Testing 75 Ohm UHF (PL259) coaxial connectors for High Voltages

EDIT: after 3 years this harness had a shot with applied 4kV… It’s much better and cheaper build something described here

In Friedrichshafen I’ve found some 75 Ohm UHF connectors and I’ve bought a dozen, male and female,  for few euro.

The idea is use them for connect the high voltage power supply to the cavity of tube power amplifier, voltage of power supply is about 4kV.

So i tested the strenght of connectors and cable (RG59), I’ve used a variable power supply from Heinzinger (0-40kV, max 10mA)


  • RG 59 is ok at 12kV (not tested with higher voltage)
  • male and female are ok at 7kV, with 8kV I see a spark between the pin and the chassis, not trough the dieletric.
  • cable fully assembled resists for 20 minutes at 6kV with no sparks

Here some poor quality pictures taken with cellphone.

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