[Antennas] Phased Butternuts?

[Jim Miller]

I have two Butternut antennas (HF6V and HF9V) now that I have the parts one rebuilt.  I would like to consider phasing them and expect it would work for "any" particular band but wonder what the effect would be on the other bands.  Would other bands be degraded or could both antennas be driven with the proper phasing (by band) and be effective?  What physical separation distance would be recommended as a base for the phasing (10 or 80?)?

TIA es 73, de Jim KG0KP