Umformer E.U.a 4 for the Ukw. E. e

Umformer E.U.a4

Nr.370323

This is the power supply dynamotor for the Ukw. E. e receiver. There were four different versions of this umformer, the one here being the 4th.

The operating concept involves a 12.6 DC Volt power supply from either a battery or a generator. A portion of the 12.6 DC Volt current goes straight to the Ukw. E. e and supplies the filament voltage for the vacuum tubes. The umformer generator produces approximately 190 Volts at 0.015 Amps without a load for the anode voltage. When the Ukw. E. e is connected to the umformer and powered on, the voltage drops to around 130 to 145 Volts due to the increased internal resistance of the receiver. The umformer is switched on by a 12 Volt relay that gets activated from the power switch of the receiver

This is one of the original umformers pulled out of the Panther 5a that was submerged under water for 46 years. Many of the screws and other small parts are still salvageable. I was able to extract the original brushes from these umformers to use as spare parts.

This is the second umformer. Judging by the extra wear on the graphite-aluminum brushes, this umformer powered the primary receiver of the Panther.

The manufacturer's shield on the relic umformer. It was made in 1943, the motor rotates at 4000 RPM, 12 Volts, 2.3 Amps input, 130 Volts 26 mA output.

Here is the very nice excellent condition E.U.a4 that we will use.

The manufacturer's plate.

The umformer with cover removed.

The inside of the cover with a schematic for the earlier model E.U.a 2 umformer. Looks like it's a swapped lid. The schematic is almost identical.

Upon extracting the component section of the umformer, I examined and tested the main integrated capacitors, and they tested out both for capacitance and leakages. The operating voltage is 130 Volts, but it will handle spikes of up to 500 Volts. There are 3 capacitors inside one box

This is the 12 Volt relay that gets energized when the receiver is switched on.

After detaching the motor/generator assembly, and removing it from the umformer case, the brushes and 12.6 Volt motor portion can be seen. The brushes are held firmly in place and are pressed against the brass contacts by a spiral-loaded spring mechanism, the copper braided wires carry the current to the motor.

Here is one end of the motor/generator assembly with two filter capacitors attached directly to the generator brush pedestals. Their job is to send any unwanted AC directly to ground. We don't want any AC out of this generator.

One of the two inductors in the filtering circuit.

Finally, the name of the firm that assembled this umformer is "Tornado".

The other side of the battery connection. The top is the "+" and the bottom, the "-" is connected directly to ground.

The inside of the connector to the receiver.

The battery connector.

Unfortunately one of the brushes was broken off. I replaced the pair with one from the salvaged umformer, and it worked GREAT!!!

On the left is an original pair of brushes, and on the right is the pair I got from the salvaged umformer.

Upon detaching the motor, I saw "MADE IN SWEDEN" written on the ball-bearing. Sweden was a major ball-bearing manufacturer for the Third Reich during the war.

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