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 2.GQ Geiger Muller Counter
 remote GM tube connected with coax
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10 Posts

Posted - 05/01/2016 :  22:17:35  Show Profile  Reply with Quote
I'm interested in connecting my tube(s) remotely from the GMC-300e+ hardware. I'm considering using coax, possibly with a BNC connection.

My first question about this is regarding the coax. I understand the coax will introduce changes to the circuit operation, especially if it is long. What changes would need to be made to the GMC to account for the addition of coax between the hardware and the GM tube?

I was considering hard wiring coax instead of using a connector (BNC), but I was considering using RG-6 because I can get long lengths for free. this is a 75ohm coax instead of 50ohm. would that cause any other issues for this purpose?

Also, I think the 300E+ circuit counts pulses from the ( - ) connection of the tube? If that is true, it seems better to run negative ( - ) on the center conductor of the coax to shield the signal. is that correct?

Reply #1


192 Posts

Posted - 05/03/2016 :  11:34:51  Show Profile  Reply with Quote
I suppose you need to pump up the jam voltage considering the resistance of the cable.
Read the "how to measure voltage" thread and measure at the end of the cable.

GMC-300E+ V4.20 with sbt-11a alpha tube

My statements are "stuff-a-hobbyist-says" and not in any way professional.

Edited by - Distelzombie on 05/03/2016 11:36:07
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