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Radio History

Subject:  Radio History
  Date:   Sun, 11 May 97 16:35:57 EDT
  From:   pierson-at-gone.ENET.dec-dot-com
    To:       
mail11:;;;;-at-us4rmc.pko.dec-dot-com-at-us4rmc.pko.dec-dot-com-at-unknown.domain.pupman-dot-com;;;
(-at-teslatech)
    CC: 
        pierson-at-gone.ENET.dec-dot-com


>> Has anyone every heard of an arc transmitter?
        Tes.  Got about two shelf feet of OLDE books ther eon.


>Arc or spark gap transmitters were fairly close to being Tesla coils.
        Arc and Spark transmitters are different animals.  A Spark
        transmitter is (IMO) indistinguishable from a tesla coil. 
        EXCEPT a spark transmitter is optimized for radiatioon of RF,
        while a TC is optimized for high voltage/sparks.

        An ARC transmiotter, properly so called, uses the negative
        resistance characteristic of an arc [nb: an arc is differen than
        a spark...] to creat an oscilattor.  (any neagtive resistance
        device can be used an amplifier.  Nothing mysterious...)

        Properly operated, they madde fairly decent sinusoids, they are
        NOT just charge/discharge devices.  As suc, one could be used to
        do a 'tubeless CW tesla coil;.

>They operated as CW ie. morse code transmitters.
        Arc transmitters did.  Spark Morse in NOT CW, as the spark wave
        is NOT continuous.  (getting deep into this is well off topic.
        So i won't.)  Howsomever, i believe ther are some things to
        be learnt from the Spark Transmitters, etc, as they handled
        similar voltages and frequencies and powers.  The techiques
        cannot be followed withouyt thought, as the goals are/were
        different.

>Things like rotary spark gaps were first developed for use with spark
>gap transmitters.
        Just so.

>> This makes me wonder if a Tesla Coil can be modulated?
        It is.  At the break rate.

>>What if you modulate the 120 VAC line into the neon transformer?
        Very noisy signal.  8)>>

>>What if  you modulate a 3rd coil on the ground end of the secondary
>>coil?  
        Its been done.

>> What if you modulate a TC with a carrier frequency and voice?
        The rf from the tesla coil IS a carrier frequemcy.  Spark
        oiiscillators are generally too noisy/discontinuos for voice.

>>Has  anyone ever tried to use a Tesla Coil as a transmitter? 
        Sure.  Nikola Tesla, for one...

>All of the above will get you one pink ticket from the F.C.C. and
>they would probably confiscate all your equipment.
        Yep....

===========================================
I would like to thank the list for the clarification on Dr Tesla's
Doctorate.  LAST time i asked that, no-one had verified the
honorary doctorate,  I know Tesla had a history of turning down
some 'honors', so it was interesting to see that he accepted these.

        regards
        dwp