Ocean Reef M100 Portable Surface Transceiver Unit 33165 029058

Mfg Part #: 33165
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  • Portable surface to divers communication system
  • Allows surface personnel to talk with divers in the water or visa versa
  • Wireless communication through a 30 foot transducer cable
  • Operates on one channel
  • Uses a 9V battery giving up to 9 hours of operation (not included, see below to order)
  • Unit turns on when headphone/microphone is plugged in
  • Small enough to be worn on the operators belt  
  • Transeiver Unit
  • Headphone/ microphone
  • Transducer cable 30 foot

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Questions and Answers for Ocean Reef M100 Portable Surface Transceiver Unit:

  • Mark:

    Is this unit compatible with the Ocean Reef GSM Dual Channel Communication Unit Dual Channel

    Darrick  (Certified Scuba Instructor at Scuba.com):

    Hello Mark, yes you can use this with the GSM unit.

  • igor:

    Hi, why do you need Wireless communication through a 30 foot transducer cable if is wireless? would you need to put the cable in the water to be able to speak to the divers?

    Bob  (Certified Scuba Instructor at Scuba.com):

    Wireless in terms for scuba communication means you are not hard wired directly to the diver at all times. The cable with the transducer stops, but the diver can keep on diving beyond the limiting length of the transducer, wirelessly.

  • Ryan:

    Hi, I am interested in using this system but I am completely new to it. If I bought this unit and a Neptune mask, what else do I need to complete what I need? Thank you

    Bob  (Certified Scuba Instructor at Scuba.com):

    The mask would need a com system as well.

  • Barry:

    Do you offer noise-cancelling headphones with this unit? If not, could it be retrofited with different headphones?

    Bob  (Certified Scuba Instructor at Scuba.com):

    Ocean Reef does not list any of their headphones as noise cancelling. So long as the headphone connections/jack are the same alternate headphones could be used.

  • Donald:

    Hi, Is this compatible with an older U.S. Divers Buddy Phone MK2. Thanks, Don.

    Darrick  (Certified Scuba Instructor at Scuba.com):

    Hello Donald, you would need to contact the manufacture directly to see if your older system will with with this unit. You can contact the manufacture at 800.922.1764.

M100 G-DIVERS transceiver portable surface unit

1. Technical characteristics

Main parts of the unit are:

Battery housing: inside the battery housing there is a label with the serial
number and the polarity to insert the battery. Battery should be a 9volt
alkaline one, rechargeable batteries will last shorter. The autonomy with
the alkaline battery (receiving mode) is around 30 hours with 30 minutes of
low battery alarm (one “beep” every 30 seconds)starting when voltage
goes below 6.8volt.

Antenna: It consist of a 10 meter cable directly connected to the main
unit, at the bottom end there is the ceramic antenna, made to transmit
and receive ultrasound to a frequency of 32.768 kHz.
PTT button: it is a magnetic one, positioned right below the headset
connector on the main unit

Headset and microphone assembly with adjustable volume.
Metal clip to attach the unit to the belt of the operator.

8 Pin plug to connect the headset with microphone.G.divers Communications unit manual rel.1.3 September 2010 17

2. Attaching the surface unit to the belt
The M100 G.divers is designed to comfortable and easy to use. The main unit can be
clipped to a belt or jacket, giving the operator an increased range of motion from other
surface units.

3. Checking before use
Once the battery has been installed and you have checked that the cap and cover have
been closed properly, insert the headset with microphone in the plug on the main unit,
the M100 G.divers will turn on automatically. You will hear a “beep” indicating

Run a finger along the black cylinder at the bottom side of the antenna. You will hear a
“zzzzzz” type sound coming from the speaker.
Try to bring the antenna transducer near the antenna on a M101A G.divers unit, or the
antenna on a GSM G-Divers unit (about 5 cm / 2 inches). You should also be able to hear
the communication when the unit is not immersed in water.
If you hear a repeated “beep” (about every 30 seconds) this means that the battery is
running low. Change it.

4. Basic Instructions for communicate with divers underwater

The following is the recommended operating procedure:
Ensure the battery is properly installed with the correct polarity.
Close the battery compartment. You can use some grease to make this
operation easier.
Attach the main unit to a secure place on your person such as a belt.
Lower the transducer into the water. If you are on a boat, lower the
transducer until it clears the hull. Under non circumstances should the
transducer lie on the sea floor, this will reduce the signal strength and
Connect the headset to the main unit, the unit turns on automatically upon
The unit is now in the receiving mode. To send a message push and hold
the PTT button located on the main unit. After a short “beep” you may
begin speaking. When you release the button, the unit will return to
receive mode.
To improve the communication quality set the antenna the near as possible
to diver’s depth.
It is important that the transducer does not lay on the bottom
When speaking to divers, keep in mind that they have a lot of things going
on while underwater. It is better to have divers attention before starting
the communication.
Talk slowly and clearly
Do not make long sentences.
A good exercise is to make them repeat what they understood.

Do not get the headset wet
Do not put the unit underwater, it will not function as an underwater unit
Do not attempt to keep the PTT button permanently depressed! You will not be
able to receive messages from the divers and you may damage the unit.


1. OCEAN REEF communication units are guaranteed to be free of material or
manufacturing defects for a period of 24 months from the time the unit is
purchased. For the duration of the guarantee, the Company’s responsibility is
limited to replacement of any parts that are defective in our opinion, and that
have not been used incorrectly or handled negligently. The unit must be returned
to the outlet from which it was bought, along with the warranty card. The cost of
transport is to be prepaid by the customer.
2. Even during the guarantee period, this guarantee shall not be valid where:
o Damage was caused by incorrect handling or carelessness.
o Damage was caused by the unit falling after it was purchased.
o Damage caused by fire, earthquake, floods, lightning, or other natural
disasters, pollution or electrical charges.
o The warranty card is not produced.
o Our name, the date of purchase, and the seller’s name do not appear on
the warranty card.

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