I am reverse-engineering a device so that I can develop my own, compatible device. There are a number of SMD Ferrite Chips (size 0603) inside.

A quick look at Digikey shows that there are almost 600 different size 0603 Ferrite Chips in stock and active.

I'm looking for guidance on how I can characterize the original parts and come up with a suitable alternative. Measuring the DC resistance is easy. But I'm not sure about the rest.

What approach might allow me to choose a suitable device?


This is for an interface to a digital walkie-talkie. UHF band: 400 - 470 MHz. Speaker & Mic connections are my main concern.

My first thought (after I posted my question) is to use a cheapie spectrum analyzer and signal generator and spot-check attenuation using the 50 Ohm input impedance of the spectrum analyzer.

I'm not sure what else I should be looking for..

  • 1
    \$\begingroup\$ Do you have access to a network analyzer? \$\endgroup\$ – jalalipop Feb 13 '18 at 20:46
  • 2
    \$\begingroup\$ What role are the ferrite beads doing? Power supply filtering in digital circuits, or is it a RF circuit? \$\endgroup\$ – peufeu Feb 13 '18 at 20:49
  • \$\begingroup\$ Failing a network analyzer, got a spectrum analyzer with tracking generator? \$\endgroup\$ – Spehro Pefhany Feb 13 '18 at 20:57
  • \$\begingroup\$ Generally low mu ferrite is used for UHF and high mu for HF but it is used for DC filter and low impedance circuits where adding 50~500 Ohms is desired for immunity \$\endgroup\$ – Sunnyskyguy EE75 Feb 13 '18 at 21:42

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