High voltage homemade connectors

My tube amplifiers are powered by an external power supply for filament, bias voltage and anode high voltage.

Since the beginning I had problems with the connectors to be used with the anode voltage (about 4kV)

I don’t like hv unipolar wires around, so Millen connectors aren’t a solution…I prefer to use a coaxial cable: any accidental breakage shorts to ground the high voltage, burning the fuse.


Over the years I’ve tried cables with UHF, N, C and a quite rare 75 Ohm UHF connectors, wrote about it in an old post

Unfortunately, sooner or later, all these connectors have had a shot…..


The UHF 75 Ohm connector has worked for last 2 years without any problem, BUT yesterday, during an EME session in a hot humid day, he shots too…

So i’ve decided to update the system with an idea taken from a 40kV Heinzinger power supply in use at QRL

For a complete HV connection we need:

  • 2x SO-239-UHF panel Female
  • 2x PL-259-UHF Male
  • RG213 coax cable
  • pvc/delrin/ptfe pipe with 10 – 10.5 mm diameter
  • a drill with 7mm-7.5mm tip
  • epoxy 2 components glue
  • a soldering iron

First we cut 70mm of the pipe


With the soldering iron heat the central pin of the UHF female, then remove it with a shot (don’t lose it!), then drill the connector and remove completely the dieletric inside. Now with epoxy glue fix the central pin, just removed, at one side of the pipe and fix the female UHF connector, without dieletric, at the other side as in the picture


Strip the RG213 cable leaving 10mm of the braid and 75mm of dieletric.


Heat with soldering iron the pin of UHF male connector and remove it, drill the connector with 7-8mm tip then assemble the connector as in picture


Done! Now, with minimal expense, we have an high voltage harness that can be used well over 10kV



One Response to “High voltage homemade connectors”

  1. That’s pretty cool…
    I will give it a try.

    Andy, DL1AKP

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