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Wednesday, October 18, 2017

Power Supply with ELROG ER274A


Here some photos of the first power supply I built for the ER274A rectifier.

The owner of one of the sets of 211/211 amplifiers requested to convert the power supplies to use the new ELROG rectifier. How could I say no to that?

Two of the TV Dampers got replaced by the directly heated rectifiers. Two TV dampers remained for a slow ramp up of the high voltage.

Now not only the amplifier sections exhibit the bright thoriated tungsten glow, but the power supplies as well.

Not sure yet if I even prefer this to the blue glow of the mercury vapour PSUs.

Quite spectacular light show!

Amp section and PSU side by side:

The gap between the two plates gives a nice view to the filament.

Best regards



  1. Hello Thomas,
    How come that the 274 A rectifier complies with the high voltage required by 211 power tubes ( 1000-1300V DC)?

    1. Hi!
      The Elrog ER274A can handle higher voltages. But in this PSU they are part of a bridge configuration which has less peak reverse voltage across the tube

  2. Are the two anodes of each 274 parrelled?