I knew that I already had two phases in the guest room.
A couple of cheap extension cords was all it took, with one blade of a
"three prong adaprer" inserted into each hot side of each extension. Guest
220 in 5 minutes!

I'd feel ok drawing 8A this way, but you shouldn't try this at home...I'm a
professional. (:-)

Linears should have either
1- both 110 and 220 internal wiring options, or
2- just 220

But 120 is is a real stretch.
======================
Steve , Tnx for providing the 'full' picture.
Assuming a 67 percent efficiency (am I too pessimistic?) a legal RF
power amp would need 1.5*1500 = 2250 W (say overall maximum of 2400W)
which at 220 V means 12 Amperes.
So, a shack without 220 -234 V power supply would need a dedicated
supply from the switchboard .

Here in the UK we do have 115V industrial power tools,which need to be
used with a 230/115V (usually portable) safety transformer with the
secondary having an earthed centre tap ,such that in the event of a
'fault' personnel is exposed to a (peak) voltage not exceeding 1.4*58 =
81V which is considered sufficiently low to prevent electrocution.

The nominal domestic supply voltage within EU countries has now been
'normalised' to 230V ,meaning that (within a voltage band) the same
equipment can be used in all the countries.
Before , the UK had 240V and continental countries 220V . This often
meant that for example an (clothing) iron for 220 V had a very limited
life when used in Britain .
The voltage at my place (rural area) is nowadays usually 236-237 V
,whereas earlier it was up to 250 V or sometimes even higher.

Frank GM0CSZ / KN6WH