[R-390] I had a working R-390A before I started (sort of)

[Flowertime01 at wmconnect.com]

Jim,

Do a guy thing and just jump right into the middle.
Start with 150 UV into the IF deck as follows.
You can divide the problem back to the IF and Audio or RF deck.
Check between MGC and AGC. this may help you isolate a problem.

I will go for a bad mechanical lug mount hard ware on one of the caps.

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

You are really looking for that 30 db change in the IF deck.
If the IF deck will not get past this procedure, there is nothing in the RF 
deck that will overcome the IF deck's lack of performance.

Do not worry if your signal generator is not calibrated. Set R519 about mid 
scale. Adjust the generator for a -7 volts on the DC load. The audio with 
modulation against the audio with out modulation (CW) should be more than 25 
db difference on the meter.

If you do not have an AC volt meter with a DB scale find the inspection 
list on Barry's page. There is an AC volt table to use with a 600 ohm resistor 
and you can do the comparsion as AC voltages.

<http://home.comcast.net/~rbethman/inspectionlist_34.doc>



Once you get the IF deck and Audio deck back to par, you can then go on to 
the RF deck and crystal calibration problems.

Roger AI4NI</HTML>