A Tale of Two Meters

I am an amateur radio operator and subscribe to several mailing lists that discuss building and testing amateur radio equipment, including the Elecraft mailing list and Flying Pigs QRP Club mailing list. I love these lists because they’re chock full of practical information from amateurs who are actively building stuff.

AADE LC Meter IIB KitOne item that is frequently discussed on these lists is the AADE L/C Meter IIB Kit. Many hams like it because it’s inexpensive ($100), easy to build, and apparently, accurate and useful.

Agilent E4980AThe other day, I got a press release for a similar instrument–the Agilent E4980A Precision LCR Meter. Being an Agilent product, I would guess that it’s also accurate and useful. At $13,000, the Agilent E4980A certainly costs a lot more, though.

Of course, there are other differences. For example, AADE specifies an accuracy of “1% typical,” while the “basic accuracy” of the E4980A is 0.05%. The AADE meter uses a fixed test signal, while the Agilent meter can make measurements with a test frequency betweeen 20 Hz and 2 MHz. The AADE meter measures inductance from .001 mHy (1 nHy) to 100 mHy and capacitance from .010 pF to 1 mFd. The Agilent instrument measures these parameters over a much wider range in addition to resistance, complex impedance, Q, and other related parameters.

The Agilent is, of course, a much more capable instrument, but is it worth $12,900 more than the AADE meter? For some applications, of course, but for many applications, and certainly most amateur radio applications, the AADE meter more than meets the need.

Comments

  1. Here’s a comment from Vic K2VCO on measuring inductance:

    Remember, the measured inductance of a toroid depends on the frequency at which it’s measured because of the characteristics of the toroid material. I don’t know the frequency used by the AADE unit, but if it’s far from the operating frequency of a particular toroid, the results might be misleading.

    If you must measure the inductance of a toroid, it would be better to use something like an antenna analyzer which will allow you to select the frequency at which the measurement is made.

  2. Dan,
    Another issue to consider is traceability of the measurement. Most of the ham-grade stuff doesn’t address this at all. You see specs that are typical at best and calibration is totally ignored, which is probably OK for the hobbyist market.

    “Real” instruments have to demonstrate that their accuracy is traceable back to NIST (or similar standards authority). This gets into serious metrology, calibration and traceability issues that tend to drive up the cost of the product. Of course, this probably doesn’t apply to the ham/hobbyist.

    Bob K0NR

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