a. For most of the indirectly heated ceramic tubes, the mounting position is
specified as "any".
b. For many amps, the ukrainian ham's are cooling the tubes (like the GU74 and
using 5" axial fans located on the back panel of the amp and the horisontal
of the tube is an advantage for this case (similar as for the Dentron MLA2500
c. The "pollutants" problem (if any!) may be different for the planar triodes
than for the tetrodes.
d. for the cost of the russian tubes specified as to "any mounting position", a
on this topic have no sense, and the "pollutants" problem is the last thing of
> There is a bit of debate between Polish and Ukrainian amp builders.
> The some members of the Polish school argue, based on some American
> literature, that a valve (ceramic) should be based vertically, while some
> well known Ukrainian builders, have there GU74b's amps horizontal.
> Now some Poles maintian horizontal is bad as, as for lack of a better word,
> "pollutants" which occasionally fall from the anode land on th grid, rahter
> than at the base of the valve as would be the case if the valve was verticle,
> and this eventually causes a short in the valve.
> My feeling is that rather the cooling problem is the issue here, but I wonder
> s the valves were designed with the though in mind of working in any positon.
> Any comments
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