Good to see more discussion re liquid cooling. However, aside from the
merits of various cooling agents, water cooling is probably the simplest
and most practical method for the average ham station....
I recently built and now have in full time ham CW use, a water cooled
GS-35B, a pair of GI-7BT triodes in a new 40/20 meter duel band
amplifier and I am just completing a 2 meter 2 x GI-7BT water cooled
amplifier for the shack....Like most hams I have been running various
air cooled home brew amplifiers using the general run of the mill glass
tubes and ceramics...Noisy blowers, dust accumulation etc have always
been the norm, along with the hit and miss guesses that the tubes are
running within their seal limits etc..
I decided to have a go at water cooling some of the Russian triodes
readily available and fairly cheap, and have removable anode air
coolers....There was little practical information to be found on the
internet so I went ahead and constructed two copper water manifolds for
the GS-31 and 35B triodes using only imagination and what appeared to be
a practical approach...My greatest worry was regarding the actual water
system, hoses, pump, heat exchanger etc...
I was able to get excellent advice from two members from this reflector,
many thanks to Roger and Tom.....The main points are to use vinyl hose
for transporting the water to and from the tube from the reservoir,
allowing for 1000volts per meter of hose....I am using small 12 volt
1000LPH submersible pond pumps which give me 4 liters per minute of
water flow through 1/2 inch hose...I am using small copper car heater
radiators as a heat exchanger 6x6x2 inches with a near silent 240 volt
muffin fan blowing air through the core....I wanted to keep all metal
copper but the heat exchangers have brass tanks each end of the core...I
have the heat exchanger grounded through a 0-1ma meter....My water
reservoirs contain 12 liters of distilled water....Current leakage to
ground is typically 200ua at room temperature rising to around 350-400ua
at 40C....It takes a long CW session to warm the water past 30C with
this system...
Now, my amplifiers are only run at a modest power output, however I am
completely happy with water cooling....I have no noisy blowers to
contend with, the system is clean simple and as far as I am concerned
safe....The only difference to running air cooled is the addition of the
water hoses, out of sight like other cables and the water cooler under
the operating bench...
Contrary to some beliefs these Russian tubes are excellent value and
give good account for themselves...I have only been using them for 3
years or so but have yet to have a failure....I guess one could quite
easily build a water manifold for the Yc-156, 8877 etc if one wanted to
and achieve results similar to my own experience....
Bottom line is, we are radio amateurs and with a little ingenuity we can
achieve anything..Nothing beats building your own equipment, putting it
on air and having the enjoyment of having done it yourself....
Bob..VK3ZL..
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