Search found 169 matches

by Dan Knapp
Sat Apr 21, 2018 10:53 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Detector noise problem
Replies: 9
Views: 426

Re: Detector noise problem

The noise is still there with the detector HV bias turned off.
The low pass filter suggestion sounds like a possible solution. The neutron peaks have a fast rise time, so I’m not sure how they will be affected; but it’s an easy thing to try.
Thanks again for the comments.
by Dan Knapp
Sat Apr 21, 2018 2:29 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Detector noise problem
Replies: 9
Views: 426

Re: Detector noise problem

We’ve tried running the preamp with battery power, attaching the preamp to the tube with a double male bnc (quality of connector unknown, however), and capping the preamp input with a terminator (which eliminates the noise as does leaving the preamp input BNC open. We also tried ferrites on the prea...
by Dan Knapp
Fri Apr 20, 2018 11:02 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Detector noise problem
Replies: 9
Views: 426

Re: Detector noise problem

Sorry for not explaining the two traces. The blue trace is the preamp output, and the yellow trace is the count output from the SCA. On the noise trace, there is no count pulse because the threshold was set to reject the noise peak (which also blocked the neutron peaks). The neutron peak trace was c...
by Dan Knapp
Fri Apr 20, 2018 1:31 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Detector noise problem
Replies: 9
Views: 426

Detector noise problem

We are having a problem with discriminating neutron peaks using a He-3 detector tube and seek ideas on how we might solve the problem. The detector is a one inch 4 atm. Saint-Gobain “ruggedized” He-3 detector tube operated at the recommended 1150 volts. The tube is inserted into a central bore in a ...
by Dan Knapp
Mon Apr 16, 2018 11:45 am
Forum: Vacuum Technology (& FAQs)
Topic: Can I make my own ConFlat flanges?
Replies: 27
Views: 712

Re: Can I make my own ConFlat flanges?

I was just browsing eBay and found about 45 pages of conflat components including several 8 inch flanges for under $100US. There is what I’m pretty sure is an 8 inch blank flange for $45US. The seller didn’t state the size, but the photo looks like an 8 inch. In my experience, sellers will often acc...
by Dan Knapp
Sun Apr 15, 2018 8:42 pm
Forum: Vacuum Technology (& FAQs)
Topic: Can I make my own ConFlat flanges?
Replies: 27
Views: 712

Re: Can I make my own ConFlat flanges?

It is doubtful that you could buy the SS material and pay for a CNC job and end up with a flange for less than just buying it. Check LDC Vacuum Products for some of the lowest prices from a regular vendor. Best deals are on eBay, but the “buyer beware” rule applies.
by Dan Knapp
Sun Apr 15, 2018 2:59 pm
Forum: Images du Jour
Topic: Sharing hamfest booty images
Replies: 12
Views: 1188

Re: Sharing hamfest booty images

Slim pickings, but still interesting. I finally had an opportunity to attend the legendary M.I.T. Flea Market, held monthly during the “warm” months in the Albany Street parking garage. Today was the first of this year’s series. A lot of stuff changed hands, but for my interests, it was a bit of a d...
by Dan Knapp
Mon Apr 09, 2018 11:28 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: F.I.C.S Fusion Runs
Replies: 22
Views: 1330

Re: F.I.C.S Fusion Runs

I reiterate my earlier comment. I think if you plot your fields you’ll find that the -65 kV penetrates into your center electrode and what you have built is a single beam linear fusor.
by Dan Knapp
Sun Apr 01, 2018 5:17 pm
Forum: Images du Jour
Topic: Sharing hamfest booty images
Replies: 12
Views: 1188

Re: Sharing hamfest booty images

I was looking for panel mount potentiometers. I missed those you mentioned. Even at $10 each, depending upon specs, it could have been a good deal. I'm getting low on them having built several modular HV supply controllers recently. I regret that I missed all that stainless hardware you scored. It a...
by Dan Knapp
Sun Apr 01, 2018 3:27 pm
Forum: Images du Jour
Topic: Sharing hamfest booty images
Replies: 12
Views: 1188

Re: Sharing hamfest booty images

I had a good weekend. Although I scored far less at RARSFest than Richard, its always great fun searching. My best deal was the Allen-Bradley tower light for $10. When I looked up the wiring info, I learned that this would cost $337 new! My smallest was the hemostat for 25 cents. I got two like new ...