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Some of you might have read some of my posts about my Variable PSU for He-Ne's kicking the bucket:yabbem:. After Long conversations with HemlockMike and others,:thanks: we found out that replacing the output transistors were out of the question.
Long story short, the outputs are not available and nothing crosses-over to them. (LKB Instruments proprietary components)
So, I gave up on that one and bought a new one.-Fisher/Biotech FB600-- 0-4k@0-200mA.
Now the problem with this one is; it has a safety interlock built-in where it has to detect at least 40M ohm at the ends of the HV cables in order to switch on the HV.
So when I fire it up hooked up to a He-Ne tube it won't "latch" and start the HV output. I checked the He-Ne tube(s) (3 or 4 of them) and they measure Open
I use a Piezo-electric starter circuit as described by Sam Goldwasser to provide the start-up spike.
The tube produces a bright flash down the bore ever time I push the button on the PEC.
Even with using the starter circuit the PSU will not start-up the HV.(there is still no resistance produced to trigger the interlock)
I know the PSU is working fine. If I clip two nail to the HV leads and put the tips of the nails in a glass of plain water (no salt) the PSU will "latch" and start producing HV. (and lots of pretty bubbles):beer:
My question is; How can I make the PSU "see" at least 40M ohms across the tube to make it "latch"?
I thought about putting a 40M resistor across the anode and cathode,but have no idea what that would do to the tube.
I don't think it would hurt the PSU. 40M ohm would not pull up the amperage anywhere close to 200mA even with the 4.5mA (+-) the tube would draw.
But would it keep the tube from starting? I have read (almost) all of Sam's Faq,s and looked for hours online. Of course nothing at all about this problem.
If any one has any suggestions of a course of action I would be very grateful. I don't want to jump blindly into this and possibly ruin a good tube. Or cause a melt-down or fire or a tear in the fabric of time LOL:crackup:
Thanks! Mark
Long story short, the outputs are not available and nothing crosses-over to them. (LKB Instruments proprietary components)
So, I gave up on that one and bought a new one.-Fisher/Biotech FB600-- 0-4k@0-200mA.
Now the problem with this one is; it has a safety interlock built-in where it has to detect at least 40M ohm at the ends of the HV cables in order to switch on the HV.
So when I fire it up hooked up to a He-Ne tube it won't "latch" and start the HV output. I checked the He-Ne tube(s) (3 or 4 of them) and they measure Open
I use a Piezo-electric starter circuit as described by Sam Goldwasser to provide the start-up spike.
The tube produces a bright flash down the bore ever time I push the button on the PEC.
Even with using the starter circuit the PSU will not start-up the HV.(there is still no resistance produced to trigger the interlock)
I know the PSU is working fine. If I clip two nail to the HV leads and put the tips of the nails in a glass of plain water (no salt) the PSU will "latch" and start producing HV. (and lots of pretty bubbles):beer:
My question is; How can I make the PSU "see" at least 40M ohms across the tube to make it "latch"?
I thought about putting a 40M resistor across the anode and cathode,but have no idea what that would do to the tube.
I don't think it would hurt the PSU. 40M ohm would not pull up the amperage anywhere close to 200mA even with the 4.5mA (+-) the tube would draw.
But would it keep the tube from starting? I have read (almost) all of Sam's Faq,s and looked for hours online. Of course nothing at all about this problem.
If any one has any suggestions of a course of action I would be very grateful. I don't want to jump blindly into this and possibly ruin a good tube. Or cause a melt-down or fire or a tear in the fabric of time LOL:crackup:
Thanks! Mark
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