[Amps] WATERCOOLING AMPLIFIERS

[John Lyles]

Jeff, WN3A's experience with glycol mixes and cooling power amplifiers 
is normal for systems that need to be both corrosion inhibited and also 
can be freeze-proof. In our RF plant, we use both high power solid state 
LDMOS linear amplifiers and high power high voltage tube amplifiers. For 
the former, we use a mix of deionized water and about 0.5% corrosion 
inhibitor, such as made by GE water systems; in our case a chemical we 
buy is called West C-441. This is a molybdate salt that also adds some 
RF loss to the water. It runs through the cooling plates of the SS 
amplifiers, which have some aluminum and copper construction.
We use the same solution in some long dummy loads that have nothing but 
a center conductor grounded at the far end, and water applies the

For the latter, we use DI water without additives and try to keep 
resistivity above 2 Megohm-cm. This coolant is continuously run through 
resin bed and oxygen removal bottles. This is an inexpensive way to get 
low conductivity water for high voltage systems. Since we use nearly a 
thousand gallons per minute of cooling, this is the only feasible way to 
process so much water 24/7.
73
John Lyles
K5PRO