High voltage B+ connector - Options for 'Updating' Power Supply

Discussion in 'Homebrew and Kit Projects' started by SWL37632, Sep 3, 2021.

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  1. SWL37632

    SWL37632 QRZ Member

    My 'updated' 1950's external 4KV power supply currently has the conical ceramic feed thru connector of the times for the B+.

    What 'safe' HV connector(s) is/are currently being used or recommended for this kind of application?

    Thanks in advance

  2. KU3X

    KU3X Ham Member QRZ Page

    I use the Millen HV connectors.


    Scroll down have wave down the page. The only issue I had was the HV wire I first used was rated at 20 KV but not a snug fit on the connector. The insulated part of the wire really never touched the the shoulder of the connector. I then changed to the HV wire used for neon lighting. That stuff uses #14 stranded wire and very think insulation. It's rated over 10KV. That wire looks like it was designed to be use with these connectors. The insulation is a snug fit and the wire fits inside of the copper pin with little room to spare.
    Barry, KU3X
    I just took these pix. You may not see the difference, but the red wire is 25% less in diameter than the brown neon lighting HV wire. The red wire is #18 with a rating of 20KV. The neon wire is #14 and rated at 15KV

    Neon wire link:



    Attached Files:

    Last edited: Sep 6, 2021
    SWL37632 likes this.
  3. SWL37632

    SWL37632 QRZ Member


    Very good info! Sure beats the protruding threaded screw that is there now.

    Thank you for providing the info and the picts...much appreciated!

  4. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Millen connectors are not rated for 4kV. They are just plastic and have no reliable locking device. I'll look for a link to a BA enthusiast who severely injured his hand a couple years ago from Millen connectors.

    There are modern HV connectors available, I'll look or someone else will post.

    An alternative would be to fabricate a guard from plexiglass or similar.

    N2EY and SWL37632 like this.
  5. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    MHV connector, "Miniature High Voltage", bayonet style
    Older design, rated for 1.5kv rms, 5kv peak

    SHV, "Safe High Voltage" bayonet style, long reach.
    Newer design, rated for 5kv, 5A

    Shop around, major discounts can be found from small and discount vendors.

    Suggest calling RF Connection in Maryland.
    N2EY and SWL37632 like this.
  6. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    AM Forum,

    This thread from 2018 discusses the failure of Millen connectors on a HV power supply and how KD6VXI seriously injured his hand (gory photos!). Merits and weaknesses of Millen connectors is discussed.

    Bottom Line: Millen connectors are marginal designs, not formally tested or rated and probably electrically adequate for no more than a couple hundred volts. They lack any locking device to prevent uncoupling.
    AG5CK and SWL37632 like this.
  7. SWL37632

    SWL37632 QRZ Member

    I see that they appear to accommodate an outer metallic shield ?

    This makes me think that the HV B+ wiring has a shield on some configurations that are used for AR PA's ?

    Is this correct ?
  8. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    MHV and SHV are similar to BNC bayonet connectors and designed to be used with coaxial cable.
    SWL37632 likes this.
  9. SWL37632

    SWL37632 QRZ Member

    Wow !!

    I read thru the entire amfone post with the picts...

    Looks like I'm going to rethink some things on this PS.

    Thank you very much for providing this info!

    KA0HCP likes this.
  10. KU3X

    KU3X Ham Member QRZ Page

    I am not questioning your response, but I have been using them for 35 years at 5.4 KV and never had an issue.
    KA0HCP likes this.

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