Vacuum RQ gap

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Original poster: "J. B. Weazle McCreath by way of Terry Fritz <twftesla-at-uswest-dot-net>" <weazle-at-hurontel.on.ca>


At 06:29 AM 20/12/00 -0700, you wrote:
>
>Original poster: "Chris Dobson by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <cdobson-at-microtech-dot-com.au>
>
>Hi all
> 
>I have modified an RQ type spark gap so that it is a "vacuum" type - ie,
>a vacuum motor draws air strongly through slots in the side of the cylinder,
>through each gap.  My question is, does the amount of suction affect the
>efficiency of the gap, and if so would a variac or dimmer switch be a good
>idea to control the motor speed?
> 
>Chris
>
>Riana, TAS
>
>
Hi Chris,

My RQ gap is quenched with an old Filter Queen vacuum cleaner compressor
and motor just as you describe yours.  I added plastic baffles both above
and below the copper pipe sections to direct the airflow through the gaps
from slots cut in the PVC housing.

The upper baffle has a hole in the centre to let the air be drawn up into
the vacuum unit on top of the gap.  This gave me a very high velocity air
flow through the gaps, which I could then throttle by varying the speed
of the vaccum motor.

I found by trial and error that my coil performed best when I had about
50 volts applied to the motor.  This also resulted in the motor drawing
much less current than with 120 volts applied (2 amps versus 7 amps) so
I'm able to use a comparatively small variac for control, remembering of
course not to crank it up!

I'm sure you would find similar results on your coil.  I can't comment on
whether a dimmer would do the job as well as a variac, maybe others will
help you out in that regard.  Keep 'em sparkin'!


73, Weazle, VE3EAR/VE3WZL

Listening: 147.030+ and 442.075+
E-mail:    weazle-at-hurontel.on.ca
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