Inductor Colors Calcultor- help

[aurelCB]

Hi to All.. 

[Egil]

I have seen the same code, but for resistors. Nicely done, but I beleive the conversion has been a little too fast....

I have never seen all that color possibilities in band 3 on any four bands coded RF-choke yet.
And according to http://www.learnabout-electronics.org/ac_theory/inductors04.php, colors higher than level 4 (Yellow) are never used on RF-chokes band 3.

So if you should happen to find one with color codes in band three higher than four, it will most probably be a resistor. Nowadays it is almost impossible to see the difference.

But it should be easy to fix the code  though.


Good luck!

[aurelCB]

Yes Egil you have right i just quickly change some things
program need more tweaking

[Egil]

PS. Nice addition to this program should be to add AirCore coil calculator what you think?

Maybe you can use the coil calculation routines used in my Short Dipole Calculator for that?
http://www.ionicwind.com/forums/index.php?topic=5595.msg41282#msg41282


Egil

[Egil]

The formula I use for calculating the coil is a simplified version, and will not work on VHF at all.
On VHF (and higher) you'll need a much higher presicion, and the materials you use for construction suddely become very important.
But for HF that higher presision and choice of materials do not matter that much.

The advantage of such shortened antennas is fully experienced only on HF, because very few of us are able to put up full size antennas on the lower HF bands because of the dimentions.  A shortened antenna is also a compromise. When you shorten an antenna you lose bandwith. But efficiency is still amazingly good.

I use one designed for 7.1 MHz myself. This enables me to transmit between 7070 and 7150 KHz whithout using an extra antenna tuner.
And compared to a full size dipole on the other side of the house, the received signal strengths are more or less the same on both antennas. During normal band conditions, the stations on the other end reports no difference in signal strength on my signals when shifting between the two antennas.
But under poor band conditions they report that the shortened antenna is between 0.5 and 1 S down, compared to the full size dipole.

I have a friend that is a very active SWL-er. He reports that for general listening his shortened 7MHz antenna is a good performer between 3 and 18 MHz.

Finally, I have been experimenting with antennas ever since I was a boy. And have found that when using coils in antennas, using inductance for calculations often makes no sense. Calculating impedance for a particular frequency instead of inductance is the key to success.
If you examine my code, you'll se that the program is looking for an impedance of 950 ohms, and stops calculating as soon as the impedance has become higher than this.


Egil