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  1. #1
    Join Date
    Aug 2010
    Location
    EN35
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    55

    Lightbulb DC High Voltage Breakdown Rating Of

    Well for me I'm looking for is....

    How much DC Voltage can pass through

    PL-259 and SO-239 and BNC , F , N......

    and so on

    ??????????????????

    As far as Coax Cable

    I have seen numbers applied to

    RG-58 of 1900VRMS
    RG-59 of 2300VRMS
    RG-8[PE] of 4000VRMS
    RG-213 of 5000VRMS

    and if you could imagine

    RG-6 of 2700VRMS

    Good and plenty I say

    .......But.......

    Wouldn't VRMS imply a AC Voltage

    What about DC High Voltage

    I have seen opinions for

    DC breakdown Voltages of

    RG-58 @ 10KVDC
    RG-59 @ 30KVDC
    RG-213 @ 50KVDC

    So what is the actual DC rating

    Anyone

    ???





    So why all this business



    I'm building a large multi band V/UHF amplifier

    Using multi PA decks

    With one LARGE HV Power Supply

    I need to get 1800 to 2300 Volts of B+ to all the decks

    { safely }





    Besides, haven't you had a thought on this

    subject before at one time or another





    Thank you

    Terry N0PGR

    73
    Last edited by N0PGR; 09-28-2010 at 02:23 AM.

  2. #2

    Default

    For detached amplifiers/power supplies I use high voltage wire, not coax. HV test probe cable is easy to find rated at 5kV DC, and much higher if you wish. Some of the silicone rubber insulated stuff is good for 20 kV+ and it's cheaper and more flexible than coax.

    For B+ I use either Millen 7kV connectors (very commonly found and available, and cheap) or MHV connectors.

    I wouldn't use type UHF or BNC or N, as those can be too easily confused for antenna connections.

    My grounds and B- returns are separate: A couple of paralleled ground wires run in the multi-pin connectors that are used for LV, filaments, switched AC, metering and other stuff; plus the third prong in the AC power cord provides a solid utility service return. I usually bring B- out separately from "ground," as it floats slightly above ground (not much, usually floated by the plate current meter shunt resistor and a fault diode) so I can meter plate current in the B- return path.

    The DC voltage rating for cables should always be somewhat higher than the AC RMS voltage rating, by at least a factor of 1.414. I just avoid using coax for B+ because it's too easily confused for antenna wiring, especially if a guest operator has to de-bug something when I'm not around.

  3. #3
    Join Date
    Aug 2010
    Location
    EN35
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    Default

    Quote Originally Posted by WB2WIK View Post
    For detached amplifiers/power supplies I use high voltage wire, not coax. HV test probe cable is easy to find rated at 5kV DC, and much higher if you wish. Some of the silicone rubber insulated stuff is good for 20 kV+ and it's cheaper and more flexible than coax.
    Cheap is the is the key

    Noted 7mm solid core spark plug wire can be used also

    Have coax
    Quote Originally Posted by WB2WIK View Post
    For B+ I use either Millen 7kV connectors (very commonly found and available, and cheap) or MHV connectors.

    Poked out there on the net for these

    Millens about $10 each

    MHV about $10 each

    Thats getting up there

    $100 for B+/B- connections

    and that is w/o wire

    Nice , sure is......

    Have PL-259/SO-239 just in the drawer

    Quote Originally Posted by WB2WIK View Post
    The DC voltage rating for cables should always be somewhat higher than the AC RMS voltage rating, by at least a factor of 1.414. I just avoid using coax for B+ because it's too easily confused for antenna wiring, especially if a guest operator has to de-bug something when I'm not around.
    Thought about mixing up the connectors

    Got to be a work around for that

    So if one were to use the 2300VRMS you should be covered then

    For this thing RG-213 type will be used

    Flexibility , not an issue





    Terry N0PGR






    Besides, kind of like the idea of
    ground shielded B lines

    Say if one got nicked or cut
    Keeps it inside cable
    Last edited by N0PGR; 09-28-2010 at 04:11 AM.

  4. #4
    Join Date
    Aug 2010
    Location
    EN35
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    Default

    I found something rather interesting


    I needed several high-voltage connectors for this project, each capable of working reliably at 20 kV. Rather than buying them, I made them myself, using PVC pipe, PVC sheet, ordinary banana jacks, and SO-239 (UHF coaxial) receptacles. The body of the connector is made from the PVC pipe, with the banana jack mounted at the rear in a disk cut from the PVC sheet (see the photos). Another disk, at the front, serves as a mounting flange. I removed the insulator and center contact from the SO-239 (easily accomplished by grinding the back off of it) and then mounted it in front of the panel, with the HV connector body behind the panel.

    If you cannot locate PVC sheet, it may be easily prepared by longitudinally slitting a length of pipe and then gently heating it in an oven to make it open up and lie flat!

    I fashioned the mating cable from RG-8 coax and a PL-259 UHF plug. After removing the center pin, I drilled out the PL-259 so that the insulated center conductor of the coax could pass through it; then I attached the PL-259 shell to the coax shield in the conventional manner, with the appropriate length of center conductor protruding. I soldered an uninsulated banana plug onto the end of the center conductor.

    When the cable assembly is mated to the HV connector on the chassis, the banana plug engages the jack at the rear of the connector.

    If you use this technique, be sure to obtain RG-8 cable having a hard polyethylene dielectric. There are many cables, otherwise similar to RG-8, that are made with foam dielectrics that cannot withstand the high voltage. I have seen the polyethylene cable used reliably in commercial 40 kV power supplies.

    http://www.timefracture.org/reg.html



    {holy fix oversized pictures}



    Answered my own question finally

    And Thanks to John Doran KV0L



    Terry N0PGR

    73
    Attached Images Attached Images
    Last edited by N0PGR; 09-28-2010 at 06:50 AM.

  5. #5
    Join Date
    Jan 2008
    Location
    St. Mary's County Md since 2000
    Posts
    7,471

  6. #6

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    Using the same connectors for the deadly high tension lines as you do for your Antenna and input connections is a recipe for disaster.

    Don't think that you would never make a mistake sometime.

    "Never say 'never'"...

  7. #7
    W5RB Guest

    Default

    What's with the bizarre format ? It's like you're using a template for a wall poster of the Desiderata , and it's ..... distracting .

  8. #8
    Join Date
    Jul 2001
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    21,474

    Default

    If I remember my math properly, you take the RMS values you have listed above, and multiply by 1.414. That will give you the peak of the AC voltage, which should be the same as the maximum DC voltage that the cable is rated for !

    WD has good advice. Use special HV cable rather than coax. A life is PRICELESS ! ! !

  9. #9

    Default

    I have seen modified coax connectors like the ones pictured used on a Hi-Pot tester.

    Regular PL-259, SO-239 and BNC connectors are rated for 500 Vpeak. N connectors are rated for 1500 Vpeak

  10. #10
    Join Date
    Jan 2004
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    Beautiful Downtown Colorado. (Montrose, SW corner)
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    28,534

    Default

    I think there are too many variables to come up with one figure. Instantaneous breakdown? Long term breakdown? How clean are the surfaces, etc.

    I worked in a lab that applied 50kv (briefly) to RG-8 in a pulse generator.

    TOM K8ERV Montrose Colo

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