[ARC5] Crystals in WWII

[Kenneth G. Gordon]

> 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