Mods

Archived from radmon.org - originally posted 05/12/2021

Something I really dislike is planned obsolescence, and closely 2nd to that, where things are not user serviceable and have to be returned to the manufacturer for minor things such as battery replacement. I'm a large advocate of 'right to repair'.

The battery in the Gamma Scout is a 10 year, 3.6v Lithium battery soldered directly onto the board. Gamma Scout (at last check some time ago) wanted 40 Euro plus shipping one way to Germany to replace the battery. Pfft! The original battery is about £20 all in for a replacement, but I decided to go another route and modify the Gamma Scout to take a replaceable battery. I found a supplier (ebay) of a replaceable battery with the identical specs to the original. I ordered one for ~£4.50 and the seller sent me 4! Bonus! 😄 The whole mod came to about £6.50.

Parts needed to mod the Gamma Scout:
- 1x 3.6v Lithium 3.6v 10 year battery
- 1x AA battery holder with flying leads

Instructions:
1. Remove old battery (desolder or just cut the leads, and cut the cable tie)
2. Solder + and - of battery holder
3. Insert new replaceable battery
4. Glue down with hot glue and add a bit of hot glue to the cables where they are soldered to the board. This will act as a small cable strain relief. I also glued the battery into it's holder.

Some notes:

- The placement of the AA holder is about the only place it can go without having to cut away at something. It fits like a glove, like it grew there. The battery holder is in the best orientation for when the Gamma Scout is held upwards by hand, as you normally would.

You have to be careful with the - wire (black wire), as it is very close to the screw fixing post, and can get trapped if not orientated away from the post.

- If you are going to do this mod, or simply disassemble your Gamma Scout, now would be a great time to add a very small amount of silicone lube to the a b y selector switch and spring. It made mine much nicer, smoother and has a better positive detent when selecting. It should also cut down on the plastic wearing and reduce tiny plastic particles inside the unit.

- When I did the mod, around 6 months ago, the battery read 3.6v. Today it still reads 3.6v. This does go down a little when the clicker is on as the previous battery did.

- The battery I chose has the same specs as the original: 2,700 mAh nominal (1ma draw), 100ma constant current and 200ma max current.

- 10 year batteries - There seems to be a misconception with these. Pretty much everyone I know (that are not an electronics engineer) seem to think these should last for 10 years in the appliance. That is incorrect and the 10 year life is their shelf life when they are unused and not fitted into an appliance. 10 years does not mean they will last 10 years. Can you imagine running 100mAh constantly one one of these? It would last no more than 27 hours. And if the battery did last 10 years at 100mAh, the battery capacity would be 8760000mAh, or 8760Ah!

- The original battery I replaced around May 2021 has a manufacture date of September 2013. It was still working, but when using the clicker the screen was fading away so decided to change it. So it did do well at around 7-8 years!

Datasheet for the original battery
Datasheet for the replacement battery

Archived from radmon.org - originally posted 06/12/2021

I have bought a 'PBI Microbial Air Sampler SAS Super 90' just for the simple fact it looked proper funky! I have no idea if it works, or how it works, or even exactly what it does, but bought it for shits and giggles. I paid £15. Working, they are going for about £1000!

I care not for testing microbes in the air, so I figure I can make something with it. So far I have thought I can turn it into a ridiculously powerful flash light. Something around 100w LED. I could use a liquid cooler in the body, LED and smallish heatsink at the end, use the display for something, temperature, power and battery remaining, and have a large LiPO pack over my shoulder. Or I could turn it into a nice portable PM2.5/PM10 air quality meter, and I have all the parts for that already. Or I thought of maybe a portable homebrew Radon gas meter. I could pull air inside the body and have it run through a filter. There could be a GM tube close to the filter, with a servo operated shield that shields the tube from the filter when collecting air, then samples for x seconds, then repeats. Any gamma radiation (Radon decay chain) coming from the filter would be measured by the counter.

I really think I have to do something with it because it just looks so cool! There is some kind of cap missing from the end, maybe a filter or something, but that doesn't matter.

Hmm, thinking about it I could have a SI8B or similar tube up front, I already have some low sensitivity tubes (DOB50, DOB80, SI3BG and I think 3G8B is also low sensitivity.) I would also want a very sensitive tube monitoring background. I do have a couple of SI22G's that would probably work. Then the electronics... SD Card logging, GPS, an analogue meter would be nice, but that would have to replace the LCD and I don't think it would look quite right. I'll have to wait until I get it to work out exactly what can be done with it. I do think it would be a great project.

And today I received my SAS Super 90!

The space inside the case isn't large enough for the SI22G tubes. Plenty large enough for SBM-20s, but I wanted something with the sensitivity akin to the SI22G. I'll have to look about for something suitable, or think of something else.

And now I have just the right tube for this project. It is an SI8B pancake GM tube. 80mm case and about 60mm window. It will be good for hard and soft beta and gamma. Now I just need to find some other tubes to fit in the base for background monitoring.