What is the function of military handset h-250?

Most amateur radios do not require speaker-microphones, namely a handset. However, most common radios for the military use a handset type device and H-250 handset has been used by the US military since the Vietnam war, it is to say that the H-250 has a highly approved performance quality. We, Xianglong Communication in China therefore made a similar military handset A25 with same function as H-250.
This article is written about the difference between Xianglong's A25 military and H-250 handset according to some investigation of the internal structure of the H-250 handset from Internet.

1. Required functions that written on specifications of the H-250.
The H-250 has been produced by various manufacturers, and delivered to the US military, so the products must be produced according to required specifications and pass a functional inspection.

Part of a document published online that shows the H-250 handset specifications required by the US Department of Defense (published in 1977)

2. Required performance specifications of the H-250/ A25
Item H-250 A25
Weight: Approximately 350g Matched
Speaker impedance: 1000Ω (@1kHz) 1000Ω (@1kHz)
Microphone impedance: 150Ω (@1kHz) 150Ω (@1kHz)
Microphone output level: More than -56dB(@1kHz) -59dB(@1kHz)
Distortion: Less than 5%(300Hz~3500Hz) Less than 5%(200Hz~4000Hz)
Operating temperature range -20~65 -45~55
Water resistance: Remains fully function after submerged in 3 feet (91cm) of water for 2 hours Remains fully function after submerged in 1 meter of water for 2 hours
PTT switch durability: More than 2 million actuations More than 2 million actuations

military handset microphone test
                   Calculated microphone frequency characteristic
Vibration and drop test to confirm performance quality specifications, including electric characteristics, are mandatory.
If you need this kind of military handset, welcome to contact us by email sales01@yyxlong.com or direct call 008613858299721.