[TowerTalk] Loading Coils

[Brian Beezley]

A photo at the QCoils website shows a coil attached to an HP 4275A LCR 
meter. At 2 MHz the coil reads 47.69 uH with a Q of 600.

I modeled the coil as follows:

Frequency: 2 MHz
Turns: 38 (counted from photo)
AWG 10
Coil inside diameter: 3.75" (website says diameter is approx 3.75")
Coil length: 10" (from website)
Annealed copper, no plating
Four 0.375" support rods (no Q degradation for any plastic)

Results:

L 47.0 uH
Q 673

I believe what the HP meter says. The small zeros shown in the Q readout 
may mean that accuracy is limited in those digits. Perhaps an HP expert 
can chime in.

The wire distributor says the tinned wire conforms to ASTM B-33 and 
MIL-SPEC A-A-59551. I looked up both and could not find a plating 
thickness specification in either. But the measured and calculated Q 
figures suggest that plating loss is insignificant at 2 MHz.

Coil calculator:

https://k6sti.neocities.org/coil

Brian