It is hard to give you the right final answer.
In the Russian military power amplifier BRIG (8 x GU-74B) all tubes are in
horizontal position. And it works without any problems. And number of hams
using it in the shacks. The only problem is that you can have around 1500W
output power and PA will consump about 7500W from the power line. Monkey
I think it could be because tubes working not hard and in order with all
pasport data. As I know anod voltage is only 1200V. And tubes working in 4
+ 4 system, in distribute amplification mode (not sure I'm right with this
technical term, sorry for my bad English).
But if you would like to use them in hard operation conditions - better to
use those tubes in the vertical position. Distances between inner parts
are small and if you will pump the tube on maximum ranges the grids in
horizontal tube could overhang (or deform)... and you can imagine the
Sorry ones again for my bad English.
73, Remi LY2MW
>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
>rahter than at the base of the valve as would be the case if the valve
>verticle, and this eventually causes a short in the valve.
** I would go with base down. I have seen many 8877s/3cx800A7s-et
cetera with gold-sputtering 'pollution' that were still usuable if the
gold meltballs could be safely parked in the base.
>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
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