[ARC5] Trimmer Cap Values

[Kenneth G. Gordon]

On 12 Apr 2014 at 13:17, Robert  Eleazer wrote:

> 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?

That seems logical, but the only way I would know for sure is to test them.
 
> 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.

According to both what I have learned from several sources, and on my own 
experimentation, the air-variables are FAR more stable than the 
compression-trimmers, and also more reliable.

>  I have some of
> such caps but for at least some of them I have no idea of the value.   

Then test them. Won't take very long. I bought one of those new 
Chinese-made cap and inductance testers off eBay some time ago since it 
was cheap and I was curious (also, cheap). Testing against any of several 
other harder-to-use test instruments I have here proved it to be both reliable 
and accurate.

> 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.

Agreed. To me they are simply far more aethestically pleasing too.

Ken W7EKB