[600MRG] restoring old crystals ??

[John Gibbs]

A long time ago I used a cleaner called "Bon Ami" with a bit of water to 
make a paste which I smeared on a piece of window glass and moved the 
quartz blank in a figure eight pattern to make the ft-243 xtal higher in 
frequency..   Also tried tooth paste with not as good results.  A lot of 
times I wasn't very successful.

A bit of pencil lead on the center of the blank tended to lower the 
frequency a bit. 

Hydrofluoric acid works too.. but totally dangerous and these days 
probably not easily obtained.

73  John / VE7BDQ