[Boatanchors] Tube filaments

[Glen Zook]

One "story" that has been around for decades was that by having a different filament voltage for the rectifier tubes that there would be no temptation to use 6.3 volts (the nominal terminal voltage of a 3 cell lead-acid battery is where this came from) for the rectifier which would then put B+ on the filament string.  Of course this was for rectifiers that use a true filament for a cathode.

For those rectifiers that have a separate cathode most use 6.3 volts for the heater.

Glen, K9STH

Website:  http://k9sth.com


--- On Thu, 12/3/09, David Knepper <collinsradio at comcast.net> wrote:

Does anyone know why RCA, etc. chose 5 volts for their rectifier tubes and 6.3 volts for their receiving tubes?