[ARC5] Trimmer Cap Values

[Robert Eleazer]

Do any of y'all know if there is some kind of a code or other marking that gives the values of trimmer caps? For example, if one made by Johnson says "20M8" could that be 8 to 20 pf? 

I just busted a 1.5 to 20 pf trim cap whole working on a National NC-270 and I need to replace it.  I recall hearing that small air variables give better stability than do the compression type like the one I broke.  I have some of such caps but for at least some of them I have no idea of the value.   

I like the idea of using air variables instead of compression padders in any case because you can actually see what they are doing and they would seem to be far less vulnerable to getting filled with rust and dirt.

Thanks,

Wayne