Search found 731 matches

by Jerry Biehler
Wed Sep 04, 2019 4:06 am
Forum: Vacuum Technology (& FAQs)
Topic: Turbomolecular pump troubleshooting (EXT255H with EXDC80)
Replies: 44
Views: 7022

Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Sounds dead to me. But make sure your switch is connected to ground and not 24v. It pulls the start switch low to start.
by Jerry Biehler
Fri Aug 09, 2019 7:21 am
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Reforming capacitors in consumer electronics?
Replies: 5
Views: 3203

Re: Reforming capacitors in consumer electronics?

About the only thing I have worried about reforming is my big yag laser welder. It sat for about 15 years before I powered it up. To reform the caps on that I used a 300v power supply and charged the bank up over a period. Seemed to work fine, nothing blew up when I connected it to mains. Im not sur...
by Jerry Biehler
Fri Aug 09, 2019 7:10 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: Interest in RGAs (possibly a candidate for an FAQ?)
Replies: 18
Views: 7140

Re: Interest in RGAs (possibly a candidate for an FAQ?)

The preamp and amp circuits for the faraday cup designs are out there. I have the schematics for the quadrex RGAs, should be easy enough to copy. But I still would never want to build a RGA. I have other things I would rather be not doing. lol Yeah, we were looking at possibly just recoating the cha...
by Jerry Biehler
Thu Aug 08, 2019 5:38 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: Interest in RGAs (possibly a candidate for an FAQ?)
Replies: 18
Views: 7140

Re: Interest in RGAs (possibly a candidate for an FAQ?)

Just use a faraday cup. You really don't need the extra sensitivity of a EM for most things. I suppose you could also take the guts out of a small PMT and use that too. Or salvage the MCP out of an old image intensifier tube. A friend and I were looking at what it would take to rejuvenate a channelt...
by Jerry Biehler
Sat Aug 03, 2019 2:05 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: Interest in RGAs (possibly a candidate for an FAQ?)
Replies: 18
Views: 7140

Re: Interest in RGAs (possibly a candidate for an FAQ?)

The ceramic part comes off, it is probably there for shipping to support the ends. But yeah, its simple but expensive and it needs to be to spec otherwise the head unit will detect something wrong because it measures current. Its just one of the things to watch out for when buying a used RGA. There ...
by Jerry Biehler
Fri Aug 02, 2019 7:12 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: Interest in RGAs (possibly a candidate for an FAQ?)
Replies: 18
Views: 7140

Re: Interest in RGAs (possibly a candidate for an FAQ?)

Not all filaments can be rebuilt. The ones on my dymaxions are two rods with a loop of filament wire. You cut the support off after you install it so once it's installed it pretty much over with. I did manage to move a good filament from my 100amu one with issues to my 200amu by making a fixture to ...
by Jerry Biehler
Thu Aug 01, 2019 6:32 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: Interest in RGAs (possibly a candidate for an FAQ?)
Replies: 18
Views: 7140

Re: Interest in RGAs (possibly a candidate for an FAQ?)

I have a couple Dymaxion RGAs and a Inficon Quadrex 200. Outside of leak finding they are not going to be too terribly useful on a fusor. If you get a electronics unit and probe separate you will probably have to recalibrate it. The software for the dymaxion has that all built in. I think the quadre...
by Jerry Biehler
Sat Jul 27, 2019 7:05 am
Forum: Vacuum Technology (& FAQs)
Topic: Construction of Nonconductive Internal Components of Vacuum Systems
Replies: 9
Views: 7185

Re: Construction of Nonconductive Internal Components of Vacuum Systems

You use PVC if you machine off the outer surfaces where the mold releases are. It does not outgas much. There is polyamide (kapton) and polysulphone. I have used caption all over in vacuum systems. There's alumina ceramic too. The stuff they make heat shrink out of, polyolefin, works pretty well too...
by Jerry Biehler
Wed Jul 17, 2019 7:27 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: Transparent Ceramic Viewports
Replies: 8
Views: 4299

Re: Transparent Ceramic Viewports

What people have been referring to as transparent aluminum is aluminum oxynitride (ALON) which is a transparent ceramic. Really expensive and kind of pointless for a vacuum window when there are so many other materials that will work just fine. Though it has one interesting characteristic in that it...
by Jerry Biehler
Fri Jul 05, 2019 8:10 am
Forum: Items For Sale
Topic: [REQUEST] 1 kV 10 A Diode and 10 kV Cable
Replies: 8
Views: 5166

Re: [REQUEST] 1 kV 10 A Diode and 10 kV Cable

Why do you need 100 and why 10 amps?

Plasma surge?

A ballast resistor is really all you need if you need to limit current.