Okay, a little background to begin with. I have a Henry 2K Classic X,
2x3-500 tubes and a reasonably substantial power supply. It is the eXport
model with the heavier duty power supply components and also has the extra
capacitor in the resonant choke filter for 50Hz operation. HS is a 50Hz
country so we are plagued by slow blowers and warmer transformers as well as
an ambient year round 30 degrees C. I have no complaints in general about
the 2K, it works and puts out the watts but wary of the need to make it as
reliable as is reasonably possible I have long thought about improving the
cooling for the tubes, with both the inner and outer top covers in place the
stock blower provides barely enough air to lift 3 sheets of 80gsm paper!
All of the 3-500 tubes I have are the type with a phenolic, or some such,
ring. The ring has an approximate ½?hole in its middle.
The Henry is fitted with Johnson 275 type ceramic sockets, this has a hole
in its middle that matches the one in the base ring of the tube. There are
no other air routes when the tubes are properly fitted and all air must
travel through the small hole and then turn right angles to flow over the
base seals. From there it is ducted upward by the action of the fitted
chimney, another right angle turn and leaves the chimney having been flowed
somewhat over the anode seal.
By contrast the air system socket has an almost 2? opening that would
permit air to exhaust almost straight up and through the hole in the tube
ring.
My question concerns which might be better assuming the stock blower is left
in place. I want to leave the matter of possible blower improvements to
another time. Here I am concerned about the relationship between the likely
flow rates and the best cooling for the tube seals which are stated to be
the key point with the 3-500. I can imagine that the small hole and forced
turning of the air through the Johnson socket will reduce its rate of flow,
increased back pressure, but would the air system sockets greater opening
permit turbulence around the ring to extract hot air from the vicinity of
the base seal in addition to that being fed to them? Assume that the regular
Eimac chimney is fitted. Or would the use of the air system sockets provide
less protection for the precious base seals?
Though I can surmise that the bag-o-meter will likely show a higher flow
rate with the air system sockets I?m not convinced (yet) that this is
necessarily the whole story.
Comments enjoyed.
Thanks
Martin, HS0ZED
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