In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.
Subject: Re: Capacitive manometers, tips
Date: Jan 18, 3:16 pm
Poster: Richard Hester
On Jan 18, 3:16 pm, Richard Hester wrote:
For information on the Tylan transducers that Richard Hull mentions in his previous post, visit the Millipore web site and do a product search using the key word "capacitive" (I forget the precise URL). The Tylan product looks 100% compatible with all the others with respect to supply voltages and output voltage range. I didn't check the pinout, but it's probably industry standard as well.
I agree with Richard Hull about using a DVM instead of a factory standard readout up to a point. It may be the only option for the severely cash-strapped. However, the DVM had better be pretty good, especially for reading the lower couple of decades of the scale (0-10V output, range to about 10-4 of full scale, you do the math). The factory readouts allow one to adjust the scale with DIP switches for direct readout - not really necessary, but very convenient. More importantly, they allow the system to be zeroed at the meter rather than at the transducer. This is the recommended procedure for setting up the MKS transducers in a system. Maybe this might have something to do with interaction between the zero and span adjustment pots on the transducer - I'll have to ask. Other devices may be different. Readouts have popped up on Ebay periodically (buyer beware), I got one that way for about $60. Full price on the transducers is about 1500 to 1800 dollars for the ranges of interest to this group (temperature controlled, 1 or 0.1 torr full scale). Used prices range from a reported low of $10 in the last post (wow, Mr. Hull) to $500 from established used vacuum dealers. I paid from $20 (est., it was in a big pile of stuff)to $100 for mine. Chance favors the prepared eye.
Richard Hull wrote (condensed) -
>Capacitive manometers for most vacuum enthusiasts are a distant dream,however, due to their cost. please, never ever pay for a controller. Any digital multimeter will work with them. Just supply +\- 15 volt supplies and a voltmeter and you are measuring vacuum.