Search found 686 matches

by Andrew Seltzman
Sun May 20, 2018 10:45 pm
Forum: Images du Jour
Topic: Sharing hamfest booty images
Replies: 18
Views: 1788

Re: Sharing hamfest booty images

Today's (May 20) turnout MIT Flea Market was much bigger than last months, with easily 4x the number of sellers. There were tables all the way up to the top of the parking garage. I got a 22" new in box LCD display for $60 and two 1sccm mass flow controllers for $10 ea. My haul 32952163_101028544775...
by Andrew Seltzman
Tue May 08, 2018 12:36 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Second pulse from He3 tube
Replies: 5
Views: 453

Re: Second pulse from He3 tube

In this case I don't think termination or ringing of a cable is the issue; a 650us delay would equate to a 400000ft long RG58 cable (5 ns/m (1.54ns/ft) delay).
by Andrew Seltzman
Sun Apr 15, 2018 5:04 pm
Forum: Images du Jour
Topic: Sharing hamfest booty images
Replies: 18
Views: 1788

Re: Sharing hamfest booty images

I was just over there are the M.I.T. Flea Market as well, yes, it had pretty slim pickings. It probably has a bigger turn out in the summer.
by Andrew Seltzman
Mon Apr 02, 2018 12:55 am
Forum: New User Chat Area
Topic: Thermocouple Gauges VS Vacuum Gauges
Replies: 6
Views: 626

Re: Thermocouple Gauges VS Vacuum Gauges

I'd recommend an MKS 901p, it's a combination piezo/pirani gauge that will function between atmospheric and 1e-5torr
by Andrew Seltzman
Sun Apr 01, 2018 9:54 pm
Forum: Vacuum Technology (& FAQs)
Topic: Critique this turbomolecular pump backed by Welch 1400 setup
Replies: 17
Views: 943

Re: Critique this turbomolecular pump backed by Welch 1400 setup

I would recommend a pfeiffer duo 2.5, or pfeiffer duo 1.5 vacuum pump if you are going to back a turbo. They are nice scientific pumps with an NW10 flange and available on ebay at a low cost. The Yellowjacket pump is designed for air conditioning service and will require some adapting to provide a c...
by Andrew Seltzman
Mon Mar 26, 2018 3:12 am
Forum: Vacuum Technology (& FAQs)
Topic: Operating Pfeiffer TC100 Controller
Replies: 16
Views: 771

Re: Operating Pfeiffer TC100 Controller

50 microns might just be the maximum vacuum of the backing pump. It's more then sufficient to pack a turbo pump. Jumping to atmospheric when the turbo is switched on is very unusual, I suspect a problem with the gauge. I would recommend an MKS 901P vacuum gauge instead https://www.ebay.com/itm/MKS-9...
by Andrew Seltzman
Mon Mar 26, 2018 2:09 am
Forum: Vacuum Technology (& FAQs)
Topic: Operating Pfeiffer TC100 Controller
Replies: 16
Views: 771

Re: Operating Pfeiffer TC100 Controller

McMaster is a US company, they ship fast and have a good selection of products.

What are you using for your vacuum pump, do you know the lowest pressure with the turbo off?
How are you connecting the Yellowjacket to the turbo?
by Andrew Seltzman
Mon Mar 26, 2018 1:31 am
Forum: Vacuum Technology (& FAQs)
Topic: Operating Pfeiffer TC100 Controller
Replies: 16
Views: 771

Re: Operating Pfeiffer TC100 Controller

It is very likely a leak. The pfeiffer vent valve is a G1/4 thread, also known as a BSPP. These threads are designed to seal with a captive o-ring. This is a parallel thread and will not seal with an NPT, which is a taper thread as they will bind and are a different pitch. Do not attempt to thread t...
by Andrew Seltzman
Sat Mar 17, 2018 11:22 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: Testing A Regulator
Replies: 3
Views: 254

Re: Testing A Regulator

It can't hurt to test with argon if you have it. Argon is cheaper and non-flammable.

As far as calibration, I would trust the pressure gauges on the regulator as long as they're not physically damaged.
by Andrew Seltzman
Sat Mar 17, 2018 1:43 pm
Forum: New User Chat Area
Topic: Is baking worth it?
Replies: 14
Views: 862

Re: Is baking worth it?

For a "proper bakeout" (limited to 450C by the conflat o-rings), these high temperatures are only used when desorbing hydrogen from the stainless parts. This in only required for systems pushing the 1e-13torr range, for baking out H2O a little over 100C is a reasonable temperature. You don't have to...