[R-390] R390_Inspection_List_Part_4

Wed Sep 12 15:53:17 EDT 2012

Q IF And Audio Module Tube Optimizing
Optimizing the vacuum tube lineup in the signal path isanother technique to maximize performance. Start with the tubes in the IFstrip. These are the 5749W's IF amps, V-501, V-502 and V-503. The 6AK6 4th IFamp V-504 and the detector, V-506, a 5814A. Continue with the Audio moduletubes. Then do the RF module tubes last. The tubes can be optimized before anyalignment is conducted. But the usual procedure is to do a signal alignment,conduct the tube optimization and then do another complete signal alignment.Normal procedure is to conduct the signal alignment and tube optimizationtogether in module by module stages IF and Audio modules, then RF and oscillatormodules. Watch the noise level of each tube with the modulation off. The metershould lie quietly. If the meter needle is bouncing then consider this asadditional noise from the tube. It may take several passes in a poor receiverto grade other noisy tubes out of the receiver and reach acceptable levels ofperformance. Use the best tubes on hand and place them in the optimumperformance order. New tubes may not be better than existing tubes. When newtubes are received, grade them against all like tubes on hand. Keep track ofthe spares and their values. If the signal to noise ratios are good some meterbounce is expected. If you reach the point where you believe you have goodtubes through the receiver and the meter just will not lie quietly, then youhave to start looking for, leaky caps, poor resistors, bad solder joints, dirtytube sockets, dirty connector pins, loose or corroded tie lugs.

___ 01 Set the Line Meter OFF
___ 02 Set the Line gain to 0
___ 03 Set the ANT Trim to 0
___ 04 Set the AGC to MED
___ 05 Set the LIMITER to OFF
___ 06 Set the Band Width to 2KHz
___ 07 Set the BFO Pitch to 0
___ 08 Set the Audio Response to WIDE
___ 09 Set the Breakin OFF
___ 10 Set the Function Switch to MGC
___ 11 Set the BFO to OFF
___ 12 Release the Zero Adjust
___ 13 Release the Dial Lock
___ 14 Set the Local Audio to max
___ 15 Set the RF to max
___ 16 Remove P114 from J514
___ 17 Remove P213 from J513
___ 18 Remove P218 from J518
___ 19 Remove J116 adapter from the back panel if necessary
___ 20 Couple P114 to J513
___ 21 Couple P116 to J116
___ 22 Couple J116 to the signal generator RF output
___ 22 Adjust signal generator for 455 KHz output frequency
___ 24 Adjust signal generator for 150 micro volt RF output 
___ 25 Adjust signal generator for 30 % audio tonemodulation (400 Hz)
___ 26 Meter diode load output for –7 volts DC
___ 27 Place a 600 ohm load across the local audio output
___ 28 Meter local audio output for 450 milliwatts, 27 db,or 17.3 Volts AC
___ 29 In pass one gather all the spare 5749’s
___ 30 Pull the BFO and VFO 5759 tubes (V505, V701)
___ 31 Pull the AGC IF AMP (V508)
___ 32 Remember the goal is best signal to noise ratio oreach tube
___ 33 Set the signal generator modulation on and record theaudio output
___ 34 Set the signal generator modulation off and recordthe audio output
___ 35 The difference in these two values is the merit ofthe tube in V501
___ 36 Place each spare 5759 into V501 to find a merit valuefor the tube
___ 37 Grade the spare 5749’s from worse to best
___ 38 Place the worse tube in V503
___ 39 Place the second poorest tube in V502
___ 40 Start over and re-grade the 5749’s in V501 (32, 33,34)
___ 41 Select the very best signal to noise 5749 for theV701 (VFO)
___ 42 Place the second best 5749 in V501
___ 43 Place the third best 5749 in V502
___ 44 Place the fourth best 5749 in V503
___ 45 Place the fifth best 5749 in V505 (BFO)
___ 46 Place the sixth best 5749 in V508 (AGC IF AMP)
___ 47 In pass two gather all the spare 6AK6’s
___ 48 Remove V604 Line Audio
___ 49 Set the signal generator modulation on and record theaudio output
___ 50 Set the signal generator modulation off and recordthe audio output
___ 51 The difference in these two values is the merit ofthe tube in V504
___ 52 Place each spare 6AK6 into V504 to find a merit valuefor the tube
___ 53 Place the worse tube in V603 Local Audio
___ 54 Start over and re-grade the 6AK6’s in V504 (49, 50,51)
___ 55 Place the best 6AK6 in V504 (4th IF Stage)
___ 56 Place the second best 6AK6 in V603 Local Audio
___ 57 Place the third best 6AK6 in V604 Line Audio
___ 58 In pass three gather all the spare 5814’s
___ 59 Remove V507, V509, V205, V206
___ 60 Set the signal generator modulation on and record theaudio output
___ 61 Set the signal generator modulation off and recordthe audio output
___ 62 The difference in these two values is the merit ofthe tube in V601
___ 63 Place each spare 5814 into V601 to find a merit valuefor the tube
___ 64 Place the worse tube in V602
___ 65 Place the second worse tube in V506
___ 66 Start over and re-grade the 5814’s in V601 (60, 61,62)
___ 67 Place the best 5814 in V506 Detector
___ 68 Place the 2nd best 5814 in V601 1stAF AMP and Follower
___ 69 Place the 3rd best 5814 in V602 Local AFAMP
___ 70 Place the 4th best 5814 in V507 Limiter
___ 71 Place the 5th best 5814 in V205Calibration Oscillator
___ 72 Place the 6th best 5814 in V206 100 KCMultivibrator
___ 73 Place the 7th best 5814 in V509 AGCRectifier
___ 74 Adjust signal generator for 455 KHz output frequency
___ 75 Adjust signal generator for 150 micro volt RF output 
___ 76 Adjust signal generator for 30 % audio tonemodulation (400 Hz)
___ 77 Meter diode load output for –7 volts DC
___ 78 Set the Band Width to 2 KHz
___ 79 Adjust the IF gain R519 for –7 V DC on the diode load
___ 80 Meter local audio output for 450 milliwatts, 27 db,or 17.3 Volts AC
___ 81 Set the signal generator modulation on and record theaudio output
___ 82 Set the signal generator modulation off and recordthe audio output
___ 83 Meter local audio output for 1 milliwatt, 0 db, or.775 Volts AC
___ 84 If the difference must be greater than 27 db. (30likely)
___ 85 Remove all test equipment
___ 86 Return the receiver connections to their originalconfigurations

R. Adjust T208, C520, L503, and Zero BFO
___ 01 Set the Line Meter OFF
___ 02 Set the Line gain to 0
___ 03 Set the ANT Trim to 0
___ 04 Set the AGC to MED
___ 05 Set the LIMITER to OFF
___ 06 Set the Band Width to 2KHz
___ 07 Set the BFO Pitch to 0
___ 08 Set the Audio Response to wide
___ 09 Set the Breakin OFF
___ 10 Set the Function to MGC
___ 11 Set the BFO OFF
___ 12 Release the Zero Adjust
___ 13 Release the Dial Lock
___ 14 Set the Local Audio to max
___ 15 Set the RF to max
___ 16 Adjust signal generator for 455 KHz output frequency
___ 17 Adjust signal generator for 75 micro volt RF output
___ 18 Adjust signal generator for 30 % audio tonemodulation (400 Hz)
___ 19 Meter diode load output for –7 volts DC
___ 20 Place a 600 ohm load across the local audio output
___ 21 Meter local audio output for 450 milliwatts, 27 db,or 17.3 Volts AC
___ 22 Connect the signal generator to E211 through acapacitor.
___ 23 Adjust signal generator for diode load output of –7volts DC
___ 24 Adjust T208 for peak (This adjustment is broad)
___ 25 Adjust signal generator for diode load output of –7volts DC
___ 26 The signal level should be less than 75 micro volt RFoutput (50)
___ 27 The signal with 30% modulation should output 450milliwatts audio
___ 28 Set the signal generator modulation on and record theaudio output
___ 29 Meter local audio output for 450 milliwatts 27 db,ormore
___ 30 Set the signal generator modulation off and recordthe audio output
___ 31 Meter local audio output for 1 milliwatt, 0 db, orless
___ 32 Set the Band Width to .1 KHz
___ 33 Rock the signal generator for maximum diode loadoutput
___ 34 Adjust signal generator for diode load output of –7volts DC
___ 35 Record the signal generator output level
___ 36 The following steps should produce six marks aroundC520
___ 37 Switch the generator output up 60 db (two switchsteps on URM 25)
___ 38 Increase the generator frequency until output dropsto –7 volts DC
___ 39 Adjust C520 for a dip in the diode load voltage
___ 40 Mark the can and label this H (5 o’clock)
___ 41 Adjust C520 for the other side dip in the diode loadvoltage 
___ 42 Mark the can and label this H (7 o’clock)
___ 43 Decrease the generator frequency until output dropsto –7 volts DC
___ 44 Adjust C520 for a dip in the diode load voltage
___ 45 Mark the can and label this L (4 o’clock)
___ 46 Adjust C520 for the other side dip in the diode loadvoltage 
___ 47 Mark the can and label this L (8 o’clock)
___ 48 Divide each pair of dips and mark the can C
___ 49 Set C520 to the C mark (either 4:30 or 7:30)
___ 50 Rock the signal generator (to 455) for maximum diodeload output
___ 51 Adjust signal generator for diode load output of –7volts DC
___ 52 Set the Band Width to 1 KHz
___ 53 Adjust L503 for peak output
___ 54 Set the BFO switch ON
___ 55 Loosen the clamp on the BFO shaft extension
___ 56 Zero the BFO knob
___ 57 Zero the BFO against the signal
___ 55 Tighen the clamp on the BFO shaft extension
___ 56 Set the BFO switch OFF
___ 57 Disconnect the generator

S 2nd Crystal Oscillator Alignment
When adjusting the 2nd Crystal Oscillator you canhear the noise peak better than you can measure it with the meter. Peak thecaps up with both the meter and head phones.

___ 01 Meter the local audio output across a 600 Ohm load
___ 02 Meter the diode load for – 7 volts DC
___ 03 Use a good set of head phones to monitor the audiooutput
___ 04 Set the function switch to CAL
___ 05 Set the BFO OFF
___ 06 Set the KHz to 500
___ 07 Set the KHz to 31
___ 08 Set the Bandwidth to 2 KHz
___ 09 Rock the KHz to produce maximum indication on thediode load
___ 10 Set the Local Output meter range to provide a midscale reading
___ 11 Use the head phones to hear the noise peak as youmake adjustments
___ 12 Screw the slug of T401 out until only one peak can beobtained while turning trimmer capacitor 31 through its entire range.
___ 13 Set trimmer capacitor slightly away from peak
___ 14 Adjust the slug in T401 for peak output
___ 15 Readjust capacitor 31 and ensure it has two peaks.
___ 16 Adjust capacitor 31 to peak (watch the meters for bestindication)
___ 17 Move the MHz down one detent (you can hear the noisepeak)
___ 18 Adjust the corresponding capacitor to peak
___ 19 Stop at 8MHz

T 1st Crystal Oscillator Alignment
___ 01 Meter the local audio output across a 600 Ohm load
___ 02 Meter the diode load for – 7 volts DC
___ 03 Use a good set of head phones to monitor the audiooutput
___ 04 Set the function switch to CAL
___ 05 Set the BFO OFF
___ 06 Set the KHz to 500
___ 07 Set the MHz to 7
___ 08 Set the Bandwidth to 2 KHz
___ 09 Rock the KHz to produce maximum indication on thediode load
___ 10 Adjust the slug in T207 for peak output

U VFO Band Spread Test
___ 01 Set the Line Meter OFF
___ 02 Set the Line gain to 0
___ 03 Set the ANT Trim to 0
___ 04 Set the AGC to MED
___ 05 Set the LIMITER to OFF
___ 06 Set the Band Width to 2KHz
___ 07 Set the BFO Pitch to 0
___ 08 Set the Audio Response to wide
___ 09 Set the Breakin to OFF
___ 10 Set the Function to CAL
___ 11 Set the BFO to ON
___ 12 Set the Zero Adjust to center
___ 13 Release the Dial Lock
___ 14 Set the Local Audio to max
___ 15 Set the RF to max
___ 16 Set the KHz knob to -000
___ 17 Adjust the BFO Pitch to zero beat
___ 18 Set the KHz knob to +000
___ 19 Rock the KHz knob to zero beat
___ 20 The VFO band spread should be less than 300 Hertz

V VFO Band Spread Adjustment
___ 01 If needed continue from the preceding section
___ 02 Set the FUNCTION switch to CAL
___ 03 Set the MHz to 9 MHz
___ 04 Set the Zero Adjust to center
___ 05 Set the KHz knob to 000
___ 06 Remove the Oldham coupler spring
___ 07 Remove the VFO from the receive
___ 08 Remove the end point adjustment cap screw
___ 09 Attach the output cable and harness cable
___ 10 Adjust the VFO shaft for a zero beat
___ 11 Mark the coupler and VFO face (9,000 3,455)
___ 12 Set the KHz knob for 9,+000 (9,+000 2,455)
___ 13 Dial 10 turns on the VFO shaft and align the marks
___ 14 If the span is not exact make a small adjustment tothe end point
___ 15 Do not over adjust the end point to a complete zerobeat
___ 16 Observe the pitch is closer to zero beat
___ 17 Back off the 10 turns on the VFO shaft (only work oneway)
___ 18 Set the KHz knob to 000
___ 19 Adjust the VFO shaft for a zero beat
___ 20 Mark the coupler and VFO face (9,000 3,455)
___ 21 Set the KHz knob for 9,+000 (9,+000 2,455)
___ 22 Dial 10 turns on the VFO shaft and align the marks
___ 23 If the span is not exact make a small adjustment tothe end point
___ 24 Do not over adjust the end point to a complete zerobeat
___ 25 Observe the pitch is closer to zero beat
___ 26 Repeat steps 17, 18, 19, 20, 21,22, 23, 24 and 25until span is exact
___ 27 Make a small adjustment to the end point (CW longerCCW shorter
___ 28 Do not over adjust the end point to a complete zerobeat
___ 29 replace the end point cover screw
___ 30 Return the VFO shaft to its original location
___ 31 Reinstall the VFO into the receiver
___ 32 Carefully verify the 10 turn operation of the VFO
___ 33 Adjust the mechanical position of module for bestshaft alignment
___ 34 Adjust the Oldham coupler for a free spacing ofshafts
___ 35 Replace the Oldham coupler spring
___ 36 Attach an antenna to the balanced input
___ 37 Tune WWV at 20MHz, 15Mhz, 10MHz or 5Mhz
___ 38 Set the BFO to OFF
___ 39 Set the bandwidth to .1Khz
___ 40 Set the KHz to 000
___ 41 Loosen the front KHz shaft clamp on the Oldhamcoupler
___ 42 Rock the VFO to peak WWV through the crystal filter
___ 43 Tighten the front KHz shaft clamp on the Oldhamcoupler
___ 44 Set the BFO to ON
___ 45 Set the BFO Pitch to 0
___ 46 Loosen the extension shaft clamp on the BFO
___ 47 Adjust the BFO shaft to zero the BFO Pitch
___ 48 Tighten the extension shaft clamp on the BFO
___ 49 Set the FUNCTION Switch to CAL
___ 50 Adjust the CAL Adjust Trim to zero the CalibrationOscillator

W. RF Alignment

___ 01 Install a 600 ohm resistor on the line level output.
___ 02 Place a meter and 600 ohm load on the Local Audiooutput TS 585
___ 03 Connect the generator to the receiver’s balancedantenna input
___ 04 Place a DC meter on the diode load
___ 05 Turn the receiver on and allow it to warm up for 1hour
___ 06 Turn the signal generator on and allow it to warm upfor 1 hour
___ 07 Set the R390 or R390A Function switch to "MGC
___ 08 Set the R390 or R390A Bandwidth to 2kc
___ 09 Set the R390 or R390A RF gain full CW (Clock Wise)
___ 10 Set the R390 or R390A AF line gain full CW
___ 11 Set the Line Meter range switch to + 10
___ 12 Set the R390 or R390A AF local gain full CW
___ 13 Set the R390 or R390A BFO off
___ 14 Set the Audio response to wide
___ 15 Set the Limiter to off
___ 16 Set the receiver and generator to the same frequencyof choice
___ 17 Rock the generator for a peak in to the band pass
___ 18 Set the initial generator output to 10uv
___ 19 Set the generator modulation level to at 30% 400 Hz or1 KHz
___ 20 Use the Ant Trim to peak the receiver
___ 21 Reduce the signal generator RF output for –7 volts DC

___ 22 Use 550 for L213, L224-1,, L224-2 Slugs 1stOctave
___ 23 Use 950 for C201-B, C230-1, C230-2 Caps 1stOctave
___ 24 Use 1,100 for L215-1, L215-2, L215-3 Slugs 2ndOctave
___ 25 Use 1,100 for C291-1, C291-2, C291-3 Caps 2ndVariable IF
___ 26 Use 1,250 for L232-1, L232-2, L232-3 Slugs 1stVariable IF
___ 27 Use 1,900 for L233-1, L233-2, L233-3 Slugs 2ndVariable IF
___ 28 Use 1,900 for C205-B, C233-1, C233-2 Caps 2ndOctave
___ 29 Use 2,250 for L217, L226-1, L226-3 Slugs 3rdOctave
___ 30 Use 3,800 for C209B, C236-1, C26-2 Caps 3rdOctave
___ 31 Use 4,400 for L219, L227-1, L227-2 Slugs 4thOctave
___ 32 Use 7,250 for C283-1, C283-2, C283-3 Caps 1stVariable IF
___ 33 Use 7,600 for C213B, C239-1, C239-2 Caps 4thOctave
___ 34 Use 8,800 for L221, L227-1, L227-2 Slugs 5thOctave
___ 35 Use 15,200 for C217B, C242-1, C242-2 Caps 5thOctave
___ 36 Use 17,600 for L223, L229-1, L229-2 Slugs 6thOctave
___ 37 Use 30,400 for C221B, C241-1, C241-2 Caps 6thOctave

___ 38 Observe 27 DB (17 Volts AC) on the Local Audio
___ 39 This should also be 450 milliwatts on the Local Audio
___ 40 Observe + 10 on the Line Meter (0 VU + 10 switch)
___ 41 Set the signal generator to CW
___ 42 The Meter on the Local Level should drop 20 DB
___ 43 The Line Meter should drop 20 DB
___ 44 The signal generator RF level should be less than 3micro volts
___ 45 Record the frequency and the output of the generatorin micro volts
___ 46 This value is the 20 DB S/N + N receiver level atthis frequency
___ 47 This is the relative receiver noise floor level atthis frequency

___ 48 Use the following check the mechanical filters at onefrequency
___ 49 Set BANDWIDTH KC switch S501 to position 1.
___ 50 Adjust the signal generator output for -5 volts onthe diode load
___ 51 Tune the KILOCYCLE CHANGE to one side of the center
___ frequency until the multi-meter reads 2.5 volts.
___ 52 Note the frequency indicated on the receiver frequencycounter.
___ 53 Tune the receiver KILOCYCLE CHANGE control to theother side
___ of the center frequency until the meter reads 2.5 volts.
___ 54 Note the frequency indicated on the receiverfrequency counter
___ 55 Subtract the lower from the higher of the two values
___ 56 This is the receiver bandwidth for 1 Kilohertz BandWidth 0.8 to 1.3
___ 57 Set BANDWIDTH KC switch S501 to 2 KHz position
___ 58 Repeat steps 50 through 55 for the 2 KHz band width1.9 to 2.3
___ 59 Set BANDWIDTH KC switch S501 to 4 KHz position
___ 60 Repeat steps 50 through 55 for the 4 KHz band width3.6 to 4.4
___ 61 Set BANDWIDTH KC switch S501 to 8 KHz position
___ 62 Repeat steps 50 through 55 for the 8 KHz band width7.5 or more
___ 63 Set BANDWIDTH KC switch S501 to 16 KHz position
___ 64 Repeat steps 50 through 55 for the 16 KHz band width12 or more
___ 65 No bandwidth test is required for 0.1 KC setting.