User Manual For Amron International, Inc. Model 2820A and 2825A

User Manual
For
Amron International, Inc.
Model 2820A and 2825A
Two Diver Communicator
S/N ____________________
1380 Aspen Way, Vista California 92081-8349
United States of America
Phone: (760) 208-6500
Fax (760) 599-3857
Email: sales@amronintl.com
Web: www.amronintl.com
This manual and the information contained herein are provided for use as an operation and maintenance
guide. No license or rights to manufacture, reproduce, or sell either the manual or articles described
herein are given. Amron International, Inc. reserves the right to change specifications without notice.
Copyright© 2017 Amron International, Inc.
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
TABLE OF CONTENTS
1
INTRODUCTION AND SPECIFICATIONS .......................................................................................... 1
1.1
INTRODUCTION ........................................................................................................................... 1
1.2
ELECTRICAL SPECIFICATIONS ................................................................................................ 1
1.3
MECHANICAL SPECIFICATIONS ............................................................................................... 2
1.4
AMCOM II MODEL 2820A DIVER COMMUNICATOR ................................................................ 3
1.5
AMCOM II MODEL 2825A DIVER COMMUNICATOR ................................................................ 4
2
LIMITED WARRANTY AND SERVICE POLICY .................................................................................. 5
2.1
LIMITED WARRANTY .................................................................................................................. 5
2.2
SERVICE POLICY ........................................................................................................................ 5
3
OPTIONS AND ACCESSORIES .......................................................................................................... 6
3.1
OPTIONS ...................................................................................................................................... 6
3.2
ACCESSORIES ............................................................................................................................ 6
4
TENDER AND DIVER CONTROLS AND CONNECTIONS ................................................................. 8
4.1
TENDER CONTROLS .................................................................................................................. 8
4.2
TENDER CONNECTIONS ............................................................................................................ 9
4.3
DIVER CONTROLS .................................................................................................................... 10
4.4
DIVER CONNECTIONS .............................................................................................................. 10
4.5
OTHER CONNECTIONS AND CONTROLS .............................................................................. 11
4.6
OPTION CONTROLS: HELIUM SPEECH UNSCRAMBLER/26DSP3 ..................................... 12
4.7
OPTION CONTROLS: WIRELESS TENDER /28A OPTION ..................................................... 13
4.8
DRAWING, 2-WIRE CONNECTIONS ........................................................................................ 14
4.9
DRAWING, FULL DUPLEX (4-WIRE) CONNECTIONS ............................................................ 15
4.10 DRAWING, OPERATOR CONNECTIONS, P-T-T MICROPHONE ........................................... 16
5
INSTALLATION AND OPERATION................................................................................................... 18
5.1
OPERATION ............................................................................................................................... 18
5.2
CHARGING THE BATTERIES: /23 AND /24 RECHARGEABLE UNITS ................................. 18
5.3
BATTERY CONDITION .............................................................................................................. 19
5.4
BATTERY INSTALLATION – STANDARD AND /23 RECHARGEABLE UNITS ..................... 19
5.5
BATTERY INSTALLATION – /24 AC POWERED UNITS ......................................................... 19
5.6
MODES OF OPERATION ........................................................................................................... 20
5.7
VOLUME CONTROLS – 2-WIRE ............................................................................................... 22
5.8
OTHER DIVER CONTROLS – (2-WIRE) ................................................................................... 23
5.9
VOLUME CONTROLS – 4-WIRE (FULL DUPLEX)................................................................... 23
5.10 OTHER DIVER CONTROLS (4-WIRE MODE) .......................................................................... 24
5.11 OTHER TENDER CONTROLS................................................................................................... 24
5.12 WIRELESS OPTIONS ................................................................................................................ 26
6
MAINTENANCE AND TROUBLESHOOTING ................................................................................... 28
6.1
FULL DUPLEX (4-WIRE) CHECK.............................................................................................. 28
6.2
2-WIRE CHECK .......................................................................................................................... 28
6.3
GENERAL MAINTENANCE ....................................................................................................... 29
6.4
RECOMMENDED MAINTENANCE SCHEDULE ....................................................................... 29
6.5
TROUBLESHOOTING ................................................................................................................ 31
2820A & 2825A-UM
REV 8.0
i
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
7
FULL DUPLEX (4-WIRE) – WHAT, WHY AND HOW ....................................................................... 35
7.1
WHAT ARE 2-WIRE AND 4-WIRE MODES? ............................................................................ 35
7.2
WHAT IS FULL DUPLEX (4-WIRE)? ......................................................................................... 36
7.3
WHY FULL DUPLEX (4-WIRE)? ................................................................................................ 37
7.4
HOW DO YOU USE FULL DUPLEX (4-WIRE)? ........................................................................ 37
8
DRAWINGS ........................................................................................................................................ 39
8.1
PARTS IDENTIFIER FRONT PANEL MODEL 2820A .............................................................. 40
8.2
PARTS IDENTIFIER, FRONT PANEL MODEL 2825A ............................................................. 41
8.3
PARTS IDENTIFIER, MODELS /24, /24/26DSP3 & /24/28A OPTION ...................................... 42
9
PARTS LISTS ..................................................................................................................................... 43
9.1
AMCOM II MODEL 2820A.......................................................................................................... 44
9.2
AMCOM II MODEL 2820A/23 ..................................................................................................... 45
9.3
AMCOM II MODEL 2820A/24 ..................................................................................................... 46
9.4
AMCOM II MODEL 2825A.......................................................................................................... 47
9.5
AMCOM II MODEL 2825A/23 ..................................................................................................... 48
9.6
AMCOM II MODEL 2825A/24 ..................................................................................................... 49
9.7
AMCOM II MODEL 2825A/24/26DSP3 ...................................................................................... 50
9.8
AMCOM II MODEL 2825A/24/26DSP3 (CONTINUED) ............................................................. 51
9.9
AMCOM II MODEL 2825A/24/28A ............................................................................................. 52
9.10 2820-301 CASE ASSEMBLY – AMCOM II ................................................................................ 53
9.11 2820A-400M FRONT PANEL ASSEMBLY................................................................................ 53
9.12 2825A-400M FRONT PANEL ASSEMBLY ................................................................................ 54
9.13 2824-500B BATTERY BOX INTERNAL CHARGER ................................................................. 55
9.14 28XX-FS-01 FIELD SPARES KIT FOR 2820A, 2825A ............................................................. 55
9.15 OPTIONAL SPARES .................................................................................................................. 56
2820A & 2825A-UM
REV 8.0
ii
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
1
INTRODUCTION AND SPECIFICATIONS
1.1 INTRODUCTION
The AMCOM II Series is a family of full-featured hard-wired, two-diver communicators. The
AMCOM II is offered in two basic versions. The units are identical except the Model 2825A
has independent microphone and earphone volume controls for each diver and the tender.
The Model 2820A has a single earphone volume control for diver’s volume (down-link) and a
single volume control for the tender (up-link).
AMCOM II units have push-to-talk and separate isolated inputs for each diver. Both are
portable two-diver communication systems, delivering 20 Watts “voice power”, operating from
internal batteries or external 12 VDC power source.
Models with the /24 option can be operated from either a 110/220 V AC, external 12 VDC power
source, or an internal 12 VDC battery.
The Model 2820A and Model 2825A have the capability of 2-Wire and/or Full Duplex (4-Wire)
communication modes. 2-Wire and Full Duplex (4-Wire) modes can be used simultaneously.
Full Duplex is a communications system designed from the ground-up to take advantage of
current state-of-the-art semiconductor technology and to provide superior diver hard-wire
communication.
This portable diving radio has the ability to work with both dynamic and pre-amplified
microphones in either 2-Wire or 4-Wire modes. The circuit detects the type of microphone
that each diver is using, and then automatically switches from the preamp mode to dynamic
mode, adjusting the specific diver’s gain (volume). The tender’s volume is set louder than the
diver’s volume. This allows the tender to hear the divers in a noisy environment while
maintaining the diver’s volume at a comfortable level.
1.2
ELECTRICAL SPECIFICATIONS
Input Impedance (Each Input) ................................................................................... 250 Ohms
Frequency Response ........................................................................................ 300 - 10000 Hz
Common Mode Rejection .................................................................................. 40 dB Minimum
Current Drain Maximum Full Volume ............................................................................. 3 Amps
Minimum Quiescent ............................................................................ 0.25 Amps
Output Impedance ........................................................................................................... 4 Ohm
Power Supply Voltage ....................................................................................... 12 VDC Nominal
(9 Volts Minimum - 18 Volts Maximum)
Model 282XA/24 .................................................................................... 90-264 VAC, 47-440 Hz
Sensitivity (Input) ............................................................................................................. 0.5 mV
Output Power (RMS @ 4 Ohm Load, 12 VDC) ..................................................20 Watts Audio
2820A & 2825A-UM
REV 8.0
1
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
Battery Life
Model 2820A & 2825A ................................................................................................. 40 Hours
Model 282XA/23 .......................................................................................................... 30 Hours
Model 282XA/24 .......................................................................................................... 20 Hours
1.3
MECHANICAL SPECIFICATIONS
Panel
..................................................................................... Powder Coated Stainless Steel
Enclosure ...................................................................................... High Impact Resistant Plastic
Enclosure Color ................................................................................. Bright International Yellow
Dimensions
Length .......................................................................................................... 14.5 In. (36.8 Cm)
Width
............................................................................................................ 9.0 In. (22.9 Cm)
Height
.......................................................................................................... 10.0 In. (25.4 Cm)
Weight with Batteries
Model 2820A............................................................................................... 17.35 Lbs. (7.87 Kg)
Model 2820A/23 with External Charger ...................................................... 20.53 Lbs. (9.31 Kg)
Model 2820A/24 ......................................................................................... 17.98 Lbs. (8.16 Kg)
Model 2825A............................................................................................... 18.20 Lbs. (8.26 Kg)
Model 2825A/23 ......................................................................................... 21.13 Lbs. (9.58 Kg)
Model 2825A/24 ......................................................................................... 18.53 Lbs. (8.40 Kg)
Model 2825A/24/26DSP3 ........................................................................... 19.18 Lbs. (8.70 Kg)
Model 2825A/24/28A with Remote Wireless Tender Kit .......................... 23.28 Lbs. (10.56 Kg)
2820A & 2825A-UM
REV 8.0
2
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
1.4
AMCOM II MODEL 2820A DIVER COMMUNICATOR
The Model 2820A AMCOM II is a full-featured, hard-wired diver communicator. The 2820A features a
single earphone volume control for the divers (downlink) and a volume control for the tender (uplink).
Divers can be wired in either 2-Wire or 4-Wire mode for maximum flexibility. It can be ordered in the
following configurations:

Non-rechargeable batteries (2820A)

Rechargeable batteries with external charger (2820A/23)

Rechargeable batteries with internal charger (2820A/24 – Shown Above)
2820A & 2825A-UM
REV 8.0
3
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
1.5
AMCOM II MODEL 2825A DIVER COMMUNICATOR
The Model 2825A AMCOM II is a deluxe hard-wired diver communicator. The 2825A features
individual earphone volume controls for each diver (downlink) as well as a volume control for the
tender (uplink). Both divers and the tender have microphone volume controls. Divers can be wired in
either 2-Wire or 4-Wire mode for maximum flexibility. It can be ordered in the following configurations:

Non-rechargeable batteries (2825A)

Rechargeable batteries with external charger (2825A/23)

Rechargeable batteries with internal charger (2825A/24 – Shown Above)

Rechargeable batteries with internal charger and Wireless Tender Option (2825A/24/28A)

Rechargeable batteries with internal charger and Helium Speech Unscrambler (2825A/24/
26DSP3)
2820A & 2825A-UM
REV 8.0
4
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
2
LIMITED WARRANTY AND SERVICE POLICY
2.1
LIMITED WARRANTY
AMRON INTERNATIONAL, INC., (Amron) warrants that its products are free from defects in
material and workmanship under normal use and service for a period of 90 days from date of
shipment as described in Amron literature covering this product. Amron’s obligation under
this warranty is limited to the repair of or replacement, at Amron’s option, of defective
material. This warranty shall not cover defects which are the result of misuse, negligence,
accident, repair or alterations.
2.2
SERVICE POLICY
For technical assistance or to request a repair, please call (760) 208-6500, Monday – Friday,
8 a.m. to 5 p.m. PT. Have the model number and serial number handy and be prepared to
offer as much information as possible about the problem.
Please do not return any product without obtaining a return authorization number. Detailed
instructions will be provided at the time of request.
2820A & 2825A-UM
REV 8.0
5
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
3
OPTIONS AND ACCESSORIES
The following options are available to customize the AMCOM communicator. Options have to be
ordered at the time of purchase or the communicator has to be returned to AMRON for the option to
be installed.
3.1
OPTIONS
3.1.1
MODEL /23 – EXTERNAL BATTERY CHARGER
The communicator is equipped with 4 gel-cell sealed lead-acid batteries and
includes an external universal input (115/230 VAC) battery charger. Operating time
is approximately 30 hours.
3.1.2
MODEL /24 – INTERNAL BATTERY CHARGER
The communicator is equipped with an internal universal input (115/230 V AC)
battery charger along with a rechargeable battery. Operating time is approximately
20 hours.
3.1.3
MODEL /26DSP3 – HELIUM SPEECH UNSCRAMBLER (HSU)
Amron’s DSP3 HSU uses state-of-the-art Digital Signal Processor (DSP)
technology to correct raw helium speech into clear, intelligible voice. The /26DSP3
option includes a complex noise reduction filter to improve communications in
situations with high background noise levels. This option must be ordered with the
/24 option and is only available on the 2825A.
3.1.4
MODEL /28A – WIRELESS TENDER OPTION
The communicator is equipped with a wireless module and includes a Model 282911 Wireless Tender Headset. The wireless headset allows the tender freedom to
move around. It requires the divers to be wired in 4-Wire mode. This option must
be ordered with the /24 option and is only available on the 2825A.
3.2
ACCESSORIES
The following accessories are available for the AMCOM communicator. Accessories can be
ordered at any time.
3.2.1
MODEL 2401-28 – AMRON HEAVY-DUTY HEADSET
The Model 2401-28 is a heavy-duty headset with boom microphone. It comes
equipped with color-coded, dual banana plugs that mate directly to AMCOM diver
communicators. It includes a 6-foot (1.8-meter) cord.
3.2.2
MODEL 2460-28 – AMRON STANDARD HEADSET
The Model 2460-28 is a light and comfortable headset designed for extended wear
at an economical price. It comes equipped with color-coded, dual banana plugs
that mate directly to AMCOM diver communicators as well as a spiral cord that can
be extended up to 8 feet (2.4 meters).
2820A & 2825A-UM
REV 8.0
6
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
3.2.3
MODEL 2405-28 – AMRON PUSH-TO-TALK MICROPHONE
The Model 2405-28 is a hand-held, noise-canceling, push-to-talk microphone that
provides excellent sound quality to the diver. It comes equipped with a spiral cord
that can be extended up to 6 feet (1.8 meters).
3.2.4
MODEL 2822-28 – AMRON REMOTE WALK-AND-TALK MODULE
Designed for Full Duplex (4-Wire) applications, the Model 2822-28 provides the
tender with mobility around the dive site while maintaining communications with the
diver. It comes equipped with a small clip-on belt module that contains the
connectors for the headset, and 25 feet (7.6 meters) of lightweight flexible cable.
Custom cable lengths are available.
3.2.5
MODEL 2821-28 – AMRON REMOTE PUSH-TO-TALK MODULE
Designed for 2-Wire applications, the Model 2821-28 provides the tender with
mobility around the dive site while maintaining communications with the diver. It
comes equipped with a small clip-on belt module that contains a push-to-talk
switch, connector for the headset, and 25 feet (7.6 meters) of lightweight flexible
cable. Custom cable lengths are available.
3.2.6
MODEL 2829-11 – AMRON WIRELESS TENDER HEADSET
A heavy-duty headset combined with a wireless belt module that is compatible with
the /28A option. One headset comes with communicators ordered with the /28A
options but additional headset can be ordered to allow other crew member to
monitor communications.
2820A & 2825A-UM
REV 8.0
7
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
4
TENDER AND DIVER CONTROLS AND CONNECTIONS
Before using the AMCOM II series diver communications system, you should familiarize yourself with
its operating controls and connections. Improper use of controls and connections will deprive the user
of the full benefits of this communication system. We strongly recommend the tender read FULL
DUPLEX (4-WIRE) – WHAT, WHY AND HOW located in section 7 of this manual.
4.1
TENDER CONTROLS
4.1.1
POWER SWITCH – This switch controls power to the unit.
4.1.2
SPEAKER SWITCH – This switch allows the tender to turn off the speaker. If the
tender is using a headset, it may be necessary to turn off the speaker in order to
prevent acoustic feedback.
4.1.3
PUSH-TO-TALK ALL DIVERS BUTTON – This button allows the tender to talk to
all the divers when operating in the 2-Wire mode. It is not necessary to use this
control in the Full Duplex (4-Wire) mode. When using Full Duplex mode, this
control allows the tender to interrupt the divers by forcing them into listen only
mode.
4.1.4
EARPHONE VOLUME – This control sets the volume for the tender's earphone
and/or PANEL SPEAKER. Rotate this knob clockwise to increase the volume from
all the divers.
4.1.5
MICROPHONE VOLUME (Model 2825A only) – This control sets the level for the
tender's microphone and/or PANEL MICROPHONE. Rotate this knob clockwise to
increase the tender’s volume to all the divers.
4.1.6
BATTERY CONDITION INDICATOR – A steady GREEN light indicates battery
charge level is good. Blinking GREEN light indicates battery charge level is at a low
level with less than 3 hours of running time available. Steady RED light indicates
battery charge level is below the level necessary to guarantee proper operation.
WARNING: When BATTERY CONDITION INDICATOR is steady RED light, the
batteries should be replaced or recharged immediately.
4.1.7
PANEL SPEAKER – A waterproof, acoustic horn speaker that allows the tender to
listen to the divers. The volume level is controlled by the EARPHONE VOLUME
control and it can be turned off using the SPEAKER SWITCH.
4.1.8
PANEL MICROPHONE – A water-resistant condenser microphone that allows the
tender to talk to the divers using the PUSH-TO-TALK BUTTONS. On the 2825A,
the volume level is controlled by the MICROPHONE VOLUME control. The PANEL
MICROPHONE is muted when the SPEAKER SWITCH is turned off.
WARNING: Do not plug or cover the PANEL MICROPHONE hole. This may
dampen the tender-to-diver communications or damage the microphone
requiring replacement.
2820A & 2825A-UM
REV 8.0
8
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
4.2
TENDER CONNECTIONS
4.2.1
TENDER HEADSET JACK – This is the dual banana jack (color-coded black) that
functions as both an output (earphone) and input (microphone) for the tender as
controlled by the PUSH-TO-TALK BUTTON and PUSH-TO-TALK JACK. Using this
connection, the tender can be wired in either 2-Wire or Full Duplex (4-Wire) mode
regardless of the mode used for the diver.
To connect the tender in the Full Duplex (4-Wire) mode, connect the earphone
(black) banana plug of the headset to this jack and the microphone (red) to the
TENDER MICROPHONE jack (red) as shown in the wiring diagram in section 4.9.
In this mode, the tender does not have to use the PUSH-TO-TALK BUTTON to
communicate with a diver who is also connected in the Full Duplex (4-Wire) mode.
This configuration can be used even if the diver is connected in 2-Wire mode. In
that situation, the tender is required to use the PUSH-TO-TALK BUTTON or
PUSH-TO-TALK JACK.
The headset microphone is always active, which means that there can be acoustic
feedback between the PANEL SPEAKER and the microphone if the tender is near
the communicator. To prevent this, the PANEL SPEAKER can be turned off using
the SPEAKER SWITCH. Another option is to move the tender away from the
communicator by using the Amron Model 2822-28 Walk-and-Talk Module
accessory. This allows the tender to communicate while other members of the
surface crew listen using the PANEL SPEAKER. This module comes with 25 feet
(7.6 meters) of cable (custom cable lengths are available).
The tender can also be connected in 2-Wire mode by stacking both the earphone
(black) and microphone (red) banana plugs into this jack as shown in the wiring
diagram in section 4.8. The diver does not have to be connected in 2-Wire mode if
the tender is in 2-Wire mode. In order to talk to the diver, the tender must use
either the PUSH-TO-TALK BUTTON or PUSH-TO-TALK JACK. Since the headset
microphone is not active until one of the push-to-talk methods is used, there is no
chance for acoustic feedback to occur and surface conversation or noise is not
transmitted to diver and the PANEL SPEAKER can be left on. This may, for some
situations, make for a better overall diving experience. If the tender requires more
mobility at the dive site, the Amron Model 2821-28 Remote Push-to-Talk Module
can be used to extend the headset cable. It includes a push-to-talk button on a clipon belt module and comes standard with 25 feet (7.6 meters) of cable (custom
cable lengths are available).
The tender may also use the optional Amron Model 2405-28 Push-to-Talk
Microphone. This microphone comes with two color-coded banana plugs. The
black plug goes into the TENDER HEADSET jack and the yellow plug goes in the
PUSH-TO-TALK JACK as shown in the wiring diagram in section 4.10. To
communicate with the diver, the tender presses the button on the side of the
microphone. There is no chance of acoustic feedback since the PANEL SPEAKER
is cut off when the tender uses the microphone. When using the Push-to-Talk
Microphone, the SPEAKER SWITCH must be turned on in order to hear the diver.
2820A & 2825A-UM
REV 8.0
9
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
4.2.2
TENDER MICROPHONE JACK – This is a dual banana jack (color-coded red) that
functions as the microphone input from the tender's headset. It is only used if the
tender is in Full Duplex (4-Wire) mode. On the 2825A, the TENDER
MICROPHONE VOLUME control adjusts the sensitivity of the input.
4.2.3
PUSH-TO-TALK JACK – This is a dual banana jack (color-coded yellow) that
allows for remote keying of the push-to-talk function of the communicator. It is use
by the Push-To-Talk Microphone (Amron Model 2405-28) and the Remote WalkAnd-Talk Module (Amron Model 2822-28).
The difference between using the PUSH-TO-TALK JACK and PUSH-TO-TALK
SWITCH is that the switch allows the tender to communicate using the PANEL
MICROPHONE. If both are used at the same time, the PANEL MICROPHONE is
active. This allows another crew member to talk to the diver using the PANEL
MICROPHONE even if the tender is away from the communicator using the
Remote Push-to-Talk Module in 2-Wire mode.
4.3
4.4
DIVER CONTROLS
4.3.1
DIVER EARPHONE VOLUME (Model 2820A) – This control sets the earphone
volume level to both divers.
4.3.2
DIVER EARPHONE VOLUME (Model 2825A) – The 2825A has separate earphone
volume controls for each diver. This allows the tender to set the best individual
volume for each diver.
4.3.3
DIVER MICROPHONE (Model 2825A) – The 2825A has separate microphone
volume controls for each diver. This sets amplification level of each diver’s
microphone signal controlling that diver’s volume to both the tender and the other
diver.
4.3.4
PUSH-TO-TALK-DIVER – There is a separate PUSH-TO-TALK button for each
diver. Normally used in 2-Wire mode, this control allows the tender to talk to only
one of the divers. The diver selected will hear both the tender and the other diver
allowing crosstalk between the divers controlled by the tender. It can be used in
Full Duplex (4-Wire) to cut off the microphone of an individual diver.
DIVER CONNECTIONS
4.4.1
DIVER MICROPHONE – This is a dual 5-way binding post jack (color-coded red)
that functions as both an output (earphone) and input (microphone) for the diver as
controlled by the PUSH-TO-TALK BUTTON and PUSH-TO-TALK JACK. Using this
connection, the diver can be wired in either 2-Wire or Full Duplex (4-Wire) mode
regardless of the mode used for the diver.
To connect the diver in 2-Wire mode, connect both the diver microphone and
earphone to this jack. If the diver umbilical uses banana plugs, simply stack both
plugs into this jack as shown in the wiring diagram in section 4.8. In this mode, the
diver microphone will be active and heard on tender headset and/or PANEL
SPEAKER unless the PUSH-TO-TALK BUTTON or PUSH-TO-TALK JACK is used.
When a pre-amp microphone is used in the 2-Wire mode setup, it is required to
2820A & 2825A-UM
REV 8.0
10
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
have special speakers supplied only by Amron. Contact Amron for more
information.
To connect the diver in Full Duplex (4-Wire) mode, connect the diver microphone to
this jack and the diver earphone the DIVER EARPHONE jack as shown in the
wiring diagram in section 4.9. The diver can use this mode even if the tender is
wired in 2-Wire mode.
4.4.2
4.5
DIVER EARPHONE – This is a dual 5-way binding post jack (color-coded black)
that functions as the output for the diver's earphone. It is only used when the diver
is in Full Duplex (4-Wire) mode.
OTHER CONNECTIONS AND CONTROLS
4.5.1
EXTERNAL BATTERY JACK – The communicator can be powered using an
external battery or power supply via the two color coded TIP jacks. The red TIP
jack is the positive power input and the black is the negative power input. The input
voltage must be between 9 and 18 VDC and must be able to supply a peak current
of 3 Amps for proper operation. The following warnings need to be heeded when
using the EXTERNAL BATTERY JACK. A minimum wire size of 18 AWG and
maximum wire run of 3 feet (1 meter) is recommended.
It is strongly recommended that an Amron External Charger Model 2823-603 be
used as the external power supply. The Amron External Charger was specifically
designed for use with all Amron communicators and has a high degree of insulation
between the primary and secondary circuits for diver protection and safety.
WARNING: The EXTERNAL BATTERY JACK can be used to recharge the
2820A/23 & 2825A/23 with rechargeable sealed lead acid battery. It is strongly
advised to use the provided Amron External Charger, Model 2823-603, to
charge or operate the communicator. This charger has been designed with
the necessary electrical isolation to prevent dangerous currents from the AC
lines from reaching the diver.
If you use an external power supply, the maximum voltage needs to be
limited to 15 Volts if the rechargeable battery is in the unit. If a higher voltage
is to be used, it is advised that the battery be disconnected or removed from
the communicator to prevent possible damage to the battery.
4.5.2
TAPE RECORDER – This is a single RCA Phono jack (color-coded black) that
provides a transformer isolated of both the diver and tender communications. It is
designed to drive the standard line-level inputs of audio or video recorders with
input impedances as low as 600 Ohms.
4.5.3
AC POWER (/24 Option) – The AC power cord is located in the option panel
located on right side of the communicator front panel. The option panel has an AC
POWER LED to identify the presence of AC power. When the communicator is
plugged into AC power, the LED will be on regardless of the POWER SWITCH.
The internal battery charger has a universal input voltage range from 90-264
VRMS over a frequency range from 47-440Hz. No operator adjustment is required.
2820A & 2825A-UM
REV 8.0
11
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
4.6
OPTION CONTROLS: HELIUM SPEECH UNSCRAMBLER/26DSP3
The controls for the DSP3 Helium Speech Unscrambler (HSU) are located in the options
panel on the right side of the front panel as shown below.
4.6.1
ON/OFF SWITCH – Allows the selection of air (OFF) or helium (ON) operation. In
the OFF position, the divers’ microphone signal bypasses the HSU. In the ON
position, the microphone signals are routed to the HSU and the tender can adjust
the controls as necessary.
4.6.2
TREBLE BOOST – Selects the amount of gain added to the High Frequency (HF)
portion of the divers’ microphone signals. This compensates for the HF drop-off in
the sensitivity of most microphones. The TREBLE BOOST feature allows for
optimum frequency enhancement and improved intelligible speech from the diver’s
voice.
2820A & 2825A-UM
REV 8.0
12
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
4.7
4.6.3
DEPTH CONTROL – Selects the amount of frequency correction performed by the
HSU to produce intelligible speech. This control uses a multi-turn potentiometer
and is equipped with a turn counting knob and lock. Once the desired setting is
reached, the lock can be used to prevent accidental changes to this control.
4.6.4
NOISE REDUCTION FILTER – The Noise Reduction Filter (NRF) uses a complex
Digital Signal Processor algorithm based on a statistical-model of human voice
activity to capture the background noise and reduce it without affecting the divers’
speech. The noise level can be reduced by up to 17 dB.
OPTION CONTROLS: WIRELESS TENDER /28A OPTION
This option is mounted in the right hand side of the front panel. This Wireless Tender Option
is for four-wire (Full Duplex) operation only. System comes standard with a remote wireless
tender module.
4.7.1
WIRELESS OPTION PANEL – Comes standard with antenna and power on/off
switch. The “ON/OFF” switch powers the wireless PC card inside the
communicator. The antenna has a swivel and tilt that allows the antenna to be
folded down during shipment. For operation, the antenna should be pointing
upwards. For installations where the Diver Communicator is located inside a
structure, there is an optional Remote Antenna kit available. This kit allows the
antenna to be located outside the structure for maximum effective range.
IMPORTANT: When the wireless option is not used, turn the option panel switch to
“OFF”. When option panel switch is turned “ON”, the wireless remote should be
“ON”. Otherwise a static noise may be heard through the communicator’s panel
speaker as it scans for available Remote Wireless Tender.
4.7.2
REMOTE WIRELESS TENDER MODULE – This module comes standard with an
internal rechargeable battery. Headset and external 110V charger jacks are located
on remote module.
4.7.3
ON/OFF-VOLUME CONTROL – Adjusts the listening volume and turns the unit
“OFF” when it is turned completely upwards.
4.7.4
TALK PUSH BUTTON – This button is located on the top of the unit and is labeled
TALK. When it’s first turned on, the Remote Wireless Tender Module is in Standby
Mode (listen only) as indicated by the LED closest to the button being red. When
the button is pressed, the Remote Wireless Tender Module is in “Talk Mode” (listen
and talk, full duplex) and the LED is green. Pressing the TALK button toggles
between the two modes. Multiple Remote Wireless Tender Modules can be in the
Standby (listen only) mode at the same time. Only one module can be in the talk
mode.
4.7.5
HEADSET JACK – Located on the side opposite the ON/OFF-Volume Control.
Plug the remote wireless headset to this jack.
4.7.6
CHARGE JACK – Located on the side next to the ON/OFF-Volume Control. Plug
the remote wireless charger to this jack.
2820A & 2825A-UM
REV 8.0
13
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
4.8
DRAWING, 2-WIRE CONNECTIONS
2820A & 2825A-UM
REV 8.0
14
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
4.9
DRAWING, FULL DUPLEX (4-WIRE) CONNECTIONS
2820A & 2825A-UM
REV 8.0
15
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
4.10
DRAWING, OPERATOR CONNECTIONS, P-T-T MICROPHONE
DRAWING, OPERATOR CONNECTIONS, HEADSET
2820A & 2825A-UM
REV 8.0
16
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
2820A & 2825A-UM
REV 8.0
17
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
5
INSTALLATION AND OPERATION
5.1
OPERATION
The AMCOM II portable diver communicators are supplied in a yellow enclosure. To open the
enclosure, release the two latches on the front of the unit and raise the lid. The lid of the
communicator can be removed by sliding the lid to the side.
The AMCOM II panels are graphically divided into sections; Tender Controls, Diver Controls,
and Options. Items within these areas are functions or controls relating to the Tender,
Diver(s) or Optional items.
WARNING: When operating your Amron Diver Communicator from AC mains, it is
critical to use a Ground Fault Circuit Interrupter (GFCI) and/or isolation transformer for
tender and diver safety. Surges and spikes are common on AC lines found onboard
ships, from local generators, or at the end of a long extension lines. These spikes can
exceed 1kV! Such spikes can be high enough to cause the input fuses on the battery
charger to blow and, in extreme cases, actually damage the charger circuitry. Amron
has designed the Model 2823-603 (/23 Option) battery charger and the internal battery
charger (/24 Option) to isolate such faults to ensure that they will not cause a safety
issue for the diver or tender. Amron cannot guarantee that non-Amron power supplies
meet the same high standards and strongly advises against using any such device to
power your diver communicator.
5.2
CHARGING THE BATTERIES: /23 AND /24 RECHARGEABLE UNITS
With the /23 option to charge the batteries after use, connect the battery charger to the
external battery jacks on the front panel of the unit then connect the charger to a AC outlet.
The charger will automatically adjust to the input voltage. The customer will have to use a
power cord approved for the country of use.
It is recommended the unit be placed on charge and left on charge until the unit is to be used
again. This ensures the unit will always be ready to use, and the batteries are fully charged.
The charger is designed not to damage the batteries when left on continuous charge. Full
charge will occur in ten hours (depending on the battery age and the surrounding
temperature). If the unit is in constant use (daily) it is recommended the unit be left on charge
during the weekend to top off the batteries. Batteries must be recharged periodically, a
minimum of at least once every six months.
The /24 option includes an internal 12V sealed lead-acid battery for backup operation in the
event of loss of AC power. The switch over to battery operation is completely automatic, and
occurs whenever AC power is interrupted. The internal 12 volt battery is maintained at full
charge while the unit is operating from AC power. AC power indicator on the option panel
confirms the presence of AC power.
Operating time for the rechargeable 12V battery depends upon the age of the batteries.
Sealed lead-acid batteries have a life of 300 cycles, or 3 years. These batteries do not have
memory; they can be placed on charge at any time.
2820A & 2825A-UM
REV 8.0
18
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
NOTE: Do not continue to operate rechargeable batteries below the low battery condition or
permanent damage will occur. When the battery condition indicator turns to red, turn the unit
off and charge batteries.
5.3
BATTERY CONDITION
5.3.1
POWER ON – BATTERY CHECK
Turn power switch “ON” and observe the battery condition indicator. The battery
indicator will display the condition of the battery.

A steady green light indicates the battery has sufficient voltage to operate the
unit.

A blinking green light indicates the battery is low and will need charging shortly,
two hours of operating time remain.

A steady red light indicates the battery voltage is too low to operate the unit.
Communication should stop.
NOTE: Batteries which have not been used for a period of time will display a higher
voltage state when initially turned on, this will rapidly dissipate. This condition is
known as a surface charge, when the battery is placed under a load the voltage will
fall rapidly. It is a good idea to leave the unit on for five minutes before relying upon
the battery condition indicator.
5.4
BATTERY INSTALLATION – STANDARD AND /23 RECHARGEABLE UNITS
The standard and /23 rechargeable units are supplied with four spring-top dry cell or gel-cell
batteries. To install the batteries, remove the four brass thumb screws from the front panel
and lift unit out of the case. Set brass screws aside in a safe place where they won’t be lost.
1. Stand unit on end (end opposite of speaker), and release the two stainless steel
latches on the sides of the unit. Lift battery cover and move to one side. Notice the
contact side of the battery cover. The battery contact card is designed to make
contact with a spring top battery in any of the four rotational positions. This design
facilitates the easy installation of batteries, with no wires to connect, and a very
positive connection. There is a second battery contact card located in the bottom of
the battery enclosure.
2. To install the batteries, slide two batteries into the case, spring terminals down. Install
the second two batteries with the spring terminals up. Replace battery cover plate,
battery contact side toward batteries, push down on the battery cover and latch in
place. When replacing expended batteries, remove and discard all four batteries and
replace with four new fresh batteries. Place unit back in case and secure with the four
brass thumbscrews.
5.5
BATTERY INSTALLATION – /24 AC POWERED UNITS
The units with the /24 AC powered option are supplied with a single gel-cell, sealed lead-acid
battery and an internal charger. To remove and install the battery, remove the four brass
thumb screws from the front panel and lift unit out of the case. Set brass screws aside in a
2820A & 2825A-UM
REV 8.0
19
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
safe place where they won’t be lost. Set unit on flat stable surface with front panel facing up.
Remove the four screws located on the sides of the chassis. Lift out radio using the handles
and set it on its right side (side away from speaker). The 12V battery is now accessible. Lift
out battery and remove color-coded slide terminals. Install the battery and close unit in the
reverse order.
5.6
MODES OF OPERATION
The Model 2820A and 2825A have the ability to operate in either 2-Wire or Full Duplex (4Wire). Both the diver and tender can be connected in either mode and a combination of
modes can be used. If either the diver or the tender is wired in 2-Wire mode, the tender must
use a push-to-talk, either the PUSH-TO-TALK ALL SWITCH or PUSH-TO-TALK JACK, when
talking to the diver.
2-Wire communication is defined as a single communication path, normally the diver is the
priority signal path – tender listens to diver. Signal reversing is accomplished by pushing the
PUSH-TO-TALK BUTTON – diver hears tender. Often times a 4-conductor communication
cable is used with 2 wires tied together as a pair for redundancy, this is still a 2-Wire system.
Since only one person can talk at a time, there is a level of discipline that goes with using 2Wire mode in order to obtain clear communication. One advantage of 2-Wire is that the
tender's microphone is not active unless one of the two push-to-talk controls, PUSH-TOTALK BUTTON or PUSH-TO-TALK JACK, are active. This eliminates any possible acoustic
feedback between the tender's microphone and the PANEL SPEAKER. It also prevents noise
from the surface reaching the diver and allows the tender to communicate with other
members of the surface crew without involving the diver .
Full Duplex (4-Wire) communication is defined as a dual communication path, a signal path
(a pair of wires) for up-link and a signal path (a pair of wires) for down link. A common
example of Full Duplex communication is the telephone. Full Duplex (4-Wire) has the
advantage of natural communication without having to use the PUSH-TO-TALK BUTTON.
This keeps the tender's hands free to perform other task. It does not require the same level of
discipline to achieve clear communications that 2-Wire does. It has the advantage that
neither the diver nor the tender are cut off when the other is talking. Because the diver's
microphone is not connected in parallel with the earphone, the diver is louder and potentially
clearer in Full Duplex (4-Wire) mode. More information on this mode can be found in Section
7, FULL DUPLEX (4-WIRE) - WHAT, WHY AND HOW.
5.6.1
2-WIRE OPERATION
To connect the diver in 2-Wire mode, connect the communication umbilical wires to
the DIVER MICROPHONE binding post jack on the communicator as shown in the
wiring drawing in section 4.8. If the umbilical uses a banana plug, simply insert the
plug into the binding post jack. Verify that it is firmly and completely seated. This
may require that the external plastic nut be tightened down. If the umbilical uses
bare wires, loosen the external plastic nut of the binding post jack. Either insert the
bare end of the wire into the hole in the metal shaft of the binding post or firmly
wrap the wire around the shaft. Tighten the nut until the bare wire is firmly fastened
by the nut. The nut should not be fastened on the insulation of the wire nor should
any of the bare wires touch.
2820A & 2825A-UM
REV 8.0
20
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
The tender can operate in 2-Wire without a headset or push-to-talk microphone by
using the PANEL SPEAKER as both a speaker and microphone. When the tender
wants to talk to the diver, he presses the PUSH-TO-TALK BUTTON on the front
panel and speaks clearly into the PANEL SPEAKER at a distance of between 4 to
8 inches (10 to 20 cm). When done speaking, the tender releases the PUSH-TOTALK BUTTON to allow the diver to communicate.
When the tender uses a headset or push-to-talk microphone, follow the connection
instructions in section 4.2 and in the wiring diagram in sections 4.8 and 4.10. When
using the Amron Model 2405-28 Push-to-Talk Microphone, the tender presses the
push-to-talk button on the side of the microphone and speaks clearly at a distance
of between 1 and 2 inches (25 to 51 mm). When done speaking, the tender
releases the push-to-talk button to allow the diver to communicate.
Whenever either the diver or the tender are connected in 2-Wire, the tender must
use one of the push-to-talk methods when talking to the diver.
5.6.2
4-WIRE OPERATION
To connect the diver in Full Duplex (4-Wire) mode, connect the communication
umbilical wires to the DIVER MICROPHONE and DIVER EARPHONE jacks as
shown in wiring diagram in section 4.9. If the umbilical uses a banana plug, simply
insert the plug into the correct binding post jack. Verify that it is firmly and
completely seated. This may require that the external plastic nut be tightened. If the
umbilical uses bare wire ends, loosen the external plastic nut of the binding post
jack. Either insert the bare end of the wire into the hole in the metal shaft of the
binding post or firmly wrap the wire around the shaft. Tighten the nut until the bare
wire is firmly fastened by the nut. The nut should not be fastened on the insulation
of the wire nor should any of the bare wires touch. The diver microphone will be
louder in Full Duplex (4-Wire) mode than in 2-Wire mode. This can be a significant
advantage when using longer dive umbilical cables.
To use Full Duplex (4-Wire) mode, the tender must use a headset and connect per
the instructions in 4.2. The tender will have to use the PUSH-TO-TALK BUTTON to
communicate if the diver is in 2-Wire mode. The tender can also use the PUSHTO-TALK BUTTON to cut off the AUDIO AUXILIARY INPUT signal from the diver
even if the tender is connected in Full Duplex (4-Wire) mode. When the tender
uses a headset, the SPEAKER SWITCH should be turned off to prevent acoustic
feedback. Acoustic feedback can also be avoided by moving the tender away from
the communicator by using the Amron Model 2822-28 Remote Walk-and-Talk
Module. In this way, the PANEL SPEAKER can allow other members of the diving
crew to monitor the dive operation or to communicate to the diver by pressing the
PUSH-TO-TALK BUTTON and talking into the speaker.
Up to three divers can be “stacked” onto a single diver channel. Connect the diver’s
microphones in parallel by stacking the banana plugs on the microphone jack and
do the same with the diver’s earphone plugs on the earphone jack. In this setup, all
the divers will share the microphone and earphone volume controls. This can
become a problem if the earphone or microphone for one diver is significantly
2820A & 2825A-UM
REV 8.0
21
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
weaker than the others. It is strongly advised that the setup be carefully tested
before use.
5.7
VOLUME CONTROLS – 2-WIRE
Turn unit ON; adjust all volume controls to mid-scale. For 2-Wire Mode, Tender has to
depress PTT Switches in order to talk to Divers. Tender and Divers talk to each other during
Tender adjusting volume controls as below:
5.7.1
5.7.2
MODEL 2820A

Tender – While diver is speaking, adjust Tender Volume Control to a
comfortable level.

Diver – Depress the push-to-talk switch and while talking into the panel
microphone, adjust diver volume control to a comfortable level for the diver.
MODEL 2825A
NOTE: On the upper row of volume controls, set the microphone volume, on the
lower row of volume controls, set the earphone volume. Tender controls are
considered master controls. The optimum settings are when controls are closely
matched, with differences compensating for differences in diver levels.
Set all volume controls at mid-scale.
Tender should don headset and talk to himself. If adjustments are required,
increase or decrease volume (controls). This will establish a system volume level.
Tender

Tender Earphone Volume – Divers talk while tender adjusts to a comfortable
listening level.

Tender Microphone Volume – Tender talks while depressing PTT ‘All Divers
Switch’, divers determine a comfortable listening level, having the tender adjust
as needed.
Diver 1

Diver 1 Earphone Volume – Tender talks while depressing Diver 1 PTT Switch,
diver 1 determines a comfortable listening level while having the tender adjust
as needed.

Diver 1 Microphone Volume – Diver 1 talks while tender adjusts to a
comfortable listening level.
2820A & 2825A-UM
REV 8.0
22
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
Diver 2
5.8

Diver 2 Earphone Volume – Tender talks while depressing Diver 2 PTT Switch,
diver 2 determines a comfortable listening level, having the tender adjust as
needed.

Diver 2 Microphone Volume – Diver 2 talks while tender adjusts to a
comfortable listening level.
OTHER DIVER CONTROLS – (2-WIRE)
5.8.1
PTT ALL DIVERS SWITCHES
PUSH-TO-TALK BUTTONS are located below earphone volume control for each
diver section. PTT will allow the specific diver to hear tender and other divers, it
changes the diver to be in listening mode and tender in talking mode.
5.9
VOLUME CONTROLS – 4-WIRE (FULL DUPLEX)
Turn unit on and adjust volume controls as follows:
5.9.1
5.9.2
MODEL 2820A

Tender – Set at mid-scale. While diver is speaking, adjust to a comfortable
listening level.

Diver – Set at mid-scale. Talk to divers, and adjust until divers hear tender at a
comfortable listening level.
MODEL 2825A
NOTE: The upper row of volume controls set the microphone volume; the lower
row of volume controls set the earphone volume. Tender controls are considered
master controls. The optimum settings are when controls are closely matched with
differences compensating for differences in diver levels.
Set all volume controls at mid-scale.
Tender should don headset and talk to himself. If adjustments are required,
increase or decrease volume (controls). This will establish a system volume level.
Tender

Earphone Volume – Divers talk, while tender adjusts to a comfortable listening
level.

Microphone Volume – Tender talks and divers determine a comfortable
listening level, having the tender adjust as needed.
2820A & 2825A-UM
REV 8.0
23
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
Diver 1

Earphone Volume – Tender talks and diver 1 determines a comfortable
listening level.

Microphone Volume – Diver 1 talks, while tender adjusts to a comfortable
listening level.
Diver 2
5.10

Earphone Volume – Tender talks and diver 2 determines a comfortable
listening level.

Microphone Volume – Diver 2 talks, while tender adjusts to a comfortable
listening level.
OTHER DIVER CONTROLS (4-WIRE MODE)
If conditions change as a group, the tender volume controls can be used as master volume
control.
Connect tender headset earphones to headset (input), and headset microphone to Tender
Microphone (input). Turn speaker off to avoid acoustic feedback. Operation with speaker is
possible by extending tender's headset away from the speaker. Use Amron Model 2822-28
headset extension cable (25 foot).
Operating the PTT (push-to-talk) switch will establish a priority channel for communication.
PTT cuts out the diver’s microphone and prevents divers from talking.
This allows an important conversation to be carried on without interruption, or the ability to
establish a clear channel of communication.
NOTE: Acoustic feedback may occur when operating with a standby diver who does not have
his hat/helmet on. On the 2825A, this can be avoided by turning his DIVER MICROPHONE
VOLUME control down. This cuts off his microphone but will enable him to monitor the
diver/tender conversation via his earphone. On the Model 2820A, the diver microphone
cannot be disabled.
5.11
OTHER TENDER CONTROLS
5.11.1
SPEAKER ON/OFF SWITCH
For normal operation, the speaker switch is left on. When operating in noisy
conditions, it may be advantageous to use a headset to cut out the background
noise. In this case it will be desirable to shut off the speaker. There are other
conditions when turning off the speaker is desirable; situations where the nature of
the work requires a confidential handling of communications.
2820A & 2825A-UM
REV 8.0
24
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
5.11.2
PUSH-TO-TALK SWITCH
Activation of this switch connects the tender to the diver which is necessary for 2Wire conversations and optional for Full Duplex (4-Wire) conversations. Always
used when using the speaker for talking to the divers.
5.11.3
MICROPHONE JACKS (RED)
Connection for headset microphone: insert red banana plug into this jack when
operating in the Full Duplex mode.
5.11.4
HEADSET JACKS (BLACK)
Connection for headset earphones, external speaker: insert both headset banana
plugs (red & black) into the black headset jacks, red & black when operating in the
two wire mode. Insert in only the black headset banana plug when operating in the
Full Duplex mode. Insert hand-held microphone black banana plug into the black
headset jacks. Hand-held microphone is a standard item for the Model 2825A.
5.11.5
PUSH-TO-TALK JACKS (YELLOW)
Connection for remote control of the push-to-talk function: insert the hand-held
microphone yellow banana plug into this jack. Operation of the hand-held
microphone is simple and straight forward. Hold the microphone in your hand,
place the microphone within one half inch of your mouth, depress lever on side of
microphone and speak clearly and distinctly into the microphone.
The Model 2825A has an automatic speaker disconnect relay which disconnects
the front panel speaker when using the hand-held microphone. This greatly
reduces the background noise during transmissions to the divers. This feature is
also functional when using an AMRON headset, and headset extender (Model
2821-28).
5.11.6
TAPE RECORD JACK
Isolated audio output to drive an audio tape recorder or VCR. Use standard RCA
type audio cable to connect the diver radio to the audio recorder. Test record
audio, checking both tender to diver conversation and diver to tender conversation
for proper record levels.
5.11.7
EXTERNAL BATTERY JACKS
The unit may be operated from an external 12-volt battery or power supply.
Connect the positive side of the battery to the red jack and the negative side of the
battery to the black jack. The jacks on the front panel are pin jacks; mating plugs
are available from Amron or any electronic supply store.
2820A & 2825A-UM
REV 8.0
25
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
5.12
WIRELESS OPTIONS
5.12.1
WIRELESS TENDER OPTION /28A
This option is installed in the right-hand section of the Diver Communicator’s front
panel. Amron’s Full Duplex Wireless Tender is designed to allow the top-side
tender to communicate to divers with hands-free operation. This allows the tender
to check equipment and perform other tasks while still maintaining constant contact
with the divers. This option can also be used in the 2-Wire mode to listen to the
diver-tender communications.
The Wireless Tender Option operates on one of 40 frequency channels. This
allows multiple systems to operate in close proximity without interfering with each
other. There is a master transceiver located inside the diver communicator. The
channel is selected by setting a set of eight dip switches (located under the
battery). Both the remote and master transceivers must have the same dip switch
setting. The factory default setting is 1,1,1,1,0,0,0,1 (1 is ON). In order to change
the channel of operation, it is required to apply changes to both units (master and
remote). Amron recommends that the channel be changed by a trained technician.
Additionally, 2829-11 Wireless Headset and Transceiver Kits can be purchased for
use with the AMCOM as standby “listen only” devices. Only one transceiver can be
used to talk and listen to the divers at any one time but any number of transceivers
can be used in listen-only mode. The transceiver models operate at a frequency of
2.40 to 2.46 GHz using frequency modulation. They have a range of 120 yards
(110 meters) with clear line-of-sight.
The remote unit (transmitter/receiver) is housed in a rugged plastic casing that can
be clipped to a belt or slipped into a pocket. A single charge of the NiMH battery
from the included AC adapter is capable of operating (transmitting and receiving)
continually for up to 5 hours. In standby (listen only) mode, the battery will last for
up to 8 hours. The standard headset is a tough over-the-ear single ear muff design
with adjustable boom microphone.
Operation of the unit is automatic; speaking into the remote unit transmits a RF
signal to the diver communicator. The diver communicator sends the signal down
the umbilical to the diver. When the diver speaks, the signal is sent up the umbilical
to the diver communicator. The signal is then transmitted as a RF signal to the
remote module(s).
IMPORTANT: When the wireless option is not used, turn the option panel switch to
“OFF”. When option panel switch is turned “ON”, the wireless remote should be
“ON”. Otherwise a static noise may be heard through the communicator’s panel
speaker as it scans for the available Remote Wireless Tender.
OPERATION: Turn option power switch to “ON”, turn remote unit “ON/OFF”
Volume to “ON”, set remote unit to Talk Mode (press the Talk Button is once) and
plug headset to remote unit.
2820A & 2825A-UM
REV 8.0
26
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
5.12.2
HELIUM SPEECH UNSCRAMBLER OPTION /26DSP3
The Helium Unscrambler option is installed into the option panel located on right
side of the communicator. A Communicator with this option accommodates a wide
range of operating depths. This state-of-the-art digital design can accommodate a
multitude of functions ranging from the correction of the diver’s raw helium speech
to normal intelligible voice levels, advance treble boost and complex noise
reduction filters (NRF)
Diver radios configured with this option are only supplied with the AC power option.
This is due to the power requirements of the Unscrambler option. The radio can be
operated in the air mode by turning the HSU off.
Amron’s advanced NOISE REDUCTION FILTER (NRF) incorporates a complex
DSP algorithm which filters out background noise while allowing the diver’s speech
to be clear and intelligible. Amron NRF automatically captures the frequency
spectrum of applied background noise within the audio frequency bandwidth and
reduces it without affecting the diver’s speech.
The Treble Boost Control provides a means of adjustment to enhance the diver’s
microphone performance. The treble boost feature allows for optimum frequency
enhancement and improved intelligible speech from the diver’s voice.
The Depth Control is used to change the amount of shift in the frequency of the
diver’s voice. The depth control is advanced as the diver’s depth increases. There
is a certain amount of interaction between the controls, and also a difference
between diver voices, therefore it is necessary to tune the unit to the diver.
Intelligibility is the desired result; each operator will find a combination which works
best. The frequency shifting algorithm changes the amount of correction to the raw
helium speech. The Depth Control is a multi-turn control with a locking feature. This
allows the tender to finely adjust the level necessary and lock the control to prevent
accidental adjustments.
At power-up, all the controls should be in the minimum (far left) position. Have the
diver speak and adjust the DEPTH CONTROL as necessary to achieve the best
speech quality. Then adjust the TREBLE BOOST as necessary to improve the
quality. There is some interaction between these controls so you may have to go
back and adjust the DEPTH CONTROL. Once the best speech quality settings are
found, the NOISE REDUCTION FILTER can be adjusted, if necessary, to reduce
any background noise.
Operating in 2-Wire and Full Duplex (4-Wire) modes are possible with the HSU. In
2-Wire mode, the tender's push-to-talk switch interrupts signals from the diver. In
Full Duplex mode, the tender will hear the diver at all times and tender must use a
headset to talk to the divers without using the push-to-talk switch. Use of a headset
to monitor helium speech is strongly recommended to enhance intelligibility.
2820A & 2825A-UM
REV 8.0
27
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
6
MAINTENANCE AND TROUBLESHOOTING
The following section describes the procedures for checking the operation of your diver
communicator, general maintenance procedures, and how to troubleshoot common problems.
6.1
FULL DUPLEX (4-WIRE) CHECK
This procedure checks the communicator functions in the Full Duplex (4-Wire) mode.
1. Set all volume controls to the mid-scale (halfway) position.
2. Turn the SPEAKER SWITCH off to avoid acoustic feedback.
3. Turn on the communicator and verify the BATTERY CONDITION INDICATOR is on
or blinking. If the LED does not come on at all, then replace or recharge the battery. If
that does not resolve the problem, then go to the troubleshooting section to
determine the cause.
4. Identify the microphone and headset leads. When using an Amron headset, the
microphone is the red banana plug and the headset is the black banana plug.
5. Plug the microphone lead into the TENDER MICROPHONE (red) jack and the
headset lead into the TENDER HEADSET (black) jack.
6. Don the headset and talk into the microphone. You should be able to hear yourself in
the headset. Adjust the DIVER TO TENDER VOLUME control and verify the level
can be adjusted to a comfortable level.
7. Move the headset microphone lead to the DIVER MICROPHONE (red) jack. Talk into
the microphone. You should be able to hear yourself in the headset. Adjust the
DIVER TO TENDER VOLUME control and verify that the level can be adjusted to a
comfortable level.
8. Move the headset lead to the DIVER EARPHONE (black) jack. Talk into the
microphone. You should be able to hear yourself in the headset.
9. This completes the check of the Full Duplex (4-Wire) function of the communicator. If
at any point in the test you were not able to hear yourself in the headset as indicated
by the test, refer to the troubleshooting section to determine the cause.
6.2
2-WIRE CHECK
This procedure checks the communicator functions in the 2-Wire mode.
1. Set all the volume controls to the mid-scale (halfway) position.
2. Turn the SPEAKER SWITCH off to avoid acoustic feedback.
3. Turn on the communicator and verify the BATTERY CONDITION INDICATOR is on
or blinking. If the LED does not come on at all, then replace or recharge the battery. If
that does not resolve the problem, then go to the troubleshooting section to
determine the cause.
2820A & 2825A-UM
REV 8.0
28
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
4. Identify the microphone and headset leads. When using an Amron headset, the
microphone is the red banana plug and the headset is the black banana plug.
5. Plug the microphone lead into the TENDER HEADSET (black) jack and the headset
lead into the DIVER MICROPHONE (red) jack.
6. Don the headset. Talk into the microphone while pressing the PUSH-TO-TALK
BUTTON. You should be able to hear yourself in the headset. Adjust the TENDER
TO DIVER VOLUME control and verify that the level can be adjusted to a
comfortable level.
7. Unplug the microphone lead. Turn on the SPEAKER SWITCH. Press the PUSH-TOTALK BUTTON while speaking into the PANEL SPEAKER. You should be able to
hear yourself in the headset. Adjust the TENDER TO DIVER VOLUME if necessary
and verify that the level can be adjusted to a comfortable level.
8. Plug the microphone lead into the TENDER HEADSET (black) jack. Short the PUSHTO-TALK JACK (yellow) with a short piece of wire. Talk into the microphone and
verify that you hear yourself in the headset. Remove the short. Turn off the
SPEAKER SWITCH.
9. Move the microphone lead to the DIVER MICROPHONE (red) jack and move the
headset lead to the TENDER HEADSET jack.
10. Talk into the microphone and verify you can hear yourself in the headset. The PUSHTO-TALK BUTTON should not be pressed. Adjust the DIVER TO TENDER.
6.3
GENERAL MAINTENANCE
The AMCOM II diver communicator is designed to provide years of continuous, failure-free
service when properly used and maintained. There are a few important things that the user
can do to extend the life of their equipment
1. Handle the diver communicator with care. Do not throw it around or drop it. Select a
work area where the communicator and wire connecting to it are out of everyone's
way so it does not get knocked over.
2. Clean the communicator after use or when needed. If the equipment is on an
extended work program, have the tender clean the equipment during slow work
periods. Rinse off salt deposits with fresh water. Clean the diver connections with a
mild vinegar and water solution using a soft brush. Rinse off the connectors with
water after cleaning.
6.4
RECOMMENDED MAINTENANCE SCHEDULE
The following sections outline the recommended scheduled maintenance for the
communicator and communicator.
2820A & 2825A-UM
REV 8.0
29
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
6.4.1
DAILY MAINTENANCE
Wipe off any accumulated salt or salt spray on the front panel or connectors using
a clean, damp cloth. Pay particular attention to where the various front panel
components attach to the panel. Inspect the outer case for any damage.
6.4.2
WEEKLY MAINTENANCE
Wipe off any accumulated salt or salt spray on the front panel or connectors using
a clean, damp cloth. Pay particular attention to where the various front panel
components attach to the panel. Inspect the outer case for any damage.
6.4.3

Inspect the PUSH-TO-TALK BUTTON, binding posts and volume controls for
smooth operation.

Inspect the case lid O-ring for any damage and replace if necessary.
6 MONTH CHECK
Wipe off any accumulated salt or salt spray on the front panel or connectors using
a clean, damp cloth. Pay particular attention to where the various front panel
components attach to the panel. Inspect the outer case for any damage.
6.4.4

Inspect the PUSH-TO-TALK BUTTON, binding posts and volume controls for
smooth operation.

Inspect the case lid O-ring for any damage and replace if necessary.

Inspect the front panel gasket for any damage and replace if necessary.

On the communicator - recharge the battery using the Amron 2823-603 Battery
Charger.

Perform the 2-Wire and Full Duplex (4-Wire) system checks as described in
section 5.2.
YEARLY CHECK
For maximum service life, it is recommended that the diver communicator be sent
back to Amron for a yearly check.
6.4.5
LONG TERM STORAGE
If the diver communicator is to be stored for a period greater than 30 days, it is
recommended that it be stored in a cool dry location. Make sure that the POWER
SWITCH is turned off during storage. The communicator should be stored
connected to the 2823-603 Battery Charger to ensure that the communicator will
be fully charged and ready to use when needed.
2820A & 2825A-UM
REV 8.0
30
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
6.5
TROUBLESHOOTING
Most problems are usually simple issues that can often be found by careful inspection of the
diver communicator, diving umbilical, and diver wiring. The following section will describe the
troubleshooting procedure for several common issues. If these sections do not cover your
particular issue, it is recommended that the diving umbilical be disconnected from the diver
communicator and the check-out procedures in section 5.1 be conducted. If the diver
communicator passes the check-out procedures then the issue is most likely in the umbilical
connections, the umbilical itself, or the wiring of the diver's hat/helmet.
6.5.1
CONNECTION ISSUES
Most diver communicator problems are caused by bad connections. Making good
connections will result in years of good communications. For longer life, all
connections should be soldered and copper wire must be tinned. It is strongly
suggested that dual banana plugs be used topside to provide convenient and
secure connections.
All cable splices must be soldered. Splices should be staggered and covered with
shrink tubing (preferably shrink tubing with an adhesive sealant) and a general
splice cover to protect the connections. Potting the splices to create a reliable
splice is preferred but not necessary to create a reliable splice.
6.5.2
LOW BATTERY INDICATION
The BATTERY CONDITION INDICATOR indicates the battery level or state-ofcharge by monitoring the battery voltage. The battery voltage can be measured
independently using a Voltmeter by measuring the voltage across the EXTERNAL
BATTERY JACK. The voltage has to be 9 Volts or greater for the communicator
with rechargeable battery to operate. It is recommended that the communicator be
recharged for at least 10 hours if the measured voltage is less than 12 Volts
(depending on the age of the battery and the surrounding temperature). If the
BATTERY CONDITION INDICATOR indicates a low (blinking LED) or bad (off
LED) after charging, then either the battery is bad and needs to be replaced or the
charger has malfunctioned.
6.5.3
UNIT NOT OPERATING
The most common reason that a diver communicator appears to be dead when the
POWER SWITCH and SPEAKER SWITCH are turned on is a bad or loose battery.
Check the battery per section 5.3.2. If the battery is good, then disconnect any
diving umbilical and perform the communicator check out procedure per section
5.1.
If the battery and battery connections appear good and the communicator fails the
check-out procedure, then remove the screws holding the front panel. Lift the front
panel up carefully as the panel components are connected to a Printed Circuit
Assembly (PCA) by a wire harness. Verify that the connectors on the PCA are
firmly seated. Check that the wire harnesses are soldered to the various
connectors, controls, and speaker. There should be no loose wires in the system.
Remove the fuse from the PCA. It is marked FH1 and is a cylindrical component.
2820A & 2825A-UM
REV 8.0
31
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
Verify that the fuse is good by checking the continuity with a multi-meter. If the fuse
is open, replace with the same type: 3.15 Amp, 250V, Fast Acting. Close the front
panel; re-install the screws and re-test the communicator. If the communicator still
appears dead, contact Amron per section 2.2 for further assistance.
6.5.4
LOW VOLUME
Check the volume control settings and adjust if necessary. Check the diver
connections and verify that the diver and tender are connected as intended. Verify
the wires and connector are clean and tight (see section 5.3.1 for additional
information). Check the BATTERY CONDITION INDICATOR and test the battery
per section 5.3.2 if necessary. If the problem persists, disconnect the diver
umbilical and perform the communicator check out procedure per section 5.1. If the
communicator fails the check-out procedure, contact Amron per section 2.2 for
further assistance.
If the communicator checks out, then the problem is likely in either the diver
umbilical communication cable, the wiring of the diving hat/helmet, or the diver's
microphone/earphone.
6.5.5
GARBLED VOICE TO DIVER
The TENDER TO DIVER VOLUME control is set too high. Reduce this control until
the voice signal clears. If this does not solve the problem, check the diver's
earphone for corrosion or other defect. Replace if necessary. If the tender is using
a headset, remove the headset and communicate to the diver by pressing the
PUSH-TO-TALK BUTTON and talking into the PANEL SPEAKER. If this solves the
problem then the tender headset may be wet or defective. If the tender is using the
PANEL SPEAKER to talk to the diver, check the speaker for any accumulated
water. Drain the speaker if necessary. If these steps do not solve the problem then
disconnect the diver umbilical and perform the communicator check out procedure
per section 5.1. If the communicator fails the check-out procedure, contact Amron
per section 2.2 for further assistance. If the communicator checks out, then the
problem is likely in the diver umbilical communication cable. If possible, substitute a
known good cable to verify.
6.5.6
GARBLED VOICE TO TENDER
The DIVER TO TENDER VOLUME control is set too high. Reduce this control until
the voice signal clears. If this does not solve the problem, check the diver's
microphone for corrosion or other defect. Replace if necessary. If the tender is
using a headset, remove the headset and listen to the diver using the PANEL
SPEAKER. If this solves the problem then the tender headset may be wet or
defective. If the tender is using the PANEL SPEAKER to talk to the diver, check the
speaker for any accumulated water. Drain the speaker if necessary. If these steps
have not solved the problem, then disconnect the diver umbilical and perform the
communicator check out procedure per section 5.1. If the communicator fails the
check-out procedure, contact Amron per section 2.2 for further assistance. If the
communicator checks out, then the problem is likely in the diver umbilical
communication cable. If possible, substitute a known good cable to verify.
2820A & 2825A-UM
REV 8.0
32
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
6.5.7
DIVER CUTS OFF
This is usually caused by an intermittent connection between either the umbilical
and the diver communicator or the umbilical and the diver's hat/helmet. The
intermittent connection could also be inside the diver's hat/helmet. Check all
connections to verify that they are clean and tight. If the problem continues,
substitute the communication cable with a known good cable. If this solves the
issue, then the communication cable in the original umbilical is damaged and
needs to be replaced or repaired. If none of these solutions fixes the problem,
contact Amron per section 2.2 for further assistance.
6.5.8
FEEDBACK FULL DUPLEX (4-WIRE) MODE
There are two forms of feedback that can affect the communicator: acoustic
feedback and cable crosstalk. Acoustic feedback occurs when an active
microphone is close enough to pick up and amplify the signal from a speaker or
earphone. The required distance between the microphone and speaker/earphone
is dependent on the volume setting and the amount of acoustic isolation. For
example, a tender headset left sitting on a work table my cause acoustic feedback.
When the tender dons the headset at the same volume level, the acoustic
feedback will no longer occur. The tender's head provides acoustic isolation
between the microphone and earphone of the headset. The same is true for the
diver's microphone and earphone.
To troubleshoot acoustic feedback issues first determine the source. One way to
quickly determine the source of the acoustic feedback is to cover each active
microphone with your hand, one at a time. Another method is to adjust the volume
controls one at a time. The volume control that stops the feedback indicates the
source. For example if the TENDER TO DIVER VOLUME control stops the
feedback, then the problem is likely in the diver's hat/helmet. Common sources are
feedback between the tender's headset microphone and the PANEL SPEAKER of
the communicator. If the tender wants to operate with the headset and leave the
PANEL SPEAKER on, Amron recommends the tender move away from the
communicator by using the Amron Model 2822-28 Remote Walk-and-Talk Module.
This module provides an "extension" cord for the tender headset allowing the
tender to operate away from the communicator.
Crosstalk is caused by signal leakage between the microphone and earphone
wires in the umbilical cable. In a good cable with all the wires open (not connected)
the resistance between any two wires should be greater than 10 Meg-Ohms. Over
time, the cable can be damaged and this resistance drops to the point that
crosstalk can occur. When this occurs, the communication cable in the umbilical
should be replaced. For a temporary solution, you can try swapping the position of
the diver earphone wires on the DIVER EARPHONE jack. If you are using a
banana plug, simply unplug the diver earphone and rotate by 180 degrees before
reconnecting. If this does not solve the problem and the umbilical cannot be
immediately replaced, then operate in 2-Wire mode until a replacement umbilical
can be used. Amron strongly recommends the use of the Amron CC1
communication cable. It has been specially designed for clear communications and
long service life.
2820A & 2825A-UM
REV 8.0
33
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
6.5.9
PUSH-TO-TALK DOES NOT WORK
If used, check the connection to the handheld microphone. A common issue is that
the yellow banana plug is not properly seated in the PUSH-TO-TALK JACK. If the
tender is using the PANEL SPEAKER as the microphone with the PUSH-TO-TALK
BUTTON, make sure the SPEAKER SWITCH is turned on. If neither of these
solves the problem, there could be a broken wire inside the diver communicator.
Open the front panel and inspect as described in section 5.3.3. If that does not
resolve the problem then contact Amron per section 2.2 for further assistance.
2820A & 2825A-UM
REV 8.0
34
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
7
FULL DUPLEX (4-WIRE) – WHAT, WHY AND HOW
Amron has designed the AMCOM Full Duplex (4-WIRE) mode from the ground up, taking advantage
of state-of-the-art electronics technology to provide a superior hard-wire communication experience.
Full Duplex (4-Wire) mode has the following advantages:

Up to 285% more signal strength from the diver microphone over the 2-Wire mode using standard
8-Ohm microphones.

No push-to-talk required leaving the tender's hands free for other tasks.

The diver and tender can hear themselves talk providing a more natural communication
experience.
These advantages produce superior communications and the system is easier to operate by
eliminating the need for using a push-to-talk switch. Another advantage is that the system is easy to
troubleshoot. In fact it is easier to troubleshoot than 2-Wire system once you understand what is
happening. Full Duplex (4-Wire) mode pays off in better communications, something that many of our
competitors have yet to achieve. Better communications means higher diver production, safer dive
conditions and less down time.
7.1
WHAT ARE 2-WIRE AND 4-WIRE MODES?
7.1.1
2-WIRE MODE
2-Wire mode is the most commonly used communication mode in the commercial
diving industry. Technically it is defined as a single communication path using a
minimum of 2 wires in a communication cable. Being a single path, there can only
be one talker at a time. Commonly the diver has the priority and the tender listens
as the diver talks. In order for the tender to talk to the diver, this communication
path has to be reversed. This is done by the tender pressing a push-to-talk switch.
This switch activates a set of relays that switch the diver connection to the output
side of an audio power amplifier and the tender connection to the input side. This
allows the tender to talk while the diver listens.
Most diver communication cables, such as the "Army surplus Comm-Cable," have
four wires. These four wires are often separated into two sets of twisted-wire pairs.
In many diving operations, these two sets of twisted-pairs are connected in parallel
for redundancy. A breakage in a single wire in the cable does not cause a loss of
communication, as each wire has a parallel wire to take over. This arrangement is
still a 2-Wire mode even though 4 wires are being used.
7.1.2
4-WIRE MODE
4-Wire mode uses two communication paths: an uplink from the diver to the tender
and a downlink from the tender to the diver. This allows voice communications to
go in both directions at the same time. An example of this type of communication
system is the telephone. Another example is called Round Robin communications.
Amron's Full Duplex (4-Wire) is not the same as Round Robin.
2820A & 2825A-UM
REV 8.0
35
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
7.2
WHAT IS FULL DUPLEX (4-WIRE)?
It is a 4-Wire dual communication path system that uses special audio amplifiers on the
microphone and earphone connection to eliminate the issues associated with Round Robin
systems. It allows everyone on the communicator to talk to each other just as if they were on
a telephone.
7.2.1
WHY ARE SPECIAL AMPLIFIERS NEEDED?
When developing a 4-Wire communication system, the biggest problem facing the
designer is oscillation caused by feedback. This can occur in two ways. The most
common is acoustic feedback, also called the Larsen effect, which occurs when the
microphone picks up the sound from the speaker and feeds it back into the
amplifier. This signal is amplified and sent out the speaker at a higher level. Given
the right conditions, this process repeats until the amplifier reaches maximum
signal level. The result is usually a high pitch, howling sound commonly heard in
public address systems when the volume is turned up too high.
The solution for acoustic feedback is to turn down the amplifier volume and to
isolate the speaker from the microphone. In a dive helmet, the diver's head makes
a good acoustic isolator. On the surface, a tender using a headset may get some
acoustic feedback via the PANEL SPEAKER. The solution is to put some distance
between the tender and the PANEL SPEAKER by using the Amron Model 2822-28
Walk-and-Talk Module accessory. Alternatively, the PANEL SPEAKER can be
turned off using the SPEAKER SWITCH located on the front panel.
There exists a second, more difficult to avoid feedback path that can also cause
oscillation. In 4-Wire mode, there are two sets of wire pairs. One pair carries the
signal from the diver microphone to the communicator microphone input. This is an
extremely low level signal, typically in the range of about 1mVRMS. The second
carries the output signal from the communicator power amplifier to the diver's
earphone. This signal can be as high as 4VRMS. The earphone signal is typically
about 1000 times greater than the microphone signal and can be as much as 4000
times greater. If the signal on the earphone wire pair were to couple to the
microphone wire pair, the result would be a feedback path that can lead to
oscillation. To prevent such coupling, the dive cables are constructed using two
individual twisted wire pairs and in high quality cables, such as Amron's CC1
communication cable, each pair can be shielded to provide additional protection.
Shielding does decrease the amount of coupling between the wire pairs but without
special amplifiers, the full capability of using twisted wire pairs is lost.
Amron Diver Communicators are designed with a special balanced circuit,
differential input and output amplifiers. In a balanced circuit, each wire in the
twisted pair carries an equal and opposite signal. Each wire generates an
electromagnetic field that is in opposition with the field of other wire. The net result
is that strength of the radiated electromagnetic field is significantly reduced if not
totally eliminated. In addition, any external fields, either from the other wire pair or
an external noise source, will be coupled to both wires equally creating a commonmode signal. The differential microphone amplifier in Amron Diver Communicators
cancels the common-mode signal while amplifying the signal from the microphone.
2820A & 2825A-UM
REV 8.0
36
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
Communicators without both differential input and output amplifiers cannot match
the performance of Amron Diving Communicators. This is an extreme simplification
of the common-mode coupling effect and common-mode signal rejection but shows
the power of Amron's Full Duplex (4-Wire) mode of operation.
7.2.2
ISN'T ROUND ROBIN THE SAME THING?
In Round Robin communication systems, each diver is connected using a 4-Wire
cable like the Amron Full Duplex (4-Wire) mode. This is where the similarities end.
In Round Robin systems all the microphones are connected together in parallel
and connected to the microphone input of the communicator. All the earphones are
also connected in parallel and connected to the earphone output of the
communicator. Each microphone is loaded by all the other microphones in the
system causing lower output. In a two diver setup where the diver microphones
have a typical impedance of 8 Ohms and the tender's microphone has an
impedance of 150 Ohm, the diver microphone output level will be reduced by about
50% while the tender's microphone is attenuated by out 95%. On the earphone
side, the diver earphones commonly have an impedance of 8 Ohms while the
typical tender earphone impedance is around 175 Ohms. These two factors
combine to create a serious volume imbalance which requires higher volume
settings resulting in more noise and less system stability.
7.3
WHY FULL DUPLEX (4-WIRE)?
Amron Diver Communicator uses an independent microphone amplifier for each diver circuit
as well as for the tender. This allows Amron Diver Communicators to use the power of
common-mode rejection to cancel any coupled noise for each microphone as well as
providing less loading of the microphone than in 2-Wire mode. In 2-Wire mode, the diver
microphone is wired in parallel with the diver earphones. Assuming that the impedance of the
microphone is the same as the earphones, the signal from the microphone is attenuated by
65%. By separating the microphone from the earphones, the output signal from the
microphone increases by 285%. With more signal, the volume level can be decreased
resulting in less noise and improved system stability for a significant improvement in overall
clarity.
7.4
HOW DO YOU USE FULL DUPLEX (4-WIRE)?
In order to use Amron's Full Duplex (4-Wire) mode, you need the following items:

An AMCOM series diver communicator

A good quality dive communication cable with four wires (two twisted wire pairs) like
Amron's CC1

A dive hat/helmet with connection for 4 wires such as a Marsh Marine connector
To connect the system together, refer to appropriate section of the operating manual for
AMCOM diver communicator. In general it involves three steps (using the Amron CC1 cable):
2820A & 2825A-UM
REV 8.0
37
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
1. Install male Marsh-Marine 4-pin connector in hat/helmet. Attach black and white
wires to binding post and both speakers. Attach red and green wires to leads from
microphone. It doesn’t matter which color goes to which lead. Use 8-32 x 1/4 SS
screw and nuts, cover each with tape or shrink tubing. You are now finished with the
diving hat/helmet.
2. Install 4-pin female Marsh-Marine connector on diver's end of communication cable.
Connect red and green wires to the light colored pair of communication cable wires;
black and white wires to black pair of communication-cable wires. You are now
finished with this step.
3. Install black dual banana plug to black pair of wires on tender end of diver
communication-cable and attach red dual banana plug to lighter color pair of wires. If
you don’t have red dual banana plugs, red tape will serve to identify that pair as the
microphone circuit. YOU ARE FINISHED!
To setup and check-out the communication link:
1. Attach hat/helmet to umbilical.
2. Attach communication cable to AMCOM diver communicator. Connect the red
banana plug to DIVER MICROPHONE (red) jack and the black banana plug to
DIVER EARPHONE (black) jack.
3. Set the volume controls to mid-range on the communicator. Turn on the
communicator. There may be some acoustic feedback, if that occurs then reduce the
volume until it feedback stops.
4. Don the hat/helmet and start talking. You should hear yourself in earphones. Adjust
the volume as necessary for clear communications.
To revert back to 2-Wire mode, simply remove black banana plug from DIVER EARPHONE
(black) jack and plug it on top of DIVER MICROPHONE (red) plug.
Things to keep in mind when using Amron's AMCOM diver communicators:
With the AMCOM diver communicators you can mix 2-Wire and Full Duplex (4-Wire) modes
of operation. For example, the diver can operate on Full Duplex (4-Wire) mode while the
tender operates in 2-Wire mode. The tender can use the panel speaker to listen to the diver
and talk to the diver by pressing the push-to-talk button and using the panel speaker as a
microphone.
When using AMCOM diver communicators with multiple diver capacity, each diver can be
wired in either 2-Wire or Full Duplex (4-Wire) mode. All divers do not have to operate in the
same mode.
The push-to-talk button overrides the diver conversation by forcing all divers into listen only
mode. This occurs whether the diver is wired in 2-Wire or Full Duplex (4-Wire) mode.
2820A & 2825A-UM
REV 8.0
38
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
8
DRAWINGS
The following drawings illustrate the electrical and mechanical details of the AMCOM II Diver
Communications. The corresponding parts lists for each drawing are detailed in the parts lists section,
or are included as part of the drawing.
2820A & 2825A-UM
REV 8.0
39
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
8.1
PARTS IDENTIFIER FRONT PANEL MODEL 2820A
2820A & 2825A-UM
REV 8.0
40
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
8.2
PARTS IDENTIFIER, FRONT PANEL MODEL 2825A
2820A & 2825A-UM
REV 8.0
41
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
8.3
PARTS IDENTIFIER, MODELS /24, /24/26DSP3 & /24/28A OPTION
2820A & 2825A-UM
REV 8.0
42
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
9
PARTS LISTS
The parts lists include both mechanical and electrical parts. The following information will be useful in
interpreting data which is not self-explanatory.
REVISIONS
The parts lists in this manual are for the current model of diver communicator as of the printing date.
To Order Replacement Parts Contact:
Amron international, Inc.
1380 Aspen Way, Vista, California, 92081 U.S.A.
Telephone: (760) 208-6500 Fax: (760) 599-3857
Email: sales@amronintl.com
Web: www.amronintl.com
When ordering replacement parts, you should give as much information as possible to enable us to
supply the correct part. This information should include the part number, description, reference
designator, value, radio model number, and serial number. Failure to provide sufficient information
may hinder our ability to fill your parts orders promptly and correctly.
2820A & 2825A-UM
REV 8.0
43
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
9.1
AMCOM II MODEL 2820A
REF
PART #
DESCRIPTION
N/S
2832-202-02
PC CARD ASSEMBLY AMCOM II STD
N/S
2820-301
AMCOM II CASE ASSEMBLY
N/S
2820A-400
FRONT PANEL ASSY WIRED
N/S
2820-500
CARD AND BATTERY BOX ASSY
N/S
2890-03
BATTERY 6V SPRING TERMINAL
23
8-32X3/4KTSB
SCREW KNURLED THUMB BRASS ¾
24
8FWF
WASHER FLAT FIBER NO 8
19
492
HANDLE ROUND 1.5X5.5X5/16
N/S
10LWSSS
WASHER SPLIT LOCK NO10 S/S
N/S
10-32X1/2SSPHP
SCREW 10-32X1/2IN SS PH PL
N/S
8-32X5/16SSPHP
SCREW 8-32 5/16IN SS PH PHILL
N/S
8ISW
WASHER NO 8 INTERNAL STAR S/S
N/S
8-32X1/4SSPHP
SCREW 8-32 1/4IN SS PH PHILL
N/S
2820-007
PANEL OPT. BLANK AMCOM II
21
6-32X3/8HSBHC
SCREW 6-32 X 3/8IN S/S
22
6NUTSSL
NUT LOCKING 6-32 S/S
N/S
39-01-2040
RECEPTACLE 4 PIN MINI-FIT
N/S
39-00-0039
TERMINAL FEMALE CRIMPMINI-FIT
N/S
1710-8-32A-24
ST/OFF 1/4IN 8-32 2.25IN ALUM
N/S
TAT-3/16
HEAT SHRINK TUBING 3/16IN BLACK
N/S
2820A-25A-UM
USER MANUAL FOR ALL 282XA
2820A & 2825A-UM
REV 8.0
44
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
9.2
AMCOM II MODEL 2820A/23
REF
PART #
DESCRIPTION
N/S
2832-202-02
PC CARD ASSEMBLY AMCOM II STD
N/S
2820-301
AMCOM II CASE ASSEMBLY
N/S
2820A-400
FRONT PANEL ASSY WIRED
N/S
2820-500
CARD AND BATTERY BOX ASSY
N/S
2890-04
BATTERY RECHARGE 6V GEL 5AMP
23
8-32X3/4KTSB
SCREW KNURLED THUMB BRASS 3/4
24
8FWF
WASHER FLAT FIBER NO 8
19
492
HANDLE ROUND 1.5X5.5X5/16
N/S
10LWSSS
WASHER SPLIT LOCK NO10 S/S
N/S
10-32X1/2SSPHP
SCREW 10-32X1/2IN SS PH PL
N/S
8-32X5/16SSPHP
SCREW 8-32 5/16IN SS PH PHILL
N/S
8ISW
WASHER NO 8 INTERNAL STAR S/S
N/S
8-32X1/4SSPHP
SCREW 8-32 1/4IN SS PH PHILL
N/S
2820-007
PANEL OPT. BLANK AMCOM II
21
6-32X3/8HSBHC
SCREW 6-32 X 3/8IN S/S
22
6NUTSSL
NUT LOCKING 6-32 S/S
N/S
39-01-2040
RECEPTACLE 4 PIN MINI-FIT
N/S
39-00-0039
TERMINAL FEMALE CRIMPMINI-FIT
N/S
2823-603
CHARGER ASSEMBLY EXTERNAL
N/S
1710-8-32A-24
ST/OFF 1/4IN 8-32 2.25IN ALUM
N/S
TAT-3/16
HEAT SHRINK TUBING 3/16IN BLACK
N/S
2820A-25A-UM
USER MANUAL FOR ALL 282XA
2820A & 2825A-UM
REV 8.0
45
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
9.3
AMCOM II MODEL 2820A/24
REF
PART #
DESCRIPTION
N/S
570-1008-23
PC CARD ASSEMBLY AMCOM II STD
N/S
2820-301
AMCOM II CASE ASSEMBLY
N/S
2820A-400
FRONT PANEL ASSY WIRED
N/S
2824-500B
BATTERY BOX-INTERNAL CHARGER
N/S
2890-05
BATTERY RECHARGE 12V GEL 7.2 AMP
23
8-32X3/4KTSB
SCREW KNURLED THUMB BRASS 3/4
24
8FWF
WASHER FLAT FIBER NO 8
19
492
HANDLE ROUND 1.5X5.5X5/16
N/S
10LWSSS
WASHER SPLIT LOCK NO10 S/S
N/S
10-32X1/2SSPHP
SCREW 10-32X1/2IN SS PH PL
N/S
3500
CABLE TIE NY 3/32IN X 3.5IN
N/S
8-32X3/8SSPHP
SCREW 8-32 3/8IN SS PH PHILL
N/S
8ISW
WASHER NO 8 INTERNAL STAR S/S
N/S
8-32X1/4SSPHP
SCREW 8-32 1/4IN SS PH PHILL
N/S
160-0320-07
RECEPTACLE 3 PIN HOUSING .156"
N/S
160-0105-02
CONTACT SOCKET CRIMP 18-22AWG
N/S
2-520194-2
SLIDE TERM(18/22).032 X .187
N/S
2824-007
OPTION PANEL 2824
20
P-2392
CORDAC EURO 3 COND (7421.072)
32
3207
GROMMET.114-.250 DIA. HOLE
29
LEDGREEN
LEDGREEN BRITE
16
LEDHOLDER-BLK.25
MOUNTING CLIP FOR 5MM LED
21
6-32X3/8HSBHC
SCREW 6-32 X 3/8IN S/S
22
N/S
6NUTSSL
4/18-22
NUT LOCKING 6-32 S/S
TERMINAL RING, NO 4 STUD/18GA
N/S
180-1011-01
CABLE ASSY AC POWER LED
N/S
180-1012-01
CABLE ASSY BATTERY POWER
N/S
TAT-1/8
HEAT SHRINK TUBING1/8INBLACK
N/S
GEE62F-C0
GROMMET EDGING BLACK
N/S
2820A-25A-UM
USER MANUAL FOR ALL 282XA
2820A & 2825A-UM
REV 8.0
46
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
9.4
AMCOM II MODEL 2825A
REF
PART #
DESCRIPTION
N/S
2832-202-01
PC CARD ASSEMBLY AMCOM II DELUXE
N/S
2820-301
AMCOM II CASE ASSEMBLY
N/S
2825A-400
FRONT PANEL ASSY WIRED
N/S
2820-500
CARD AND BATTERY BOX ASSY
N/S
2405-28
MICROPHONE PUSH TO TALK
N/S
2890-03
BATTERY 6V SPRING TERMINAL
23
8-32X3/4KTSB
SCREW KNURLED THUMB BRASS 3/4
24
8FWF
WASHER FLAT FIBER NO 8
19
492
HANDLE ROUND 1.5X5.5X5/16
N/S
10LWSSS
WASHER SPLIT LOCK NO10 S/S
N/S
10-32X1/2SSPHP
SCREW 10-32X1/2IN SS PH PL
N/S
8-32X5/16SSPHP
SCREW 8-32 5/16IN SS PH PHILL
N/S
8ISW
WASHER NO 8 INTERNAL STAR S/S
N/S
8-32X1/4SSPHP
SCREW 8-32 1/4IN SS PH PHILL
N/S
2820-007
PANEL OPT. BLANK AMCOM II
21
6-32X3/8HSBHC
SCREW 6-32 X 3/8IN S/S
22
6NUTSSL
NUT LOCKING 6-32 S/S
N/S
39-01-2040
RECEPTACLE 4 PIN MINI-FIT
N/S
39-00-0039
TERMINAL FEMALE CRIMP MINI-FIT
N/S
2823-603
CHARGER ASSEMBLY EXTERNAL
N/S
1710-8-32A-24
ST/OFF 1/4IN 8-32 2.25IN ALUM
N/S
TAT-3/16
HEAT SHRINK TUBING 3/16IN BLACK
N/S
2820A-25A-UM
USER MANUAL FOR ALL 282XA
2820A & 2825A-UM
REV 8.0
47
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
9.5
AMCOM II MODEL 2825A/23
REF
PART #
DESCRIPTION
N/S
2832-202-01
PC CARD ASSEMBLY AMCOM II DELUXE
N/S
2820-301
AMCOM II CASE ASSEMBLY
N/S
2825A-400
FRONT PANEL ASSY WIRED
N/S
2820-500
CARD AND BATTERY BOX ASSY
N/S
2405-28
MICROPHONE PUSH TO TALK
N/S
2890-04
BATTERY RECHARGE 6V GEL 5AMP
23
8-32X3/4KTSB
SCREW KNURLED THUMB BRASS 3/4
24
8FWF
WASHER FLAT FIBER NO 8
19
492
HANDLE ROUND 1.5X5.5X5/16
N/S
10LWSSS
WASHER SPLIT LOCK NO10 S/S
N/S
10-32X1/2SSPHP
SCREW 10-32X1/2IN SS PH PL
N/S
8-32X5/16SSPHP
SCREW 8-32 5/16IN SS PH PHILL
N/S
8ISW
WASHER NO 8 INTERNAL STAR S/S
N/S
8-32X1/4SSPHP
SCREW 8-32 1/4IN SS PH PHILL
N/S
2820-007
PANEL OPT. BLANK AMCOM II
21
6-32X3/8HSBHC
SCREW 6-32 X 3/8IN S/S
22
6NUTSSL
NUT LOCKING 6-32 S/S
N/S
39-01-2040
RECEPTACLE 4 PIN MINI-FIT
N/S
39-00-0039
TERMINAL FEMALE CRIMP MINI-FIT
N/S
2823-603
CHARGER ASSEMBLY EXTERNAL
N/S
1710-8-32A-24
ST/OFF 1/4IN 8-32 2.25IN ALUM
N/S
TAT-3/16
HEAT SHRINK TUBING 3/16IN BLACK
N/S
2820A-25A-UM
USER MANUAL FOR ALL 282XA
2820A & 2825A-UM
REV 8.0
48
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
9.6
AMCOM II MODEL 2825A/24
REF
PART #
DESCRIPTION
N/S
570-1008-20
PC CARD ASSEMBLY AMCOM II DELUXE
N/S
2820-301
AMCOM II CASE ASSEMBLY
N/S
2825A-400
FRONT PANEL ASSY WIRED
N/S
2824-500B
BATTERY BOX-INTERNAL CHARGER
N/S
2405-28
MICROPHONE PUSH TO TALK
N/S
2890-05
BATTERY RECHARGE 12V GEL 7.2A
23
8-32X3/4KTSB
SCREW KNURLED THUMB BRASS 3/4
24
8FWF
WASHER FLAT FIBER NO 8
19
492
HANDLE ROUND 1.5X5.5X5/16
N/S
10LWSSS
WASHER SPLIT LOCK NO10 S/S
N/S
10-32X1/2SSPHP
SCREW 10-32X1/2IN SS PH PL
N/S
3500
CABLE TIE NY 3/32IN X 3.5IN
N/S
8-32X3/8SSPHP
SCREW 8-32 3/8IN SS PH PHILL
N/S
8ISW
WASHER NO 8 INTERNAL STAR S/S
N/S
8-32X1/4SSPHP
SCREW 8-32 1/4IN SS PH PHILL
N/S
160-0320-07
RECEPTACLE 3 PIN HOUSING .156"
N/S
160-0105-02
CONTACT SOCKET CRIMP 18-22AWG
N/S
2-520194-2
SLIDE TERM(18/22).032 X .187
N/S
*NOT AVAILABLE FOR SALE
OPTION PANEL 2824
20
P-2392
CORDAC EURO 3 COND (7421.072)
32
3207
GROMMET.114-.250 DIA. HOLE
29
LEDGREEN
LEDGREEN BRITE
16
LEDHOLDER-BLK.25
MOUNTING CLIP FOR 5MM LED
21
22
6-32X3/8HSBHC
6NUTSSL
SCREW 6-32 X 3/8IN S/S
NUT LOCKING 6-32 S/S
N/S
4/18-22
TERMINAL RING, NO 4 STUD/18GA
N/S
180-1011-01
CABLE ASSY AC POWER LED
N/S
180-1012-01
CABLE ASSY BATTERY POWER
N/S
TAT-1/8
HEAT SHRINK TUBING1/8INBLACK
N/S
2820A-25A-UM
USER MANUAL FOR ALL 282XA
2820A & 2825A-UM
REV 8.0
49
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
9.7
AMCOM II MODEL 2825A/24/26DSP3
REF
PART #
DESCRIPTION
N/S
570-1008-20-HSU
PC CARD ASSEMBLY AMCOM II DELUXE
N/S
2820-301
AMCOM II CASE ASSEMBLY
N/S
2825A-400
FRONT PANEL ASSY WIRED
N/S
2824-500B
BATTERY BOX-INTERNAL CHARGER
N/S
2405-28
MICROPHONE PUSH TO TALK
N/S
2890-05
BATTERY RECHARGE 12V GEL 7.2A
23
8-32X3/4KTSB
SCREW KNURLED THUMB BRASS 3/4
24
8FWF
WASHER FLAT FIBER NO 8
19
492
HANDLE ROUND 1.5X5.5X5/16
N/S
10LWSSS
WASHER SPLIT LOCK NO10 S/S
N/S
10-32X1/2SSPHP
SCREW 10-32X1/2IN SS PH PL
N/S
3500
CABLE TIE NY 3/32IN X 3.5IN
N/S
8-32X3/8SSPHP
SCREW 8-32 3/8IN SS PH PHILL
N/S
8ISW
WASHER NO 8 INTERNAL STAR S/S
N/S
8-32X1/4SSPHP
SCREW 8-32 1/4IN SS PH PHILL
N/S
1-480698-0
CONNECTOR 2 CIRCUIT PLUG
N/S
350550-3
CONTACT SOCKET 20-14 AWG
N/S
2-520194-2
SLIDE TERM(18/22).032 X .187
N/S
*NOT AVAILABLE FOR SALE
PANEL OPTION HSU DSP3
20
P-2392
CORDAC EURO 3 COND (7421.072)
32
3207
GROMMET.114-.250 DIA. HOLE
29
LEDGREEN
LEDGREEN BRITE
16
LEDHOLDER-BLK.25
MOUNTING CLIP FOR 5MM LED
21
22
6-32X3/8HSBHC
6NUTSSL
SCREW 6-32 X 3/8IN S/S
NUT LOCKING 6-32 S/S
N/S
8NUTSSL
NUT LOCKING 8-32 S/S
N/S
8/18-22
TERMINAL RING, NO 8 STUD/18GA
N/S
43025-0800
RECEPTACLE 8PIN MICRO-FIT
N/S
43025-1800
RECEPTACLE 18PIN MICRO-FIT
N/S
2324-J2
J2 CABLE ASSY, RECHAREABLE
N/S
TAT-1/8
HEAT SHRINK TUBING1/8INBLACK
N/S
TAT-3/16
HEAT SHRINK TUBING 3/16INBLACK
N/S
39-01-2040
RECEPTACLE 4PIN MINI-FIT
N/S
43030-0007
CONTACT 3.0mm FEMALE SOCKET
N/S
39-00-0039
TERMINAL FEMALE CRIMPMINI-FIT
34
SW-201
SWITCH TOGGLE ON/OFF DPDT
37
SWB-0001
BOOT TOGGLE SOFT GRAY
4
P16NP-10K
POTENTIOMETER 10K OHM W/KNOB
2820A & 2825A-UM
REV 8.0
50
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
9.8
AMCOM II MODEL 2825A/24/26DSP3 (CONTINUED)
REF
PART #
DESCRIPTION
35
113-10K-05
POTENTIOMETER; 10K OHM +/-5%
36
190-0500-15
KNOB; TURN-COUNTING DIAL
N/S
8511-30-00
CLIPCORD WHITE STYLE C2A
N/S
570-1006-02
DSP3 HSU PROGRAMMED
N/S
2836
SHORTY BUSHING.750 HOLE
N/S
2820A-25A-UM
USER MANUAL FOR ALL 282XA
2820A & 2825A-UM
REV 8.0
51
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
9.9
AMCOM II MODEL 2825A/24/28A
REF
PART #
DESCRIPTION
N/S
570-1008-20
PC CARD ASSEMBLY AMCOM II DELUXE
N/S
2820-301
AMCOM II CASE ASSEMBLY
N/S
2825A-400
FRONT PANEL ASSY WIRED
N/S
2824-500B
BATTERY BOX-INTERNAL CHARGER
N/S
2405-28
MICROPHONE PUSH TO TALK
N/S
2890-05
BATTERY RECHARGE 12V GEL 7.2A
23
8-32X3/4KTSB
SCREW KNURLED THUMB BRASS 3/4
24
8FWF
WASHER FLAT FIBER NO 8
19
492
HANDLE ROUND 1.5X5.5X5/16
N/S
10LWSSS
WASHER SPLIT LOCK NO10 S/S
N/S
10-32X1/2SSPHP
SCREW 10-32X1/2IN SS PH PL
N/S
3500
CABLE TIE NY 3/32IN X 3.5IN
N/S
8-32X3/8SSPHP
SCREW 8-32 3/8IN SS PH PHILL
N/S
8ISW
WASHER NO 8 INTERNAL STAR S/S
N/S
8-32X1/4SSPHP
SCREW 8-32 1/4IN SS PH PHILL
N/S
160-0320-07
RECEPTACLE 3 PIN HOUSING .156"
N/S
160-0105-02
CONTACT SOCKET CRIMP 18-22AWG
N/S
2-520194-2
SLIDE TERM(18/22).032 X .187
N/S
4/18-22
TERMINAL RING, NO 4 STUD/18GA
N/S
*NOT AVAILABLE FOR SALE
OPTION PANEL AC WIRELESS
13
190-0000-01
ANTENNA 2.4GHZ
20
P-2392
CORDAC EURO 3 COND (7421.072)
N/S
180-1001-00
CABLE, RG315 SMA
32
3
3207
7580K6
GROMMET.114-.250 DIA. HOLE
SWITCH TOGGLE SPST
20
P-2392
CORD AC EURO 3 COND (7421.072)
29
LEDGREEN
LEDGREEN BRITE
16
LEDHOLDER-BLK.25
MOUNTING CLIP FOR 5MM LED
8
5168
SEAL HALF BOOT TOGGLE GREY
21
6-32X3/8HSBHC
SCREW 6-32 X 3/8IN S/S
22
6NUTSSL
NUT LOCKING 6-32 S/S
N/S
2829-11
REMOTE WIRELESS KIT W/CASE
N/S
570-1002-00
PC CARD ASSEMBLY WIRELESS
N/S
8-32X1SSPHP
SCREW 8-32 1IN SS PH PHILL
N/S
8-32X1/4SSPHP
SCREW 8-32 1/4IN SS PH PHILL
N/S
TAT-1/8
HEAT SHRINK TUBING 1/8IN BLACK
N/S
2820A-25A-UM
USER MANUAL FOR ALL 282XA
2820A & 2825A-UM
REV 8.0
52
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
9.10
2820-301 CASE ASSEMBLY – AMCOM II
REF
PART #
DESCRIPTION
1
2820-301
CASE ASSEMBLY
2
2820-3006
GASKET, LID TO CASE
3
2820-3031
GASKET, PANEL
9.11
2820A-400M FRONT PANEL ASSEMBLY
REF
PART #
DESCRIPTION
1
*NOT AVAILABLE FOR SALE
PANEL FRONT AMCOM II STD
2
PBSWITCH
SWITCH PUSH BUTTON SEALED N.O
3
7580K6
SWITCH TOGGLE SPST
33
757-3522
SWITCH TOGGLE DPST ON-ON
5
1498-102
JACK, BANANA RED
6
1498-103
JACK, BANANA BLACK
7
1498-107
JACK, BANANA YELLOW
8
5168
SEAL HALF BOOT TOGGLE GREY
9
105-0602-001
JACK, TIP RED
10
105-0603-001
JACK, TIP BLACK
11
ME161-2003
JACK, PHONO W/NYL WSHRS NKL/BLK
14
14002B
5-WAY BINDING POST (BLACK)
15
14002R
5-WAY BINDING POST (RED)
18
SA818
SPEAKER 8 OHM 15 WATT
4
P16NP-10K
POTENTIOMETER 10K OHM W/KNOB
12
1/4-20X1.25HSBHC
SCREW 1/4-20 X 1.25IN S/S
13
1/4-20NUTSSL
NUT NYLOK1/4-20
N/S
1/4FWSS
WASHER FLAT 1/4304 S/S
16
LEDHOLDER-BLK.25
MOUNTING CLIP FOR 5MM LED
17
LT2462-24-D51
LED, BI-COLOR RED/GREEN
25
24XX-MIC
MICROPHONE ASSY ELECTRET
2820A & 2825A-UM
REV 8.0
53
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
9.12
2825A-400M FRONT PANEL ASSEMBLY
REF
PART #
DESCRIPTION
1
*NOT AVAILABLE FOR SALE
PANEL FRONT AMCOM II DELUXE
2
PBSWITCH
SWITCH PUSH BUTTON SEALED N.O
3
7580K6
SWITCH TOGGLE SPST
33
757-3522
SWITCH TOGGLE DPST ON-ON
5
1498-102
JACK, BANANA RED
6
1498-103
JACK, BANANA BLACK
7
1498-107
JACK, BANANA YELLOW
8
5168
SEAL HALF BOOT TOGGLE GREY
9
105-0602-001
JACK, TIP RED
10
105-0603-001
JACK, TIP BLACK
11
ME161-2003
JACK, PHONO W/NYL WSHRS NKL/BLK
14
14002B
5-WAY BINDING POST (BLACK)
15
14002R
5-WAY BINDING POST (RED)
18
SA818
SPEAKER 8 OHM 15 WATT
4
P16NP-10K
POTENTIOMETER 10K OHM W/KNOB
12
1/4-20X1.25HSBHC
SCREW 1/4-20 X 1.25IN S/S
13
1/4-20NUTSSL
NUT NYLOK1/4-20
N/S
1/4FWSS
WASHER FLAT 1/4304 S/S
16
LEDHOLDER-BLK.25
MOUNTING CLIP FOR 5MM LED
17
LT2462-24-D51
LED, BI-COLOR RED/GREEN
25
24XX-MIC
MICROPHONE ASSY ELECTRET
2820A & 2825A-UM
REV 8.0
54
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
9.13
2824-500B BATTERY BOX INTERNAL CHARGER
REF
PART #
DESCRIPTION
N/S
*NOT AVAILABLE FOR SALE
BRACKETSUPPORT RAIL
N/S
*NOT AVAILABLE FOR SALE
CHASSIS UNIVERSAL CARD
N/S
190-0101-01
POWER SUPPLY PC CARD MODIFIED
N/S
GEE62F-C0
GROMMET EDGING BLACK
N/S
4NUTSSL
NUT LOCKING 4-40 S/S
N/S
8-32X1/4SSPHP
SCREW 8-32 1/4IN SS PH PHILL
N/S
8ISW
WASHER NO 8 INTERNAL STAR S/S
N/S
8-32X3/8SSPHP
SCREW 8-32 3/8IN SS PH PHILL
N/S
4-40X5/8HSBHC
SCREW 4-40 X 5/8” S/S
N/S
*NOT AVAILABLE FOR SALE
CHASSIS BATTERY BOX-UNIVERSAL
N/S
MFCCA-1/2
SPONGE ½ CC ADH BK
N/S
320-0091-01
STANDOFF 4-40 X1/4 FEM HEX
N/S
4ISW
WASSHER NO 4 INTERNAL STAR
N/S
180-1009-01
CABLE ASSY DC POWER
9.14
28XX-FS-01 FIELD SPARES KIT FOR 2820A, 2825A
REF
PART #
DESCRIPTION
QUAN
1
7580K6
SWITCH TOGGLE SPS
1
2
757-3522
SWITCH TOGGLE DPST ON-ON
1
3
PBSWITCH
SWITCH PUSH BUTTON SEALED N.O
2
4
8-32X3/4KTSB
SCREW KNURLED THUMB BRASS ¾
2
5
P16NP-10K
POTENTIOMETER 10K OHM W/KNOB
2
6
105-0602-001
JACK, TIP RED
1
7
105-0603-001
JACK, TIP BLACK
1
8
5168
SEAL HALF BOOT TOGGLE GREY
2
9
1498-102
JACK, BANANA RED
2
10
1498-107
JACK, BANANA YELLOW
2
11
1498-103
JACK, BANANA BLACK
2
12
14002B
5-WAY BINDING POST (BLACK)
2
13
14002R
5-WAY BINDING POST (RED)
2
14
0034.6019
FUSE 3.15A/250V MICRO QUICK
2
15
0034.6617
FUSE 1.6A/250V SLOW
2
16
LEDHOLDER-BLK.25
MOUNTING CLIP FOR 5MM LED
2
17
LT2462-24-D51
LED; BI-COLOR RED/GREEN
2
18
LEDGREEN
LED GREEN BRITE
2
2820A & 2825A-UM
REV 8.0
55
2820A AND 2825A TWO DIVER COMMUNICATOR USER MANUAL
9.15
OPTIONAL SPARES
REF
PART #
DESCRIPTION
QUAN
1
570-1008-20
AMPLIFIER CARD ASSEMBLY
1
2
570-1008-23
AMPLIFIER CARD ASSEMBLY
1
3
570-1008-20-HSU
AMPLIFIER CARD ASSEMBLY
1
4
190-0101-01
POWER SUPPLY PC CARD MODIFIED
1
5
2405-28
MICROPHONE PUSH TO TALK
1
6
2890-05
BATTERY 12VDC SLIDE TERM. GEL
1
2820A & 2825A-UM
REV 8.0
56
Download PDF
Similar pages