[ARC5] [Glowbugs] "Using Defective Crystals" 1937

[Roy Morgan]

Ken,

I am thinking you are right.  The FT-243 crystal blanks do get frequency from thickness - I ground some up in frequency years ago.  Based on what I have read, the behavior of quartz crystals is pretty complicated.

I used to own one of the type shown in the article.  If I do discover it, I likely will not crack the blank to see what happens !

I have also owned one of the crystal filter crystal units from early Hammarlund HRO receivers.  The quartz piece in them actually moves around enough so it can rattle when you shake the thing.

Roy

> On Jun 21, 2020, at 11:11 PM, Kenneth G. Gordon <kgordon2006 at frontier.com> wrote:
> 
> On 21 Jun 2020 at 22:59, Roy Morgan wrote:
> 
>> Hue,
>> 
>> This is an interesting article.  I have had one of the round crystal holders shown, but never took it apart.
>> 
>> The business about
>> 
>> "If it (the crystal) has been cracked ... possible to get several good
>> crystals from an inch square plate ... all of which will oscillate on
>> the original frequency."
>> 
>> is pure baloney, based on all I have learned about quartz crystals and
>> how they operate.
>> 
> 
> You are probably correct, BUT, the frequency at which some cuts of crystal oscillates is
> primarily determined by its THICKNESS.
> 
> Ken W7EKB

Roy Morgan
K1LKY since 1958
k1lky68 at gmail.com