G'day Martin.
It seems that nobody has done any quantitative
research and measurement on this subject.
To me, common sense would suggest that you are
going to see equal or better cooling on the tube
pins/seals. The air system sockets have more
metal in the pin receptors and they are in the
direct air flow. This will serve to draw more
heat from the socket pins and get it away more
quickly in the much enhanced air stream.
Also, one would expect improvements at the top
end of the tube. Improved air flow reaching the
anode connector must surely result in better cooling.
Dunno what the Henry anode connectors are like
but I have anode connectors on my 3-500's where
you remove the manufacturer's anode cap and
attach the finned anode cooler directly to the
thinner anode rod protruding from the glass
envelope. Whilst I have no scientific proof, I
reckon it oughtta help keep the lid on the metal/glass seal temperature.
73 and good luck with the project,
Alek. VK6APK
PS: I scored a spare 5CX1500 tube for Sam
yesterday. Unknown state but very cheap, so worth the risk.
At 05:19 PM 16/04/2011, Martin Sole wrote:
>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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