Re: Rotary Gaps

Quoting ed-at-alumni.caltech.edu (Edward V. Phillips):

> Re: Volume 5 of Radiation Lab Radar Series
> Richard:

> You may have overlooked one comment there (can't quote
> page and line as my copy is in my book case at work) which 
> mentioned that the guys at Rad Labs tried some of the earlier
> "radio transmitter" rotating gaps and found they didn't work
> any better than the ones they eventually ended up with, which
> mostly had pointed electrodes.  I have seen many radar 
> modulatro (modulator) spark gaps, and all had more or less 
> sharp points. The flat, wide electrodes came about because of 
> the desire to keep the circuit resistance very low.  An 
> "ultimate" ham transmitter at 200 meters (1500 kHz) used an 
> 0.01 mfd capacitor, with a reactance of about 11 ohms.  Any 
> circuit resistance at all knocked the primary circuit Q 
> (increased the decrement) to pieces.  

Yeah, I have noticed this. The points keep the dwell and quench
times low.

> Wonder what radar set used the rotary you mentioned,
> with electrodes like a tongue depressor?

The rotor electrodes were thin, say 3/16 inch, tungsten. Only the
stationary electrode was flat, and mounted so that it would
pivot. By pivoting the stationary electrode the dwell could be

Richard Quick

... If all else fails... Throw another megavolt across it!
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