Micro-Ion ATM gauges on eBay

Every fusor and fusion system seems to need a vacuum. This area is for detailed discussion of vacuum systems, materials, gauging, etc. related to fusor or fusion research.
Dan Knapp
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Micro-Ion ATM gauges on eBay

Post by Dan Knapp » Wed Mar 13, 2019 2:53 pm

I just bought a Granville-Phillips (now MKS Instruments) Micro-Ion ATM gauge on eBay at a very good price, and the seller has four more available (https://www.ebay.com/itm/163551703123). Be aware that from the photos, at least one of these has heavy burn contamination on the inside of the flange. If you can get a clean one, it is quite a deal as these normally cost $1800. I have been using another one of these for several years and am very happy with it. I combines a diaphragm gauge, a heat loss gauge, and a (dual) hot filament gauge to span from atmosphere to 10-9 Torr. The sensor head is replaceable on these, but doing so is pricey ($800) unless you can find a replacement on eBay. You should be aware that the model for sale (390515-2-YG-T) is a custom version with the gauge enable control reversed from the standard described in the manual. You have to connect pin 3 to pin 5 to turn these on. Without knowing this, you would likely conclude that you've received a nonworking gauge and return it. There are other less important changes I could share with you if you buy one; PM me. I haven't actually received mine yet (I'll update this if indicated), but thought I'll share this with the group before they are gone.

Chris Giles
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Re: Micro-Ion ATM gauges on eBay

Post by Chris Giles » Wed Mar 13, 2019 9:29 pm

There is also a Series 354 available in US eBay cheaper. However, this covers only the high vacuum range so needs to be combined with another gauge. I got one of these but haven't got my high vacuum section running yet so haven't tried it out. Mine is RS-485 only..

Jerry Biehler
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Re: Micro-Ion ATM gauges on eBay

Post by Jerry Biehler » Thu Mar 14, 2019 1:01 am

Chris, those are DeviceNet. Good luck talking to them.

ian_krase
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Re: Micro-Ion ATM gauges on eBay

Post by ian_krase » Thu Mar 14, 2019 6:53 am

Yeah, I made the very bad mistake of buying a Devicenet pirani gauge.

It has a display, so not totally useless, but unlike most of the other industrial fieldbuses, Devicenet is extremely difficult to connect to anything.

Chris Giles
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Re: Micro-Ion ATM gauges on eBay

Post by Chris Giles » Thu Mar 14, 2019 10:12 pm

Jerry Biehler wrote:
Thu Mar 14, 2019 1:01 am
Chris, those are DeviceNet. Good luck talking to them.
Good point. The one I have is RS-485, for which I have a USB adaptor. I have no experience with DeviceNet.

Dan Knapp
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Re: Micro-Ion ATM gauges on eBay

Post by Dan Knapp » Tue Mar 19, 2019 10:51 pm

I received the Micro Ion ATM gauge today. It was too good to be true. They were listed as "Used," which, by eBay definition means fully functional, but it had an open filament. I told the guy I would try another one of his batch, but I suspect he got a batch of burned out gauges. Sorry for the false alarm on a good deal.

Jim Stead
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Re: Micro-Ion ATM gauges on eBay

Post by Jim Stead » Tue Mar 19, 2019 11:44 pm

Sorry to hear that. I bought one of these gauges too, and expect to get it on the 25th. I'll let you know what I end up with.

Jim Stead
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Re: Micro-Ion ATM gauges on eBay

Post by Jim Stead » Sun Mar 31, 2019 2:03 am

I received my gauge on Monday. Unfortunately it fried itself after about 5 minutes of operation

It powered up normally with the 25.16vdc I supplied it with from a pair of serially connected 12v batteries. I connected no other pins but power and 3 to 5. The screen showed 7.6e2 Torr in (A)bsolute measurement upon power up, which is good.

Roughing down, the gauge followed the pressure change while displaying a pressure a bit higher than my DV-6 thermocouple which has been calibrated using a reference tube.

At about 20 micron on the 390, or 15 micron on the TC, the 390 switched to Ion mode. The green light started blinking, which is a good sign for the filaments. The display now showed 1.0e-10. Obviously very wrong. Hoping that a lower pressure would get it out of that weird reading, I started the turbo pump.

While the turbo came up to speed, the ATM gauge did not change its display at all. After a few minutes I heard a light "pop" sound and the gauge went dark. I would guess the vacuum to have been in the e-4 or e-5 range when this occurred.

The gauge now smells of burned electronics and does not power up at all. Very disappointing. I'm guessing the previous user of this gauge had a current limited supply that was being shut down by this gauge. Hence the move to taking it out of service and subsequently selling it.

Dan, did you get your replacement gauge?

Dan Knapp
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Re: Micro-Ion ATM gauges on eBay

Post by Dan Knapp » Sun Mar 31, 2019 2:34 am

I sent the seller information on how to check the filaments, and he said all of the gauges he had tested bad. I just got a refund on my purchase. The one I received worked ok for the low vacuum stages but shut off when it transitioned to the ionization gauge. He still has them with the same listing on eBay. Buyers beware.

Chris Giles
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Re: Micro-Ion ATM gauges on eBay

Post by Chris Giles » Sun Mar 31, 2019 7:23 pm

I sent the seller information on how to check the filaments
I see in the manual for the 354 gauge that it shows you can check the two filaments are 0.2 Ohms and the Grid 0 Ohms (p43 of service manual). I haven't got round to using my gauge yet (RS485 bit of a pain & I dont have my high vacuum stage ready) so I did this test on mine; the two filaments are approx 0.17 Ohms, grid 0.07 Ohms (this was a 2-wire measurement.. not that accurate). So I hope that is OK. I expect they normally fail open-circuit? Short circuit is obviously hard to measure for the filament.

To be clear, mine is a Granville-Phillips Micro Ion 354005-YD-T and not from the same seller as the other being discussed.

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