[R-390] R-390A Alternate way to set IF Gain by Chuck Rippel in 1998

[Larry H]

The following is the 'heart' of Chuck's original post on this subject: 

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From: crippel at ...
Date: Mon Feb 2, 1998 5:35 am 
Subject: [R-390] R-390A IF gain Setting Technique

Procedure to set R390A IF Gain - Alternate
Allow the receiver to warm up for at least 1 hour then:
• Disconnect the antenna
• Set receiver for 15.2 mHz
• Set the FUNCTION control to MGC
• Select the 4kc filter with the BANDWIDTH
• Set RF GAIN control to 10 or maximum
• Peak ANTENNA TRIM for maximum noise indicated on the LINE LEVEL meter
• Set Line Meter switch to -10db scale
• Set Line Gain control to full CW or 10.
• Adjust IF gain control, R-519 to cause Line Level meter
    to indicate between -4 to -7 db.

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End of Chuck's procedure.

Before I went through my RF deck and IF deck tubes and installed selected low noise and high gain rated correct tubes (as outlined by Roger Ruszkowski), I used Chuck's procedure to set the IF gain.  It ended up at the -4 db reading, with the IF gain set at about 1/2.  I felt that this was good (and it was) at the time.

Now with the correct low noise and high gain tubes installed and setting it at the -4 db reading, the IF gain is set at about 1/4.  I'm sure that the difference is due to the tubes used, and of course a realignment was done due to the tube change (this had no affect).

However, because the antenna I'm using does not have much output on some bands, and the measurements I made a few weeks ago indicate a higher gain setting is not a problem, I set it at 1/2.  This equals a +3 db level (switch on -10).  I'm very pleased with the performance at this level.

Thanks Chuck and Roger!

Side note - I've found that in Chuck's procedure, as long as you can peak the 'ant trim', it does not make any difference in the measurement if the antenna is shorted, terminated, or open.

Regards, Larry