Geiger Tube Problem?

[bradford412]

Hello,

First of all, the kit is fantastic... awesome job designing it!

I seem to be having a problem with mine though. When I turn it on, I get the high-pitched whine I am supposed to hear, but no clicks or LED flashes. I have adjusted the variable resistor all the way in both directions, but still nothing. I do get an LED flash and a click when I short the two tube holders.

The problem may be in my soldering, but then why would it jump when I touch a wire to each of the ends? I hate to say this, but could the problem be with the tube?

[mightyohm]

Do you have the tube installed the right way? The positive end (marked +) should be connected to J1.

Also, do you have a radioactive source you can test with? Even if you don't, you should be getting beeps every 5-10 seconds.

[bradford412]

It looks as if the polarity of my tube was indeed wrong. I had the SBM-20 text closer to the positive connector, but upon turning it around to check I got beeps. There does appear to be a small arrow above the CMB-20 writing, which I guess may be pointing to the (real) positive end.

Sorry to end up with such an easy question... thanks for all the help though!

[mightyohm]

No problem, enjoy your kit!