[GreenKeys] Nice old picture

[Kevin DeWitt]

To add to Howards explanation, the PE-77 power plant in the tactical
teletype set is DC output, which eliminates the need for the RA87
rectifier. The PE-77 will drive both the motor and loop (using a line unit
and plug adapter). The thing I learned about the tuning forks is they
aren't exactly the same so if you use the tuning fork from one set to tune
another, your readings may be different. Not a huge deal but I spent an
afternoon trying to understand why.

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On Thu, Feb 11, 2016 at 9:50 AM, Howard Weeks <weeksh at att.net> wrote:

> A synchronous motor requires a stable AC frequency to keep the motor RPM
> on target. The U.S. Army signal Corps used motor driven generators in the
> field
> which was rarely running on frequency - therefore, they used governed
> motors
> which could be checked with a tuning fork and adjusted to speed by the
> operator.
>
> Howard K5JCP
>
>
> On 02/09/2016 08:51 PM, Dave Horsfall wrote:
>
> On Tue, 9 Feb 2016, Richard Knoppow wrote:
>
>
> Maybe different frequencies or DC being available.  In the Los Angeles
> area the City Department of Water and Power was 60Hz but Burbank, and
> some other areas were 50Hz. Warner Brothers, in Burbank, had motor
> generators to convert from 50 to 60 Hz for their RCA sound equipment
> that used synchronous motors.
>
> Didn't someone post an article here about the US' various power systems?
> I.e. DC/25/50/60/etc?  Can't seem to find it...
>
> I know that Edison, when Tesla's polyphase AC system was challenging his
> DC system, used to round up every stray dog and electrocute them with AC,
> to show just how dangerous it was...  I'll bet that he never did it with
> DC :-)  The irony is that DC is far more dangerous, because the muscles
> clamp and cannot let go; with AC, there is at least a zero-crossing point
> (well, that's what why eletrician Dad, bless him, taught me).
>
>
>
>
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