USB Interface for Digital use
1. Use a USB sound device, Using the stereo audio out jack Left side for audio and Right side for PTT , the right side audio is wired to a dedicated switch ciruit that is used for PTT.
Note: this circuit may be used with a standard audio devise build it to your PC or Laptop.
See Circuit Below
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2. This is the methord i use , this devise is maid up 3 main componints ( 4 Port USB Hub, USB Audio Device, USB to RS232 Device ) i hard wire these device togeter to avoid connectivaty problem, need less to say we add all the isolatiod devices is as well.
See Circuit Below
3. Radio Interface for Amateurs
A Radio interface is used for digital operating modes such as SSTV, ECHO LINK, RTTY, PSK-31 and FT-8. A radio interface breaks the galvanic connection between the computer and the radio and thus prevents equalizing currents and hum.
The radio interface connects the audio from the radio to the computer, some offer a PTT control. The connection to the computer is usually always done via RS232 or USB. More modern radio interfaces have their own USB sound card integrated, otherwise the sound card built into the PC is used or and external USB sound device. Settings can be made separately for amateur radio applications. Ideally, the manufacturers of some interfaces also offer suitable cables for as many different radios as possible. So you don't have to solder cables yourself. Properly configured, a universal sound card interface works with just about any software that uses the standard interface of a computer.
There are many brands of interfaces available to connect a PC to an amateur radio often homebrew interfaces are used. They all do essentially the same thing.
They key the radio to transmit “PTT “, pass a signal based on the mode of operation from the PC to the radio, then de-key and go back to receive mode.
It's pretty easy to get an Amateur working on digital modes if you have a radio, and a PC with a soundcard. Other than these, all it takes is some free software, and a few components.
Here's an example of what the circuit looks like, which allows the use of a Sound card ( or USB clone )
This is a typical example of Audio circuit with isolation transformers.
This is a typical example of Audio circuit with isolation transformers.
PTT Circuits may differ as there are many different types of radios. Rule of thumb is that most Radio’s transmission is started but grounding the PTT pin. “Pulling the PTT to Ground “and if the PTT is HI then the radio will start to receive again, Here are two Examples of how the PTT circuits look.
There are many other ways of creating PTT circuits.
One of the challenges is that many modern PC’s do not have RS232 ports that were predominantly use back in the day, everything now days uses USB, One could use USB to RS232 adaptors to drive the PTT circuits or just simply use VOX in the radio if this feature is available.
Here are a few manufactures of Radio interfaces
- Digimaster from ZLP Electronics. A variety of interfaces and connecting cables are available.
- PCInterfaces In both kit and pre-constructed form.
- Microkeyer USB interface from Microham. Other models are available.
- SignaLink from Tigertronics. Two models available, one that used the computer soundcard and DB9 connection, the second has a built in soundcard and connects via USB
- Rascal GLX from Bux CommCo. Available in kit or constructed form. A variety of cable options are also available from the site.
- Rigblaster from West Mountain Radio. Has interface models with both USB and RS232 DB9 connections. Includes inbuilt rig control capability.
- RigExpert USB interfaces and MixW software.
Home Brewing
Interfaces can be fairly simple and thus are easily home-brewed. Here is a simple circuit and board layout
Parts List :
2x Audio Transformers
2x 2K2 0.25 Watt resistors
1x 1N4001 Diode
2x 1N4148 Diodes
1x 4N25 Opto coupler
2x 2K2 0.25 Watt resistors
1x 430E 0.25 resistor
2x 0.1uf non polarized1x 1N4001 Diode
2x 1N4148 Diodes
1x 4N25 Opto coupler
