DIY Universal Radio Clone Cable Using CP2102 USB Interface – TX/RX Isolation & Common Clone Bus

In this project, I designed and built a DIY radio programming and clone cable using a CP2102 USB-to-UART interface and a simple signal-isolation circuit. The purpose of this project is to create a practical, low-cost interface for connecting a computer to compatible two-way radios for programming, configuration, and radio-to-radio cloning functions.

The interface uses the CP2102 to provide USB connectivity to the computer while converting the computer's USB data into serial TX/RX signals required by the radio interface. A key part of my design is the use of diodes on the TX and RX signal paths. These provide electrical isolation between signal drivers and allow the required signals to be combined onto a common clone/bus signal line without directly tying active outputs together.

Instead of using a separate USB interface for every radio connection, the design focuses on a reusable interface section with interchangeable radio-side connections. This makes the cable easier to build, test, modify, and adapt for different radio interfaces.

CP2102 USB-to-UART module x1

1N4148 diode x1

This DIY clone cable provides a USB connection between a computer and a compatible two-way radio. It is designed to carry the serial communication required for radio programming, configuration, and compatible radio-to-radio cloning functions.

The computer connects to the cable through the CP2102 USB-to-UART interface. The CP2102 converts the USB data from the computer into serial TX/RX signals.

On the radio side, the interface uses a common clone signal / bus line. The TX and RX paths are coupled through diodes, allowing the required communication signals to share the clone line while providing isolation between the signal-driving paths.

Basic signal flow

Computer USB → CP2102 → TX/RX interface → diode isolation → Clone/Bus signal line → Radio

The cable is designed as a reusable interface rather than a dedicated cable for only one radio model. The radio-side connector and pinout can be adapted according to the particular radio being interfaced.

Main functions

1. USB connection to a computer
2. USB-to-UART conversion using CP2102
3. Serial TX/RX communication
4. TX/RX signal isolation using diodes
5. Common clone/bus signal connection
6. Connection to compatible radio programming interfaces
7. Reusable DIY construction for different compatible radio connections

The important part of this design is the signal-isolation arrangement. Instead of simply connecting two active serial outputs together, the diode network provides a controlled way to combine the required signals onto the shared clone line.

The exact electrical arrangement must always be matched to the radio's programming interface and signal-voltage requirements. This cable should therefore be used only with radios for which the connector pinout and electrical interface have been verified.

The interface uses a CP2102 USB-to-UART converter together with a single 1N4148 switching diode connected between the TX and RX signal paths.

In this design, the 1N4148 provides the required isolation between the TX and RX lines, while the clone signal is taken from the RX side of the interface.

The basic arrangement is:

CP2102 TX → 1N4148 → RX / Clone Signal

The diode allows the signal to pass in the intended direction while helping prevent the RX-side signal from directly driving back into the TX output.

Why the 1N4148 is used

The 1N4148 is a small, fast-switching silicon diode that is well suited to low-current digital signal applications. In this project it is used as a simple signal-isolation component rather than as a power diode.

The diode provides a controlled path between the TX and RX nodes. This is useful when the radio's cloning interface uses a shared or combined communication signal.

The RX side is used as the clone-signal pickup point. This allows the signal present on the shared line to be monitored by the CP2102 receive input while the TX path provides the transmitted data.

he main interface is built around the CP2102 USB-to-UART converter and a single 1N4148 diode.

The important signal connections are:

CP2102 RX → 1N4148 anode (A)

1N4148 cathode (K / banded end) → CP2102 TX

Clone signal → RX / anode side

The RX side is therefore the clone-signal pickup point in this design.

Basic wiring

1. Connect the CP2102 to the computer through USB.
2. Identify the CP2102 TX and RX pins.
3. Connect the anode (A) of the 1N4148 to the RX side.
4. Connect the cathode (K), identified by the band on the diode body, toward the TX side.
5. Take the clone/bus signal from the RX/anode side.
6. Connect the required signal ground (GND) between the CP2102 and the radio interface.
7. Connect the appropriate radio-side connector according to the radio's verified pinout.

Simplified connection

CP2102 RX / Clone Signal

↓

1N4148 Anode (A)

1N4148 Cathode (K)

↓

CP2102 TX

The diode orientation is important. Installing the 1N4148 backwards changes the signal path and can prevent the clone interface from communicating correctly.

Before connecting the radio

Use a multimeter to check:

1. Continuity of the ground connection
2. Correct TX and RX identification
3. Correct 1N4148 polarity
4. No accidental short circuit between signal and ground
5. Correct radio connector pinout
6. Correct voltage level for the radio interface

Do not assume that a physically similar connector has the same pin assignment on another radio model.

Build note: The wiring shown here describes the configuration used in this project. The radio-side connection should always be adapted to the specific radio being tested.

For the Icom IC-2200H, I use a 3.5 mm TRS 3-pole stereo male connector for the clone connection.

The connector has three contacts: Tip, Ring, and Sleeve.

Contact Wiring

3.5 mm TRS Contact Connection Function

Tip (T)

Not connected

Not used

Ring (R)

Clone Signal

Radio clone/programming data

Sleeve (S)

GND

Signal ground

This makes the IC-2200H connection simple and easy to check when assembling the cable.

For the Motorola GM950E, I use an RJ45 connector for the radio-side connection.

The RJ45 connector provides the two connections required for this clone interface:

RJ45 Pin Connection Function

Pin 2

Clone Bus +

Clone/programming signal

Pin 5

GND

Signal ground

RJ45 Connection

RJ45 Pin 2 → Clone Bus +

RJ45 Pin 5 → GND

The Clone Bus + signal is connected to the clone-signal output of the interface. The ground connection is connected to the common ground of the CP2102 interface.

This makes the GM950E connection simple and easy to check when assembling the cable.

Important: This pin assignment is documented according to the configuration used in this project. Verify the GM950E connector wiring before connecting a DIY cable to the radio, particularly if working with a different cable or radio variant

The Baofeng UV-5R uses two separate audio/data connector plugs:

1. 2.5 mm plug
2. 3.5 mm plug

For my DIY cable, these two plugs provide separate RX, TX, and GND connections.

UV-5R Connector Wiring

2.5 mm Plug — RX and GND

Important — 1N4148 Diode

The 1N4148 diode used for the shared clone/bus configuration is not used in the direct UV-5R TX/RX connection.

The UV-5R has separate TX and RX connections through its two plugs. Therefore, the radio-side connections are wired directly to the corresponding TX and RX signals.

Shared Clone Cable Configuration

For radios using the shared clone/bus arrangement, the interface uses:

TX → 1N4148 → RX / Clone Signal

The 1N4148 provides the signal-isolation function for that configuration.

UV-5R Configuration

For the UV-5R:

CP2102 TX → 3.5 mm Sleeve → UV-5R TX

CP2102 RX → 2.5 mm Ring → UV-5R RX

CP2102 GND → 2.5 mm Sleeve → UV-5R GND

There is no 1N4148 in these direct TX/RX signal paths.

This is an important distinction because putting the diode into the UV-5R's direct TX/RX path can alter the signal and may prevent reliable communication.