[ARC5] More -Whink and crystals.

[Dennis Monticelli]

John,

It is very easy to overshoot when you're looking for sub 1KHz of movement.
 The WW2 blank as-is usually has a rough surface left from the the final
grinding operation.  It has many loosely attached pieces of SiO2 which are
quickly removed by your etching solution.  This in turn rapidly reduces the
mass of the blank (vs the effect of thinning) and after that you get into
the harder task of acid etching a well-ordered crystal lattice.  In other
words the etch rate can be very non-linear in the beginning with these old
WW2 crystals.  Note this effect if not the result of etch solution
exhaustion.  In the final year of the war, Bliley's invention of the HF dip
as the final phase of bringing the blank into the desired frequency largely
eliminated this behavior and the associated frequency drift in the field
(as loose particles vibrated free with use).

BTW if you have a virgin WW2 crystal with low activity, it may be due to
excess loading of the blank.  You might try a quick dip in your etch bath
as a "clean" step.  The frequency will probably increase a few hundred Hz,
but your activity may become markedly better.  I have observed this
improvement myself, but it only produces the desired result some of the
time as it depends upon what is causing the low activity in that particular
rock.

Dennis AE6C


On Mon, Aug 5, 2013 at 9:57 AM, John McCarty <jmccarty at alcatel-lucent.com>wrote:

>
> How about the round plastic container that electrical tape (3M) comes in??
>
> I've been interested in the work that Ken has been doing as I have xtals
> for frequencies like 8006.76kHz that I want to move to 8.008. It seems
> Whink works faster on the thinner xtals at higher frequencies. I tried
> to etch one using the bottom of a MacDonald's coffee cup which has a
> double thick bottom. I over shot. It's harder to get dead on when
> multiplying by 18 for two meter rigs.
>
>
> 73
>
>
> John n9hrt
>
>
>
>
>
>
>
>
> On 8/5/2013 11:07 AM, Kenneth G. Gordon wrote:
>
>> On 5 Aug 2013 at 10:03, Bill Cromwell wrote:
>>
>>  A peanut butter jar seems awfully large for the job.
>>>
>> That is MUCH too big.
>>
>> Ken W7EKB
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