Tube styles

Dan, your new unit comes with a SBM 20, how is it attached to the pcb inside the unit? clipped in or wired and glued in? probably why some, including myself, was wondering if there was a internal picture of it. I have some M4011 tubes here for a spare, looking at the SBM 20, it looks like the same length as the M4011. Trying to make up mind whether to get it with or without the tube or just get it and hang on to it for a backup.

Ok, thanks. On the kit versions of your units, did I read somewhere that the main boards are assembled, just need to put the rest together, enclosure, cable, etc. correct?

LOL. Been posting about my purchase of an SBT-11A from Sovtube in 'News'.
Just discovered this section.
Found the small, rectangular window tube interesting and sensitive. Asked some questions and got some good feedback. Below is one quoted:.
Posted by : Juzzie
URL : http://radmon.org/index.php/kunena/radmon-org-news/240-gm-tubes-sov-tube-purchase/1529
I have poked around inside a broken one, and I have a circuit diagram. There are four segments which could also be considered four GM tubes.
There are indeed only three positive connection pins - the outer two pins belong to the outer two segments and the inner pin is connected to the inner two segments.
The two negative connection pins are...joined together inside.
It's all a little odd really.

The specs give a current range of 0.3 to 1.5 uA per segment so, when open to a strong radioactive source, all the segments are firing like crazy, you may end up with a voltage drop ( and a drop in counts) due to a lack of current if you use only one resistor. You could use only one resistor of a lesser resistance to overcome this, but then there is a risk of damaging the tube at low counts.
****

Originally, I simply shorted the three anode pins on my first SBT-11A together and hooked them to a 10 meg resistor. That worked too. Atomic Dave suggested just shorting the two (middle) ground pins together. At $30.00 this was a great bargain. Hooking two in parallel should give a great alpha sensitivity. Because they are mostly hard plastic, mounting with glue or epoxy should be easy.

Here is the schematic -