717 Radiation Detector

[AlphaTea]

I have to admit, I'm a flaming dumbass because I have no idea what any of the above means.

"Pardon me stewardess, I speak Nerd" (second time I wrote that, Im gonna have to change my sig line...)
If you want a cheap radiation detector for your preps, these are adequate without breaking the bank. You just need to understand the limitations of the detector(s).

BTW, I dont know about the 'flaming' part, but you are not a 'dumbass'. After all you did get this site rolling.
This is why I am here. We can each offer up our areas of expertise to fill in somebody elses blanks. I watch more than I post and I for one have gotten a lot from you folks than you will ever know. I will try to jump in whenever I see something I know about.

[AlphaTea]

Ditto what AlphaTea said. I checked this last night against my buddy's troxler case which has a TI of 0.3. The lower end of the scale (0.01X) is way out of whack, at higher scales (1X and 10X) it was OK, but just. BTW I was checking the Cesium source. The lower end of the scale is problematical. As has been pointed out above this is not a super fine instrument. KI4U will calibrate for $92, which is more than I have in the instrument, so I will probably do that. But I still don't expect good results on the lower end. The CDV 717 was designed primarily for surveys on the high end after a nuclear event. That being said, this will be used to get an initial reading which I can then plug into TOM's spreadsheet to calculate decay rates and when it will be safe to go out.
Or, I'll get blown up in the event and you guys can divvy up my remaining preps.
ETA: This is for gamma radiation.

I was having a little trouble deciphering what you actually did here.
When you are calibrating, or checking the calibration, you cant just put the instrument in a radiation field and check all the ranges with just one doserate. Each range has its own cal pot. To get a source with enough activity to check the high scale, you would need a source that emmited 2-2.5R/hr @ ~20 inches from the source. You aint gonna find that.
That high of a doserate will have to be in a well type calibrator or a box calibrator (like a safe).
Most of the range type calibrators I have used usually had a max (usable) doserate of about 200mR/hr. You could then use a DR(r)^2 calculation to get the lower doserates.
My advice?
Pony up the bucks and have KI4U do it for you.
If anybody is interested I can show you how to make your own check source for the lower range to at least check the operability of your meter.

[The Stig]

After all you did get this site rolling.

Actually RedJohn gets the credit for that but thank you for the kind words.

[Grumpy Old Man]

I was having a little trouble deciphering what you actually did here.
When you are calibrating, or checking the calibration, you cant just put the instrument in a radiation field and check all the ranges with just one doserate. Each range has its own cal pot. To get a source with enough activity to check the high scale, you would need a source that emmited 2-2.5R/hr @ ~20 inches from the source. You aint gonna find that.
That high of a doserate will have to be in a well type calibrator or a box calibrator (like a safe).
Most of the range type calibrators I have used usually had a max (usable) doserate of about 200mR/hr. You could then use a DR(r)^2 calculation to get the lower doserates.
My advice?
Pony up the bucks and have KI4U do it for you.
If anybody is interested I can show you how to make your own check source for the lower range to at least check the operability of your meter.

What I was doing was using the cesium source in the backscatter position just to see if the instrument was functioning. It wasn't meant to try and calibrate, just to see how it was working. That source isn't very strong but it can give a good idea of what needs to be done. That was where the detachable feature was useful. And yeah $92 is cheap at KI4U. It beats $150+ for my nukalert (which also has a battery shelf life).

[LUNCHBOX]

I'm with Stig on this, I heard gamma and thought of the Hulk. It must be late. Really though, you guys sound like your on your game. I hope we don't need any of those cause I'm hit if we did.

[AlphaTea]

What I was doing was using the cesium source in the backscatter position just to see if the instrument was functioning. It wasn't meant to try and calibrate, just to see how it was working. That source isn't very strong but it can give a good idea of what needs to be done. That was where the detachable feature was useful. And yeah $92 is cheap at KI4U. It beats $150+ for my nukalert (which also has a battery shelf life).

Cool. as long as you understand you are doing a response check, not in any way should this be used to adjust the meter. Any adjustments should be done in a controlled environment where the field strength, backscatter and geometry effects have been accounted for.
I have a couple of those Nukalerts. Matter of fact I have one of the prototypes. Accuracy on them is actually pretty decent across the range once they settle in.
Wifey used to keep one in her purse but she stopped because the chirping was driving her nuts. Seems they dont like quick temperature changes and during the winter her in NY her purse could change temps quickly. Getting it cold makes it think there is a radiation field nearby.
Anyway NukAlert.com has a battery/calibration deal where you get a new case (they get scratched up after a while), battery and desiccant change and a new calibration for $35.
Mine are better than 10 years old and still chirp. I occasionally check them at work

[Grumpy Old Man]

A response check is what I thought I was describing. I have nothing here to calibrate with-no sources, so that is out of the question. As I said previously, I'll spend the $92 at KI4U for calibration.

On a separate note, KI4U is now marketing a dosimeter sticker that is relatively inexpensive. I may pick up some of them as well. The dealer out here is Cal-Quake Inland Empire. The are about $5 each so that is a pretty cheap way to get a dosimeter. They do have a minimum order of 5, so that could easily cover a typical small family today.

[bacpacker]

Alpha, Do you all use a pulser for a part of your calibrations? We use A Ludlum Model 500, for a lot of our cal's at work. for the linearity portions of the cal's.
Did you and grumpy get your nukalerts at KI4U? I've thought about gettin a couple for me and the wife.

[Twitchy]

RedJohn should consider becoming a distributor of KI4U... Money to be made!

[AlphaTea]

Alpha, Do you all use a pulser for a part of your calibrations? We use A Ludlum Model 500, for a lot of our cal's at work. for the linearity portions of the cal's.
Did you and grumpy get your nukalerts at KI4U? I've thought about gettin a couple for me and the wife.

I moved out of the Calibration Lab a few years ago, but if I remember correctly it was a Ludlum model 500A Pulser. We would use it for most any GM or BF3 type detector and some PM detectors for ranges we could not get to with a source. Of course this would not work on an Ion chamber as those are just glorified ampmeters.
When I worked in the Cal Lab, we bought a few of the NukAlerts from KI4U to evaluate for our emergency response teams. While they are pretty neat and the price is not too high, they did not have the precision we were looking for. Our management decided to spend more for something with a lot more features. Since the NukAlerts were "orphan" instruments that we were not going to use, they were up for grabs. I got three and gave one away.