[Milsurplus] Hig frequency power

[Mike Hanz]

Jack Antonio wrote:

> I'm currently bringing an R-61/ARQ-5 receiver back to
> life, and the tag says it takes 400 to 2600 Hz power.
> I've also seen that spec on a couple of other pieces
> of gear.
> Why the spec for power up to 2600 Hz? Were there any
> power systems that went up that high in frequency? 


Happens when you lose an engine and can't feather the prop... :-)

More seriously, the frequency of wartime AC generators was anything but 
constant, and the Navy aircraft had both 400~ and 800~ (nominal) 
generators that established the initial range.  Even the 800-1 could go 
significantly over nominal frequency in normal operation - I think 
Richard Brunner mentioned a >900Hz figure he measured on his at one 
point in testing, and the engine driven generators were even wider in 
range, depending on the engine settings.  That's the only reason I can 
think of for such a wide range.  The problems associated with generator 
inductance as you go higher and higher in frequency grow significantly - 
one reason the Navy abandoned the 800~ standard they were trying to 
hold.  I've never seen a WWII rotary inverter above 800Hz nominal, but 
perhaps they made one in an attempt to get the last ounce of weight 
off.  Would work okay if it was designed for/dedicated to one piece of 
equipment and could be tuned to that load.

Just random thoughts, really - I've often wondered the same thing.

73,
Mike