What is the Structure of military handset A25? (1)

For this handset, users can't disassemble it by force except PTT switch after glued. So you have to cut all components apart by a saw.

The A25 handset is constructed as a main body, speaker, microphone (dynamic microphone) and PTT switch. The speaker and microphone are water-resistant, and the PTT switch is also covered by a rubber gasket, so it is also waterproof.

The PTT switch is secured by screws, the cover for speaker and microphone are attached on the main device body so it is inseparable. It seems that if any damage or malfunction occurred on the speaker or the microphone, there is no way to repair them but replace with a brand-new handset. However, the whole device is apparently glued together by a kind of super adhesive, and so it does not look fragile nor easy to break.

 Explosed drawing of A25 handset

A simple structured hook attached at the back of the device, to use to hang on a carrying handle or on a backpack.

Furthermore, the hook can hang on the strap of helmet and places the speaker close to ear to use as a headset.

PTT switch

The insertion requires to be deeply stroked in or transmitting will not function. Once pressed PTT switch, MIC line connects radio, and the PTT line drops to GND then switches the device to the transmit mode.

 Inside the PTT switch. Left: when the PTT switch is released. Right: when pressed down, the MIC line is activated to transmit signals.

What interesting is that the switch uses a magnet instead of a spring? When the switch is released, the magnet pulls itself to the metal frame to turn the switch back to its original position. This design enables the switch to achieve a durability of over 2 million actuations, unlike a normal spring whose tension fatigue occurs sooner.

The action of a PTT switch not using a spring. The magnet pulls the metal contact to return the switch back to its original position.

The switch is a bipolar single-throw switch which the result of PTT and MIC lines worked together. When the switch is pressed, MIC line connects radio first, then the PTT line drops on GND. The slightly different timing in action is caused by the different sizes of the pair of prominences at the connecting point.

In next article, I would update the information of microphone and speaker of this kind of military handset. If you have any interest of this A25 handset, please contact us directly by email: sales01@yyxlong.com or mobile phone 008613858299721.