Browse via
or

#### Recent Posts

- International Space Station NA1ISS contact with GB4YOTA
- Building a 70MHz quarter wave ground plane
- Receiving SSTV images from the ISS – ARISS 20th Anniversary
- 1/4 Wave Antenna Calculator
- A long break…
- 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

#### Recent Comments

- Stu Martin on Icom IC-7100 SO-239 to N-Type
- John M0UKD on Slim Jim and J Pole calculator
- Randy Kisch on Slim Jim and J Pole calculator
- Gary Johnson on 144MHz 2m Portable Yagi VHF Beam Antenna
- Gary Johnson on Slim Jim and J Pole calculator

#### Archives

#### Site Map

- Home
- About Me
- Homebrew
- Calculators
- Slim Jim and J Pole calculator
- 1/4 Wave Ground Plane Antenna Calculator
- Ohms Law Calculator
- dBm, dBW, µW, mW, Watt, KW and MW 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

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

#### Links

#### Common Tags

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

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

« Aug | ||||||

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! 🙂

I just came across this site. I ran some numbers when designing the shunt for my HiQ antenna and found yous to be more accurate than others. My SWR was good without but I wanted to get rid of some unwanted wind noise on digital modes in the especially in the 20 meter band. I used the center of the coil “(ID+OD)/2” which was 37.6mm x 32mm x 10.5 turns. The wire is #8 (3.2mm) dia. My first calculations were less but when I measured it I got 3.1 µH. Yours calculated 3.146. The other calculators I tried online were estimating from 2.2 to 2.8 µH. The wire was some common copper ground wire I picked up at a local hardware store.

Good job on the calculator.

Robert N9NQ