Re: How best to inexpensively clean degraded variable caps?


Guy Atkins
 

My method has been 91% isopropyl alcohol, using a long bristle, very soft brush for working the liquid down between the vanes. I don't worry too much about washing out the bearing grease as I prefer to just re-grease the pivot points (Caig De-Oxit L260D lithium grease) after blowing out the remaining alcohol with compressed air.

The thought of using a micro-controller and stepper motor (mentioned earlier) to move the variable cap makes me shudder at the chance of creating RFI anywhere near these sensitive FSL antennas, much less the introduced mass of metal nearby. This approach was something I tried years ago while trying to create a viable remotely-tuned FSL, but I decided the complexity of motors etc. wasn't worth it. Varactor diodes aren't worthwhile either, as have been discussed at length in the forum. It's tough to beat the excellent "Q" of a top-notch air variable cap!

A simple enough approach to give a modicum of weather resistance to the caps--and forestall weathering-- is to build the FSL components inside of a tote box. I describe that method here: https://swling.com/blog/2017/01/a-new-approach-to-fsl-antenna-construction/

73,
Guy Atkins
Puyallup, WA

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