DC High Voltage Breakdown Rating Of

Discussion in 'General Technical Questions and Answers' started by N0PGR, Sep 28, 2010.

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  1. N0PGR

    N0PGR Ham Member QRZ Page

    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


    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



    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

    Last edited: Sep 28, 2010
  2. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    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. N0PGR

    N0PGR Ham Member QRZ Page

    Cheap is the is the key

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

    Have coax

    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

    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: Sep 28, 2010
  4. N0PGR

    N0PGR Ham Member QRZ Page

    I found something rather interesting ​


    {holy fix oversized pictures}

    Answered my own question finally

    And Thanks to John Doran KV0L

    Terry N0PGR

    Last edited: Sep 28, 2010
  5. KB4QAA

    KB4QAA XML Subscriber QRZ Page

  6. KE3WD

    KE3WD Ham Member QRZ Page

    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. W5RB

    W5RB Guest

    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. AG3Y

    AG3Y Guest

    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. K7NI

    K7NI Ham Member QRZ Page

    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. K8ERV

    K8ERV Ham Member QRZ Page

    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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