31-10-2015, 07:27 AM
According to the r-type org site the U10 is described as a directly heated job but it then goes on to say that it has cathode tubes that are connected to one side of the heaters:
http://www.r-type.org/exhib/aaa0643.htm
The layout for the U10 on the radiomuseum site shows no cathode tube:
http://www.radiomuseum.org/tubes/tube_u10.html
The Radio Valve Data book (Iliffe) also describes the U10 as directly heated and as a consequence shows no cathode tube that's internally connected to one side of the heaters, the UU5 however from the same data book is described as indirectly heated and shows the cathode tube internally connected to one side of the heaters.
The r type org site is a very useful resource but it does contain lots of errors eg: read the heater description for the DW2 rectifier then look at the actual Mullard data sheet:
http://www.r-type.org/pdfs/dw2.pdf
I've always assumed that a directly heated cathode is just that, directly heated ie: the current that heats the cathode flows through the cathode itself.
I think as a general indication the heater current can sometimes reveal as to whether or not the valve has a directly heated cathode as opposed to an indirectly heated cathode.
Make of it what you will.
Lawrence.
http://www.r-type.org/exhib/aaa0643.htm
The layout for the U10 on the radiomuseum site shows no cathode tube:
http://www.radiomuseum.org/tubes/tube_u10.html
The Radio Valve Data book (Iliffe) also describes the U10 as directly heated and as a consequence shows no cathode tube that's internally connected to one side of the heaters, the UU5 however from the same data book is described as indirectly heated and shows the cathode tube internally connected to one side of the heaters.
The r type org site is a very useful resource but it does contain lots of errors eg: read the heater description for the DW2 rectifier then look at the actual Mullard data sheet:
http://www.r-type.org/pdfs/dw2.pdf
I've always assumed that a directly heated cathode is just that, directly heated ie: the current that heats the cathode flows through the cathode itself.
I think as a general indication the heater current can sometimes reveal as to whether or not the valve has a directly heated cathode as opposed to an indirectly heated cathode.
Make of it what you will.
Lawrence.
