Build a 12v Portable Power Box for Your Mobile Ham Radio Gear

Ham operators often take their gear to different locations out in the field and need a battery to power up their radios and other gear.

The video below shows one way to put together a mobile power battery box using an inexpensive Plano field box.

Parts Needed

Tools Needed

JT65 Digital Mode HF Radio

Ham radio is no longer all about a guy with a mic and a stack of radios plugging away in analog radio, looking for far away contacts.

Now, there are many new digital modes becoming popular– fusing computers and radio together.

JT65 is one of those digital modes that melds a computer and software into the ham experience, and yielding something like an internet modem– without the internet.

JT65 operators can send images, forms, chat, and more, including using frequencies BELOW the audible range.

Here’s a quick introduction to JT65 for beginners from HamRadioConcepts.

Free software to run on JT65 is available for Windows, Linux, and Mac:

Build Your Own 3D Printer – Video

This 3-part video series from RZtronics shows how to home-build your own Arduino based 3-D printer. Uses a lot of purchased parts but there’s still a lot of savings over the expensive commercially available 3D printers.

3D Printer Build Part 1
3D Printer Build Part 2
3D Printer Build Part 3

The Arduino software, parts lists and sources can be found below the video on YouTube OR here at the RZtronics website.

Morse Code – Letter Shape Learning System

Morse code is no longer required for an amateur radio ham license, but its still beneficial to learn.

I found this neat system created by the fine people at to teach the basics of Morse Code (Also referred to as CW or Constant Wave) in about an hour.

The SHAPES of the letters are used to remember the pattern of “dits” and “dahs” (dots and lines) that make up letters and numbers.

There also is an app created by the same people to help you practice.

Of course this is just a temporary crutch to get you started remembering enough to practice, and eventually you’ll want to just hear the letters like you would a second language without the interim translation step.

Quick-Reference Morse Code Letters and Numbers Chart

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 which will help with the calculation.

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

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:

Amateur Radio Guide to DMR by W2XAB (PDF Download) :

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.

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:

Backup Archive of Schematics:

Minima Arduino code on Github:

Discussion of Minima on FreeList:,24

PCB for Minima builds:

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’s Pactor HF email system.

Checkout for more information.

Carrier Email to SMS Gateways

  • Alltel – [10-digit-phone-number]
  • AT&T – [10-digit-phone-number]@
  • Boost Mobile – [10-digit-phone-number]@
  • Cricket – [10-digit-phone-number]@
  • Sprint – [10-digit-phone-number]@
  • T-Mobile – [10-digit-phone-number]@
  • US Cellular – [10-digit-phone-number]@
  • Verizon – [10-digit-phone-number]@
  • Virgin Mobile – [10-digit-phone-number]@

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.