GQ Electronics Technical Support Forum Active Users: / Visits Today:
Highest Active Users:
GQ Electronics Technical Support Forum
Home | Profile | Register | Active Topics | Members | Search | FAQ
Username:
 Password:
Save Password
Forgot your Password?

 All Forums
 GQ Electronics Forums
 2.GQ Geiger Muller Counter
 Will GMC080 work with 900v tubes?		  New Topic  Reply to Topic
 Printer Friendly
Author Previous Topic Topic Next Topic  

Radman96

USA
4 Posts
Posted - 05/13/2012 :  17:38:35  Show Profile  Reply with Quote
I'm anxiously awaiting the arrival of a GMC080 kit. I'm wondering if it will work with a 900v tube like the 6993 from the old civil defense geiger counters. I read somewhere that newer models had a mod for higher voltage output. Or, if not, would a simple voltage doubler work?

Thanks,
-Alex
Reply #1

ZLM

1261 Posts
Posted - 05/15/2012 :  13:32:20  Show Profile  Reply with Quote
The GMC-080 has a adjustable high voltage circuit. It can trigger the 900V tube I believe.
Go to Top of Page
Reply #2

Radman96

USA
4 Posts
Posted - 05/16/2012 :  18:45:09  Show Profile  Reply with Quote
So far I've unfortunately had none such luck. The max voltage my DMM reads is about 400 vdc on the pcb clips. Bypassing the second anode resistor gives about a 450v reading. Bypassing both resistors gives a reading of about 550v.

After messing around with lots of ideas for homemade tubes, I've still got nothing. Might just have to scrape together some money and buy a m40ll or SBM-20.
Go to Top of Page
Reply #3

ZLM

1261 Posts
Posted - 05/19/2012 :  18:05:47  Show Profile  Reply with Quote
You DMM reading is not a actual voltage value.

When measuring High Voltage from tube clips, the reading is depending on your DMM internal resistance.

So, the voltage reading is much lower than actual voltage.

If your DMM 1000V internal resistance is 11M ohms, then the 200V reading is about 380V~400V actual voltage.

Normally the high voltage is calculated based on the DMM reading. And there is a 1G ohms resistor used in serial with DMM.
Go to Top of Page
  Previous Topic Topic Next Topic  
 New Topic  Reply to Topic
 Printer Friendly
Jump To:
GQ Electronics Technical Support Forum © Copyright since 2011 Go To Top Of Page
Generated in 0.06 sec. Snitz's Forums 2000