[ARC5] Crystal Question

[Henry Mei'l's]

Good Morning (UTC +1 time),

Re my comment yestereday about metal-on metal
rectifying RF:
One of my experiments was using the contacts
on my J-38 and home brew keys as detector
by adjusting the spacing so that the
oxidized contact surfaces barely made contact.

On the more curious side, some have experienced
having there tooth fillings function as detectors of broadcast
signals.

One of the causes of TVI often seen in densely populated areas
is the fact that overlapping metal objects (e.g. rain gutters) not
having good galvanic connection will rectify RF transmissions
and create harmonics.

BTW didn't early radio detectors also include liquid electrolytic
solutions?

Henry, Cph.



----- Original Message ----- 
From: "Brian Clarke" <brianclarke01 at optusnet.com.au>
To: "Robert Eleazer" <releazer at earthlink.net>; "Discussion of AN/ARC-5 
military radio equipment." <arc5 at mailman.qth.net>
Sent: Friday, November 12, 2010 1:46 AM
Subject: Re: [ARC5] Crystal Question


> Hello Wayne,
>
> The word 'crystal' has many meanings. In physical chemistry it usually
> refers to the solidus phase of an element or a compound. This can be the
> result of drying out a saturated solution of a compound - such as table 
> salt
> or copper sulphate - or the temperature-related structures we find in cast
> iron and solder, to name a couple. The main characteristics of crystals 
> are
> the regularly repeated structures that resolve inter-molecular and
> intra-molecular forces.  The different shapes and colours we see in some 
> of
> the more common crystals can often be traced to the number of water
> molecules attached to each 'parent' molecule.
> * The crystal glassware that women like to display [produced by usually 
> male
> glassware artists] is based on silicon, oxygen, boron, lead and a few 
> other
> elements - but none is conductive or even semi-conductive.
> * The work of Watson and Crick in determining the structure of DNA was the
> result of painstaking analysis of X-ray crystallography images.
> * The frequency determining crystals we radio-oriented people use are made
> from quartz, a form of silicon dioxide which is a very good insulator, but
> can be made to act like a big capacitor with a small inductor. The crystal
> lattice structure is what determines the frequency stability. Silicon
> dioxide is not a semi-conductor. Some sands are also forms of silicon
> dioxide - but great heat is required to convert sand into quartz.
> * Doped silicon in contact with doped germanium can be a semi-conductor.
> These can be crystalline structures.
> * Galena is a crystalline form of lead sulphide; it does make a good
> semiconductor.
> * The crystals that greenie tree-huggers collect are not rare, not
> semi-conductors, nor very valuable. And they have no known magical or
> medicinal properties - except to scribblers / journalists for whom a 
> science
> education would be a luxury. Some gemstones are crystals, eg, ruby and the
> various '-ites'.
>
> So, the word 'crystal' has become morphed and its meaning hijacked by the
> ignorant [in the Latin sense]. But this is a characteristic of all living
> languages - so, we need to have our 'shock-proof crap detector' [Ernest
> Hemingway] working properly.
>
> How about suggesting to your foxhole constructor to use a 1N34 or a 1N21 -
> both readily available, cheap, reliable and will work straight off the
> shelf. He could have such a device hidden and put a piece of galena or a
> razor blade with its scratchy wire up front for cosmetic, suck-in purposes
> for those yet to get their Ernest Hemingway moment.
>
> Hope that helps.
> 73 de Brian, VK2GCE.
>
> ----- Original Message ----- 
> From: "Robert Eleazer" <releazer at earthlink.net>
> To: <arc5 at mailman.qth.net>
> Sent: Friday, November 12, 2010 4:08 AM
> Subject: [ARC5] Crystal Question
>
>
>>I did some looking on that website where the B-26 radio compartment
>>pictures are and found that someone has asked an interesting question.
>>
>> It seems they salvaged some parts from some warbird crash sites in 
>> Florida
>> and found some radio crystals. The one he shows looks like it is out of 
>> an
>> SCR-522 . The guy who found them wants to use these to make a WWII style
>> "foxhole radio" crystal radio receiver and is asking for help on how to 
>> do
>> that.
>>
>> It never occurred to me that a radio crystal might work as a detector in 
>> a
>> crystal set. Is this possible? And did the improvised crystal sets in 
>> WWII
>> use radio crystals? I guess that crystals from downed aircraft and 
>> wrecked
>> tanks were probably available on the battlefield in WWII.
>>
>> Thanks
>>
>> Wayne
>>
>> WB5WSV
>
>
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