Even more important, servos are easier to build for 400Hz AC.  And many
airplane operations are controlled by servos -- or at least were circa
WW2.

The same electrician I talked about advocated that *everything* --
including power distribution -- be converted to 400Hz AC.  But IRIC
there are some odd impedance effects that show themselves at 400Hz that
do not at 60Hz and would cause some problems with electric power
distribution at the higher frequency.

Mike Freeman < K 7 U I J >


----- Original Message -----
From: "Jim Kutsch" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, November 07, 2003 4:14 PM
Subject: Re: OT - Line Voltages, Frequency in History


> 400 Hz is easier to turn back into DC using much smaller capacitors in
the
> power supplies.  Think about the resulting waveform after full wave
> rectification of 60 Hz vs.,. 400 Hz.  there are much deeper valleys to
fill
> in the 60 Hz waveform.
>
> 73,, KY2D
>
> Jim Kutsch
> Jacksonville, FL
>
> ----- Original Message -----
> From: "shawn klein" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Friday, November 07, 2003 17:38
> Subject: Re: OT - Line Voltages, Frequency in History
>
>
> Definitely an interesting topic. It's funny, I hadn't
> read this thread till today, but yesterday I was just
> musing on how interesting radio must have sounded in
> the spark gap erra with DC and various freqs of AC
> being used. I wonder why the military and aviation
> decided to use 400 HZ, and you probably know that the
> phone system uses 25 HZ AC ring current. Just think,
> if everybody'd stuck to DC we wouldn't have to deal
> with 60 HZ RFI. On the other hand, getting
> inadvertently zapped by 120 volts DC might be a bit
> more dangerous, I once heard, because your muscles
> would contract and not let you let go. It's doubtfull
> that the high voltage power line cancer scare would
> have occurred.
>