[GreenKeys] Tuning Fork

[Gary]

Larry Tighe wrote:
> Howdy Folks,
> 
> I noticed a TTY tuning fork on eBay.  How was a tuning fork used and 
> what was it used for?
> 
> My guess would be the speed of governed motors...yes?
> 

That is the most likely use.  But hams also made use of tuning forks for 
a tone reference source.  With some magnetic coupling a tuning fork 
could be used in a resonant circuit for an audio oscillator.  A 425 Hz 
tuning fork source could be multiplied x5 and x7 to get the common 2125 
and 2975 Hz tones for wide shift.

There is a circuit in "The New RTTY Handbook".  Never tried it myself.


Gary