Refer to the article "QSK for the TL-922 and SB-220 With Circuit Improvements for the TL-922" written by Rich Measures, AG6K on his web site www.somis.org. All these mods are explained there.
7. Anode and grid circuit
by Ed Kulchenko, VE3FWA, (ra2fz at hotmail.com), 2008