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Author Topic: My plate cap heat dissipators for the 4-400 tube  (Read 284 times)

Posts: 313

« on: March 25, 2019, 07:29:35 AM »

I have a bunch of 4-400 rigs, thunderbolts and thus a lot of finals.  When I was under the covers this week, I tried out an idea that I have been kicking around.  To reduce stress on the tubes bigger fans were installed and I tried out a different plate dissipator cap.

The 3D printers use a heat sink for their print heads which looks like it had possibilities for making a bigger plate cap.  I was suprised to see that the center hole was very close to the size of the metal stem coming out of the 4-400's top.  With some modification I ended up with a larger diameter and somewhat taller plate cap that would allow more surface area for cooling.

The biggest benefit possibly comes from a better connection to the "stem" after cleaning off corrosion, and the tighter fit with an aluminum dissipator.  There is one less piece in this approach which reduces thermal resistance.  I have tried to show the process on my video, sorry for having only two hands and the Blair Witch shakey images.  To add to the approach, thermal compound was added between the stem and the aluminum dissipator, with the intent of making a better thermal bond. The original dissipators I have have a bore hole of about 0.366" and the plate caps are about 0.358" which allows the set screw and one side of the cap to touch slightly.  Again this cap is between your dissipator and the stem making three elements in the thermal path to the cooling air stream.

No measurements were possible, IR guns dont work on shiny metallic surfaces and I dont want to add a thermal couple to the 3000 volt plate circuit.  I just would appear that a bigger cap tightly bonded to the stem should help cool the plate a bit, ENJOY.

W  Grin  Grin D Y  N4MQ
« Last Edit: March 25, 2019, 07:34:43 AM by N4MQ » Logged
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