Vintage Oremaster Scintillation Geiger Counter Diagnosis Attempt

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14 thoughts on “Vintage Oremaster Scintillation Geiger Counter Diagnosis Attempt

  1. Photo multipliers are extremely sensitive , a gen3 nvd tube might only be
    40k-60k X light gain.
    You can tell if the crystal is still good if it is clear, if it is dark and
    discolored its bad.
    They will only light up enough to see it with the naked eye with a xray
    source, and even with this it is much lower light output than a xray
    intensifying screen.

  2. I looked up the data for the 931A photomultiplier used in the 1077 and it’s
    response dies around 670nm. Infrared starts at about 700nm so I think the
    B&K just can’t “see” the remote controls output. 

  3. I think you confused IR and UV around, remotes use IR, not UV. (that looked
    like a DirectTV remote, which if I recall can also do RF, but that doesn’t
    matter here) As for the 60hz strobing LED picking up on that odd test rig
    (interesting, I don’t think I caught what that was, and have no idea what
    that would even be for)… I suspect that the photomultiplier tube is
    either A) overwhelmed by the light, or the LED bulb is causing
    interference. – I don’t recall if you mentioned if the scintillation
    detector was working before you started taking it apart or not. As for the
    crystal, I do recall someone doing a video on them, (here is one of them: a
    close look INTO a scintillation crystal (radiation detector) / sodium
    iodide + thallium / NaI(Tl)). Also while looking I found a really good
    video comparing scintillators and Geiger counters (Geiger Counter vs.
    Scintillator )

  4. Hello, Well i should say ive watched all your vids. Just never said so
    until now. But i do want to say, i was at my local supermarket a week or so
    back and picked up out of the box some Tangelos, or Mandarins, one of the
    2, i like them, easy to peal and nice taste, I looked again and it said
    product of japan. First thought Fukushima. Next thought Tepco lies. LOL i
    put them straight back and thought what a shame. I would never now want
    anything from Japan. Nice old Geiger counter you have, fix it so i can loan
    it aye, The supermarket trolleys are big enough to handle your old school
    counter 🙂
    Ps like ya underground vids the most

  5. I, for one, am glad that Shango has decided to repair his safety equipment.
    Once he has it operational, hopefully he’ll be able to adjust and calibrate
    it to manufacturer’s specifications and use it as a safety monitor when
    repairing/restoring vintage tube-chassis color television sets. When
    working on these sets, one never knows how much X-radiation one is being
    exposed to. It would be interesting to see it in action at the beach in
    monitoring radioactive water currents/plutonium particles from Fukushima.

    Folks might already know this, but that bit of radioactive material under
    the tape on the side of the housing of the scintillation counter is there
    so one can test to see if it’s working; just hold the probe up to it.
    Growing up during the Cold War, these things were pretty commonplace back

  6. Hi Shango, I enjoy your site. When those crystals get yellow they are no
    good. The yellowing is caused the the oxidation of the Na. Once you have a
    scintillator tube open you have to let it sit for 8 hours or so until all
    of the photons escape or else the detector will show a high background.
    Those radiation levels I saw the guy in CA reading were really very small,
    it takes 3300cpm to equal 1mR in many GM tubes.

  7. Was the PMT getting any high voltage from the oremaster? Unplug the PMT and
    check between pins 12 and 7 for about 1kv. You’ll need a very very high
    impedance meter since the current is so small. The CRT hv meter should
    work. Once you have high voltage, throw the bad crystal away and get one of
    the plastic crystals on ebay. The plastic ones don’t absorb water and go

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