Rajko M83 MCCR


Arak M83 conversion to MCCR

Rajko from Serbia sent me interesting information about the conversion of his Arak M83 ‘Drina’. He converted this former yugoslavian-origin oxygen rebreather into a manually operated closed circuit rebreather. Read below the steps he took to arrive at this fine unit! Rajko thank you very much for your contribution! I would like to invite all divers in Serbia to send more information of diving systems being used!

Rajko MCCR Serbia 006

In order to explain my modifications of the ARAK M-83 rebreather, I made a drawing (modification of original M-83 schematics), some photos and an explanation of how the modifications work.

First, my modification has 2 versions, first with two O2 sensors and second with three O2 sensors.

The first version uses a Revo Dream with its HUD connected with two O2 sensors and a Shearwater Petrel Standalone. This version uses original M83 (ĐĐ made) oxygen first stage. The second version uses three O2 sensors, a Petrel EXT and a Apeks DS4 oxygen clean first stage.

Drina mCCR schematics:

Rajko MCCR Serbia 001
Rajko MCCR

First, I had to make service opening in the counterlung in order to install the sensor correct and also fitted the other connections. I did this by installing a watertight zipper.

Rajko MCCR Serbia 002
Counterlung with watertight zipper in CL.

Now, through service opening I was able to install the p=port (Draeger) for the sensors holder (TecMe) in order to fit the PSR-11-39-TME oxygen sensors. I also fitted the inlet (ĐĐ) for the Manual Addition Valve (MAV) for the diluent. The MAV was self-made and I added an OPV (Froschmann). I also made a automatic/manual addition valve but I don’t use it often.

Rajko MCCR Serbia 003
Counterlung with P-port and selfmade connections for the diluent addition

The complete set for upgrading ARAK M-83 to Drina mCCR with 2 sensors looks like this:

Rajko MCCR Serbia 004
All ports on the CL

At the end, I modified housing in order to mount it on the harness:

Rajko MCCR Serbia 005

Complete Drina mCCR set, aside of modified counterlungs, it consist of a diluent tank (any kind that can be attached to the back of the harness), BO and BCD. When applicable, the Diluent tank can also be used as a bailout. Since the rebreather is chest mounted, the Atlantis combat swimmer vest can be used as BCD. The Corrugated hoses are also new, manufactured in France by group of Oxygers users.

Rajko MCCR Serbia 006
Rajko MCCR Serbia 007

Rajko, thank you very much for contributing to my website!


Therebreathersite was founded by Jan Willem Bech in 1999. After a diving career of many years, he decided to start technical diving in 1999. He immediately noticed that at that time there was almost no website that contained the history of closed breathing systems. The start for the website led to a huge collection that offered about 1,300 pages of information until 2019. In 2019, a fresh start was made with the website now freely available online for everyone. Therebreathersite is a source of information for divers, researchers, technicians and students. I hope you enjoy browsing the content!

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