PMT preamp power supply questions

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Tom Dressel
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PMT preamp power supply questions

Post by Tom Dressel » Wed Aug 22, 2001 1:35 am

The seller of the EMI 9856 PMT said it needs a 15 volt power supply. Just how clean does it have to be?

I have a couple of power supplies that I made. They are built around a 24 volt transformer with filter caps connected to 7815 voltage regulator. Would this be clean enough to power the PMT preamp?

Tom Dressel

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Richard Hull
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Re: PMT preamp power supply questions

Post by Richard Hull » Wed Aug 22, 2001 1:21 pm

That EMI PMT needs three supplies.
1. HV supply of +900 volts approximately at 30 ua or less.
2. +15 volts 20ma +/-3%
3. -15 volts 20ma +/-3%

This is normal for all PMT/preamp combos. The tolerances are not critical at all here as we are not doing spectroscopy.

If his paperwork calls for a single 15 volt supply, he has outdated material. Let me know and I can send more modern stuff.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

Tom Dressel
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Re: PMT preamp power supply questions

Post by Tom Dressel » Wed Aug 22, 2001 2:29 pm

Richard:

I have the Bertran 0-10 KV power supply that I bought from Al Dieken two weeks ago, with all the other NIM stuff.

The seller wasn't that specific, just stated 15 volt supply. My home made, 7815 voltage regulator based power supply, has +15 volts and -15 volts. So it should work.

That Harshaw SCA you sold me, also has a nine pin plug on the back, to supply preamp power. It looks like five of the pins are actually connected to wires in the case. I will have to tear opened the sealed plastic bag to read the manual, and and get the pin out for the connector. There may be +15 V, -15 V, and ground available out the back of the SCA.

Tom Dressel

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Richard Hull
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Re: PMT preamp power supply questions

Post by Richard Hull » Wed Aug 22, 2001 5:07 pm

I would think that the NIM system will supply only what is on the buss to the preamp plug. +/- 12v and +/-24V. Actually, the +/- 12 v should work just fine with a slight level shift to the base line being a volt or two below the zero line (-2v signal bias). That nice Harshaw SCA might just allow you to raise the base line with a "zero" ten turn pot often found as a screwdriver adjust on the front face. NIM stuff often provides several ways to skin a cat in a mixed signal situation.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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