The AM Forum

After using this thing for a little while I decided to start the alignment process and see if it is running to full capacity.  I've run into a section that has confused me a little.  First off here is the service manual for it http://bama.edebris.com/download/military/r392/TM11-5820-334-35.pdf

I'm at section 84 (alignment of 455khz if stages) At the end of this section on page 114 paragraph h, i, and j are the spots I'm referring to.  First of all it mentions to set bias adjust r532 for maximum indication.  So the bias cranked all the way down is the highest indication (0 ohms on var resistor) is the maximum indication.  So why even put the var resistor there if this is the procedure?  Next it mentions the var cathode resistor for v504(the previous if stage).  It says to adjust r521 for an indication of approximately 2.5 volts, which is not nearly what I'm getting at J615. Well R521 is a fixed 10K resistor.  It looks factory is this a change that was made later on?  I thought it was odd that to get to r521 you have to remove the lower deck assembly but r532 is easily adjusted on the rear of the receiver.  Maybe somebody has a lot of experience with these things.  Thanks, Nathan

I found a copy of more of a "user manual".  In the schematics in THAT book the circuit is as mine is.  10k fixed resistor on 4th IF amp and 10k variable on 5th IF amp. I guess I will just play with the bias and see where it works best.  I assume that to much gain may cause noise?

Too much gain causes oscillations at IF.
Test for no oscillation with and without BFO
Test at 2 4 an 8 kHz selectivity and during selectivity changes by rotating the knob.

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