[Boatanchors] Drake Crystals

[Richard Knoppow]

    I think it depends on how the crystal is made and mounted. 
Until about the 1960s most crystals were mounted between metal 
contacts and were not coated with anything. These could be 
treated with an abrasive or lowered in frequency by using a soft 
pencil on the surface. More modern crystals are plated. The 
plating acts as the electrode on each side. This results in a 
more stable crystal and also makes it possible to trim the 
frequency very precisely by controlling the thickness of the 
plating. I don't think there is much you can do to trim the 
frequency.
     I can't give you a specific citation but there were a lot of 
articles on modifying crystals in ham magazine just after WW-2 
when great quantities of surplus crystals were on the market. 
Many of these were in the sort of mountings where you could open 
them up to work on the crystal element.
On 9/18/2021 9:56 AM, KA2PTE wrote:
> Tech question on crystals in general -
> 
> Is it possible to raise the resonant freq by shaving / trimming 
> the crystal inside the casing ?
> 
> 
> -- 
> Steve Hearns [ KA2PTE ]
> 
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-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL