[TowerTalk] QCoil Inductor Measurements

[Brian Beezley]

I borrowed a coil from QCoil Inductors to measure with my HP 4342A Q meter.

This coil did not have the black, UV-resistant dielectric spreaders of 
production coils, but it was otherwise the same. Here's what I tested:

23 turns #10 wire
Coil length = 6.25"
Coil diameter = 3.625"
Length of each #10 lead = 4.25"

All dimensions are wire center to wire center. I supported the coil 
horizontally above the 4342A by its leads. The side of the coil nearest 
the 4342A enclosure was 3.25" above it.

Measurements followed by results from coil.exe:

MHz    Q    uH    Calculated
1.8   580  22.6   547   22.4
3.7   730  23.7   753   23.5

The 3.7 MHz measurement was highly sensitive to my hands on the Q meter. 
  I positioned them for maximum Q. I figured that current through lossy 
flesh can only reduce Q.

I modeled annealed copper wire. The wire was very stiff. Calculated Q 
for hard-drawn copper was 536 and 739. At these frequencies the 
dielectric composition of the four 0.25 rods I modeled embedding the 
turns (Air Dux style) had virtually no effect.

https://qcoil.net

https://k6sti.neocities.org/coil.htm

Brian