| Reply #2
madmikeg
USA
5 Posts |
 Posted - 11/01/2014 : 07:00:20
|
Hi,
Just to add another data point, I tried a little experiment with my GMC320+ today, placing it very close to a radioactive source (lantern mantels in a plastic bag) and took some measurements for several minutes with the unit running on battery, connected to computer USB port, charger included with the unit, and a charger from an old smart phone (Palm Pre).
On battery power only: approx 440CPM
USB power from computer: approx 500CPM
Palm Pre charger: approx 500CPM
The charger included with the GMC 320+: approx 3700CPM
During all measurements I was careful not to move either the unit or the source sitting under it, it could have moved slightly during some of the measurements, but I have never been able to measure anything close to 3700CPM with this source no matter what I did with it on the battery power. The other odd thing about this is the sound of the clicking never changes regardless of the power supply, so I'm guessing only the part of the meter that actually records the counts in memory is being affected, presumably by electrical interference from the power supply in the included charger, although the seemingly 10% increase in counts on both the Palm Pre charger and computer USB power might indicate something else is affecting the counter as well, maybe slightly higher supply voltage, I don't know, more testing under better controlled conditions may be need for that bit.
Current background at the testing location is 14-18CPM (on battery power) connecting any of the power supplies does not seem to affect background readings at all.
Hope this helps, I don't mind shooting a little video to demonstrate if that will help debug the issue.
the included power supply I received is is branded as:
"Designed by WHP in California"
Model No. A1265
I'm not sure I'll use this charger anymore after doing some Google searches on it. |
 |
|
Charging Vs on Batter
