| T O P I C R E V I E W |
| DeivF |
Posted - 11/15/2025 : 15:32:34
I recently purchased a new GMC-600 Pro directly from GQ Electronics. I already have a GMC-600+ and a Black Cat Systems GM-45. Just as with both the GMC-600+ and GMC-600 Pro, the GM-45 also uses the LND7317 "pancake" detector.
Soon after acquiring the GMC-600 Pro, I noticed that it seemed to be reading anomalously low. Just to check, I logged all three detectors continuously for three days. I placed all three detectors side-by-side on a table with the LND7317 windows facing up and nothing (except the table) for several feet in any direction from the detectors. Over the three day period, the GMC-600+ recorded an average of 47.2 CPM, the RM-45 recorded an average of 48.2 CPM, while the GMC-600 Pro recorded and average of 34.0 CPM.
In other words, over the three-day period, the GMC-600+ and the RM-45 recorded averages within 2.3% of each other, while the new GMC-600 Pro recorded approximately 28% less (it recorded a three-day average that was only 72% of the other two detectors).
Soon after, I took the GMC-600+ and the GMC-600 Pro on a commercial aircraft flight from California to Chicago and back. I placed both detectors side-by-side in my nylon-sided carry-on bag which I placed in the overhead storage. Both units had the LND7317 windows facing up and had nothing except one thickness of nylon (the top of the bag) over them. The one-hour running average (OHRA) readings from the GMC-600 Pro, both on the ground and at altitude and on both flights, were consistently only 70% to 74% of the OHRA readings from the GMC-600+.
While I don't have any calibration sources, I assume that since the readings from both the GMC-600+ and the RM-45 have historically been similar (within a few percent of each other), the new GMC-600 Pro is giving anomalously low readings.
Can this be corrected? Or do I need to return the GMC-600 Pro to GQ Electronics?
|
|
|
