Use petrol or gas as they call it in the US. Suck some up in a syringe then dribble it into the base, leave to sit for a few hours then push and twist, seat the base, then leave to dry. This "melts" the original stuff.
Andy.
Andy.
It did not work for you, but was recommended from the UK Vintage radio site, and has worked on the tubes I tried it on. So not 'BS'; it is an easy option before the other options need to be considered. Maybe this is not a NOS tube, and the glue that fixes the base is different composition?
There is a useful video about this issue on the "Tube lab" youtube channel of valvesnmore - they sell NOS tubes. They use shellac injected with a syringe and cured with a heat gun, after wrapping the base in blue tape to protect from spillage and excess heat. Apparently, there are two main adesive compounds that have been used for the purpose: the older one is sensitive to alcohol and does bear some affinity with shellac, the "modern" glue is syntetic and insensitive to alcohol.
Absolutely no BS. I first tried mentholated spirits with no success but tried petrol on a completely loose base of a 866A MVR, the petrol dissolved the gunk. I re-seated the base, soldered up the pins and put a big elastic band around the valve overnight. It was still a tad loose so I moved the valve to somewhere warm, it stuck.
I didn't want to use glue due to the risk of the glue cracking the glass when hot, not having any experience with any glues. So, up to you, only trying to help.
Andy.
I didn't want to use glue due to the risk of the glue cracking the glass when hot, not having any experience with any glues. So, up to you, only trying to help.
Andy.
I used krazy glue on a 6SN7 and it's been find for months. Of course, 6SN7 doesn't get as hot as KT88.
I would also consider using corn syrup. The heat will caramelize it. It might smell like burning carbon for a while though LOL
I would also consider using corn syrup. The heat will caramelize it. It might smell like burning carbon for a while though LOL
I will try that high temp epoxy, give me day or two.
Othewise thanks everybody for the suggestions. I appreciate it.
Othewise thanks everybody for the suggestions. I appreciate it.
Same problem.., I have a still good old valve from the 30s with a loose base.
Me too I tried before by letting food ethanol dripping after 24h so the internal paste softens slightly and adheres again to the glass.
Yet the problem is that it tends to dry up againe with time and rapidly with > 80° and it happened like this to me.
In my case I also have some fragment inside jingling if I turn the tube upside down and I don't want it were a bad thing.
Any alternative idea for a product that can be found on the European market at a low price?
I also tried black silicone for high temperatures but it remains very elastic and making it uniform is a mess. Most of the epoxy resin is in my opinion to be avoided due to the different thermal expansion compared to glass.
Suggest you apply the epoxy to a warm valve/tube as it will make the glue more fluid and seep better, and/or use a hair-drier.
Since glass is a particular material I would try a specific glue for glass like this (just as an example)
https://www.amazon.com/Loctite-Glass-Glue-2-Gram-233841/dp/B000PSBBM8
taking care to try how it adheres to the material of which the base is made by placing a droplet on the outside of it and only then by carrying out a gluing.
There are also UV light cure adhesives for the glass, but frankly I don't know if they are suitable for that purpose.
https://www.amazon.com/Loctite-Glass-Glue-2-Gram-233841/dp/B000PSBBM8
taking care to try how it adheres to the material of which the base is made by placing a droplet on the outside of it and only then by carrying out a gluing.
There are also UV light cure adhesives for the glass, but frankly I don't know if they are suitable for that purpose.
I bought a tube of this: https://www.amazon.com/dp/B000FKF80M?psc=1&ref=ppx_yo2ov_dt_b_product_details
Going to try a syringe on a couple not so valuable tubes. My biggest fear would be that some adhesives maybe conductive.
Even slightly would be a big problem. Good luck with your mission.
Going to try a syringe on a couple not so valuable tubes. My biggest fear would be that some adhesives maybe conductive.
Even slightly would be a big problem. Good luck with your mission.