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fluorocarbon for a tektronix p6015 hv probe .....

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Patrick

Wed Nov 17 2010, 12:36AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Steve McConner wrote ...

Try to get hold of Terry Fritz, he had a few P6015s and about 10 cans of the Freon stuff last time I looked.

I have not been able to find a conact for Terry Fritz yet, does he have his own website now that someone else does the pupman site?

Sulaiman

Wed Nov 17 2010, 01:13PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

For my P6015 I have tried a couple of dielectrics,
I am currently using Butane (lighter refil gas) .... YES , I know it could be flammable BUT
I put a lot in (1cm liquid) and let it boil off to about 5mm,
the cylinder by that point should have very little oxygen left,
then I seal it. .....so far so good, and it's cheap & easily obtainable.

Without dielectric I flashed it over at about 20 kV, with butane I haven't flashed it over yet.

If anyone has a really good alternative I too would like to know.

teravolt

Wed Nov 17 2010, 08:14PM

Registered Member #195 Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111

I have 3 probes with the same problems I think they will hold off 13k with out freon and 20k with. I have also herd of silicon oil working to 20kv but I am not shure of the dialectric constant of freon and silicon oil if they are the same no adjustment may be nesisary.

Patrick

Wed Nov 17 2010, 08:40PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Sulaiman wrote ...

For my P6015 I have tried a couple of dielectrics,
I am currently using Butane (lighter refil gas) .... YES , I know it could be flammable BUT
I put a lot in (1cm liquid) and let it boil off to about 5mm,
the cylinder by that point should have very little oxygen left,
then I seal it. .....so far so good, and it's cheap & easily obtainable.

Without dielectric I flashed it over at about 20 kV, with butane I haven't flashed it over yet.

If anyone has a really good alternative I too would like to know.

i think the risk of explosion is remote, the risk of flash fire no greater then the HV itself.

hmmm butane, i will look that up. im looking in the Merck chemical index and CRC handbook it looks like butane does have low pressure, with dielectric strength greater then air, but good numbers are hard to quote, need to do more searching.

EDIT: butane vapor pressure = 2.4 atm. (17% higher pressure then the tek specified dielectic)

since Sulaiman hasnt lost any fingers, or gained pressure burst flak in his gut, Butane may be a acceptable solution. I find it hard to think up anything better. TY to Sulaiman.

Herr Zapp

Thu Nov 18 2010, 01:21AM

Registered Member #480 Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644

Sulaiman -

You mentioned that youi experienced a "flashover" in your P6015 probe at around 20KV when used without any Freon fill.

By flashover, do you mean a surface flashover across the 100M resistor?

Here is a link to an old Tek paper on oscilloscope probe design, including a schematic of the compensator box used with the P6015 probe. I wasn't aware that the cable from probe to compensator box used a special resistance wire inner conductor.

Herr Zapp

Patrick

Thu Nov 18 2010, 06:58AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Grenadier wrote ...

i saw this too before, but if i have to goto the trouble of finding a qualified person to recieve it, and pay 49.95$ then i want something better then a pre 1970 rusted out s**t can thats probaly leaky/empty. wisconsin is bannig even R134A! without certification.

Proud Mary

Thu Nov 18 2010, 09:42AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Does the dielectric constant of the insulating medium not matter?

Steve Conner

Thu Nov 18 2010, 01:38PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Proud Mary: As long as the dielectric constant is not too different to the original Freon, the adjusters in the compensating box can be twiddled to get the probe's square wave response good again.

Butane has a dielectric constant of 1.73-something according to Wikipedia.

I told Sulaiman's idea to the other guys here in the lab and they all cracked up laughing. But the more I think about it, the more it seems brilliant in a warped way.

Maybe butane vapour can become the poor man's SF6, and we'll see a butane insulated QCWDRSSTC spewing flames from every point of the compass.

Patrick

Thu Nov 18 2010, 03:09PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

i cant remember if freon-12 is flammable or not, ill look this up after class.

Adam Munich

Thu Nov 18 2010, 08:30PM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

It is not.

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