Audio Recording

This article will take a look at the best sound card interface for ham radio applications. Essentially for best results digitally, you should be aiming for a 24bit, 96Khz soundcard. If you are a beginner and do not have any idea about this, essentially “ham radio” is just the same as “amateur radio”. They are used for worldwide communications using shortwave radio bands.

Ham radio before is limited to a transceiver often powered in vacuum tubes and transistors. They are very useful when a natural calamity occurs and is often a very reliable form of wireless communications that can reach long distance like thousands of kilometers. Ham radio is used for fun and practice in wireless communications as well as socializing with fellow ham radio operators. In the digital age, ham radio can be interfaced with computers. Ham radio is an analog equipment so it means it operates with “analog signals” such as voltages and currents. Personal computer is a digital based equipment, it operates in series of 1 and 0 (often called binary or digital signals). See the schematic of interfacing amateur radio with a computer:

To successfully interface ham radio to computers, it needs an analog to digital converter or vice versa (digital to analog converters) and should operate in full duplex mode (two way communications simultaneously). To make this happen, your computer needs to have “sound card”. You might ask what kind of sound card that you need for a ham radio application. To answer this short, all types of sound card will do even the low end ones. But since there is a substantial difference between low end and high end sound cards, you might have limited features when you use a low end sound card (for example the on-board soundcard you commonly encounter with modern motherboards). Soundcards for ham radio can be classified as follows:
1.) 16bit/44.1Khz/48Khz
2.) 24bit/96Khz

The first set is one that most low end and onboard sound cards belong. The second set are commonly found as PCI or PCI express sound cards. The second one can be considered as “high end” card because of its high input sampling rate capability and as well as the bit depth. The main advantage is a more accurate reproduction of analog signals in digital domain. The following are the recommended 24bit/96Khz soundcards for ham radio applications:

1.) M-Audio Delta44:


Price: $175 in Amazon

Advantage: Presence of breakout box for more connectivity options.
Disadvantage: Does not have microphone gain adjustments.

2.) Creative Labs Sound Blaster Audigy SE Sound Card

Price: $28 in Amazon

Advantage: 24bit/96Khz soundcard at a very low price with internal microphone pre-amplification adjustments.
Disadvantage: Limited connectivity

There are still a lot of soundcards available but it doesn’t support 24-bit/96Khz inputs and if they support, they are very expensive. If you are looking for the lowest price while maintaining 24-bit/96Khz quality, you can choose the Audigy soundcard. If you need more connectivity options which is also important for radio applications, you can choose the M-audio Delta-44 soundcard. Another thing you need to take note about interfacing your ham radio with the soundcard is that you need to provide some isolation between the sound card and your ham radio. The purpose is noise reduction and level matching. You can read more about this topic here about interfacing sound cards to ham radio using transformer. Some of the common questions relating to this topic:

1.) What is the benefit of using high end sound cards for ham radio? Well, if you are using software defined radio (SDR), high end soundcards provides low noise, better signal to noise radio and more accurate analog to digital/D-A converter; thus a better radio system overall.

2.) Why built-in microphone pre-amp is important when selecting a sound card for ham radio? Unlike professional music production where outboard mixer is used. Ham radio applications does not use any mixer. Instead the ham radio and an isolation transformer is used to connect to the PC sound card. During these ham radio to sound card adjustments or configuration you need to tweak your input signals which will be using the microphone gain of your sound card.