Any hopes for these bottles? Looking at the limited datasheet it looks like high mu types designed for positive grid drive. ?
I got these when helping cleaning out somebody's closet so to speak.
I think these require 1500V or more to sing well, so I doubt I will ever build with them. Perhaps make a pedestal and just have the filament glowing and have a neat light on the shelf...
The other pic is the big philips transmitter tubes I also got, and same problem with them. An 813 is on the right for size.
I got these when helping cleaning out somebody's closet so to speak.
I think these require 1500V or more to sing well, so I doubt I will ever build with them. Perhaps make a pedestal and just have the filament glowing and have a neat light on the shelf...
The other pic is the big philips transmitter tubes I also got, and same problem with them. An 813 is on the right for size.
Attachments
Transmitting valves, designed for use in class C.
Similar to the 813. See page 4 of your data sheet for maximum operating conditions. I wouldn't go any higher than 1100v with a load of 2k Ohm.
Similar to the 813. See page 4 of your data sheet for maximum operating conditions. I wouldn't go any higher than 1100v with a load of 2k Ohm.
mu of 14.5, rp of 2500 at 1000 volts plate, not so bad....in triode mode
the data shows the plate at 100 watts....
a 7.5k opt is not so hard to make compared to a 15k one...
the data shows the plate at 100 watts....
a 7.5k opt is not so hard to make compared to a 15k one...
Thanks for replies. Well I am feeling encouraged. 1100-1200V is nothing. My mental barrier is about that. Perhaps I need to look into the classic WE designs, or AN, or even Thorardson. It will be interstage/driver transformers all the way if I do build with these.
Big $ for quality interstage trafos. 🙁 A cost effective alternative is DC coupling MOSFET source followers to the O/P tubes' grids. Also, other than (possibly) the O/P "iron", transformers inside a NFB loop is asking for trouble. Damping factor and/or linearity considerations may make loop NFB of some kind desirable.
This will be SET. No GNFB. Cannot be any worse than my 6AS7 SET without GNFB and they are amazing. (Granted, I am not an audiophile, just enjoying the music).
Btw. On the base of the 813 there is a radioactive symbol. What does that mean? That they are hardened or full of kryptonite?
813's have a thoriated filament. Thorium is a mildly radioactive element, so technically any true 813 can emit low level radioactivity.
The half life is really long, so old tubes are just as radioactive as new ones, but some new production tubes do not use thorium.
The warning labels came some time after WWII, so many old tubes are not marked.
The half life is really long, so old tubes are just as radioactive as new ones, but some new production tubes do not use thorium.
The warning labels came some time after WWII, so many old tubes are not marked.