[RTTY] FW: Slightly off topic, history of 850 Hz shift?

[Jan Palmquist]

The old 850 Hz shift used 2121 and 2975 as
frequencies.

2125 is fifth harmonics of 425 Hz
and 2975 is the seventh harmonics.

So you can use a standard 425 Hz tuning fork
as tuning aid.

73 de Jan - SM5FUG


> The following is posting for Chris, N3JLY, who is not on the RTTY-Contesting
> reflector. If you respond, please copy Chris Smolinski
> <csmolinski at blackcatsystems.com>
> 
> Dick AA5VU
> 
> ------ Forwarded Message
> From: Chris Smolinski <csmolinski at blackcatsystems.com>
> Date: Thu, 28 Sep 2006 11:29:19 -0400
> 
> Hi Dick,
> 
> Sure, please go ahead and post it, thanks!  I'm sure someone out
> there knows the history. I am curious if the shifts commonly used are
> based on some engineering/technical reasons, or if they were
> arbitrarily chosen.
> 
>> On 9/28/06 8:45 AM, "Chris Smolinski" <csmolinski at blackcatsystems.com>
>> wrote:
>>
>>>  Someone asked me why much of the military RTTY on HF commonly uses
>>>  850 Hz shift. I am curious if anyone knows the history behind the
>>>  selection of this shift rate, or if it was just arbitrary.
>>>
> ------ End of Forwarded Message
> 
> 
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