[TowerTalk] Top Hat Switch (mercury)

[Tom Rauch]

Hi Ford,

> The mercury switch is a vacuum.  The leads are about 1/4" apart as they
> escape the envelope.  At 21 volts per thousanth of an inch (handbook #), a

Voltage breakdown varies greatly with shape and rate of change in 
the electric field between the two conductors. I think the number 
you saw is for a uniformly distributed electric field and likely it was 
for some set of moisture conditions and doesn't allow for surface 
creepage. 

> 1/4" gap should handle many KV.  (I only run 1KW max here at this time ~~
> 3KV).  I know nothing about the conductivity of mercury.  For all I know
> it will explode in this environment! 

If it does explode, don't let it get into your water or food supplies. 
You'll be known as "Mad-as-a-hatter-Ford". 

Now that I think about it, maybe mercury exposure is more 
common than I realized in ham radio. Perhaps grabbing an 866 and 
swigging it down instead of an 807?

73, Tom W8JI
W8JI@contesting.com 

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