Related Manuals for Racal Instruments RA6790/GM
Summary of Contents for Racal Instruments RA6790/GM
- Page 300 RACAL RA6790/GM ALIGNMENT AND TUNING MANUAL From Maxhdrm2@comcast.net February 2003...
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Page 301: Section I. Assembled Receiver Alignment
Racal RA6790/GM Alignment & Tuning Manual 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 contained in Section I and procedures for an end-to-end check presented in Section II. - Page 302 Racal RA6790/GM Alignment & Tuning Manual 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. Low Pass Filter, Assembly Al.
- Page 303 Racal RA6790/GM Alignment & Tuning Manual 45 MHz RELATIVE LEV EL>20dB 0.5MHz 40.453MHz <^ EACH GRATICULE 10 MHz Figure 3-2. Alignment Waveforms 45 MHz RELATIVE LEVEL> 20dB EACH GRATICULE lOdB <^ EACH GRATICULE 10 MHz Figure 3-2. Alignment Waveforms Page 4 of 20...
- Page 304 Racal RA6790/GM Alignment & Tuning Manual 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 align the first mixer assembly A2.
- Page 305 Racal RA6790/GM Alignment & Tuning Manual 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 are at least 20 dB down from a reference level at 30 MHz.
- Page 306 Racal RA6790/GM Alignment & Tuning Manual cable A3W2 to J6. 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...
- Page 307 Racal RA6790/GM Alignment & Tuning Manual generator Note reading 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.
- Page 308 Racal RA6790/GM Alignment & Tuning Manual 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.
- Page 309 Racal RA6790/GM Alignment & Tuning Manual TABLE 3-1. BANDPASS FILTER CHARACTERISTICS Bandpass Filter sband - Hz Stopband - Hz Maximum Attenuation 60 dB Minimum Attenuation From Below Above 400 Hz -200 +200 -1240 +1240 -600 +600 -3600 +3600 6.8 kHz...
- Page 310 Racal RA6790/GM Alignment & Tuning Manual 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. Reduce the AM/FM signal generator output to -113 dBm (0.5 uVolts). Select MAN AGC, cancel SHORT AGC, adjust R19 for 64 +10 millivolts indication on RF millivoltmeter.
- Page 311 Racal RA6790/GM Alignment & Tuning Manual 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 frequency counter and 50-ohm adapter, listed in Table 1-2.
- Page 312 Racal RA6790/GM Alignment & Tuning Manual 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.
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Page 313: Section Ii. Assembled Receiver Test
Racal RA6790/GM Alignment & Tuning Manual SECTION II. ASSEMBLED RECEIVER TEST 3-3. GENERAL. This section provides 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 the Receiver and to ascertain that its functional capabilities have not been impaired. - Page 314 Racal RA6790/GM Alignment & Tuning Manual standard is 5 MHz +1 Hz. Disconnect digital frequency counter and reconnect PI of cable W4 to J2 and RF Gain Control. This test requires the distortion analyzer and signal generator listed in Table 1-2.
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Page 315: Test Results
Racal RA6790/GM Alignment & Tuning Manual Set the Receiver controls as follows: Power Gain Mode AGC-SHORT Detection Mode 3 kHz (or closest bandwidth available) ON (word BFO displayed in Mode LCD) Disconnect W6P2 from J5 on the A4 module. Using the 50 ohm adapter, connect the digital frequency counter to W6P2 to monitor the BFO frequency. - Page 316 Racal RA6790/GM Alignment & Tuning Manual kHz +50 Hz as indicated on the digital frequency counter. Set the AF output level to 1 milliwatt using the LINE LEVEL control on the Receiver front panel and phone output. Select Receiver bandwidth of 6.0 kHz (or closest bandwidth available) and AM detector mode.
- Page 317 Racal RA6790/GM Alignment & Tuning Manual Receiver to 12.55 MHz. Adjust the manual IF gain control on the Receiver for a -10 dBm reading on the RF millivoltmeter. Tune the Receiver to 12.05 MHz and set step attenuator to 5 dB. Note that the RF millivoltmeter reads 65 dB below reading in step 5.
- Page 318 Racal RA6790/GM Alignment & Tuning Manual panel. Tune the Receiver to 5.0 MHz. Adjust RF signal generator to 5.0 MHz with a +3 dBm output level. Set vector impedance meter frequency range to 4.5-14 MHz and magnitude range to 100.
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Page 319: Reference Frequency
Racal RA6790/GM Alignment & Tuning Manual On the Receiver select LSB and manual AGC. TABLE 3-3. SPECIAL FILTERS DELAY TEST PARAMETERS FILTER FILTER REFERENCE START STOP DELAY NUMBER SLOT FREQUENCY FREQUENCY FREQUENCY MICROSECONDS 455825 455600 457850 1000 454175 454400 452150...