Information for Those Who Would Like to Use a Baofeng Transceiver With TNC-X or TNC-Pi

(while these directions picture the TNC-X, the same approach can be taken with the TNC-Pi)

The Baofeng UV-5R and similar radios are extremely inexpensive dual band (2m/70cm) HT's that are widely used for FM voice communication. But what about using them on packet radio? Yes, this is possible, but a number of people have had problems with either home made cables are some that were bought commercially. The major problem is that the radio keys, but does not unkey. It seems to be a grounding problem because when you bring your hand close to the radio, it then unkeys.

One way to overcome this is to make your own radio/TNC cable using a speaker/microphone that is designed for the Baofeng radio. You then cut off the microphone and just use the cable and connector. This may sound expensive, but as it turns out, speaker/mics are available for the Baofeng on line in the $5 range. Do a search on Amazon for "Baofeng Speaker" and you will find them. You will also need a 5 pin DIN plug for the other end of the cable. These plugs are available on the TNC-X website.

Or buy the DIN Plug here ($2):

 

Here is the Baofeng Speaker/Mic that I purchased from Amazon. It cost $6.03 for two of them with free shipping. Speaker/Mic
Microphone Connections

Here I've removed the 3 screws that hold the microphone back in place and opened it up. You can see that the wires are labelled on the printed circuit board, which makes it easy to figure out which wire is which. On this microphone the connections are as follows:

Red = TXAudio

White = Ground

Black = PTT

Green = RXAudio

NOTE: I have found some of these mics have the M- (ground) and SP+ (RXAudio) wires reversed. Since these wires are connected to the speaker, this doesn't matter for the operation of the speaker/mic, but it does matter for TNC connections. Typically the white wire is ground and the green wire is RXAudio. You can check to be certain by desoldering the SP+ wire and see if there is continuity between the M- connection and the sleeve on the small plug that plugs into the radio. If continuity is found, the wire soldered to M- is ground. If continuity is not there, check the wire that was soldered to the SP+ connection.

NOTE 2: I have received a few Baofeng speaker/mics that don't work.  I suggest that before you cut the cable, make sure the speaker/mic works with your Baofeng HT.  If it does not work, the cable probably won't work either. 

The next step is to cut off the microphone altogether. It can be discarded. Then strip the wires and tin them with solder. IMPORTANT: Make sure that at this point you put the black cover of the DIN connector over the cable as shown. If you forget to do this you'll be sorry later! Microphone wires
Solder Connector

Next solder the connector on to these wires. With the pins going around over the top the order should be:

RED - GREEN - WHITE - NO CONNECTION - BLACK

Next attach the shell (two pieces). The first to go on is the one that is then crimped to the outer black cable. Then add the other piece and slide up the black cover to complete the installation. SHELL
Cable

Here's the completed cable, ready to go! As you can see it is not a difficult assembly process. However, if you would like to buy one already built, they are available for $20 plus shipping.

TNC-X Cable for Baofeng UV-5R or Similar ($20).

TNC-Pi Cable for Baofeng UV-5R or Similar ($20)