Capewell XABH-9000 User manual

Helmet Tester
The XABH-9000 Helmet Tester is a hand-held,
battery powered instrument for verifying the
proper operation of aviation-type speakers
and microphones, individually or as part of
complete headsets.
FEATURES & SPECIFIC ACTIONS
•The case size is 4.3”w x 9.5” H x 2.25” Thick.
•Operating temperature 0°C to 55°C (32°F-130°F)
•The unit is compatible with dynamic microphones
ranging from 5 to 600 ohms, “amplified” electret
microphones (commonly used for carbon mic
replacement), and polarized electrets condenser
microphones. It is designed for speakers and
speaker systems ranging from 4 to 600 ohms,
however it can measure speakers up to 1700
ohms with diminished output level.
•A 2-line 20-character backlit LCD shows
microphone type and current (for electret types)
or ohms (for dynamic types), speaker ohms,
and relative microphone output level in response
to input sound.
Helmet Tester
PN: XABH-9000

PRODUCT DESCRIPTION AND
OPERATION
The unit simulates an intercom system for verifying proper
operation by wearing the headset and speaking into the
communications microphone. Includes a built-in microphone
and a speaker for testing individual speakers and microphones
and for trouble-shooting in the event normal loop-back testing
fails. The internal microphone has automatic gain control so
that it can be used up close or sitting on a table picking up
ambient noise.A six-position rotary switch selects the operating
mode...
Normal - headset microphone is connected to the headset
speakers.
Mic test- headset microphone is connected to the headset
speakers and the internal speaker.
Spkr test - internal microphone is connected to the headset
speakers.
Preset A, B, C - same as normal mode but compares readings
to stored values to display error messages should the readings
deviate significantly. Presets are programmed by connecting a
known-good headset and depressing the recessed programming
switch on the top of the tester.
The volume control sets the output level of both the headset
speakers and the internal speaker.
A 13-pin connector permits interfacing with various types of
headset connectors and individual speaker and microphone
elements. Custom adapters can be provided for specific
applications. The connector includes power lines and access to
the processor for field code updates if needed, and to permit
the construction of specialized adapters that take over the
display.
The unit is powered by 3 AA cells, typical battery lifetime is
about 30 hours of actual usage and about 90 hours turned on
but not being used. Current drain is about 65ma to 90ma
while operating with the LCD back-light on and connected to a
microphone. After a few minutes the LCD back-light is turned
off to conserve power, idle current without a headset connected
is about 25ma. The back-light is restored when a headset is
connected or the mode switch is operated. Remove the
batteries when the unit is stored for more than a month.
Recommended battery type is Duracell MN1500.
The unit automatically detects the microphone type
and engages the appropriate pre-amplifier and bias. Dynamic
microphones are measured by applying a current of about
0.5ma (5V source with 10K series resistance), microphones
with a resistance of less than 25 ohms are considered
low-impedance and engage a higher gain preamp. Polarized
condenser microphones are measured by biasing from a 5V
source with 5K series resistance (1ma max). Amplified
microphones are measured by biasing from a 10V source with
560 ohms series resistance. Speakers are measured by
applying a current of about 0.45ma (0.45V source with 1K
series resistance). Output impedance is roughly 15 ohms to
minimize the volume differences between low and medium
impedance headsets.
OPERATION
When a microphone is connected, the unit detects the mic type
and selects an appropriate
Type L = dynamic microphone under about 25
ohms, 54db-gain preamp, 150 ohm input-Z
Type H = dynamic microphone over about 25
ohms, 46db-gain preamp, 150 ohm input-Z
Type P = polarized electret condenser microphone,
5V/5K bias, 12db-gain preamp
Type E = amplified electret microphone assembly,
10V/560 ohm bias, 3db-gain preamp
LCD display shows mic/speaker data and mic signal output
On power-up the unit briefly displays the battery
voltage. “LB” appears in the lower right corner if the battery
voltage is below about 3.6V, and the back-light is disabled if
the battery voltage is under about 3.1V. In normal operation
the back-light is turned off after a few minutes of non-use.
TECHNICAL NOTES
The tester uses three commonly-available alkaline AA-type
batteries, such as the Duracell type MN1500 or MX1500, or
the Energizer E91. Carefully inspect the batteries before
installing, do not use if the case shows any sign of damage or
if there is any corrosion on the terminals. Periodically inspect
the battery holder terminals for corrosion, if any corrosion or
discoloration is noted, then clean the terminals using alcohol
and a swap. Batteries must be installed correctly with the
springs contacting the flat minus terminal. Remove the
batteries when the tester is not being used for a period of more
than one month.
Rechargeable NiMh or NiCd batteries may be used, however the
LB (low battery) indicator will be shown early, and the unit must
be turned off when the back-light remains off to avoid damage
to the batteries. Leaving the unit on past the point where the
back-light no longer comes on will damage rechargeable
batteries due to polarity reversal effects.
The display shows OPEN if microphone and/or speaker is not
connected. If the microphone type cannot be determined then
displays UNKN (unknown). The speaker and microphone
readings are updated roughly twice a second. Speaker and
dynamic microphone resistance is shown in ohms.
Electric microphones are given a rating number based on current
drain:
Unit displays ma*100 for type P microphones (i.e. Mi=P50
means 0.5ma),
Unit displays ma*10 for type E microphones (i.e. Mi=E115
means 11.5ma).
Measurement accuracy is about +/-3% after stabilizing and with
no audio signal.
The 2nd line shows the relative output of the microphone
preamp, with the peak held for roughly a second to make it
easier to visualize the microphone output level in response to
speech.
Function Switch
Position 1 - normal manual operation
Position 2 - microphone test mode (turns on internal speaker)
Position 3 - speaker test mode (turns on internal microphone)
In all modes, the signal from the headset mic is
delivered to the headset speaker. In microphone test mode, the
signal from the headset mic is also delivered to an internal
speaker. In speaker test mode, a signal from an internal
microphone is delivered to the headset speaker and the signal
from the headset microphone is attenuated by about 10db. The
internal microphone has automatic gain control to adapt to the
peak sound level.
In preset modes, program the unit by connecting a good
headset and pressing the pushbutton switch located behind an
access hole on the top of the unit.

After programming, the following messages are displayed after
connecting a headset:
OK - no errors detected
Mic Open - microphone is disconnected, bad mic or
disconnected cable or connector wiring
Mic Shorted - microphone resistance is less than 2
ohms, likely shorted cable or connector
Mic Wrong - not the expected microphone type
Mic Ohms Bad - dynamic microphone ohms deviates
more than +/-30% from expected
Mic Current Bad - electret microphone current
deviates more than +/-70% from expected
(note - polarized electret mics vary widely and
may produce false errors in preset modes)
Mic Unknown - cannot determine microphone type
Spkr Open - speaker is disconnected, likely
disconnected cable or connector wiring
Spkr Shorted - speaker resistance is less than 2
ohms, likely shorted cable or connector
Spkr Ohms Bad - speaker resistance deviates more
than +/-20% from expected
(note - if headset has a volume control make sure
it is all the way up)
One Spkr Bad - speaker resistance is twice the expected value,
likely one speaker bad or disconnected
Lines Shorted - both speaker and microphone read less than 2
ohms, likely bad cable or connector
Lines Bad - one line shorted, one line open, likely bad cable or
connector
Mic & Spkr Bad - some other error involving both the microphone
and speakers
The unit beeps if the value deviates too much from the
programmed values. The programmed values are saved in
internal memory permanently until programmed again. When
switching to a preset, the display briefly shows the values pro
rammed for that preset.
When testing headsets with a volume control, turn the headset’s
volume control all the way up or the tester will add the volume
control resistance to the displayed reading.
It is normal for the current of type P microphones to vary widely
over time and in response to sound. Type P microphones require
that the + and - wires be connected correctly or they will read
UNKN.
The unit is not designed for carbon-type microphones. They
should detect as high impedance dynamic and the measure-
ment bias might permit some level of testing, but the readings
and the microphone output level and quality will vary widely.
The measured speaker ohms will fluctuate somewhat in
response to loud audio signals.
Higher impedance headsets will have less speaker output
volume; adjust the volume control as needed.
The output signal becomes slightly distorted with increased
microphone sound level, this is intentional and helps
differentiate the speaker signal from the operator’s natural
voice.
This unit measures DC resistance, not the true AC impedance.
Any electronics between the tester and the speaker or
microphone (transformers, capacitors, etc) will result in
incorrect measurement. Typically the DC resistance will be about
5%-15% less than the actual AC impedance at 1Khz, and
produce the same reading (within tolerance) as would be
obtained using a common multimeter. If true AC impedance
measurement is required then a custom adapter can be
devised.
CONNECTOR SPECIFICATIONS
CThe 13-pin side connector permits connecting adapters for
interfacing to different headset connectors and test leads for
testing individual microphone and speaker elements. The unit
comes with an adapter for headsets that use a common 4-pin
NEXUS-type connector, and a standard U173/U pin-type
connector for testing microphones. Adapters for other types of
connectors can be devised as needed, contact us for assistance.
In addition to speaker and microphone lines, the connector also
includes power and ground connections for powering
low-current external circuitry, extra audio inputs for connecting a
music player or other audio source, and connections for
interfacing with the headset tester’s processor for reprogram-
ming and other custom uses. The stock processor code for the
unit does not support user-level programming, rather these lines
make it possible to deliver code updates in the form of an
adapter and so that custom adapters can reprogram the
processor with the needed protocol.
User-constructed adapters should only connect to the microphone
and speaker lines, the audio input lines, and must draw no more
than 20ma from the +5V power line. Do Not make any
connections to the processor lines. Damage caused by improper
adapters is not covered under warranty!
The auxiliary audio input lines have an input
impedance of about 10K and are designed for signal levels of
about 1 to 2 volts RMS (the typical output level of a music
player). The signal is mixed with the microphone preamp signal
before the volume control.
The connector pins are as follows:
Pin 1 - headset microphone +
Pin 2 - headset microphone - (ground)
Pin 3 - headset speaker - (ground)
Pin 4 - headset speaker +
Pin 5 - aux audio input 1
Pin 6 - aux audio input 2
Pin 7 - aux audio ground
Pin 8 - 5V power source (20ma maximum!)
Pin 9 - power ground
Pins 10-13 - processor lines, do not connect.