Above: from top to bottom: SNM-11, SNM-32, SNM-17, SBM-20, SNM-13

An eBay seller indicates these may have been made by "VNIIRT / Soviet Institute for Scientific Radiation Technology Research"

Started making a list I found some pages

Detailed info on lots of tubes
GM: [2]
Sensitive GM: [3]
Neutron tag?

[4]

SNM tube summary
Has lots of mistakes though…current is actually

Info pullsed from those pages:

Image	Name	For	Fill	Oper V	Conduct V	Background uA (max)	Resistor @ Vmax	\| \| \| \| \| \| \|
	SBM-20	Gamma, beta		400
[eBay Sanutek 311490458155]	SNM-9 CHM-9	Neutron, slow
	SNM-11 CHM-11	Neutron	BF3	1500 - 3000	600 - 700	5.27	570 M
	SNM-12 CHM-12	Neutron		500 - 700	400+	11.0	64 M
	SNM-13 CHM-13	Neutron, slow		450 - 600	450+	5.5	110 M
	SNM-14 CHM-14								Neutron		450 - 600	600 - 700	5.27	110 M
	SNM-16 CHM-16					Neutron		2000 - 2800	2000+	25.0	110 M
	SNM-17 CHM-17					Neutron	BF3	2000 - 2800	2000+	25.0	110 M
	SNM-18 CHM-18	Neutron, slow		1275 - 1500	?	?	?
	SNM-18.01 CHM-18.01	Neutron		1700 - 3000	1450 - 1650	25.0	68 M
	SNM-19N CHM-19N	Neutron		2000 - 2800	600 - 1750	15.0	190 M
	SNM-32 CHM-32	Neutron, slow	He-3	1500 - 3000	600 - 700	25.0	120 M
	SNM-42 CHM-42	Neutron		1500 - 3000	600 - 700	25.0	120 M

Resistor calculation:

Don't exceed max corona current
Use reccomended voltages
Assume tube drop negligible (although its not really)
R = V / I type calculation
Variable voltage supply: choose R at high voltage so that voltage can be safely varied over entire range

CHM vs SNM: English interpretation of Cyrillic characters gives them "CHM" prefixes. I've been led to believe SNM is more proper although I can't really back that up

GS-PREAMP

Forum post

The SNM tubes can be a bit tricky to get working as the SNR isn't very high compared to GM tubes (like the SBM-20). Bee research says SNR is about 3.

They sell a small preamp board with Schmidt triggers to help filter out noise and instructions on how to use it. If you are looking for a relatively quick start without shelling big bucks for new tubes this is probably a good route to go.

2015-12-12: JM got board for evaluation. Will post more once I try it out

SBM-20

Datasheet: http://gstube.com/data/2398/

sbm-20 mount

http://uk.rs-online.com/web/p/fuse-clips/7874249/
Littelfuse Spring Brass PCB Mount Fuse Clip for 6.3 x 32mm Cartridge Fuse
http://www.digikey.com/products/en?keywords=01020071Z

SNM-11

Box

SNM-13

From eBay listing:

 Russian Slow-Neutron Corona Counter SNM-13
 
 Operating  Voltage - 500 V
 
 Slop of plateau, % per 100 V - ≤5
 
 Neutron sencitivity, pulses per neutron/ cm2  - 0.5
 
 Plateau Length - 150 V
 
 Natural counter background, cpm - ≤ 2
 
 Temperature range , 0C  -  -50... +100
 
 Life time - more 1500 working hours
 
 Diameter - 8.5 mm
 
 Length  - 85 mm

Box

SNM-17

Custom case

Someone on eBay is selling these. The negative electrode was completely lose...not sure if I'd trust it. Maybe it was secured in some way I missed when I took it apart? Other than that it seems pretty solid case. Some hot melt used to hold things together but its cleanly done.

SNM-32

http://www.fusor.eu/monitors.html#neutron_detector

Has very good information
Basically suggests 100M resistor with 1500V supply

eBay listing

 Russian Slow Neutron Corona Counter SNM-32
 
 Operating  Voltage - 1500V - 3000V
 
 Strating Voltage - 600V - 700V
 
 Slop of plateau, % per 100 V - ≤ 1
 
 Neutron sencitivity, pulses per neutron/ cm2 - 0.8
 
 Plateau Length - 1500 V
 
 Natural counter background, pulses/sec - ≤ 1
 
 Body Diameter - 18 mm
 
 Body Length  - 313 mm

Same thing as CHM32? Maybe the datasheet

"Sometimes references are made to this detector as the CHM-32 detector, which is identical to SNM-32, but written in Cyrillic script"

From that page:

1. наклон плато счетной характеристики % на I в

Plateau (voltage) slope count(ing) characteristics percent in I (current?) B (voltage?) (in maximum column) 0.01

2. чувствительность счетчика к нейтронам по отношению к контрольному образцы, относит .ед.

sensitivity of the counter to neutrons with respect to the control sample refers (reference) . units. (minimum column) 0.8

3. Напряжение зажигания коронного разряда, в

Corona discharge voltage (V) (min-max) 600-700

4. средний ток коронного разряда, мкА

Average Corona Discharge Current, MicroAmps (max column) looks like 28 (23?)

5. собственный фон, имп.с ^ -I

Own background (some unit of measure, which transliterates to imp.s to the negative I; S could be impulse seconds in this case and maybe I is still current?) anyway ... (max column) 0.017

6. радиационная помехоустойчивость, Р/ч

Radiation Noise Immunity (Rads/hour) (max column) 1500 uh...WOW!

7. выходная емкость, пф

Output Capacitance (pF = picofarad?) (max column) 6

Wonder what the output impedance is?

8. сопротивление изоляции, Ом

Insulation Resistance, Ohhs. (min column) 10 to the 10th

Some of the earlier blurbs:

tчетчикиа = partially snm32 snm42
etiketka = label
tчетчикиа = partially snm32 snm42, prednaznachen = intented, dlia = for, registratsii = record, miedlenih = slow, nietronov = neutron, v = in, diapasonie = diapason, energii = energy klimaticheskoi ispolnenie = climatic execution, uksl = ?, tablitcha 1 = table 1
razmer = size
massa = weight
ne bolee = no more
osnovni = main, elektricheskie = electrical, I = and, radiometritcheskie = radiometrical, parametric = parameter
tablitcha 2 = table 2
nameniovanie = name, parametra = parameter
edinitcha = one (number), izmernia = measure, forma = form/shape, ne menee = no less, ne bolee = no more
protiajennost = distance, plato tchetnoy = plateau ?, karakteristiki = characteristics
naimenovanie = name, parametra = parameter
edinitsa = unit, izmerenia = measure