Čajavec DR-M3 former Yugoslavia

[pg103]

Hello,

this is the former yugoslavian army DR-M3 geiger counter.
This device is produced in Bosnia .
It is a clone to Czechoslovak variant IT-65.

I bought several years ago in Serbia.

DR-M3 with bag:

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DR-M3 without bag:

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Analog instrument Display:

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The Tube is a Alpha sensity "Philips 18504" Tube, works with 500V:

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Inside of DR-M3.
You can see a ION chamber for High Roentgen under the potentiometers.
Here in my device is not working the ION chamber!

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I tested with a AM241 pill from a smoke detector.
The DR-M3 instrument read 100 mr/h !! is 1mSv/h.
This doing without cap of the tube.

Device has a poor sensitivity.
But if you have the cap removed completely, they have a significantly higher sensitivity for Alpha and Beta!

Here you can watch my Video the test with AM241 pill:

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The Philips tube from this device tested with Theremino System, my Video:
Reads over 117 000 cpm. ( 1 mSv/h ) I dont know the conversion factor is 100 % correct.

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Thanks!

[eliocor]

interesting... the meter has logarithmic (non linear) scale.
And LOTS of trimpots: it should be a nightmare to calibrate it!!!

[Emiliano]

Thanks for the explanation.
I have to find one for the Geiger Counter Museum..

[Francesco]

Thanks for the photos and info.
Yes, interesting... the scale is similar to the DP-5V another interesting instrument.

[Studio 1]

Hello, but the probe has provided this tool is equal to that of Graetz X50 .... or am I wrong ...?

[pg103]

hello,
thanks for reply.
I think this military counters is on the beauty's old school analog meter i have ever seen.

It is from old stocks and was never used.
Unfortunately, the ion chamber is not working.
Audio did not work, then have exchanged a capacitor and is working again