[Milsurplus] Fwd: Re: Let's appreciate crystals

[Brenda Gentry]

Microphones and phono cartridges use Rochelle salt crystals to produce 
an output.  Rochelle salt slabs are  somewhat flexible and generate 
fairly good voltages, but don't resonate very well so their use for 
frequency control in not likely to work. Quartz is much harder and 
resonates very well, but would be too stiff for a cartridge or 
microphone. I have never heard of a phono cartridge using quartz.  I do 
believe there are a couple people who make Rochelle salt crystals and 
rebuild phono cartridges and microphones. Certain musicians feel that 
Rochelle salt crystal microphones are best for their art.

       B. Gentry, KA2IVY

On 10/28/25 9:54 PM, hwhall--- via Milsurplus wrote:
> Back in the very early radio days, there were hams who were making 
> their own crystals. How many? I don't know but the radio magazines of 
> the time had articles on how to do it.
>
> Speaking of crystals, it would also be a cottage industry if someone 
> produced the crystals that were so common in microphones & record players.
>
> Wayne
> WB4OGM
>
> On Tuesday, October 28, 2025 at 07:27:10 PM MDT, Bob Camp 
> <kb8tq at n1k.org> wrote:
>
> Hi
>
> The “big deal” with synthetic quartz was its lack of twinning. You 
> need the entire blank to be left handed or right handed. If it’s “some 
> of each” the piezo polarity will shift and cancel out. Natural quartz 
> was not very consistent. The result there was that you lost a 
> noticeable percentage of what you cut.
>
> During WWII something over a hundred small outfits made crystals. It 
> was very much something a lot of folks got into. After the war, very 
> few of them survived.
>
> Bob
>
>
>>> On Oct 28, 2025, at 11:18 AM, Ken Kinderman <scr274 at gmail.com> wrote:
>>>
>>> Just watched "Crystals Go to War" on youtube.
>>> https://www.youtube.com/watch?v=wHenisSTUQY
>>> Never again will I take the humble FT-243, DC-10 and their cousins 
>>> for granted. I suppose if we thought about it, we would appreciate 
>>> the labor- and skill-intensive process, but this film drives it home.
>>> These guys and gals were heroes...
>>> - hand selecting and hand grading the quartz
>>> - dipping the raw stone into oil to identify the axes, hours at a 
>>> time: bare hands, no gloves
>>> - further grading with the casual use of X-rays: I notice only one 
>>> young lady with a bare minimum protective apron
>>> - crystal dust
>>> - bare hands in hot soapy water all day
>>> - fingers inches away from razor thin, diamond edged, spinning saw 
>>> blades
>>> - skillfully evaluating the quartz slices for imperfections and 
>>> maximum yield
>>> - acid fumes
>>> - constant exposure to watery abrasive slurry
>>> - only once did I see protective gloves: a young lady removing 
>>> blanks from the "acid bath"
>>> - coaxing the blanks, one by one, onto frequency.
>>> - putting little metal labels on with tiny screws, no doubt "girls work"
>>> I will think twice the next time I abandon an oddball frequency 
>>> crystal as unusable. Each one is a gem.
>>> 73,
>>> Ken
>>> W2EWL
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