[time-nuts] Tek high voltage probes

Chuck Harris cfharris at erols.com
Thu Sep 22 17:54:00 UTC 2011

For those that reflexively will add that butane is explosive in air:

There isn't any air in the probe if you let the butane boil for a few
seconds, and as long as there is liquid butane in the probe there won't
be any air "leaking" in.

However, if there is no liquid, you will need to purge out the butane
before operating the probe dry, or add more butane.

When I finally do run out of my supply of R114, butane will be my substitute
of choice for the R114.

-Chuck Harris

NeonJohn wrote:
> On 09/21/2011 04:57 AM, David C. Partridge wrote:
>> Howsabout HFC-236fa - very similar properties to R114 but not banned.
>>> Tektronix used a Freon in their 40 KV High Voltage probes. The Vapor
>>> pressure of some of those compounds is low at 70F, but they do have to
>>> be sealed.
> I use several of the Tek probes in my work (and of course am too cheap
> to buy the newer solid dielectric ones).  When my freon ran out, I
> searched around for a replacement fluid and found ordinary butane
> straight from the Ronsonol can to be equal to or maybe even better than
> the original freon.
> About a decade ago I wrote up a procedure on how to do the fill without
> introducing condensate into the chamber.  I posted it to Usenet.  I
> think that it's archived at http://yarchive.net.
> John

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