Search found 684 matches

by Andrew Seltzman
Sun Apr 15, 2018 5:04 pm
Forum: Images du Jour
Topic: Sharing hamfest booty images
Replies: 12
Views: 1188

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: 524

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: 735

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: 635

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: 635

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: 635

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: 200

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: 656

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...
by Andrew Seltzman
Mon Mar 12, 2018 3:28 am
Forum: New User Chat Area
Topic: Is baking worth it?
Replies: 14
Views: 656

Re: Is baking worth it?

I bake with resistive heaters on the shell to about 70-100C; it definitely desorbs water from the system. I recommend this method since it dosen't sputter grid material onto the HV feedthrough like running HV on the grid for the sole purpose of heating the chamber. Towards the end of the bakeout I a...
by Andrew Seltzman
Sun Mar 11, 2018 4:29 pm
Forum: Vacuum Technology (& FAQs)
Topic: Operating Pfeiffer TC100 Controller
Replies: 16
Views: 635

Re: Operating Pfeiffer TC100 Controller

Unsure, could you send a picture of your setup?
How long did you wait after connecting the power?
How much current is being supplied from the supply while the pump is not spinning?
Does the rotor spin freely?
Try connecting 3,4 and 5 to 7 like in my picture.