USA calibration club

[cellularmitosis]

Let's pick up this thread over here!  https://www.eevblog.com/forum/metrology/usa-cal-club-round-2/

[orin]

What inductance does the 3 turn choke have?

I took a look at this tonight, testing the inductance of just one lead of the twisted pair, using a cheap LCR meter.

Results:

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No ferrite: 2.4uH
0 turns: 3.1uH
1 turn: 5.3uH @ 721kHz
2 turns: 9.2uH @ 693kHz
3 turns: 14.9uH @ 657kHz


For fun, I got some of those cores and put one with 3 turns of ordinary solid hookup wire on the network analyzer (VNWA).  Two runs, 1 to 1001 KHz and 1 to 501MHz.

In my case, it looks like it would do best at blocking FM radio with an impedance of 1085 ohms, not so well elsewhere.

There was only about 4 inches of wire not on the core, so lower inductances are to be expected.

Edit: added picture of core and fixture.