| History & Topics |
| The easiest way to check HF inductances. |
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| In most cases, an LCR meter or an Impedance
bridge is used to measure the coil inductance at audio frequency such
as 1kHz. When the applied frequency is increased, the coil's inductance,
as well as its Q, varies due to the skin effect, high frequency characteristics
of the core material and coil itself. This is the reason why the high
frequency measurement is desired for HF coils, however, the HF devices
such as an impedance analyzer are too expensive for the daily use. The Digital Dip Meter (DDM) solves the problem. Since DDM can detect the HF resonant frequency of coil and capacitor remotely, you can calculate the unknown inductance (L) if the capacitance (C) is given. When the capacitor is variable and calibrated you can read the unknown L directly on the L scale. The calibrated variable capacitor VC740 is designed for this purpose. Although it has no coil inside, VC740 has L scale along with calibrated C scale. When DDM is set on a specified frequency and the dip is observed, the vernier indicates the unknown inductor. Range covers from 0.06 microhenry to 1000 microhenry when DDM DMC-230S2 is used. This principle is based on the "good old" Q meter. |
| History & Topics - INDEX |
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