[R-390] Setting I-F GAIN ADJ pot and tuning R-F stages on noise

[Flowertime01 at wmconnect.com]

Fellows,

Lets get this one over in the PEARLS OF WISDOM.

I like the idea of seting the meters against the receiver noise so that we 
can watch
the receiver noise change with time on the tubes. I expect noise to go up and 
sensivity go down over time.

Roger AI4NI

Over the years, I developed a simple set of procedures for adjusting the sets 
used by hobbyists, as opposed to sets in use by the Navy (which must be done 
according to the standards):

1. Adjust the RF and IF stages for a peak on front -end noise with no signal 
input. Use the LINE LEVEL meter.   The 0.5 - 1.0 MC band needs termination of 
the antenna input with a 50-ohm resistor, and then realignment with  the ANT 
TRIM control set to zero and on the antenna to be used. This most closely 
mimics weak-signal reception. Use the most sensitive combination of LINE LEVEL 
meter and LINE LEVEL pot possible. Note: as long as R-F input  levels don't exceed 
about 10 µV (as with front-end noise), the set can be aligned with the 
FUNCTION control set for "MGC."

2. Set the I-F GAIN ADJ pot for deflection of the LINE LEVEL meter to "100," 
with the LINE METER set to "+10," and the LINE GAIN pot set fully clockwise. 
This also provides a rough check of the deterioration of tubes over time.
  


Charles A Taylor, WD4INP
   Grifton, North Carolina