[R-390] Restoration questions

[Roy Morgan]

On Jun 20, 2013, at 8:40 AM, Barry <n4buq at knology.net> wrote:

> That last detente is for an optional squelch circuit.

And there is or was a detent setting plate at the front of the detent part of the switch to prevent the shaft from going to that position if the squelch parts/system is not installed.  There are one or two blank plates on the IF module if the mod is not installed.

> 
> Sounds like the IF gain needs to be adjusted.  It's easy to set it too "hot".  There should be info in the manual for setting it.

There is a simplified way to set the gain if you don't have the signal generator and/or whatever else is called for in the manual:


IF GAIN SETTING

Here is Chuck's procedure:
From: http://www.R390A.com/html/gain.html>
Text in brackets [ ... ] is mine (Roy, K1LKY)
*********************
Procedure to set R390A IF Gain:

 Once the receiver has been fully mechanically and electrically aligned, the final procedure to perform before "buttoning it up" is to set the IF gain control. [This means that you should have done the mechanical alignment - set the cams properly and so on.]
 Many otherwise very sensitive R390A's are thought not to be due to weak signals being covered by noise generated by excess IF deck gain.

 Allow the receiver to warm up for at least 1 hour then:

 1- Terminate the antenna input [This means unhook any antenna and put a 50 ohm resistor,or a 125 ohm resistor, on the balanced antenna input, no signals from any antenna or signal generator.]
 2- Set receiver for 15.2 mHz
 3- Set the "FUNCTION" control to MGC
 4- Select the 4kc filter with the "BANDWIDTH"
 5- Set "RF GAIN" control to 10 or maximum [If your receiver goes whacko at this point, reduce the IF gain setting as in step 9 till it behaves right.]
 6- Peak the "ANTENNA TRIM" for maximum noise as indicated on the "LINE LEVEL" meter [If you do not get a noticeable peak, your receivers front end and rf amplifier stages are not working right.]
 7- Set "Line Meter" switch to -10db scale [mknus 10 db]
 8- Set "Line Gain" control to full CW or "10." [Local Audio gain 0 or low if you are listening to it.]
 9- Adjust IF gain control, R-519 to cause "Line Level" meter to indicate between -4 to -7 VU.
 10- Re-zero the carrier meter control, R-523
 11- Set controls above for normal operation and reconnect antenna


Roy Morgan
k1lky at earthlink.net
K1LKY Since 1958 - Keep 'em Glowing!