Question on measuring the inductors

[vk2tty]

Are there any calculators that take how much of the toroid is wound into account, or ways to measure them that'll give the values indicated in the calculators and table?

I thought I'd measure my inductors after I'd would them, hoping to avoid the (tr)uSDX tuning game of soldering, measuring, de-soldering, dropping a turn, lathering, rinsing, and repeating. Now I've done so, I regret I've got another mystery on my hands.

turns	measured	calculated
4	0.13	0.06
5	0.23	0.10
7	0.35	0.20
8	0.38	0.26
12	0.89	0.58
13	1.07	0.68
15	1.44	0.90
16	1.59	1.02
17	1.72	1.16
18	1.96	1.30
19	2.10	1.44

Measurements with Peak® atlas LCR45 at 200kHz, 15–19 turns using the 80m toroid dropping a turn at a time until I got within cooee of the required value. Calculations with toroids.info at 0.2MHz.

[vk2tty]

Belated update: after eventually trusting my LCR and VNA and dropping turns until the inductors measured within cooee, I confirmed correct resonance and suppression for the 10m band with my VNA.

Overall method might end up:

• Try the instructions‘ turn count
• Adjust spread and turn count until measurement OK
• THEN solder
• Short out the pi filter
• Adjust spread of serial resonance coil to move S11 resonance
• Remove short
• Adjust spread of pi filter coil to move notch on S21 log mag
• THEN plug into radio
• Check power and efficiency

I'll post turn counts and suggested amendments to the procedure when I've done the lot for 10m, 15m, 40m, and 80m.

If you're using batch 2 with the included wire, you might be able to save time in the second step by starting with fewer turns per my measurements above:

• Find the batch 2 winding guide turn count on the X axis
• Trace up until you hit the “calculated” line
• Trace left until you hit the “measured” line
• Trace down to the X axis for your adjusted starting turn count

If you've substituted your own wire, or your own toroids, try measuring from 19 turns down to 4 to make your own graph or lookup table.