saw what looked like a killer deal at Salvation Army.....
bought a Hsu Research VTF-3, practically immaculate, metal spike feet, Rosenut exterior, no scratches, $40....they claim it works
I just can't figure out which particular model it is
the only other indicator is a sticker at lower left that has RV3D on it
10-12" cone, 2 ports, bunch of controls....could be a Mk4. just need to make sure it works