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Q meter ferrite bead conundrum ?

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I have constructed the Q meter circuit, illustrated on the following website https://www.edn.com/design/analog/4420157/Novel-Q-meter. Reference is made to L1 L2 and L3 being ferrite beads,to suppress unwanted parasitic oscillations at high frequencies.I must admit I have little or no experience of ferrite beads and their specific characteristics.I have used inductors.Where I get confused is when reference is made, to ferrite beads 80 nh 50 ohm impedance at certain frequencies.Has anyone else built this circuit or could shed any light on the correct ferrite beads to use ,dimensions and where to put them.

Also to limit the circuit and force it to operate, lower than 10 MHz bigger ferrite beads with higher impedance 600 ohm are mentioned. The use of these is understood.The confusion arises when specific inductance values and impedance values ,are referred to ferrite beads instead of inductors.
 
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dknguyen

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http://www.analog.com/en/analog-dialogue/articles/ferrite-beads-demystified.html

I think I asked a similar question a while ago...the conclusion I came to was the practical difference from and end-user point of view, is that ferrite beads are rated differently because they are meant to be used differently. They are optimized differently too where inductors are not lossy and ferrite beads are, but that doesn't matter to the end-user if you just follow the specs you need.

With inductors you usually care about the energy storage capability up to the resonance frequency and you just don't use the inductor's properties after that because that's when inductance drops. So at most, the inductance is charted out to the resonant frequency and no farther.

With ferrite beads you are trying to dissipate energy at certain AC frequencies, not store energy, so the ohms at different frequencies is charted out, and charted out past the resonant frequency since the ferrite bead's impedance is still of use in that application out there.

Their operating currents are also rated differently (see the link).

It's like an airliner and a fighter jet. They're both the same thing really. But you use them differently so they're built differently and specified differently because the specifications of interest are different. When shopping for airliners, you wouldn't specify it in terms of weapons payload and maneuverability, nor would you specify passenger count and fuel efficiency when looking at fighter jets.
 
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dr pepper

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Ferrite increases the magnetic field in a wound component, the field is increased by the permeability of the ferrite, this saves on copper & size.
If you slid a ferrite bar into an air core inductor its inductance increases.
The same goes for a ferrite bead, you are slipping a core around the outside of a piece of wire which is a single turn coil, so you are increasing its inductance.
Increasing inductance can be used to prevent oscillation at high frequencies.
You can get things like 'binoculars' which are effectively 2 ferrite beads joined so you can have many turns or even build a transformer.
 
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