OK I finally think I have it!  On my Flysimware Falcon 50 I opened up the panel.cfg and the RealityXP GTN.ini files after making backups.  I found the reference for the [GTN_750_1.DEFAULT].  Copied it and created a new section called [GTN_750_1.MYGTN].  In there I set the screen brightness to -40.  In the panel.cfg file there were two references for the GTn 750.  Window 6 which is in the upper section of the file and [VCockpit29] under the VC section.  In [VCockpit29] I added the reference at the end  to MYGTN ( gauge00=rxpGTN!GTN_750_1,  0,0,677,794,MYGTN).  Saved everything and started P3D v5.  Started a flight with the Falcon 50 and compared the vc gauge brightness to  the popup and they match.  Thank you for sticking with me.

51 minutes ago, jfwharton said:

Saved everything and started P3D v5.  Started a flight with the Falcon 50 and compared the vc gauge brightness to  the popup and they match.  Thank you for sticking with me.

Congrats! This is exactly it!

I'm glad you've sorted this out. Like I said it looks like a steep curve but in the end it is super easy!

And this is much more powerful than what you got used to before, because you can adjust each instance individually but you can also display both the VC and the popup at the same time.

Edited April 25, 20215 yr by RXP

7 hours ago, jfwharton said:

Thank you for sticking with me.

Thank you for sticking it out and finding satisfactory resolution.  And stick around.  Now you have the credentials to extend some user-to-user help when able. LOL! It is what Avsim is all about. That, and satisfying flying......  Enjoy!

Edited April 26, 20215 yr by fppilot

I am having one issue however.  Not a big one but one that is confusing me.  I made the same changes to my Flysimware Lear 35A, Falcon 50 in both P3D v4.5 and v5.1.  In v5.1 the GTN popups in both aircraft are very close in brightness to the VC GTN panels.  However in P3D v4.5 the popup and VC panel in the Falcon 50 are very close but they are not in the Lear 35A.  So I have no idea how to correct this and why it is happening to begin with.  I use the same installer  for both and select which version of P3D to install the aircraft to.  Any ideas?

Each aircraft requires its own calibration. Even if both aircraft are from the same vendor, it is possible the VC polygons are not using the same "rendering settings".

1 hour ago, RXP said:

Each aircraft requires its own calibration. Even if both aircraft are from the same vendor, it is possible the VC polygons are not using the same "rendering settings".

I found that to be the case with two different Milviz models as well as with two different A2A models.  I just checked my logbook and see that I have not logged hours in any Carenado models since before I built this new system last August.  So I cannot speak about brightness adjustments needed it their models at this time.

I have been playing around with the settings for the Lear 35 for P3D v4.5 and nothing affects the brightness of the VC screen.  In my attempts I somehow messed up the file and ended up copying the Reality XP GTN.ini from the P3D v5.1 installation and pasted it into the P3D v4.5 installation.  Now the displays almost match.  So don't know what was going on with the file originally in P3D v4.5 but at least the issue has been solved.