[Milsurplus] 115 VAC 400 hz power

[J. Forster]

Mike,

As to engine driven generators, I see no technical reason why they would
be problematic. As the RPM varied, the frequency would vary, but other
than possible fan or motor speed issues, the electronics should work fine.
Most all motors I've seen in radios operate on DC anyway.

So, if the alternator produces >400 Hz at idle, it'd not matter if it
produced 1200 Hz or whatever at full power.

Output voltage was regulated, of course.

This is theoretical knowlege, however.

Best,

-John

=============



>>115 VAC at 400 hz was also used as input for the power transformers in
>>some WW2 aircraft nav gear such as SCR 269, ARN 7, APN 4, APN 9 etc.
>
> As far as I can determine, all that aircraft 400 Hz power came from
> inverters.  The -1 flight manual (24APR51) for the B-29, 29A, and 29B
> (likely the WWII aircraft with the most need of 400 Hz power) indicates
> that all those loads requiring such power (including the "Raven"
> countermeasures gear) got it from multiple relatively small 28 vdc input
> single-phase rotary inverters.
>
> Engine-driven 400 Hz generation would be complex, given the requirement
> for a specific constant speed input to the generating system.  (Today's
> modern systems haven't that problem.  Honda's EU2000, for example, uses a
> microprocessor-controlled variable-speed engine to drive an alternator,
> whose output is rectified and fed to a microprocessor-controlled static
> inverter to produce some of the cleanest pure sinusoidal 60 Hz at constant
> voltage that a portable gasoline-powered 2 KW generator has ever
> produced.)
>
>>I've been tempted to amplify the output and fire it up on the 160M band
>> to
>>give the old timers a jolt, but sanity prevailed. The sound of LORAN A
>>signals is something the old timers on Top Band will never forget.
>
> One need not be an old-timer to remember 160m LORAN A signals.  The USA
> didn't close its LORAN A service until 31DEC80, a mere blink-of-an-eye
> ago.
>
> Mike / KK5F
>
> (I bought my R-65/APN-9 LORAN A at John Meshna's store in Lynn, MA, in
> 1976.
> An AN/APN-9 was installed on the Royal Netherlands Navy Destroyer Hr.Ms.
> Amsterdam, on which I was assigned in 1973, but in the North Sea we used
> the UK Decca Navigator instead as the preferred hyperbolic
> radio-navigation
> system.)
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