[GreenKeys] Tone frequency history?

[kn7sfz]

On 10/8/2021 6:54 PM, Jim Haynes wrote:
> On Fri, 8 Oct 2021, Nick England wrote:
>
>> I wonder why 425 Hz tuning forks would have been common? Musical A is 
>> 440
>> and A-flat is 415.3.
>> Maybe 2125/2975 came first and then 425 tuning forks? Hmmmmmmmmm.
>> Nick
>>
> I remember an article about building yourself a 425 Hz frequency 
> standard,
> since so few of us had access to frequency counters in the early RTTY 
> days.  The musical standard then and now was A=440 Hz, but in an earlier
> time it had been 435 Hz.  And there was someone who had a supply of 435
> Hz tuning forks for sale. 


> So what we were supposed to do was carefully
> use a rattail file at the crotch of the tuning fork and file away just
> enough metal to bring it down to 425 Hz.
>

Would you not have to ADD weight to slow it down?

Just my 2 cents....😉

Richard de kn7sfz