1 milliwatt using the line level control on the receiver front panel and phone output. (6) select receiver bandwidth of 6.0 khz (or closest bandwidth avail...
Racal ra6790/gm alignment & tuning manual page 18 of 20 receiver to 12.55 mhz. (5) adjust the manual if gain control on the receiver for a -10 dbm reading on the rf millivoltmeter. (6) tune the receiver to 12.05 mhz and set step attenuator to 5 db. Note that the rf millivoltmeter reads 65 db below r...
Racal ra6790/gm alignment & tuning manual page 19 of 20 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. Read...
Racal ra6790/gm alignment & tuning manual page 20 of 20 (4) on the receiver select lsb and manual agc. Table 3-3. Special filters delay test parameters filter number filter slot reference frequency start frequency stop frequency delay microseconds 4 fl1 455825 455600 457850 1000 5 fl2 454175 454400 ...
