Search found 1125 matches

by John Futter
Sun Sep 15, 2019 3:26 am
Forum: Vacuum Technology (& FAQs)
Topic: Turbomolecular pump troubleshooting (EXT255H with EXDC80)
Replies: 30
Views: 1088

Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

arun your power supply is one of those super cheap chinese switchers we bought one at work thankfully it blew up but it did not like talking to another switch mode down stream (in this case your upconvertor) use a linear bench supply --there is no substitute in a home lab --those switchers cause mor...
by John Futter
Fri Sep 06, 2019 9:19 am
Forum: Vacuum Technology (& FAQs)
Topic: Turbopump Bearing Kits - anybody have experience?
Replies: 3
Views: 364

Re: Turbopump Bearing Kits - anybody have experience?

ian
I have replaced bearings and transferred armatures from one pump to another
no failures yet --except for varian 550 units --just bad design
by John Futter
Fri Sep 06, 2019 9:12 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: SmCo Grid for Deuteron Deflection
Replies: 7
Views: 3408

Re: SmCo Grid for Deuteron Deflection

thanks Rich
i'm out by a factor of two

not bad for an old git who did a few calcs 25 + years ago while designing implanters with mass selection magnets
by John Futter
Thu Sep 05, 2019 8:05 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: SmCo Grid for Deuteron Deflection
Replies: 7
Views: 3408

Re: SmCo Grid for Deuteron Deflection

Trent
Protons deuterons do not get anywhere relativistic with 40kV acceleration
from memory when i did work this out years ago somewhere around 1000km/sec
all of this due to the difference between electron mass and amu mass
by John Futter
Tue Sep 03, 2019 10:37 am
Forum: Ion Gun Design and Construction (& FAQs)
Topic: Homemade Cathode Ray Tube
Replies: 6
Views: 694

Re: Homemade Cathode Ray Tube

Mark
Nice job
but by focus I mean less than 0.1mm in diameter at the distance your tube was working --this compared to a colour CRT colour purity

or if we go further a SEM with an electron scan dot size of 20nm diameter or less
by John Futter
Tue Sep 03, 2019 10:29 am
Forum: Vacuum Technology (& FAQs)
Topic: Turbomolecular pump troubleshooting (EXT255H with EXDC80)
Replies: 30
Views: 1088

Re: Turbomolecular pump troubleshooting (EXT255H with EXDC80)

Its easy for someone with your name all you have to do is#^$%^^
#$%&*$%&
$#^#$%^**%%^*%#$%#^@%
and there you are
by John Futter
Mon Sep 02, 2019 8:03 pm
Forum: Ion Gun Design and Construction (& FAQs)
Topic: Homemade Cathode Ray Tube
Replies: 6
Views: 694

Re: Homemade Cathode Ray Tube

Jacob Well done I woulod not expect a dot at that distance without a focusing element the simplest of which is the einzel lens a triplet of elements after your elecron source beam blowup at low accelerating voltages is what you are suffering from the electrons are repelling each other so the beam bl...
by John Futter
Sun Aug 11, 2019 8:01 am
Forum: Images du Jour
Topic: Hamfest booty
Replies: 10
Views: 4298

Re: Hamfest booty

Those three tubes look like crossfield ion gauges ie early penning tubes
came with Noah on the Ark
by John Futter
Sat Jul 27, 2019 7:37 pm
Forum: Vacuum Technology (& FAQs)
Topic: Construction of Nonconductive Internal Components of Vacuum Systems
Replies: 9
Views: 2986

Re: Construction of Nonconductive Internal Components of Vacuum Systems

When I was talking about boron nitride I was talking about the hexagonal variety, not the cubic cubic is expensive and is not machinable Hexagonal is very soft and machines like cheese you must protect bedways from it s another name for it is white graphite. Things like lath back stops etc suddenly ...