Search found 1229 matches

by John Futter
Tue Jan 16, 2018 6:03 pm
Forum: Vacuum Technology (& FAQs)
Topic: Double-Checking Diffusion Pump before Buying
Replies: 4
Views: 73

Re: Double-Checking Diffusion Pump before Buying

about 40 years old or older
at least the christmas tree appears to be all there
Check the heater when you get it if not working return it
by John Futter
Sat Jan 13, 2018 6:20 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: A Bunch of Failures
Replies: 46
Views: 1134

Re: A Bunch of Failures

With gas ballast closed the pump should be very quiet openeing gas ballast will give a gurgling sound that gets louder as you open the ballast further. put a nw25 blank directly on the pump does it go quiet without gas ballas??t. one should not leave these pumps on gas ballast as they will loose alo...
by John Futter
Fri Jan 12, 2018 5:55 pm
Forum: The Trading Post
Topic: Vacuum Throttle Valve
Replies: 9
Views: 254

Re: Vacuum Throttle Valve

Hunter Long
you need to change your login name to your real name
No handles only proper real names as per the rules for Fusor.net
by John Futter
Sat Jan 06, 2018 10:52 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: A Bunch of Failures
Replies: 46
Views: 1134

Re: A Bunch of Failures

you can get the right ultra grade 19 oil here
http://www.pchemlabs.com/product.asp?pid=1438
by John Futter
Sat Jan 06, 2018 7:35 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: A Bunch of Failures
Replies: 46
Views: 1134

Re: A Bunch of Failures

Anyone with a lathe some brass tube and a little brass plate would make one in under an hour
no oxy acetylene no prob just soft solder will do.

MAKE ONE!!!!
by John Futter
Tue Jan 02, 2018 6:46 pm
Forum: Ion Gun Design and Construction (& FAQs)
Topic: Electrometers and Picoammeters
Replies: 14
Views: 397

Re: Electrometers and Picoammeters

Ian
It is not the triax cable that is hard to get, it is the eye wateringly expensive cord plug
you can get them from Pasternak
by John Futter
Sun Dec 31, 2017 8:08 am
Forum: Ion Gun Design and Construction (& FAQs)
Topic: Electrometers and Picoammeters
Replies: 14
Views: 397

Re: Electrometers and Picoammeters

Analog Devices have an electrometer on a chip
we use it down to 10^-15amps FSD with no problem
you have to isolate the input lead to a teflon insulated post with appropriate guarding.
a heater resistor keeping water away is a must
by John Futter
Thu Dec 28, 2017 6:35 pm
Forum: Ion Gun Design and Construction (& FAQs)
Topic: RF Power Supply for ICP Purposes
Replies: 13
Views: 309

Re: RF Power Supply for ICP Purposes

Erik
That VSWR figure is for the attenuator it is not its with stand rating
ie the attenuator matches nearly 50 ohms resistive
more here from my web site
http://www.iel-rf.com/AttenuatorsDescription.html

all you need is a 1dB 25 watt dissipation attenuator
by John Futter
Thu Dec 28, 2017 1:34 am
Forum: Ion Gun Design and Construction (& FAQs)
Topic: RF Power Supply for ICP Purposes
Replies: 13
Views: 309

Re: RF Power Supply for ICP Purposes

Erik Make a 1dB attenuator to put on the output - you lose 20% of your output at the gain of not blowing the devices This immediately means the VSWR can not go over 8.7:1 with a dead short or open on the output (the two worst possible cases) which should be ok for that very old design Bipolar PA you...
by John Futter
Thu Dec 28, 2017 1:32 am
Forum: Ion Gun Design and Construction (& FAQs)
Topic: RF Power Supply for ICP Purposes
Replies: 13
Views: 309

Re: RF Power Supply for ICP Purposes

Erik Make a 1dB attenuator to put on the output - you lose 20% of your output at the gain of not blowing the devices This immediately means the VSWR can not go over 8.7:1 which should bew ok for that very old design Bipolar PA you have The one I linked to before with the BLF188XR can run VSWR of 65:...