Browse via
or

#### Recent Posts

- My first 23cm 1297MHz contact!
- Icom IC-7100 SO-239 to N-Type
- Reviews
- RSGB 21/28MHz Contest
- Practical Wireless 70MHz Contest
- RSGB 2nd 70MHz Contest
- Two years in the making – 70MHz 300w Amplifier
- 5th 144MHz Backpackers Contest
- Update to Slim Jim calculator
- Working Happisburgh Lighthouse on 70MHz
- 70MHz Cumulatives – 9th August 2015
- Baofeng CH-3+ Desktop Charger
- Building a 4 element 15m monoband Yagi with M0TAZ
- Operation Bunker
- RSGB RoPoCo contest

#### Recent Comments

- John M0UKD on Icom IC-7100 SO-239 to N-Type
- George M1GEO on Icom IC-7100 SO-239 to N-Type
- John M0UKD on Slim Jim and J Pole calculator
- John M0UKD on I finally put up a dipole for 70MHz (4m)
- John M0UKD on Air Cored Inductor Calculator

#### Archives

#### Site Map

- Home
- About Me
- Homebrew
- Calculators
- Slim Jim and J Pole calculator
- Ohms Law Calculator
- Loaded Quarter Wave Antenna Inductance Calculator
- ERP & EIRP Calculator
- Resonant Frequency Calculator
- PI attenuator calculator
- T attenuator calculator
- Air Cored Inductor Calculator
- Inverted Vee Antenna
- Parallel Resistor, Inductor or series capacitor calculator
- Electricity cost calculator kW/h
- Convert power levels between Watts, dBW and dBm

- Mods
- Reviews
- Other Stuff
- My Logbook
- Contact Me

#### Links

#### Common Tags

4m
10m
12v
15m
17m
18MHz
21MHz
28MHz
40m
70MHz
160m
Amsat
Antennas
Anytone AT-588
AO-51
Apollo 11
Battery
Compare
Construction
Contest
Coupler
Dipole
DK7ZB
Dungeness
Efficiency
End Fed
Fence Antenna
FT-817
FT-897D
FT-991
FTDX1200
Half Wave
HF
IC-7200
Inverted V
ISS
Photography
Portable
Secret Nuclear Bunker
Slim Jim
Space Station
SSTV
topband
Video
Yagi

M | T | W | T | F | S | S |
---|---|---|---|---|---|---|

« Mar | ||||||

1 | ||||||

2 | 3 | 4 | 5 | 6 | 7 | 8 |

9 | 10 | 11 | 12 | 13 | 14 | 15 |

16 | 17 | 18 | 19 | 20 | 21 | 22 |

23 | 24 | 25 | 26 | 27 | 28 | 29 |

30 | 31 |

LOVE YOUR CALULATOR……NOT SURE WHEN I NEED TO USE IT….I AM A HAM VIRGIN….BUT LEARNING…..

THANKS A BUNCH

LARRY

Re: Air Cored Inductor Calculator

Hi, Is the coil diameter measured outside, at the middle or inside of the coil ?

Rgds/ 73

Arto Salo

OH1ID

Hi.

I never use thick enough wire to worry, but I would use the inside diameter.

73, John.

The coil diameter uses the mean diameter of the copper coil.

A 1mm wire wound on a 14mm bobbin will have a mean diameter a bit over 15mm.

The bit over is the uncoiling that naturally occurs when one releases the tensioning force.

I use >=1.6mm diameter enameled copper wire and prefer to use 2.12mm wire wound onto an AA battery.

My mean diameter is roughly 16.9mm

9¾ Turns gives ~1uH

Is it possible to add a field for the copper wire diameter?

And use that to calculate the coil resistance in ohms?

Perhaps that would be better as a separate calculator.

What is the meaning of Coil Diameter and Coil length?

Diameter is how wide the coil is and length is how long the coil is.

hi tanx for you helping amateur radio in all of the world

i used of air core calculator.

best regards from Tehran-iran

amirhosein 73

A good approximate formula (accurate enough to 1%) is:

L = (n . d)(n . d)/l x 10^{-10) Henrys , where n is number of turns, d is diameter in mm, l is length in cms,

I love the idea that you have Pi to 50 digits. But. It is false precision in the wire length because the length depends on the Turns Per Inch as well. The true length of the line is the length of the hypotenuse of the triangle formed from the true circumference and the turn spacing. It is an error larger than the diameter of an electron, but I think I can live with your formula! ;-))

Very good Bennett! 🙂