sBitx Microphone Alternatives - drexjj/sbitx GitHub Wiki

sBitx Microphone Alternatives

The sBitX v3 ships with a stock microphone that is generally considered suboptimal for voice modes, primarily due to its low gain and hollow sound. This guide explores alternative solutions for improved audio performance.

1. Replace the Condenser Element

The primary issue with the stock microphone is its condenser element. Fortunately, it can be replaced with a higher-quality alternative.

Recommended Replacement

A good option is the AOM-5024L-HD-R electret condenser microphone. This element has a higher gain (-24 dB) and delivers improved audio clarity.

Replacement Steps

  1. Disassemble the microphone case

    • Take notes or photos of the interior before making changes.
    • Pay attention to the polarity of the existing element's wires.
    • Observe the PTT switch assembly—its spring must be correctly positioned.

  2. Remove the old microphone element

    • De-solder the old element, keeping the wire leads intact on the PCB.

  3. Install the new element

    • Solder the leads to the new microphone element, maintaining the correct polarity.

  4. Improve sound damping

    • Place some loose cotton batting or cotton balls around the microphone element to reduce resonance and improve audio quality.

  5. Reassemble the microphone

    • Ensure all components are correctly positioned before closing the case.

2. Use a USB Microphone

If you are using the v5.4 or higher of our sBitx software, then you can take advantage of using a USB Headset directly with the transceiver. This allows you to use a wide range of USB-connected microphones and headsets, which can significantly improve audio quality over the stock microphone.

Prerequisites: Ensure that your USB audio device is compatible with Linux. It must be a plug & play or driverless device such as those used with Chromebooks or other Linux operating systems.

USB headsets compatible with the Raspberry Pi 4 (or Raspberry Pi devices in general) typically rely on standard audio class drivers provided by most Linux distributions, including Raspberry Pi OS. This means a wide range of USB headsets should work out of the box, but specific models aren't always listed as "compatible" due to the vast number of products available and the general nature of USB audio support in Linux.

Considerations for Compatibility: Standard USB Audio Class: Look for headsets that comply with the standard USB Audio Class 1 or 2. These should work without needing special drivers. Power Requirements: Ensure the headset doesn’t require more power than the USB port can provide. The Raspberry Pi 4 can provide a decent amount of power over USB, but very power-hungry devices might still have issues.

Vendor Support: Some manufacturers are better than others when it comes to supporting Linux or providing information about compatibility. Here's a list of considerations and some brands/models known for good compatibility based on user reports and general Linux compatibility. However, always check the latest user reviews or manufacturer FAQs for Raspberry Pi compatibility mentions, as firmware updates can change compatibility status.

Audio-Technica:

  • Some of their USB headsets and even some USB microphones that include headphone jacks are known to be compatible.

Logitech USB Headsets:

  • Logitech H390
  • Logitech H540
  • Logitech H600 (Note: The H600 is wireless but uses a USB receiver, and generally works well with Linux)

Plantronics (Poly) USB Headsets:

  • Plantronics Blackwire 3210
  • Plantronics Blackwire 5220

Jabra USB Headsets:

  • Jabra Evolve 20
  • Jabra Evolve 30 ii
  • Jabra Evolve 40

Sennheiser (Now EPOS | Sennheiser) USB Headsets:

  • SC 60 USB ML
  • SC 165 USB

Microsoft USB Headsets: LifeChat LX-3000

Sabrent:

  • USB External Stereo 3D Sound Adapter

Other:

  • EKSA E1000 USB Headset

A full list of compatible USB devices is available at: https://www.alsaproject.org/wiki/Matrix:Main#Sound_Card_List

3. Use a Wireless Microphone

The Raspberry Pi’s built-in Bluetooth does not support Bluetooth headsets for this purpose. However, a wireless microphone or headset that uses a USB wireless receiver should work.

4. Using Other Handheld Microphones

The sBitX microphone interface uses a 3.5mm TRS (Tip-Ring-Sleeve) jack with the following pinout:

  • Tip → Mic+
  • Ring → PTT
  • Sleeve → Ground

Although TRS plugs are common, few radios use this exact configuration for mic input. You may need an adapter cable to use third-party microphones.

Compatible Hand-Mics

  • TIDRadio TD-HM060 (Requires replacing the 2.5mm TRRS plug with a 3.5mm TRS plug)
  • Baofeng-style microphones (Ensure correct wiring and replace with a 3.5mm TRS plug. It’s also recommended to disconnect the speaker element inside the mic housing.)

Wiring Diagram

Plug Base  =====|GND|=====|PTT|=====|MIC+|=>  Plug Tip

By following these alternatives, you can achieve significantly better SSB transmission quality with your sBitX.