Pluggable Module Prototyping for Baluns and other Components

RE: Pluggable Module Prototyping for Baluns and other Components

jc2048 — Tue, 22 Mar 2022 10:28:21 GMT

Fair-Rite provide graphs of permeability against frequency for their cores, so I thought it might be interesting to see the difference between the type 43 material (NiZn) of your first core and the type 77 material (MnZn) of your second one.

In case anyone is interested, here I've overlaid the 77 one (black) with the 43 one (red). I'm not wonderful with Gimp, but after a bit of fiddling around I managed to stretch the overlay to fit.

RE: Pluggable Module Prototyping for Baluns and other Components

jc2048 — Sun, 20 Mar 2022 12:04:36 GMT

Interesting experiment. Thanks for blogging about it. I don't have any experience of such things at all (I'll have to buy some suitable ferrite cores and try it for myself). It's even a bit of a struggle getting my head around the theory. The role of the ferrite seems to be quite complicated, doing different things at low and high frequency, so it's nice to see a direct demonstration of how moving the transition between the low-frequency high-permittivity area to the higher frequency 'lossy' area with the two different ferrite materials affects the performance.

Have you tried throwing fast pulses at it and seeing what emerges? If it's truly wideband it should preserve the pulse shape with reasonable fidelity.

RE: Pluggable Module Prototyping for Baluns and other Components

shabaz — Thu, 17 Mar 2022 13:37:38 GMT

This fixed it : )

This is 35 turns of the red and green wire from that pack of 4 bobbins, wound on a different core. It is Fair-Rite 5977000201

Using two of these in the same circuit as before, now I get these results; basically, it is now usable down to 50 kHz or so (with a few degrees phase error as can be seen in the mean phase automated measurement in the 'scope screenshot below; by about 100 kHz the error is down to a degree), but still functions well to 50 MHz and likely higher (I didn't test higher).

RE: Pluggable Module Prototyping for Baluns and other Components

shabaz — Mon, 14 Mar 2022 15:14:41 GMT

The pack of 4 wires looks like this, they are basically sewing machine bobbins : )

In terms of wire quantity alone it isn't worth the £10 cost, but for a small level of prototyping it's way better than spending £80+ for four larger reels. It's possible to wind a lot of ferrites with this small amount, I think there is 27 metres on each bobbin.