
Echometer Company
Model – H Manual
Phone: (940) 767-4334
5001 Ditto Lane
Page 77
Fax: (940) 723-7507
Wichita Falls, Texas 76302, U.S.A.
E-Mail:
Microphone/Cable Test
The microphone/cable test can be performed after the instrument self test has shown that the battery and
electronics are performing properly.
The microphone test is used to measure the output of the microphone when a pre-determined pressure pulse is
applied to the microphone. A rubber squeeze bulb attached to a plastic threaded cap is supplied with the gas
gun so that the gas gun microphone can be tested whenever desired. The rubber squeeze bulb applies a
compression pressure pulse to the microphone when the bulb is squeezed. Continue to squeeze the bulb for
approximately 5 seconds, and then release the bulb. When the bulb is released, a rarefaction pressure pulse is
generated which is opposite in polarity. When testing the Compact Gas Gun, the internal gas valve and the
casing bleed valve must be closed. Lifting the cocking arm closes the internal gas valve. Be sure that the
casing bleed valve is closed. When testing the 5000-psi gun, close the valve between the microphone and the
volume chamber
Attach the rubber test bulb to the end of the gas gun securely. Attach the microphone cable to the microphone
outlet BNC connector and to the instrument INPUT.