Water Cooling the GS-3A
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Manufacturing a GS-3A water cooling jacket

GS-3A with no cooler installed.

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The GS-3A is intended for water cooling. To the left, a water is jacket installed on the tube, clamped and ready for service. At the right is a cross-sectional drawing showing the tube and water jacket as installed; note that there are TWO seals, a rubber O-ring and a teflon gasket upon which the bottom of the water jacket seats.



At left: the O-ring (2.75 O/D with 1/8 thickness).



Inside view of the water jacket & top plate ass'y.

Close-up of the bottom, machined part of the water jacket tube. The O-Ring groove is evident.

Top view of the jacket & top plate ass'y, ready for installation of top cap and water connections.


The cooling jacket is fabricated from a 3 O/D brass tube with 1/8 wall thickness. Tube length is 33mm (1.300). The diameter of the jacket seat area (where the bottom gasket is installed) on the GS-3A tube is 73.5mm (2.894). The bottom of the brass tube jacket is machined to 73.4mm (2.890) to fit inside the seating area (which is 4.2mm (0.165) deep). The machined length at the bottom of the tube is 5.4mm (0.212) to allow for a gasket and O-ring. A groove was machined for the O-Ring (see picture). This is not absolutely necessary since the O-Ring will be clamped in place during installation.

Top plate for the cooler is 1/8 brass plate with 3 holes. 2 holes for hose-barbs drilled to 3/8 diameter. The center hole is drilled to diameter for the top cap.


Hose-barb water connections and top cap before installation in the cooler top plate.

The water jacket ass'y, completed and ready for the installation of the clamp ring.

Bottom of water jacket with clamp ring and O-Ring seal installed.


The treaded end of two standard 3/8 brass hose-barbs with NPT is machined to 3/8 O/D to match the outer holes in the top plate of the cooler assembly.

The top cap is made from 1 solid brass stock with the center hole drilled to 5/8 diameter and depth to clear the top cap on the GS-3A. The bottom end of the cap is machined to diameter and 1/8 long to slip inside the center hole in the top plate.

The clamp ring is made from bronze tubing with 3.5 O/D and 3.0 I/D - long. Drill 3 x 1/8 holes in the ring for the mounting screws. Slip the ring over the 3.0 tubing until the bottom of the ring is flush with the bottom machined section, 5.4mm from bottom.

Solder all pieces together.


The clips are machined from brass stock. See drawing below.


Install the bottom gasket on the GS-3A as shown in the top views of the GS-3A, above. Slip the O-Ring over the machined end of the cooler, per picture above. Install the clips and tighten the screws until the cooler bottoms out. At this time the O-Ring should be compressed 1mm (0.040) and the cooler should rest against the bottom Teflon gasket.


At left is the completed water jacket ready for installation.

To the right is a bottom view of water jacket ready for installation.


A GS-3A tetrodes with water coolers installed and a few extra coolers....

Water Cooled GS-23b

Description & pictures of a water cooling system.

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This Page Last Updated: 17 May 2004
Feedback: Paul S. Goble, III, ND2X
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