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sorenb

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  1. sorenb

    kgst

    sorenb replied to kevin gilmore's topic in Do It Yourself

    What did you see?
  2. sorenb

    kgst

    sorenb replied to kevin gilmore's topic in Do It Yourself

    Seems like Kevin's assumption about the input impedance of your DMMs is off spec might be right ... if the DMM reads 590V, and has 2Meg input impedance and the output impedance at the testpoint is 200k the actual voltage will be 59V higher. Using the HV Probe that has 75Meg input impedance will give a reading much closer to the 590V+59V ...
  3. sorenb

    kgst

    sorenb replied to kevin gilmore's topic in Do It Yourself

    The Fluke datasheet says you need a shunt resistor if you DMM has more than 10Meg input impedance .... I guess you are using the 1V range when probing with the HV probe? Sent from my iPad using Tapatalk HD
  4. sorenb

    kgst

    sorenb replied to kevin gilmore's topic in Do It Yourself

    Doesn't your Keithley have 10Meg input impedance at the 1000V range? And >10G at the 1V range? .... Sent from my iPad using Tapatalk HD
  5. sorenb

    kgst

    sorenb replied to kevin gilmore's topic in Do It Yourself

    I second that I guess there are more people interested in a variable BIAS design ...
  6. sorenb

    kgst

    sorenb replied to kevin gilmore's topic in Do It Yourself

    Is this BIAS measuring more complicated than the DMM forming a voltage divider when doing the measurement? Isn't that always the case and a 'problem' when measure something with high output impedance like the BIAS supply? ... but is it more complicated than 'guessing' that the output impedance is 5Meg (if that is what your string adds up to) and compare it against the 10Meg of the DMM ...so one would have 2/3 over the DMM and needs to multiply the measured value with 3/2 to get the real value ? While this might not be strictly correct in an academic sense, I guess it is good enough for any pratical purposes. Kevin has added a test point on some of the PSUs that connects before the 4,7Meg or what ever one has choosen for the balast resistor, there you only have 200kohms or there abouts ....and the DMM will measure something which is like 2% off .... since the BIAS voltage is set by a series of zeners seeing a value in the neigborhood of the expected should be good enough ... not much to do about it other than changing some zeners ... How a high voltage probe with high impedance apparently can bump up the voltage I do not understand
  7. sorenb
    @Gepardcv: you probably won't be disappointed @Insanity: Depends on how you see it; a bit solder wick and some flux and off it goes ... not a big deal ...had smoke from the Vishay and had to replace that and the 42 that had its own way for some reason ...anyways its only the C2M that is going to be mounted like that ... the 10m90 will get company from a DN2540 ...just havn't figured out how to do it just yet ...
  8. sorenb
    Ordered some of the Carbon boards from Birgir.Its without cascoded CSS. Cut those board to a smaller size. Besides from a PZTA42 that somehow had its own way and apparantly caused a Vishay to go south the amp was up and running without too much hassle. The Carbon definetly runs hot. The heatsink is ,45K/W - seems ok The plan is to have the amp on one side and the PSU mounted likewise on the opposit side in a Dissipante 2U/300mm wide. Looking forward to get the PCBs from MWL168 GB Big thanks to Kevin & Spritzer.
  9. sorenb
    Agree,if it doesn't tell from the pic. As far as I can tell from the reference JoaMat has posted the "Short if snap-in" is for people not using the 4pins Mundorf. @Kevin: why use the Mundorf at the output? I can understand adding the option for the unregulated input ...
  10. sorenb
    Where did you find it? and who made the "Short if snap-in" annotation?
  11. sorenb
    from the GB spreadsheet it looks like people wants 30 Dual HV, 88 FAT HV PSU and 18 Skinny PSU which translate into (30+88) x 4 + 18 x 2 = 508 caps. There´s an Estonian seller on the bay that sells those Mundorf at 29€ ....might get a better price if ordering a bunch
  12. sorenb
    http://mundorf.com/PIC/mlytic_application_note.png 680uF/550V -> 51.9€ Mundorf ...or 44.27€ 580uF .... 580uF/550V -> 39.19€ Kemet
  13. sorenb
    Nice thought anyways I have added a separate sheet that links to the official, and have a consistency check, so MWL168 can see if someone is changing their values, I assume he is going to lock the GB within the next 24 hours.
  14. sorenb
    Someone has altered the spreadsheet and added the total sum of each column in the bottom, and that someone apparently did not notice that excatly the same sum is in the top ...I don't mind if people wants the sum in the bottom ...but counting in something twice isn't the best idea ....suddenly there was more than 600 boards in the GB?? if someone wants to enhance the sheet please make sure you know what you are doing
  15. sorenb
    sometimes I have written to Mouser service and ask them to find a specific component .... works pretty well, within 24 hours they usually turn up with something usefull
  16. sorenb
    like this: http://dk.mouser.com/ProductDetail/Schurter/DF111089001001/?qs=sGAEpiMZZMv1TUPJeFpwbgHdbMTAnWqlIocQgbYZu34%3d ?
  17. sorenb
    thnx...looks ok to me, thnx for the link to Mouser
  18. sorenb
    has anyone used/traced this http://gilmore.chem.northwestern.edu/kgsshvcarboncirclotron.jpg....? seems like the upper left opto hasn't been connected at pin4/5 (assuming no ground plane) ?
  19. sorenb
    Thnx, can you share the part number for the 1kV terminals you are using? (cannot seem to find any at Mouser)
  20. sorenb
    apart from a lower voltage swing I assume the circlotron can be doneusing battries at 700V rather than 900V?
  21. sorenb
    "350V/us", does that mean you plan to bump the current in the output stage to 42mA (assuming 120pF load)? Would it be safe to use the original PSU board for the floating supplies if one lowers the voltage from 900V to 700V then the original 450V caps can be used I assume
  22. sorenb
    @b0bb: should be working again, thnx for letting me know ... I make a copy of it everyday just in case
  23. sorenb
    007 ...anybody having any experience repairing a cable that has a loose connection just before the molded plastic strain relief piece? not talking about buying a spare unless someone knows where to get it a an reasonable price?
  24. sorenb
    @UFN: Thanks, but I really do not contribute that much. This is MWL168 who is doing 99,9% of the work. Just checked the status +300 boards .... at 30USD pr board (just a figur) we're at 9000USD ... quite a substantial figur in my book. A total of 33 people participates ... lets say that unpacking takes an hour ...and 20 min for each package that is 12 hours in total ...almost two days of work I know mwl168 is too modest to accept the acknowledgement ... but honestly it will only be an acknowledgement of the contribution rather than a compensation. I have put in a column for participating in the "Acknowledgement" and as mwl168 stated people are free to participate in the GB anyways, I have taken the liberty to put "Yes" in that column, so you need to change it if you for some reason cannot participate.
  25. sorenb
    Might skipped my attention, but has the schematic for the input been posted? Had a look at the floating psu .... Seems very similar to the old kgsshv psu.... Would that pcb work using offboard caps?
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