Winding Your Own Toroid Inductors

Looking at the schematics for the Minima Transceiver, I notice that there are some inductors included in the top left corner of the schematic, and that the photos on the author’s page appear to show home wound inductors on a toroidal core.

This post is my notes on how to calculate the amount of wire needed and wind those components.

First, I found this post (How to Wind Your Own Toroidal Audio Inductors) by Oren Leavitt showing a useful technique for using a “shuttle” to hold the winding wire while making the wire wraps on the core.

A quick demo video showing a winding being done:

I also need to know how many windings are needed on a core.

The ARRL website has this handy PDF on winding air-core inductors, which includes the calculations for that type of inductor, but since I want to use a ferrite toroid, this is not the math I need.

So let’s see what else is out there…

Here’s a calculator that can calculate inductance per turn:

The above calculator needs the relative permeability of the material the core is made of. I found this handy table of magnetic permeability by medium over on Engineering Toolbox.com which will help with the calculation.

Here’s an alternate calculator that works on specific cores by part number and material:

http://www.66pacific.com/calculators/toroid-coil-winding-calculator.aspx

Using DMR Radio

Digital mobile Radio works on a digital stream that works over the internet between DMR enabled repeaters.

Kevin Loughin explains DMR Radio

Getting Started with DMR:

You’ll need to already be a licensed ham operator of Technician class or greater.

To use DMR, you need to to have your call sign validated and get a Radio ID.

Get your DMR Radio ID: https://www.radioid.net/register

Amateur Radio Guide to DMR by W2XAB (PDF Download) : https://dmr-marc.net/media/Amateur_Radio_Guide_to_DMR_Rev_I_20150510.pdf

You can also use your PC as a DMR Transceiver:

HF1 QRP Transceiver Schematics

This project is based around the recent HF1 QRP transceiver by Ashhar Farhan, VU2ESE. The transceiver is an interesting SSB design with wide tuning range from 0-30MHz and should cover several amateur bands.  The schematic for the transceiver can be found on the Minima mail list in this post with a PDF attachment.

After a front end 0-30MHz filter, the  transceiver uses a 45 MHz first IF and a 10 MHz second IF.  The famous bi directional amplifiers are used in the bi directional SSB sections of the radio.

https://vk3yy.wordpress.com/2016/05/28/hf1-qrp-transceiver-project/

Minima Transceiver Schematics & Code

For those who want to build their own superheterodyne transceiver, the Minima may fit the bill.

Designed by Ashhar Farhan, the schematics are freely available online.

Minima Schematics: http://www.phonestack.com/farhan/minima.html

Backup Archive of Schematics: https://www.freelists.org/archives/minima/01-2016/pdfavh3bHrUb6.pdf

Minima Arduino code on Github: https://github.com/afarhan/radiono

Discussion of Minima on FreeList: https://www.freelists.org/post/minima/Minima-PCB,24

PCB for Minima builds: https://yo4hhp.wordpress.com/2014/01/22/pcb-for-minima-general-coverage-transceiver/

Ham Radio to Cell Phone Communications

Useful Email to SMS gateway information that lets you text phones using your ham radio.

Video below demonstrates communications between Amateur radio equipment and cell phone equipment using email to text feature with Winlink.org’s Pactor HF email system.

Checkout http://www.winlink.org for more information.

Carrier Email to SMS Gateways

  • Alltel – [10-digit-phone-number]@message.alltel.com
  • AT&T – [10-digit-phone-number]@ tx.att.net
  • Boost Mobile – [10-digit-phone-number]@ myboostmobile.com
  • Cricket – [10-digit-phone-number]@ mms.cricketwireless.net
  • Sprint – [10-digit-phone-number]@ messaging.sprintpcs.com
  • T-Mobile – [10-digit-phone-number]@ tmomail.net
  • US Cellular – [10-digit-phone-number]@ email.uscc.net
  • Verizon – [10-digit-phone-number]@ vtext.com
  • Virgin Mobile – [10-digit-phone-number]@ vmobl.com

Cartoon Antennas

Studying for the General ham license, which is the next step up from the Technician’s license has led to some interesting (and entertaining) “ah-ha” moments for me regarding the design of radio antennas.

Prior to dipping my toes into the ham test question pools, I’d always thought of antennas as passive equipment, responsible for receiving signals only. (Keep in mind I have no prior background in electronics.)

But it transpires that antennas not only receive, they also SEND signals and as a result short mobile antennas like those used for a car rig can develop quite a bit of voltage at the terminal tip when transmitting.

This brings me to the ah-ha moment– those little balls on the end of an antenna tip are called “corona balls” and their PURPOSE is to prevent high voltage discharge from the antenna tip! They are not just decorative!

Who knew, right?

I remember from my childhood, some of the old cartoons having an animated beeping antenna where the corona ball actually lights up. (A corona is a halo of light– or electricity.) And knowing now that the corona ball prevents high voltage from dangerously flying off the tip of an antenna, that cartoon suddenly makes so much more sense.

I love science.

Hello DX World!

The joke in the programming world, of which I have been a part for many years is the first baby program is always concerned with outputting a simple “Hello World” to the screen.

So in Ham lingo, talking to the world, instead of your local area is called DX-ing.

In the old days, you need a HF (High Frequency) transceiver to make world wide contacts, but these days, with the advent of digital and VOIP modes, you can literally use your phone (via Echolink) to talk to hams in other countries.

There are other ways too, but with Echolink you can get set up in minutes and be looking for your first DX the same day you get your license.

How cool is that?