[ARC5] Crystals in WWII

[Dennis Monticelli]

I think the "dirt" problem had mostly to do with fine grit left over from
the grinding process and also quartz molecules left weakly attached to the
crystal.  Neither would appear to the eye after a routine wash.  The fix
was discovered and implemented by Bliley.  They were doing an acid etch to
take a ground blank a short distance to the final freq.  It turned out that
the etch also did an outstanding job of removing several atomic layers
(where the surface damage was) and leaving behind a clean nicely ordered
crystal lattice.  There was nothing left on the surface to redistribute
after manufacture and use, hence no "aging."   Bliley didn't want to share
the knowledge because they wanted to retain an advantage in the market
after the war.  The govt twisted their arm and the technique was shared,
just as all the previous crystal technology had been shared earlier in the
war to create the cottage industry.

Dennis AE6C



On Thu, Mar 14, 2013 at 11:01 PM, Kenneth G. Gordon <
kgordon2006 at frontier.com> wrote:

> > On Thu, 14 Mar 2013, Robert  Eleazer wrote:
> >
> > > Anyone ever hear of this book? Sounds interesting.
> > >
> > > "Crystal Clear : The Struggle for Reliable Communications Technology
> > > in World War II" by Richard J. Thompson
>
> I read it too. Some of the information was interesting, but it was not
> particularly technically good.
>
> I do remember that according to the author, the first batches of crystals,
> most
> made by small companies essentially by hand, began to have some very
> serious problems with changing of frequency in the field.
>
> I had read of this problem from other sources in the past.
>
> I don't know if the author of this book accurately described the problem. I
> think some here called it "aging" but that wasn't the real source of the
> problem.
>
> THe main problem was that the crystals were, first of all, ground to
> frequency, not etched, and then they were never cleaned properly or
> throughly after the grinding and before checking the frequency.
>
> After they got out into the field, in many cases the vibration from
> transporation and other sources essentially shook the "dirt" out of the
> crystals, radically, in some cases, changing their frequency.
>
> In any case, we eventually solved the problem, but it was a BIG problem for
> a while.
>
> As far as the book was concerned, it was a good first effort, but in order
> to
> have a really thorough job, needed someone technically knowledgeable to
> provide the details needed.
>
> I thought it was a bit short too, considering the importance and the
> seriousness of the flawed crystals.
>
> Ken W7EKB
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