AHR, Ham, iPhone and iPad, Mac

Getting into Software-Defined Radios can be confusing, especially on Mac and Apple devices. Here’s my cheat sheet. 

Andrew Woodward

My ‘first principles’ in getting back into DXing and SWLing before ‘transitioning’ to a licensed radio amateur were to get a vintage box-type radio. I got a 35-year-old Yaesu FRG-8800, and it was good fun. It worked as a radio should — signal meter, digital display, volume and tuning knobs, lights, and a big ‘coax socket’ on the back.

As I learned more about my rediscovery of radio, I started to learn about SDR radios—as in Software-Defined Radios. In short, they can be radio receivers connected directly to your computer or live on your computer network. You can also tune into the SDR on web browsers and apps. This blog post only relates to receivers. SDR transceivers are a place I have yet to venture. 

After much experimentation, frustration and cost, I have landed on a good ‘intermediate’ experience and setup. My biggest mistake was not reading the fine print about some of the dongles (SDR radios with USB A/C).

An antenna

Like any radio, SDR need an antenna. I have two—a 10-metre-long end fed from Tecsun Australia for HF and a Diamond D3000N for everything about 25 MHz (including transmission). I am happy with both. Some SDRs have indoor antenna kits (Nooelec and SDR Blog).

Getting your first SDR dongle

My first SDR dongle was a Nooelec Smart NESDR 5 via Amazon (USD40). It covers from 100 Hz to 1.75 GHz, but the fine print says “HF reception below 25MHz is accomplished with direct sampling and requires a suitable antenna”. Coverage below 25MHz requires an “upverter”, which is another USD70. 

I then read that the SDR Blog V4 (500 kHz to 1.7 GHz) has an upverter. So, I went to the official SDR Blog shop on Ali Express and ordered it. It arrived promptly from China and works perfectly. I recommend you order from the official RTL-SDR Blog Shop on Ali Express or Amazon, as counterfeit dongles proliferate. 

My setup at home on the Mac Mini is the Nooelec NESDR V5 Smart SDR with a Nooelec “Ham it Up” upverter for HF. For VHF and UHF, I use an RTL-SDR Blog V3c (and I can use both at the same time, hooked up to specific antennas). For my MacBook Air, I carry the RTL-SDR Blog V4 dongle.

It’s worth noting that the RTL-SDR Blog V3/V4 model has a choice between USB-A and USB-C. The RTL-SDR V3 model doesn’t have an upverter, but according to this video, it has some other advantages. I’m only using my V3 for VHF and UHF, so I don’t need the upverter.

I also have a broadcast FM (88 MHz to 108 MHz) filter, as I have a line of sight to six strong FM transmitters. These can overload the SDR without a filter. There’s also a version for broadcast AM, which I have ordered but have not used. 

Spending more to get a better radio

There’s no shortage of videos and articles on SDR units. From my own spinning around on an accessible SDR, I found Kiwi-SDR very good. They seem to pick everything up, are fast and responsive and use the excellent OpenWeb RX software. They’re also USD400. Priced between KiwiSDR and RTL-SDR Blog V3/V4 and Nooelec, there are a few good options. The pecking order appears to be:

Software on the Mac

Getting the right software was painful, and I spent many frustrating hours. There is no commercially developed software to buy for RTL-SDR and Nooelec dongles. Yes, there is some commercially available software, but it’s for specific radios (for example, SDR Connect for SDR Play and for Flex Radio transceivers). 

If you have a Mac, there’s only one choice, and that’s SDR++ (or plus plus). Yes, there are others, but they’re hard to install and/or clunky. Trust me. Just get SDR++. A very comprehensive manual is also available for SDR++. There’s the original version from the lead developer and a ‘fork’ called SDR++ “Brown.” Both are great on the Mac, but the Brown version has a few more cool features.

After installing SDR++

There are a few “tricks” to getting everything to work:

  1. As mentioned, make sure you have the right dongle for the correct frequencies (remember some don’t go below 30 MHz without an upverter)
  2. When you are ready to go, choose your radio and press the “play” button (triangle on its side). You should hear static.
  3. Tune to a strong FM station to see how everything works. Then, read through the manual and play with all of the buttons, slides, dials, and other things.
  4. Pay attention to the “Direct Sampling” tab—there are three choices in the drop-down menu. Fiddle with these, as they impact different frequencies and modes.

Listening to other people’s radios

A cheaper approach to SDR is to use the radios of other people worldwide. And yes, it’s simple.

Some apps pick up from these directories and package them up for your Apple devices. They’re nice, but you don’t need them. Just bookmark a page in Safari so it’s on all of your devices.

What about SDR on the iPhone and iPad?

This is probably the most disappointing thing. You can’t plug a dongle into your iPhone or iPad, string up an antenna and tune away. Why? I’ll leave it to ChatGPT and Gemini to explain.

More reading and watching

My next SDR projects

I want to get the SDR++ Server working so I can access my radio remotely (video and blog). I also want to get a plug-in so it works as a scanner.

ENDS