Re: Fw: frequency (fwd)

To: tesla-at-PUPMAN-dot-com
Subject: Re: Fw: frequency (fwd)
From: Bert Hickman <bert.hickman-at-aquila-dot-com> (by way of Terry Fritz <twf-at-verinet-dot-com>)
Date: Wed, 21 Apr 1999 11:42:25 -0600
Approved: twf-at-verinet-dot-com
Tesla List wrote:
> 
> Original Poster: Robert Volk <smrtmny2-at-earthlink-dot-net>
> 
> But why then did Tesla use high frequency generators?
> 
> Bob

Bob,

One of the objectives of early RF pioneers was to obtain high power
Continuous Wave (CW) RF to support long range communications. Tesla also
envisioned CW RF as being optimal for the wireless transmission of
electric power. Unlike intermittent, damped-wave RF obtained from a
sparkgap oscillator, CW has a narrower bandwidth (smaller frequency
deviation from the center frequency), making it more efficient and
desirable especially when more and more radio (or Tesla power
generating) stations began simultaneous operation. However, generating
high power RF was not simple in those times, since high power
transmitting vacuum tubes were not yet available when Tesla did most of
his research. 

One way to generate and research CW RF was to use specially constructed
alternators. Tesla (and others) designed some that were capable of
generating relatively high power (5 kW) at frequencies to 100 kHz.
Another way to generate high power CW was to use the negative-resistance
characteristic of an electric arc in a special atnmosphere (typically
hydrogen or alcohol vapor) and in a strong magnetic field to generate CW
RF. One of the more popular of these "singing arc" was the Poulsen Arc.
Many early high power (up to 100 kW) military and commercial radio
stations used Poulsen Arc transmitters until they were replaced with
more efficient high power vacuum tubes. 

An interesting discussion of early pioneering CW work and Poulsen Arcs
can be seen at:
http://www.cinemedia-dot-net/SFCV-RMIT-Annex/rnaughton/POULSEN_BUHL.html

Pictures of some of the Tesla's RF alternators can be seen in Thomas
Martin's "The Inventions, Researches, and Writings of Nikola Tesla",
Barnes and Noble, 1990, and in Jim Glenn's "The Complete Patents of
Nikola Tesla", Barnes & Noble, 1994. Both books are in print and
available through Barnes and Noble at http://www.barnesandnoble-dot-com/.
BTW, the latter book of Tesla's patents is a steal at $14.95!

Safe coilin' to you!

-- Bert --
> 
> 
> > Bob,
> >
> > The frequency of the secondary (and primary) is for all practical purposes
> > dependent only upon their inductance, self-capacitance, and added
> capacitance -
> > in the case of the primary, your main capacitor and in the secondary,
> your top
> > load. Altering the mains frequency (and the capacitor size accordingly) and
> > retuning the coil will only change the break rate of the spark gap -
> instead of
> > 120bps you will get 800bps (If you were using a sync rotary you would
need to
> > power the motor off the same 400Hz too). The power supply frequenccy should
> > never
> > havve any effect on, and certainly not reach the secondary - this is a
> > potentially lethal situation if a streamer with 60Hz or even 400Hz
> superimposed
> > in it hits you!
> >
> > Alex Crow