Re: [time-nuts] Tek high voltage probes
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 -- John DeArmond Tellico Plains, Occupied TN http://www.neon-john.com-- email from here http://www.johndearmond.com -- Best damned Blog on the net PGP key: wwwkeys.pgp.net: BCB68D77 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Tek high voltage probes
John: One big difference is that when most of the butane leaked out and air leaked in, you'd get a very clear indication when arcs occur. I wouldn't want to be holding it. I think Tek degrades the P6015 to 13kV without Freon - enough for my needs. Maybe someone will find out that Home Depot Bathtub Selant #17 has a breakdown of 60kV and we can all do one last refill... Jose -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of NeonJohn Sent: Thursday, September 22, 2011 10:35 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Tek high voltage probes 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 -- John DeArmond Tellico Plains, Occupied TN http://www.neon-john.com-- email from here http://www.johndearmond.com -- Best damned Blog on the net PGP key: wwwkeys.pgp.net: BCB68D77 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Tek high voltage probes
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 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Tek high voltage probes
On 9/22/11 10:34 AM, 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. Yes.. most hydrocarbons make a fine dielectric (viz. transformer oil). To a certain extent, density is key, which is why the halogenated ones are nice (F or C are more massive than H). The other thing is that those halogens are electronegative which tends to suppress breakdown (why SF6 is great.. not only is it really dense, but it's also non flammable AND it's got fluorine in it) The halogenated ones are preferred in some cases because you can get other vapor pressures and/or they don't burn. There is, of course, a whole class of nice dielectric fluids based on halogenating double ring structures: PCBs. They're really inert, great dielectric strength, immiscible with contaminants (no dissolved water, which ruins dielectric properties). The problem is that there's an unavoidable carcinogenic contaminant (dioxin-like PCBs and PCDFs). And, because they ARE so resistant to breakdown, they persist forever, and, unfortunately, are fat soluble and taken up by wildlife. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Tek high voltage probes
Note that if you change the dielectric in the probe, especially to a liquid, you may no longer be able to compensate it properly. The higher dielectric constant will increase the stray capacitances. Best, -John On 9/22/11 10:34 AM, 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. Yes.. most hydrocarbons make a fine dielectric (viz. transformer oil). To a certain extent, density is key, which is why the halogenated ones are nice (F or C are more massive than H). The other thing is that those halogens are electronegative which tends to suppress breakdown (why SF6 is great.. not only is it really dense, but it's also non flammable AND it's got fluorine in it) The halogenated ones are preferred in some cases because you can get other vapor pressures and/or they don't burn. There is, of course, a whole class of nice dielectric fluids based on halogenating double ring structures: PCBs. They're really inert, great dielectric strength, immiscible with contaminants (no dissolved water, which ruins dielectric properties). The problem is that there's an unavoidable carcinogenic contaminant (dioxin-like PCBs and PCDFs). And, because they ARE so resistant to breakdown, they persist forever, and, unfortunately, are fat soluble and taken up by wildlife. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Tek high voltage probes
It's going on 10 years now since I last filled a probe. That's the major advantage of butane. It doesn't diffuse out like the freon did. On 09/22/2011 01:53 PM, Jose Camara wrote: John: One big difference is that when most of the butane leaked out and air leaked in, you'd get a very clear indication when arcs occur. I wouldn't want to be holding it. -- John DeArmond Tellico Plains, Occupied TN http://www.neon-john.com-- email from here http://www.johndearmond.com -- Best damned Blog on the net PGP key: wwwkeys.pgp.net: BCB68D77 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Tek high voltage probes
Neither diffuses out. They leak. They could certainly leak at different rates because of differing MWs, but how tight you made the sealing screw is likely far more important. -John == It's going on 10 years now since I last filled a probe. That's the major advantage of butane. It doesn't diffuse out like the freon did. On 09/22/2011 01:53 PM, Jose Camara wrote: John: One big difference is that when most of the butane leaked out and air leaked in, you'd get a very clear indication when arcs occur. I wouldn't want to be holding it. -- John DeArmond Tellico Plains, Occupied TN http://www.neon-john.com-- email from here http://www.johndearmond.com -- Best damned Blog on the net PGP key: wwwkeys.pgp.net: BCB68D77 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Tek high voltage probes
Just a FYI, some claim Ronsonol butane isn't very pure as compared to other brands. Some lighter manufacturers suggest not to use it in their devices. I have no idea what trace substances they object to. Reality? Who knows. Seems most butane comes out of Korea and could simply be repackaged/branded. Hopefully there are few smokers on the list, and if you do, don't smoke near your instruments. I only use a lighter for camping. You guys in the UK have the best: Turboflame. I've repaired (soldered) antennas in the field with a turboflame. http://www.turboflame.co.uk/ Try lighting an Esbit square with a regular lighter versus a turbo. On 9/22/2011 10:34 AM, NeonJohn wrote: On 09/21/2011 04:57 AM, David C. Partridge wrote: 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. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
