[ARC5] SCR-274 calibration Xtals

[Bill Cromwell]

Maybe the crystal started out 70 years ago at 10 kc low <evil grin>.

73,

Bill  KU8H

On 08/19/2016 01:31 PM, Kenneth G. Gordon wrote:
> On 18 Aug 2016 at 14:57, J Mcvey via ARC5 wrote:
>
>> Just for fun, I decided to see how the magic eye transmitter calibration system
>> worked in practice. It actually worked pretty well, but the resonance  was at
>> 3502 khz instead of 3500 khz ( marked on xtal) .
> Gee!! That close? That is amazing for a crystal which is over 70 years
> old...not to mention the other components in the circuit which could effect the
> resonance frequency,
>
>> Is this typical?
> No. It is far too good. Typically, crystals drift upwards a certain amount per
> year. By now, it should have been a lot further off.
>
> As others have mentioned here, you can tweak it exactly on to frequency
> with external components. Parallel capacitance will lower the frequency.
>
> Ken W7EKB
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-- 
bark less - wag more