Got a cool package coming! Survey meter parts

[Stonent]

So a little while back I thought about getting one of those old Civil Defense survey meters on ebay and converting it to detect non-deadly levels of radiation (these ones were intended as after the mushroom cloud meters, not clicking on interesting rocks)

My idea was to remove the chamber and put a Darlington transistor in it wired up as an ion chamber. So I did a little searching and found someone on a geiger counter site who had a bunch that he was giving away for the cost of postage. So I sent him a message and he said he had given all the working ones away, but he had lots of parts he could send me. So today I get this in my e-mail:

I shipped your package this morning. It went by Priority USPS mail, so you should get it around the end of the week. I packed everything in an old "Shelter Radiation Kit" box, CD-777. :-) These are good by themselves as conversation pieces, but are also rugged boxes for shipping. :-) The box itself probably has a history. :-)
 
Unpack it carefully as there is a lot of stuff inside. The two Victoreen 6B's were from the batch I salvaged from the dumpster at the OCD repair depot. I picked two that had minimal case damage, but they all had some. As I mentioned before, ALL of these had the probes and meters missing.
 
Also in the box are two meter movements. Both of these test good, and have the CORRECT scales for the 6B. One has a crack on the mounting rim. I will tell you how to fix that later.
 
There are two probes, and one GM tube. That was the only one I had, but it tests good. GM tubes for this model are available various places. I MAY have more, but if so, they are buried deep. :-)
 
There is also an envelope full of small parts. It includes a pair of meter gaskets, the proper screws to mount the meters, some #8 solder lugs in case you have to make meter leads, (sometimes they cut these off at the OCD) some heat shrink tubing, a pair of 6000 V Silicon diodes to replace the old Selenium rectifiers, a pair of 470 Mf 16 V capacitors to replace the old 400 Mf 6 V integrating capacitors, some transistors needed to make the LED conversion and replace the input stage transistor if you get to that point, and I forgot what else. :-) Basically, I threw in all the hard to find parts. If you get to the modifications and conversions, you may need some resistors which you can find locally or on the Internet.
 
CASES
 
If you want to touch these up, get a can of Rustoleum "Safety Yellow" or "OSHA" yellow. This exactly matches the color of the 6B case. Large areas can be done by carefully controlling the spray. Small spots are best done by spraying some paint in a bottle cap or similar, and using a small artists brush. If you accidentally spray some paint on the printed nomenclature, after everything dries, you can fix this by rubbing a black crayon over the spot, then buffing it with a soft cloth stretched over a hard surface. The nomenclature is etched, so the crayon will fill it in.
 
When taking the unit apart, be aware that there is a rubber "O" ring on the switch shaft as a moisture seal. This will tend to make the switch shaft stick in the hole. Do not pull on the PC board to free it as you may damage the switch or PC board. Instead, tap on the shaft end with a pair of pliers or something similar until you work it mostly out.
 
MINIMAL RESTORATION
 
You can start with minimal restoration by just replacing the old Selenium diode and integrating capacitor. These are almost always either bad or marginal. The replacement diode has a white stripe on one end, and this corresponds to the + marking on the old Selenium. Cover the new diode with some sleeving for safety. Watch the polarity on the 470 Mf capacitor. It must be installed the same way as the old capacitor. Replace these two parts, install the probe, meter and GM tube, and give it a go.
 
I included a bunch of schematics and pictures. Most of these are a help for later modifications to the instrument. The 3 V conversion allows you to remove one of the battery holders. At the least, this makes the instrument lighter. It also makes room for other things, the most popular of which is to install a pancake GM tube in the bottom of the instrument. If you elect to try this, get in touch with me for details. The 3 V conversion requires the removal of one resistor, one cut on the PC board, and two jumpers.
 
The next step is to add LED's for "COUNT" and "POWER". There are several ways to do this. See the "Pizazz" article in the FILES section on GCE for one possible way. The other way is to drill 3mm holes in the panel. The best place to locate the LED's is right below the meter. You use the "casting marks" in the back of the panel to locate the holes. Again, write me for more details on this. Adding a "COUNT" LED requires an additional cut to the PC board, the rearrangement or replacement of a few parts, and adding a transistor to the bottom of the board, along with a resistor. This is shown in one or more of the pictures, and the electrical details are shown on one of the schematics. These modifications have been proven on MANY instruments, built by myself and others. I figured them all out originally and field tested them, but they have been shared with others. I realize the exact details are somewhat sketchy, but I am willing to help you through it should you wish to take the plunge.
 
Lastly, there are a pair of MPSA56 transistors in the envelope. One of the advanced modifications is to replace the input transistor with one of these. Should you get to this stage, hold the transistor with the flat side up, and the leads pointing towards you. Bend the center lead up slightly, and the outer leads down and out slightly. The resulting triangular pattern fits in the holes vacated by the old part.
 
Save this message for later use. :-) Be sure to ask if I have left anything out or forgotten anything.
 
Let me know when you receive the box.

Selenium diode? I wonder if it's like the Federal Rectifier from EEVBlog video 443? I guess I'll see. I'll take pictures when it comes. So it sounds about like there may be enough parts to make these work. I had 2 old victoreen units when I was a kid that my dad got from work but they never worked so they got tossed many years ago.

We will see what it looks like!