Extech automated data collection

[Joe Gwinn]

"(D exceeds 0.5 (equivalently, Q less than 2), at 1 KHz) "

D=0.5 == Q=2 I thought you were saying we need Q to approach 1/2 or D needed to be larger than 0.5 e.g. D=0.75 which is the same as Q = 1 1/3

The precise statement from the specs is a bit confusing. The hope is to find instruments that will measure fairly lossy inductors with reasonable accuracy. The spec are usually for ~1% basic accuracy, but for pickups 5% is plenty, so if the instrument is well designed, it will work OK and give consistent results even if at the edge of its spec limit.

To summarize, we are looking for instruments that claim to work with the lowest values of Q (equivalently, the highest values of D).

The new BK unit claims to support D<0.5 I have a friend who has one and I may have access to the new agilent units although they are at a much higher price point than the Extech units.

It would be interesting to know, but B&K cuts far to many corners for my taste, so I'd try using the instrument for a while, to find the unexpected gotchas. Like really slow measurement speeds, a common problem.

[Mike Sulzer]

The HAMs seem to be doing DIY or small run VNA's like these days. I am surprised someone hasn't built one for plotting out pickups and tone stacks.

I have built and used a current to voltage converter for this purpose and discussed many of the results on this forum. My thinking now is that one needs no special purpose hardware for this at all: a good quality two channel sampler intended for music recording into your computer is all the hardware necessary when used with good software.

I will try to post some results in the next couple of weeks.

[Possum]

Don't forget that the meter reads AC resistance, not DC. I find this ability is highly useful and its the first thing I look at with pickups. I'd be curious though to know if AC resistance at 10khz has any use at all. 10khz is kind of above almost everything in the pickup world. I really love the Syscomp gear I got, it gives me a good picture of what the LCR meters don't see in the higher frequencies.....