I’m told those 50,000 watt AM stations usually have them in the little house at the base of their big antenna.
This article says yes:
Peter H.
Sep 2, 2003, 9:12:00 AM
I’m sure there are still a few RCA Amplifuzz’s out there.
There are a pair of RCA BTA-50Fs (high-level plate modulated) in Cleveland.
The Harris MW-50 has tubes.
With a Harris DX-50 requiring only 86 KVA for 100 percent modulation, and an
RCA BTA-50F requiring about 150 KVA for 100 percent modulation, the economics
are heavily weighted in favor of solid-state 50 Ks.
The DX-50 can generate 50 kW from three voltages of about 200 volts and below
(see the Harris patent for details). The BTA-50F requires several kV (seven ?)
to do the same.
Almost all older transmitters of 5 kW and above were three-phase.
You could run a 5 kW or 10kW on a rotary phase converter if you were desperate.
50 kW requires three-phase, usually 277/480.
https://groups.google.com/g/rec.radio.broadcasting/c/us08XGTWq_o
Here’s the RCA Manual for them. 50K tubes last page.