RF choke in RF amplifier, how material?
N-MOSFET transistor have in drain RF choke.
Choke is toroids OD 24mm Ht 7mm (any as T94) painted on White, 11 turn , I measute L=12.4uH
Question is how type material is used?
I have yet found
1. Ferrite TN23/11/7 4C65 AL=87 [nH]
2. Senddust any as KS090-125A AL=90 [nH]
Anby other
3.May be HI-FLUX core H090-125A Al=90 [nH]
4 any other ferrites unfortunately I do not found a commercially available replacement for 4C65 (Ferroxcube)
5 Iron powder T94-52 Al=57 [nH], but I thing Iron powder have for this big core lost
Unfortunately, I do not know what rules are selected core parameters in this type coils?
Can you help me
Hi berger,
How do you make the inductance measuremetns you mentioned above? This is important because ferrite core materials has a very frequency dependent permeabilities.
Here is my opinion about the topic,
In order to charecterize your core material, you have two main steps to follow.
1) Measuring magnetic core's B-H Curve at some specific frequencies.
2) Measuring your magnetic core's complex permeability. This is a frequency dependent measurement.
After this measurements you have some curves depending field strength (H,A/m) and frequency(Hz). You can compere this curves with known curves (known core material properties) of interest.
I know these steps are very time consuming but I have no effective idea about characterizing your core material other than these steps.
Hope this helps,