This receiver arrived in excellent condition and included a copy of the original manual. The seller warned me of a fractured capacitor that was located on the bottom of the radio, and included a photo of the broken capacitor. The exterior paint and interior state of the radio were near mint, as if this receiver had not been used during the war.

During physical inspection of the radio, the following potential defects / deviations were found:

  1. The capacitor marked 103 was broken on the bottom of the radio.
  2. The resistor marked 108 was damaged next to the transformer at the top of the radio. One of its connecting heads was detached from the body.
  3. On the rear of the radio on a connecting panel, many connecting screws were loose that connected various wires from different parts of the radio.
  4. A screw that held down the transformer had broken.
  5. After testing all vacuum tubes, one was found to be defective
  6. The frequency scale illumination light burned out with the immediate application of 12.6 Volt power. There was a bright-blue flash when this happened.
  7. The two box-capacitors on the right side of the radio were degraded (as they mostly are after all these years).
  8. Receiver was generally de-tuned after 70 years after manufacture.

My repairs to the Ukw. E. e are listed below:

  1. The broken capacitor was replaced with a modern capacitor with the same characteristics. It was wrapped in electrical insulation to simulate the look of the original capacitor, with the correct writing placed on it with a special pen.
  2. Since all of the integral parts of resistor 108 were intact, I used heat (soldering iron) to reattach the head to the body successfully. The Ohmmeter read the correct resistance after this.
  3. The connecting panel screws were taken apart, cleaned, and reconnected.
  4. The broken transformer screw was successfully replaced.
  5. The broken vacuum tube was replaced.
  6. The Tungsram light bulb was replaced above the frequency scale with a new light bulb.
  7. The box capacitors were emptied of their original electrolytic material, and new, equivalent capacitors were placed inside.
  8. The receiver was then re-tuned for optimal performance

Results of testing the receiver produced excellent selectivity and sensitivity results. There was almost no deviation on the frequency scale from the correct frequency for the maximum signal received.


Ukw.E.e Panzer receiver.


The broken capacitor (50,000 pF - 250-750 Volt)



The new capacitor made to look like the original one.



The disconnected resistor 108 cap. Repaired by shaving solder wire into the cap, then inserting resistor back in and soldering it on.



After the receiver checked out as working, it had to be tuned. Here I'm testing the resonance characteristics of the 2nd intermediate frequency amplifier. I've attached a FET probe from the 141T to the input of the detector, and the output of the tracking generator to the input of the 2nd IF amplifier. The resonance curve is shown below.



Here is the frequency response before tuning. Center frequency is 3 MHz (IF of the Ukw.E.e), signal level is -50 dBm (0.7 mV). Response is 12 mV (-25 dBm). The RV12P4000 tube in new condition, so the amplification factor is approximately x17.



The sides of the amplifier response curve are quite steep indicating effective design. A deviation upwards of just 100 kHz attenuates the signal by 5 mV (or ~5dBm)



Location of the input signal terminal leads to test the 2nd IF amplifier.



The trimmer here has the same problem as in all German radios. It is frozen, so I try to unfreeze it in place with my special tool. Here the signal lead is connected to the output of the mixer to test the 1st IF amplifier stage.



Here is what the resonance curve of the combined IF stages looks like after tuning. The pass-band is 20 kHz wide and the curve looks very close to ideal. 11 mV (-26.16 dBm) amplification of a -50 dBm signal



Connecting a power cord allows for better flexibility of testing the set. Here both IF stages are being tested together. On the right side is the input connection at the anode junction of the mixer, and on the left side is the output connection with the FET probe to the 141T spectrum analyzer.



Detail of the FET probe connection.



Detail of the mixer output connection.



These are the tank circuits that control the HF, local oscillator and mixer stages.



This potentiometer is for fine tuning purposes, and allows the tuning of the 1st IF stage linearity. This circuit compensates for the differences in vacuum tube characteristics which corrects distortion problems. This potentiometer is tuned when vacuum tubes are replaced to improve the linearity of the combined tube characteristics of the whole receiver by adjusting them just for the RV12P4000 of the 1st IF stage.



The potentiometer is in the center of the yellow circle. Note the compensation circuit is connected to the cathode and screen grid of the RV12P4000.