呵呵，垃圾场捡回来的。
description: the e-v 638 was manufactured in the ླྀs by electro-voice, inc., buchanan, michigan, usa.
it was the successor of the famous e-v model 605.
its frequency response is especially recommended for ssb voice communications. it was also sold from heathkit as model hdp-21a, (hi-z).
specifications
generating element: moving coil, dynamic
frequency response: 70 to 10,000 hz
polar pattern: omnidirectional
impedance: 150 ohms or hi-z model
output level: hi-z - 150 ohms - -57 db below 1 volt per µbar
-57 db below 1 mw per 10 µbar
diaphragm: e-v acoustalloy
sensitivity rating: hi-z - 150 ohms, -153 db
-151 db
case material: chrome plated die-cast zinc
mounting: standard 5/8" -27 thread
desk stand, ptt: model 428 (423a base / switch riser)
maximum switch current: 1 ampere
maximum switch voltage: 125v ac or dc
material: die-cast zinc and plastic
dimensions w/ microphone: 10" high x 5-1/8" base diameter
net weight w/ microphone: 1-3/4 lbs.
