[R-390] the saga continues part 2

[Flowertime01 at wmconnect.com]

Only [ahem] one question this time around--Z503 with it's single slug, is it
normal for the slug to be almost all the way 'in' [bottomed] at 455kc?

73 de KA9EGW

Ok here. Z503 is the AGC trap / peak coil. You expect the tank to devlope 
amaximum votage peak that makes it into the AGC rectifier. It will peak where 
it peaks. Given 50 years of grim water and universe seeping into the parts, 
it can peak any where it wants to. Try not to read to much signifficance 
into the exactness of the AGC circuits. Since being introduced to the AGC 
circuit of R390/A I have found them to be the least exact part of the receiver.

Your Good.

With your generator and a couple of meters, you should be able to get 
things aligned.

If you are not getting 30 DB difference in the IF and audio with modulated 
to un modulated signal you will never get the receiver up to par. This value 
is published NOWHERE. Some thing the manuals never told you. Checked and 
working is no merit figure of signal to noise or sensivity. Fair radio is 
good. I like them. But there are limits to what they can do for us and still 
sell it at a reasonable price. Checked and working is checked and working. Its 
what you expect the receiver to work like before you start the semi annual 
PM not after you finish the PM.

Go to paragraph 6.2.8.2 in the Y2K manual and hook the generator up for the 
150 micro volts. Hang a DC voltmeter on the diode load. Hang an AC 
voltmeter on the local audio output on the back panel with a 600 ohm load resistor.

J Adjust the IF gain R519
___ 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 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 tone modulation (400 Hz)
___ 26 Meter diode load output for -7 volts DC
___ 27 Place a 600 ohm load across the local audio output
___ 28 Place a 600 ohm load across the line audio output
___ 29 Meter local audio output for 450 milliwatts, 27 db, or 17.3 Volts AC
___ 30 Adjust the IF gain R519 for -7 V DC on the diode load
___ 31 Observe the local audio output level is greater than 400 milliwatts
___ 32 Local Audio should be 17.3 Volts AC across 600 Ohms 450 mw
___ 33 Line Audio should be 2.45 Volts AC across 600 Ohms 10 mw
___ 34 Phone Audio should be .78 Volts AC across 600 Ohms 1 mw
___ 35 Line Audio at .78 Volts across 600 should be Line Meter Zero VU
___ 36 Set the Line Meter to +10
___ 37 Set the signal generator modulation on
___ 38 The Line Meter should read above 0 VU (10 mw)
___ 39 Set the Line Gain off max until the Line Meter reads 0 VU (10 mw)
___ 40 Set the signal generator modulation off
___ 41 Set the Meter Switch to -10
___ 42 Observe 30 db change (20 db on switch plus 10 db on meter scale)
___ 43 The Line Meter should read less than -10 VU (SN + N > 30 DB)
___ 44 Set the Line Meter to OFF
___ 45 Set the Line Gain to 0

The volt meter on the local audio should also give you a 30 DB difference 
between modulation on and modulation off.  If the IF deck and audio deck will 
not give you this 30 DB difference, there is nothing you can do in the RF 
deck to overcome this poor performance. No RF deck will let you have good 
signal to noise if you can not get this 30 DB difference from this test of the 
IF deck and audio deck.

If you are not getting this 30 DB difference its time to start swapping 
tubes.

While measuring the local audio, you can also watch the line meter and see 
the same 30 DB differences. Mostly you just have a larger better eisier to 
read meter to hang on the local audio than the line level meter.

P IF And Audio Module Tube Optimizing
Optimizing the vacuum tube lineup in the signal path is another technique 
to maximize performance. Start with the tubes in the IF strip. These are the 
5749W's IF amps, V-501, V-502 and V-503. The 6AK6 4th IF amp V-504 and the 
detector, V-506, a 5814A. Continue with the Audio module tubes. Then do the 
RF module tubes last. The tubes can be optimized before any alignment 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 optimization together in 
module by module stages IF and Audio modules, then RF and oscillator modules. 
Watch the noise level of each tube with the modulation off. The meter should 
lie quietly. If the meter needle is bouncing then consider this as additional 
noise from the tube. It may take several passes in a poor receiver to grade 
other noisy tubes out of the receiver and reach acceptable levels of 
performance. Use the best tubes on hand and place them in the optimum performance 
order. New tubes may not be better than existing tubes. When new tubes are 
received, grade them against all like tubes on hand. Keep track of the spares 
and their values. If the signal to noise ratios are good some meter bounce 
is expected. If you reach the point where you believe you have good tubes 
through the receiver and the meter just will not lie quietly, then you have to 
start looking for, leaky caps, poor resistors, bad solder joints, dirty tube 
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 tone modulation (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 or each tube
___ 33 Set the signal generator modulation on and record the audio output
___ 34 Set the signal generator modulation off and record the audio output
___ 35 The difference in these two values is the merit of the tube in V501
___ 36 Place each spare 5759 into V501 to find a merit value for 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 the V701 (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 the audio output
___ 50 Set the signal generator modulation off and record the audio output
___ 51 The difference in these two values is the merit of the tube in V504
___ 52 Place each spare 6AK6 into V504 to find a merit value for 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 the audio output
___ 61 Set the signal generator modulation off and record the audio output
___ 62 The difference in these two values is the merit of the tube in V601
___ 63 Place each spare 5814 into V601 to find a merit value for 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 1st AF AMP and Follower
___ 69 Place the 3rd best 5814 in V602 Local AF AMP
___ 70 Place the 4th best 5814 in V507 Limiter
___ 71 Place the 5th best 5814 in V205 Calibration Oscillator
___ 72 Place the 6th best 5814 in V206 100 KC Multivibrator
___ 73 Place the 7th best 5814 in V509 AGC Rectifier
___ 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 tone modulation (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 the audio output
___ 82 Set the signal generator modulation off and record the 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. (30 likely)
___ 85 Remove all test equipment
___ 86 Return the receiver connections to their original configurations

Once you get the IF and audio up to par, you can start on the RF deck.

I think you just need lots of alignment in the Rf deck at this point. You 
have played with the cams and its all off peak. Just drive what ever level 
you have to through the reciever and make several passes through the whole 
alignement of the Rf deck. It will come back to life.

Roger AI4NI</HTML>