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R_A_Ghosh.
R_A_GhoshHi all,
I am using an LND712 with an 8.5 meters long RG6 coaxial cable. The anode resistor is exact near to GM tube at the other end of cable. I have used compensation capacitor as well.
The system works and gives no issues but as soon as I touch the cable with my hands, spurious counts appear. Why such noise gets introduced just by touching. Using a long cable has been a problem with my project. Any ideas in why the problem on how to solve it ??? Is it due to cable capacitance ? Or any other reasons ?
edodd55The standard answer is to put some ferrite chokes on the cable.
These things just snap around the cable
See https://www.ebay.com/b/Ferrite-Choke/7288/bn_7023291411 if you are unsure of the nature of this part.
R_A_GhoshHow many for 8.5 meters cable ?
uRADMonitorAre you installing it in a shelter? Hope you’ll never need it but we live troubled times.
You’ll need to increase your compensation capacitor. Calculate your cable’s capacitance then add that in the equation posted on the blog. Let me know if you need help.
edodd55I’d put one on each end. You want to suppress the errant signal and stop it entering the device(s). In theory one at the receiver would work.
R_A_GhoshRG6F capacitance is 53pF/meter so for 8.5 meters it is approx 450pF.
Find attached circuit. Please guide how to make improvements.
R anode is exact near GM tube as recommended.
R_A_GhoshR_A_GhoshI have also done the same, but no improvement. Core has cathode, braid has the 500V DC.