[TowerTalk] Nut & Bolt Sealant

[KD7JYK DM09]

> For example I finished tuning a 6-cavity 10 GHz uW BPF that was so 
> amazingly sensitive to the adjustment screws position and contact to the 
> case it is hard to explain. Even the slightest change in the electrical 
> bonding of the tiny screws and their position changed the filters 
> properties drastically.

In the past I worked on certain sensors for nuclear SCRAM systems that 
were hypercritical, to say the least.  All sorts of training, and 
certification through the company I worked for, the USGS, AEC/NRC, 
traceability that would make your head spin...  One calibrator was a 
battery, power switch, and two wire-wound 10 turn pots.  It took a week 
to document any work on it, and the stack of paper was about an inch 
thick.

Critical mechanical parts were secured with Loctite 380, you could place 
a drop, it didn't migrate, and could be broken loose with an amount of 
effort when service was required.  I personally used it on some RF 
connectors, and antenna fasteners.  Pricey here, I'd shop around.  I got 
a couple bottles as free samples:

https://www.ellsworth.com/products/adhesives/cyanoacrylate/henkel-loctite-black-max-380-instant-adhesive-1-oz-bottle/

It's pretty strong, I'd try a pinhead sized drip across a couple of 
threads for starters, if you go this route.

The ultimate end-adjustment was a single PCB mounted potentiometer that 
would calibrate the sensors within one ten-thousandth of a G.  That was 
held in place with GLPT, brushed across the top of the body, and the 
flush slotted shaft, filling in the slot, and slightly adhering the 
shaft to the body to prevent changes in adjustment due to vibration, or 
temperature fluctuations, but could be broken loose later with a 
screwdriver:

https://www.jensentools.com/gc-waldom-10-9002a-red-glpt-insulating-varnish-glyptol-2-oz-bottle/p/388ae050

Kurt