N1GY- The simple Approach to Ham Radio
Recently, I had the inspiration to build a new headset adaptor. This time, for a Bao-Feng UV-5R hand held radio. These little dual-banders have become quite popular, mainly because they are very inexpensive. A friend of mine purchased one through Amazon for less than $50. The original manual leaves much to be desired because it was obviously written by someone for whom English was not their native language, however several amateur operators have stepped up to the plate and rewritten the operating manual in much clearer terms. Included in these new manuals is the information that the Bao-Feng UV-5R uses the same circuitry for the speaker-mic and/or a headset as Kenwood does on many of their rigs. A neatly drawn circuit diagram was also included in the manual I found on line.
With that information in hand it was relatively easy to design an adaptor that would allow the use of a headset (originally designed for computer use) with the UV-5R. This circuit will also work, I am told, with Kenwood and Wouxun HTs that use the same connectors. The circuit is shown below. I used the same enclosure that I have for many of my other headset adaptors (available from Radio Shack) sized approximately 1” x 2” x 3” with hardware and two lids included, one aluminum and one ABS plastic. A ½” hole was drilled in the center of the plastic lid for the PTT switch and another ½” hole was drilled in the 2” end of the enclosure for a strain relief that brings the cable into the enclosure. Two ¼” holes were drilled in the other 2” end for the 1/8” stereo jacks where the headset will be connected.
With the enclosure prepared, I found an old speaker-mic for an old Alinco DJ-F1T in my “junque” drawer and scoped out the pin-out color code. This cable uses the same 1/8” stereo plug and 3/32” stereo plug to connect to the HT as does Kenwood and Bao-Feng. With the color code of the cable worked out each of the wires in the cable was extended by soldering on about a 4” length of wire to each wire in the cable including the shield. A chart was made so that the color code changes were noted.
The components needed for this project are all available at Radio Shack with the exception of the coiled cable with the two stereo plugs pre-installed. One could easily substitute two regular straight cables and install the appropriate 1/8” and 3/32” stereo plugs that are needed to connect to the HT.
The parts list is as follows:
Quantity Part Description
1 10 uF polar Capacitor
2 1K resistor (1/8 watt)
2 3.5mm (18”) stereo jacks
1 Momentary Push Button (Normally Open)
1 1” x 2” x 3” enclosure
1 PC style Headset (These do vary in performance. You may have to try several to find one that gives you the best audio performance. I standardized on a very inexpensive headset that I found at a Dollar Tree store locally. I purchased every one they had when I found out how well they worked for my purposes..)
1 or 2 suitable cables to connect the adaptor to the HT.
1 6” length of CAT-5 or other cable to provide hook-up wire to connect the components
If you choose to build this adaptor, Install the PTT switch in the top and then solder a length of hook-up wire to one of the terminals on the switch, then set aside for now. Following the circuit diagram below, connect the appropriate components to the terminals on the back of the 1/8” stereo jack you have designated to be for the mic plug of the headset. The 2 1K resistors are soldered together in series and then one end of that assembly is soldered to the “tip” terminal of the jack. The negative pole of the polar capacitor is soldered to the “ring” terminal of the same jack. Each of the wires from the radio connecting cable is extended by soldering and heatshrinking a length of hook-up wire. This may not be necessary if you are constructing your own connecting cables, just strip the sheath back far enough to give you long enough individual wires to make the connections. I used, as mentioned before, an old coil cord from an elderly HT speaker mic and the wires in that cable, while sound, were not long enough to make the required connections inside the enclosure. Install the cable(s) using the strain relief in the ½” hole drilled in the short end of the enclosure and then solder each of the individual wires in the cable to it’s appropriate connection point on the 1/8” stereo jacks and the PTT switch.
After all solder connections have been made, install the two 1/8” stereo jacks in the holes you drilled previously in the other short end of the enclosure and install the lid with the 4 screws that came with it.
Plug in a PC style headset to the two 1/8” jacks on one end of the enclosure and plug the cable from the other end into the radio. Turn on the radio and select a quiet simplex frequency and make a test transmission giving your call sign. The PTT should put the radio into transmit mode and you should be able to hear background noise in the earphone of the headset. You may have to turn down the squelch to hear this. If you have another radio, turn it to the same frequency as the hand held and make another short transmission with the Bao-Feng. Someone listening to the second radio should hear your transmission and be able to give you a signal check. If so, and the audio quality is satisfactory for you, you are done. If not, but the PTT function is OK and you hear the other parties signal in the earphone of the headset, the problem probably is the PC headset itself. Try a different one and repeat the tests.
This headset adaptor will work with the Bao-Feng UV-5R and also should be completely compatible with any Kenwood HT that uses the same speaker-mic circuit. It will also apparently work with any Wouxun HT that uses the same speaker-mic connectors. One little problem did pop up in testing. It turns out that the Baofeng HT has connectors for the speaker mic/headset that are fairly deeply recessed into the body of the radio. Any stereo plug that has a somewhat thick insulation around the plug itself, may have difficulty seating properly. If you have this problem, either change the 3.5mm Stereo plug to a skinnier one or shave a bit of the rubber/plastic around the business end of the plug so that it can seat properly into the recessed area of the HT.
Enjoy and 73