31-07-2015, 04:47 PM
(This post was last modified: 31-07-2015, 04:48 PM by Murphyv310.)
I have never been a fan of either directly heated valve rectifiers or silicon rectifiers. This is a personal thing as neither are particularly elegant. With these types of rectifiers the off load voltage rises very quickly before the rest of the valves conduct. It's sore on the smoothing caps and even old paxolin valve bases.
Adding series resistors can reduce the the switch on surge but they are a compromise, insufficient current can be a problem with a warm set and of course series resistors like this get hot!
If at all possible I will swap a directly heated reccy for an indirect one, eg 5U4 - 5Z4. I've even replaced 4 volt reccys with a 5Z4 with no problem. My 1936 Pilot has an EZ80 in an adapter base and it's heater is 2v under run. It works 100%
Adding series resistors can reduce the the switch on surge but they are a compromise, insufficient current can be a problem with a warm set and of course series resistors like this get hot!
If at all possible I will swap a directly heated reccy for an indirect one, eg 5U4 - 5Z4. I've even replaced 4 volt reccys with a 5Z4 with no problem. My 1936 Pilot has an EZ80 in an adapter base and it's heater is 2v under run. It works 100%
