[Milsurplus] Clear protective spray on panels?

[WA5CAB at cs.com]

Well, back when I was doing our meter calibration, I'm pretty sure I wasn't 
getting quite that much per meter.  :-)  In fact (this was a little more 
than a few days ago), I think I was making $750/month.  

Not only do you need a fairly large source (one of ours was about 1/2 Ci of 
Cs-237) but it needs to be tightly collimated or you'll be in the beam 
while you're checking and adjusting.

In a message dated 7/3/2009 5:23:23 PM Central Daylight Time, 
nerd at verizon.net writes: 
> You are very correct about readings when very close, I have seen this.  
> The trouble is, for calibration, finding a strong enough source to have 
> an even field strength at a reasonable distance.  Getting the unit 
> calibrated is extremely expensive, last I checked, about $350.
> 
> 
> 
> WA5CAB at cs.com wrote:
> >FWIW, 2 mR/hr is the boundary level at which placards had to be placed 
> when 
> >doing industrial radiography, and for instrument calibration benches (or 
> >used to be - I haven't kept up with the regs since I stopped having to 
> worry 
> >about Cesium, Irridium or Cobalt sources).  Also, when measuring surface 
> >conditions, as on a meter glass, it's important to know where in the 
> instrument 
> >the detector actually is.  Because the dose rate varies by the inverse 
> >square law, at distances under a few inches you can get significantly 
> different 
> >readings with different model instruments.
> >
> >In a message dated 7/3/2009 11:58:14 AM Central Daylight Time, 
> >nerd at verizon.net writes: 
> >   
> >>I have an old altimeter which is pretty "hot" from the radium on the 
> >>dial, it gets about 2 mR through the glass.  The thorium mantles for 
> >>Coleman stoves will do about 0.5 mR.  Other than that I can measure a 
> >>little higher than normal activity from the granite countertops in the 
> >>condo I'm renting and that's all I have ever found.  I'm always looking 
> >>for examples of radioactivity but not too much around!  (I obviously 
> >>don't keep the altimeter close to me!)
> >>
> >>Btw, I have one of those PDR-27 counters, a later model which is all 
> >>solid state.  It hasn't been calibrated but agrees pretty well with one 
> >>that was current so it is probably in the ballpark.

Robert & Susan Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480