Recent new models of replacement remote controls have emphasized that they work with DTV Converter Boxes and they have done a fair job in making available the MENU screens of most original remote controls except for the Sansonic FT-300A. The RCA (code 52348) and General Electric remotes that I previously tested failed to bring up the very important Ch Scan and Ant Level functions on the Sansonic. If you bought one of these remotes to replace your broken or lost Sansonic remote control you might have felt ripped off, but thanks to GE for making these functions available on recent remotes.
I'll tell you what worked for me. Apparently, GE uses two 4-digit code versions in it's remotes. I used a General Electric model 24991 (rev C) remote control that uses 4-digit Version 1 codes. Version 1 uses codes less than about 1xxx and Version 2 uses codes ranging from about 5xxx to 8xxx. I entered the recommended code 1746 on a device key other than the TV key.
To bring up the Ant Level screen simply press the INPUT key. From there you can add an individual channel or observe the siganl meters. Press and release the key to exit the screen.
To bring up the Ch Scan screen, press PREV CH. From there you can use the remote's navigation keys to select Ch3/4, Mono/Stereo ,Time Zone or start a Channel Scan.
The current model 24991 on the Jascoproducts.com website (yes, it has the same model number as my apparently older remote but looks entirely different) uses Version 2 codes. Since I don't have a version 2 remote I can't say that it works with Version 2 codes. But I suspect that most GE remotes that use 4-digit Version 1 codes work. I'm not absolutely sure of this, but I believe you can tell which version a GE remote has just by looking at the lettering on the remote. If it's upper case (CAPITAL LETTERS) it is Version 1, and it it is lower case it's Version 2.