[Hallicrafters] SX-73 Ballast Tube

[Barry H]

Hi Gang

Anybody know what the number is for the ballast is in the SX-73?  I think I asked this before, but don't recall getting an answer.  It is only referred to as "R80" on the schematic and there's a Halli part number, which is of no use.  The number is rubbed off on this particular one I have.

Also -- is there a known tube sub.  While searching, I came across some posts about using a 6V6 in place of the 4H4 ballast in the SX-88 and that it was factory recommended and works well.

Barry