Gamma Spectrometry Forum

Hello! I'm a recent graduate in geology with a previous degree in chemistry. I've been interested in radioactive minerals and radiation detection for a while now, but my interest has really ramped up in the last couple of years. I have an Exploranium GR-130 that has served as my workhorse for geologic field studies, but I am interested in continuing to learn more about gamma spectrometry and wish to start building my own probes to use with a GS-USB-PRO that I will get around Christmas.

With my background in geology, I'm quite interested in detecting and characterizing the natural radionuclides, mainly for mineral exploration purposes. However, I also have an interest in atomic history. I'm a few hours drive from the Georgia Nuclear Aircraft Laboratory where the US tested some largely unshielded reactors designed for aircraft back in the late 50s and 60s. Supposedly some of the soil out there has been activated and nuclides such as Eu-152 can still be detected today. I'm planning a trip out there soon to see if my Exploranium spectrometer can find any.

My brother, an electrical/computer engineer, is also interested in radiation detection and has been collecting vintage detectors. Most of the old detectors we have are Geiger counters, but we have a few early scintillators. Of note are the Precision Radiation Instruments Royal Scintillator and Deluxe Scintillator. These instruments were some of the top of the line ones of their day, pricing in at a hefty $2000 and $500 in 1954 dollars, respectively. I hope to restore the Royal Scintillator at some point soon. It will need a new crystal, battery holders, and possibly some new passive components. Because it uses tube electronics, the battery requirements are intensive. It calls for 13 D cells, 5 67.5 V cells, and two 22.5 V cells.

Looking forward to learning more about probe design and making use of some of the equipment I have laying around!

Hello Evan,

Welcome to the forum.

Sounds like you have some nice antique restoration work to do, so please take some pictures and share the experience, something for everyone to learn. Also feel free to ask if you need help, someone here has sure seen it or done it before.

Steven

Of note are the Precision Radiation Instruments Royal Scintillator...

Is this the model 118? I've seen that and it's a beautiful antique! We have technically better, but not that beautiful instruments nowadays :) I don't know if they are that rare in the US as they are here in Europe, but if so, better leave it as it is, not to loose the antique value it has. Otherwise, there were quite a lot of electrolytic capacitors inside, which you definitely have to replace after these 60 years and better don't power up the tubes before you are sure in them (and the resistors too), but your brother will know what to do.

Svilen wrote: ↑

06 Oct 2019, 03:12

Of note are the Precision Radiation Instruments Royal Scintillator...

Is this the model 118? I've seen that and it's a beautiful antique! We have technically better, but not that beautiful instruments nowadays :) I don't know if they are that rare in the US as they are here in Europe, but if so, better leave it as it is, not to loose the antique value it has. Otherwise, there were quite a lot of electrolytic capacitors inside, which you definitely have to replace after these 60 years and better don't power up the tubes before you are sure in them (and the resistors too), but your brother will know what to do.

It is indeed the model 118! It is certainly a beautiful instrument! They appear pretty rare here in the states; I can't imagine many were originally sold due to its extraordinary price tag. However, many folks bought into the frenzy of the uranium rush, so who knows. Certainly more 111B Deluxe Scintillators were sold. From what I've read, the design was developed by the USGS and provided to several of the manufacturers at the time. This likely explains why several companies (PRI, Detectron, and El-Tronics) were all producing effectively the same "ray gun" style scintillator. I think no one would argue that PRI had the most attractive Geiger and scintillation counters at the time. Some of the technical papers I've read indicate that 111B Deluxe Scintillators were used into the 1970s for mineral exploration and other activities. I suppose once the batteries became too hard to come by these units fell out of favor for something lighter, more efficient, and potentially with spectroscopic capabilities.

Regarding the antique value of the 118 I have, the previous owner had already attempted to do some restorative work on it. I don't feel bad about continuing to work on this unit and get it working again. Nearly all of the old aluminum D cell holders had become corroded due to batteries being left in over the years. The unit doesn't have too many capacitors, but nearly all of the electrolytic capacitors in it are used for the RC circuit which serves as a one minute timer for the scaler function. I have no doubt they will need replacing (as well as the old carbon comp resistors). I am fortunate that my brother has a good deal of experience working with tube technology; he's collected antique radios and vintage test and audio equipment for many years now.

I'll continue taking pictures of the 118's restoration, as well as our other adventures in vintage tech. I need to source a surplus crystal for the 118; it originally had a 2.25" diameter crystal in it. It may be able to fit one of the 60mm Russian crystals, but it might be a little snug since the packaging has changed a bit since then.

...the previous owner had already attempted to do some restorative work on it.

There's no reason not to do it than. And don't forget to show us the process ;)

Greetings Even,
One of my hobbies and fascinations is collecting radioactive minerals! I am planning a trip to Poison Canyon, NM sometime soon (when all that COVID-19 craziness goes away) to the abandoned Uranium mines in the Mineral Belt! Hopefully I can build a field GS setup by then!
Enjoy the forum!