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roline 4th January 2011 12:07 AM

loose plate caps, hi temp glue???
I have several loose plate caps needing a hi temp glue, I dont want to buy a quart of the stuff which starts to limit me from the good stuff. Any suggestions where smaller quantities can be had?

radiotron 4th January 2011 02:50 AM

Suggest you try a two-part epoxy resin, I have had reasonable success regluing 807 top caps with it, dunno what the brand name would be in your part of the world, downunder the common one is Araldite - a pair of syringes joined at the hip containing resin and hardner, in a blister pack.
High temp RTV sealant might work too, some them are quite sticky.

msallen021 4th January 2011 03:16 AM


Originally Posted by roline (
I have several loose plate caps needing a hi temp glue

I used my multimeter and a thermocouple to measure the temperature on the top of a power tube and it is surprisingly low - around 105-110 degrees Celcius (just over the boiling point of water). Most epoxies will withstand this type of temperature virtually indefinitely (interesting point - some electrolytic capacitors are rated to operate for 2,000 to 3,000 hours at 105 degrees celcius).

astouffer 4th January 2011 04:00 AM

I would go for high temp RTV over epoxy. Epoxy gets soft and smells really bad when it gets hot.

Gary P 4th January 2011 04:33 AM

I've had great luck using JB Weld metal filled epoxy. JB Weld is good for 500 degrees F. I've used it to fix several 1624 top caps that were loose. Unsolder the loose cap so you can get the epoxy properly placed. After the epoxy is cured you can re solder the top cap.

trobbins 4th January 2011 05:39 AM

I can recommend Selleys 401 - a clear silicon RTV in a standard cartridge - much more cost efficient than a small tube of auto RTV (and clear looks nicer than black) - 205C continuous with 260C withstand - also good for adding/making microphonic dampers as well.

Ciao, Tim

ktuuri 4th January 2011 05:47 AM

I have used two-part epoxy resin from a dollar store with very good results.
I have done it a number of times with no problems at all.
Have done a number top caps on Mercury Vapour Rectifiers and they run very hot!

Tubelab_com 4th January 2011 02:33 PM

I'll second the JB weld. I have glued top caps and tube bases with it. I also plugged a hole in a cast aluminum oil pan on my Volvo. The repair was still good when I sold the car 4 years later.

Get it at an auto parts store, or Walmart. You want JB weld not JB quick.

Kmet 4th January 2011 04:20 PM

liquid glass
Try mixture of liquid glas (Na2SiO3) with some finegrained sand (or dust). I prefer to use quartz type of fine sand but all sorts of fine sand will work. After some experimenting I manage to glue several anode caps on 6146b tubes.
One more thing..clean all electrical contact surfaces before 'glue' makes firm bond.

Doz 4th January 2011 07:14 PM

I use fireclay exhaust paste ;)

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