Balanced Armature design SH-091a Military Headset Microphone for Crystal Radio

Description

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Here you are bidding on a NOS vintage Chinese Military Balanced Armature Headphone (
one type of the Sound Powered design
) and microphone. These communications headset microphone were manufactured around 1975, design for a Chinese Military semiconductor transceiver. This
SH-091a
headset microphone
is a collectable item and will be a welcome addition to your collection.
Perfect for ham
transceiver,
very good for coping cw signals or crystal radio listening.
Although it is low impedance (85Ω DC resistance, about 400 Ω impedance in 1000 Hz), it is extremely sensitive. As a balanced armature device, it is sensitive enough to be classed as “sound-powered”, i.e.: if connected to a similar pair of headset, voice communication is possible without the need for a battery.
If connect this headphone via a suitable high-low impedance matching transformer (such as my KPB-02
audio matching transformer (
http://www.ebay.com/itm/KPB-02-Crystal-Radio-Impedance-Matching-Transformer-200K-to-4-Selectable-/162007211102
),
or a Bogen 725 4 watt
transformer
), or directly connected the detector to the appropriate tap point on the tuning coil, this headphone would be ideally suited for crystal radio reception. I have tested it in my crystal radio and it sounds very loud, the sensitivity of this balanced armature headphone is much better than a good high impedance (DC resistance 2000 or 4000Ω) headphone.
The cable of headset is about 6 foot long. There are no
connectors on end of the cable, you can solder any type of plug according to your needs.
The red and black wire should connect to
headphone
, two white wires
connect to
microphone.
The quality of construction for this headset is great because it was designed for military application. The balanced armature elements are sealed and very difficult to open (the inside view pictures of the headphone element were taken from same type of headset)
Please E-mail any questions you may have before you bid. It is time to clean up the electronic related items in my garage, please keep an eye out for my other eBay auctions! Thanks for looking!
Please make payment arrangements within 3 days. I accept PayPal. International payment must be by PayPal only, in US dollars. Payment is expected within 10 days of auction closing, or item will be released for sale. International buyer pays shipping charge for US Postal Service First Class Package
.