My experiance with with 3-500Z (older brother of 3-400Z) I was plug 4-250A on TL-922 (g1 and g2 shortened). It's works but when you run more drive, plate lilttle bit red With 40-50 watt drive with SSB, output will be 500-600 watt, Linearity still acceptance, without change anything on TL922 circuit. Firson - YD0LZH