I was doing some cleaning yesterday, and I found a Bicron 2M1/2 that I got on eBay a while back (remember the $60 detectors?).
Right now, I'm looking for a 14-pin socket/preamp for this thing so I can use it with my Ludlum unit. Does anybody know where I can find one for a reasonable price (Don Orie perhaps)? At the very least, does anybody have a suitible circuit diagram (with a pinout for the detector) for making a preamp?
Bicron PMT socket/preamp
Re: Bicron PMT socket/preamp
hi brian,
i don't know where to find a socket, but there are a couple of preamp circuits in the "files" section. if i remember correctly, there is one by each of the richards in there.
Q
i don't know where to find a socket, but there are a couple of preamp circuits in the "files" section. if i remember correctly, there is one by each of the richards in there.
Q
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Carl Willis
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Re: Bicron PMT socket/preamp
Hi Brian,
Don's got them certainly.
The circuit diagram for the sockets is somewhere on St. Gobain's website (www.bicron.com still works), but I cannot find it now so the PDF is attached. To build your own socket assembly you still have to get a 14-pin socket somewhere, as well as the resistors and caps for the divider chain. BTW, the PX-250 charge-sensitive preamp circuit using the 2N3819 is a nice little unit for NaI detectors and will even work passably with proportional tubes.
I too bought one of those 2M1/2 units from "superdeals45". It was a good deal, but in light of the risk of not getting anything from this seller (check the feedback!) and because I waited fully two months for his package, I would not recommend him again. However, for those who like a risk, he is still peddling detectors and related electronics.
Best regards,
Carl
Don's got them certainly.
The circuit diagram for the sockets is somewhere on St. Gobain's website (www.bicron.com still works), but I cannot find it now so the PDF is attached. To build your own socket assembly you still have to get a 14-pin socket somewhere, as well as the resistors and caps for the divider chain. BTW, the PX-250 charge-sensitive preamp circuit using the 2N3819 is a nice little unit for NaI detectors and will even work passably with proportional tubes.
I too bought one of those 2M1/2 units from "superdeals45". It was a good deal, but in light of the risk of not getting anything from this seller (check the feedback!) and because I waited fully two months for his package, I would not recommend him again. However, for those who like a risk, he is still peddling detectors and related electronics.
Best regards,
Carl
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Brian McDermott
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Re: Bicron PMT socket/preamp
When using one of these with a Ludlum meter, do you connect the cable to the "HV in" connector?
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Frank Sanns
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Re: Bicron PMT socket/preamp
Yes. When you are using one lead systems like the Ludlum, you supply the HV and get the count pulse from the same socket which is the one marked HV on the Bicron unit. The other connector is a capacitively coupled pulse output for NIM setups or external pulse signal detectors.
Frank S.
Frank S.
Achiever's madness; when enough is still not enough. ---FS
We have to stop looking at the world through our physical eyes. The universe is NOT what we see. It is the quantum world that is real. The rest is just an electron illusion. ---FS
We have to stop looking at the world through our physical eyes. The universe is NOT what we see. It is the quantum world that is real. The rest is just an electron illusion. ---FS
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Carl Willis
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Re: Bicron PMT socket/preamp
Hi Brian and Frank,
I should add some clarification on this issue. The usual arrangement in socket assemblies is to have the HV line filtered in the assembly with a capacitor to ground. Also, the Ludlum counter probably has a substantial load resistance built in, often 10 Mohm. It may not be able to drive sufficient current to run a standard resistive divider chain at all, or the voltage drop on the internal resistor may be undesirably large.
To use a one-lead configuration, I recommend reworking the socket assembly to use dynode resistors of 10 Mohm or more, instead of the usual ~500k. Also, the HV filter cap (and sometimes a series filter resistor) should be removed. Often there is a load resistor also built in between the HV and the tube anode; this can be cut out entirely and the HV lead run straight to the anode. Then you're really set up for running with the Ludlum.
-Carl
I should add some clarification on this issue. The usual arrangement in socket assemblies is to have the HV line filtered in the assembly with a capacitor to ground. Also, the Ludlum counter probably has a substantial load resistance built in, often 10 Mohm. It may not be able to drive sufficient current to run a standard resistive divider chain at all, or the voltage drop on the internal resistor may be undesirably large.
To use a one-lead configuration, I recommend reworking the socket assembly to use dynode resistors of 10 Mohm or more, instead of the usual ~500k. Also, the HV filter cap (and sometimes a series filter resistor) should be removed. Often there is a load resistor also built in between the HV and the tube anode; this can be cut out entirely and the HV lead run straight to the anode. Then you're really set up for running with the Ludlum.
-Carl