The modified Model 1264 powder feeder addresses problems associated with wheel pulsation by replacing the original 12-slot powder wheel with a 120-hole wheel. The 120-hole powder wheel offers uninterrupted carrier gas flow and virtually pulse-free feeding. Pinch valves added to the feeder address an undesirable suction effect, which can draw certain powders from the canister, even when the powder feeder is turned off. The pinch valves completely eliminate any unintended powder feeding by shutting down instantaneously while maintaining canister pressure.