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Re: New solid state pictures
Hello,
At 11:45 AM 5/13/00 , you wrote:
>Original Poster: "R.E.Burnett" <R.E.Burnett-at-newcastle.ac.uk>
>
>
>Hi David, all,
>
>>>>snip<<<<<<<<
>
>I used very thin wire for the SSTC pictured on my web page to keep the
>overall TC very compact, but I'm sure the current is far too high near
How small IS small? I use #28 AWG, but have found similar heating with #24
AWG magnet wire. The #24 was a bit closer coupling, but no observable
corona between it and secondary (in dark!).
>the bottom of the resonator. The resonator pictured on the web page
>actually got too hot to touch after a 2 minute CW run. Some turns near the
>bottom shorted and actually burned complete rings in the varnish !
Yes! This was my first warning! I obviously failed to heed it, then. I
found the PVC tube had some real warpage, and had carbonized some time
before actually failing...
>
>I must try the audio modulation trick also.
>
>The point about smoke and flames is very valid. I was amazed at the
>severity of fires which develop instantly if there was a flashover. I
>tightened the coupling too far, and there was a flashover. I cut the
>power as soon as I saw the ball of flame between the primary and
>secondary, but the secondary was burned beyond repair !
>
>I'm actually glad that happened, because it was a graphic demonstration
>of what would happen if someone accidentally got a limb too close :-(
I have melted surgical steel with the output of a VTTC....
>
>> See my photos running with half-wave pulsed DC at
>> http://www.pond-dot-net/~davidt/webdoc2.htg/Photos.htm
>>
>> Regards,
>> David Trimmell
>
>Very impressive, I particularly like that spidery effect. Do you know why
>the sparks are totally free of any branching ???
>
>Does a VTTC coil track the drop in resonant frequency as there is breakout
>from the resonator ??? Maybe this causes the long straight sparks ???
Since I was using a level shifted supply, I believe the spike in plate
voltage is responsible for the nice pointy sparks, but am not sure, as one
can get fuzzy sparks also.
Grid feedback (as far as *I* know) doesn't follow F changes fast enough. I
did find that while running under Staccato mode <20 PPS that it did seem to
affect tuning, though.
Regards,
David Trimmell
>
> Cheers,
>
> -Richie,
>
>