Testing used test equipment for accuracy - Page 1
Forum section: electronics / testgear

author: h_p
author_rank: Unknown
timestamp: May 07, 2017, 01:20:16 pm
content: So after working in electronics for 19 years (10 years US Navy Comms/Radar ET) and then 9 years now as a civilian (Medical field service; MRI, PET, CT, Linear particle accelerators) I am finally at a point where I can set up a home lab as I'm not in a big grey tin can or in field service anymore and always on the road. I have acquired a Rigol DS1054Z, Agilent E3610A, EEVBlog multimeter, a GW Instek GDM-8251A, a Rigol DG1022, and I have a fluke 115 I use around the house for home repairs. I am also building my own bench supply. This got me to thinking; how do I verify that all the used equipment is good? I began looking around at decade resistors, capacitors, inductors, voltage standards, etc.. and there are a ton on the market and I assume this would be the best budget way to verify accuracy. I was hoping for some recommendations on which are of a high enough quality for hobby use and in the under $100 range. I also have never had to test my own equipment. So I am wondering what tests/calibrations I need to perform to ensure that all this equipment is accurate (enough) for home/hobby use. Thank you.Oh and I picked up a Hakko fx-888d to boot. It's nothing like the solder rework station I had in the Navy but it'll get the job done. I saw in a video that Dave said the clone FG-100 temperature testers worked well. Anyone have any experience with these?

author: David Hess
author_rank: Super Contributor
timestamp: May 07, 2017, 02:27:27 pm
content: In most applications, working properly is more important than absolute accuracy so an absolute standard is not required for every type of measurement and range. I do not have a 6.5 or 7.5 digit voltmeter for absolute accuracy; I have it for measuring high resolution differences.Calibrating frequency is easy; use a GPSDO as a frequency reference.Ohms requires a couple of inexpensive resistance standards. Combined with a precision voltage source and precision transconductance amplifier and these become DC current standards.For DC voltage, I have a precision standard which checks the calibration on my best voltmeter which checks the calibration on my lessor voltmeters.For AC voltage I chop a precision DC source to make a precision AC source and use correction factors when applying this to average and RMS reading voltmeters.Transient response is a tough one. A fast reference level pulse generator and fast oscilloscope can verify proper operation of RF attenuators, oscilloscopes, oscilloscope probes, feedthrough attenuators, etc. But how do you know the fast reference level pulse generator and fast oscilloscope have accurate transient response? I have a sampling oscilloscope to verify my fast reference level pulse generator so the sampling oscilloscope indirectly verifies the performance of my other oscilloscopes and various RF parts. Unfortunately nobody makes a hobby level sampling oscilloscope. Most users will rely on their fastest oscilloscope in place of a sampling oscilloscope for this.The RF-nuts (volt-nuts, time-nuts, etc.) with have a VNA in place of a reference level pulse generator and sampling oscilloscope.A leveled RF signal generator is a time saver but how do you know it is leveled? I use a sampling oscilloscope to verify mine but a more traditional instrument to do this is a thermal RF power meter which can be calibrated against low frequency and DC sources.

author: h_p
author_rank: Unknown
timestamp: May 07, 2017, 02:42:59 pm
content: David,Yes working properly and accuracy are my concerns. I am not concerned about absolute accuracy as I neither have the time nor the money to buy expensive equipment or standards.To the rest of your post I haven't the faintest idea how to do any of the things you mentioned but I am ready, willing and able to learn how to do these things. One of the reasons I am building a home lab/bench is so that I can expand my understanding of electronics.