cheap Yellow jacket 1 micron or 0.5 micron HVAC gauges


by now most of you guys know im cheap. any of you guys using the LCD digital Yellow jacket gauges for reading vac depth? are they accurate and reliable?

There are 2 models im interested in… 69075 (atmos down to 1 micron) and 69070 (1999 micron down to .5 micron greater, resolution but they use same sensor).

these can be had for less than 150 shipped in good used condition on ebay


Replacing sensor on yellow jacket vac guage
Non Decarbed crude causing high pressure?

If those are universal, I got a replacement one from bullseye for60 shipped


I use yellow jackets often as secundary gauge pirani after the coldtrap and the yellow jacket before the coldtrap or on the glasswear till 10 micron i find them pretty good i am not sure of the models i have
But i ll check
Even When gooing deep with the diffusion pump i place them on the rig for as long as the go in blank/error i know i am deep😀

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Looks like bullseye and yellow jacket use same rebranded sensor



I am convinced they are the same sensor which means the handheld display is what you are paying the extra three to four hundred dollars for with the bullseye weather that is worth it to you or not is completely up to you but yellow jacket makes or did make a readout that goes from .5 to 1999 micron which is actually more fine then the bullseye whether or not the sensor can resolve that level of accuracy is another question.

Does anyone know if the bullseye sensor is a 4 to 20 milliamp signal?

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I’ll be picking one up a la Rogue’s recommendation to settle my fear of killing a bullseye. Noob question, but how would you connect that sensor to your glass?

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Place it in the vacuum line after the cold trap, the traps will keep all the trash off the sensor. Otherwise its bound to die a early death in an enviroment like that.


I think I’ll heed that advice for sure. I saw photos of people running bullseye gauges right after the condenser despite all the warnings I hear not to do so which lead to some confusion, but Rogue had a fair point about the cheaper gauges. So I was thinking of running my bullseye after the cold trap and a cheaper yellow jacket after the condenser just to learn the system, then eventually just capping the first gauge port and solely running off the post-cold trap bullseye.

Or am I over complicating this?

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I take a vac reading 3 places.
There is a general thermocouple type guage used behing the cold trap for ballpark low vacuum, then there are pirani sensors before and after the diffusion pump.


the sensor type in these are accurate down to .001 torr

they are called Agilent Type 531 thermocouple vacuum gauge sensors

I am finding many similar sensors that may all be swappable.

Please note these units (yes including bullseye are not as accurate as pirani sensor units)


Yellow jacket plug


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found this on ebay

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Buy a 1/4 " s flare soldering fitting at the hvac shop and a tube slodering conector and with a piece of tube to the glas
Or My Rogue way
Take the s flare that fits your glass port
Tape the flare Shut
Turn flare and glass in a manner that in between glas and flare both sanded and cleaned with acetone. Can be reached with syringe with epoxy fill coupling with epoxy warm the gleued seal with heatgun to make airbubbles pop before epoxy hardening let. dry and drill a hole in the epoxy
Treu the flare hole
This can also be done with a s flare coupling with srhedder valve only glueing is a little more complicated


I can confirm the MASTERCOOL 98061 HVAC readout indicators do not work with the Agilent 531 sensors used in the bullseye. only proprietary mastercool sensors appear to work

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How is that mastercool sensor working? I have been looking at this and the yellow jacket also.

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