R rjuly Well-known member GDIY Supporter Joined Jun 14, 2012 Messages 158 Location Gloucester, UK Apr 11, 2022 #21 CJ said: …Watch your heater voltage. The EF804/806s run with 680 degrees C, the coldest cathode for any type of pentodes ever made. Do not increase the voltage above 6.6V otherwise the carbonates burn off… Click to expand... Thanks for that advice, I will be careful not to do so. Is there a lower limit for the heater voltage? - Richard
CJ said: …Watch your heater voltage. The EF804/806s run with 680 degrees C, the coldest cathode for any type of pentodes ever made. Do not increase the voltage above 6.6V otherwise the carbonates burn off… Click to expand... Thanks for that advice, I will be careful not to do so. Is there a lower limit for the heater voltage? - Richard
