Dual Push-To-Talk (PTT) headset adapter for GMRS/FRS radios - Page 1
Forum section: electronics / beginners

author: colorado1876
author_rank: Newbie
timestamp: April 15, 2024, 12:55:31 pm
content: Hello, I am trying to connect a headset to a dual channel GMRS/FRS radio. There are multiple dual PTT speaker/mic accessories (e.g., Baofeng AR-152, Baofeng UV-82, BTech QHM22D). However, they do not accept a standard ⌀3.5mm headset (e.g., for gaming). There are GMRS/FRS standard headset adapters, such as the BTECH 3.5mm Audio Adaptor Cable. However, it only hasonePTT button. To my knowledge, a Dual PTT standard ⌀3.5mm headset adapter does not exist yet for the commonKenwood 2-pin radio connector.There is not much information regarding dual PTT circuits for theKenwood 2-pin radio connector. However, here are a few relevant links with schematics:https://www.miklor.com/COM/UV_Technical.phphttps://www.instructables.com/DIY-Baofeng-Radio-Dual-PTT-for-35mm-Headsets/Attached is my draft for a custom schematic. The general idea is to purchasetwoDual PTT Speaker/Mic accessories. One will be used as is, but only for the Dual PTT buttons (speaker and mic will not be used). The other Dual PPT will be used to connect the custom PCB to the GMRS/FRS radio. Its Kenwood 2-tip connector and cable will be cut (speaker/mic removed). The cut end of the cable will be soldered to pads on the custom PCB.Standard ⌀3.5mm TRS-TRS and/or TRRS=TRRS audio cables will connect the custom PCB to an audio amplifier, a headset mic jack, and a custom Dual PTT accessory.Additional notes:-Wire color choices in the schematic are chosen as they match the BTech QHM22D Dual PTT Speaker/Mic wires (see attached image)-The Audio Amplifer and Headset Mic will always be used.-The Custom Dual PTT accessory will only be used sometimes. When it is not used, a Dual PTT Speaker Mic such as the BTech QHM22D will be used.-The cases for the Custom Dual PTT PCB and the Custom Dual PTT accessory with be plastic.-The Audio amplifier is a standard portable headphone amplifier (battery powered).-The Headset mic jack is a standard ⌀3.5mm boom mic jack commonly found on gaming sets (easy to replace mic when it fails).-The schematic is adraft and has errors.Do not use as is!Questions:1. According to this post (https://superuser.com/questions/1379215/gaming-headset-3-5mm-trs-mic-plug-pinout), a standardTRSheadset mic is wired as follows:-Tip = mic signal (signal input)-Ring = +5V bias-Sleeve = 0V (shield/ground)In the schematic, what should the pink wire in the schematic connect to in the Custom Dual PTT PCB?2. In the Custom Dual PTT accessory, is ground needed, given the case will be plastic? In the attached image of the internal PCB of the BTech QHM22D, a Ground solder pad is present. However, as the PCB is multilayer, I can't visually reverse engineer the circuit to see what the Ground connects to.3. Is the wiring for the TRS-TRS cable to the Audio Amplifier correct? I don't think it is. The GMRS/FRS radio only outputsmonoaudio. The Audio Amplifier ⌀3.5mm jack acceptsstereoaudio input. So the output of the Custom Dual PTT PBC is +/- speaker audio which differs from normal L/R audio, which the Audio Amplifier is expecting.4. Other than 1,2, & 3 above, is there anything wrong with the plan? The grounding is an aspect that is particularly confusing to me.Thank-you for any assistance. I will update the schematic as needed. The eventual plan is to learn PCB CAD to have several PCBs made for personal use.Edits: tried to fixed typos and formatting.