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     Peter Miles
     Northam, Western Australia
     QRZ Page: VK6YSF

 

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AIR COIL INDUCTOR DESIGN

Air coil inductor design.


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The approximate inductance of a single layer close wound air-coil may be calculated from the below formula.  

 

Where

L = Inductance in µH

r = Former radius in mm

 = Length of winding in mm

N = Number of coil turns

 

Example:

Coil has 20 turns close wound on to a 25mm diameter (12.5mm radius) former and the wire is 1.2mm diameter which will make the overall length of the coils 24mm.  

 

A slightly more practical formula for determining the number of coil turns for a given value of inductance.

 

 

Example:

Required Inductance of 7µH on close wound single layer air inductor with a 25mm former and the wire is 1.2mm diameter which will make the overall length of the coils 24mm.  

 

 

 

The below chart shows inductance in uH of inductors with 7 different former sizes against the number of coil turns.

 

Fig 1 The chart shows inductance in uH of inductors with 7 different former sizes against the number of coil turns.

 

 

Reference http://hamwaves.com/antennas/inductance.html

 

  

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Page initiated 08 April, 2016 

Page last revised 05 November, 2025 

 

 

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   Notice Board

VK6YSF JS8Call and Olivia 8/250 operations.

Current activity is generally focused - though not restricted to - JS8Call operations on the 20m, 30m, and 40m bands.

Currently there is a particular emphasis on JS8Call on the 10 and 12 m band between 00:00 and 12:00 Z, often extending beyond this period.

Olivia 8/250 is used occasionally on the 20m band.

Proposed band and mode activity is often communicated on HamSpots: https://hamspots.net/js8/ or my profile on 

X: https://x.com/vk6ysf97230 .  

Feel free to contact me to discuss or arrange a schedule for a contact.

Post date: 7 December 2025

 

Western Australian SSTV net 

Popular Western Australian SSTV net for both digital and anolog SSTV.

Generally found at 7214.0kHz LSB every afternoon from 08:00 UTC (4:00pm WST)

For more details: https://www.wasstv.net/wasstv.net/index.html

Post date: 8 December 2025

 

VK6MJM LF (136kHz) and MF (474kHz) Beacon

VK6MJM is a  LF/MF station located in Manjimup, Western Australia.

Common Mode: FST4W 300 (Similar to WSPR)  

Note: other modes and sub-modes may be used.

Station details were presented by Peter Hall (VK6HP) at PerthTech 2024.Presentation PDF: Peter Hall VK6HP at PerthTech

QRZ Page: VK6MJM on QRZ.com

Post date: 10 March 2025

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Amateur Radio Station VK6YSF - Promoting amateur radio communication and experimentation.