This shortwave receiver was manufactured for the Kriegsmarine and is built like a battleship as well. It weighs a hernea-producing 65 kg (140 lbs). It was used on battleships like the Prinz Eugen or the Bismark, and it was used in u-boats. Many coastal ground stations also used this receiver. Rommel's Aftika Korps used the Lo6K39a as well because of its incredible sensitivity to intercept enemy transmissions. This is one of the most sensitive shortwave receivers ever built, and it must have cost the Germans a large sum per unit. Like with many other radio sets produced specifically for the military, the amount of intricate hand assembly and precise engineering used here is unequaled for that time period. This Lo6K39a was meticulously restored by Vladimir Dvorkin, from whom I purchased this radio.

The purpose for this receiver's design is very unique. It is a direct amplification receiver for a reason. On super-heterodyne receivers, the oscillator generates a weak signal at the required intermediate frequency. There is a danger, however small, that this signal escapes the receiver through the antenna, and will be triangulated by enemy direction finders. Whether or not this is in fact true, the Germans took no chances, and used a TRF receiver on their battleships.

Principle:

TRF - tuned radio frequency or direct amplification receiver, with manual regenerative (feed-back) control

Frequency Ranges:

8 frequency ranges

240 Volt utility power

Speaker system:

This set has no built-in loudspeaker. It requires a separate loudspeaker or headset.

Case material:

Vacuum Tubes:

(6) RV12P2000   StV150/20

The front view of the receiver.

One of the 8 frequency ranges on this receiver.

This is the frequency range selector switch. It is the size of bank vault handle, and feels like it when you turn it.

ON-OFF switch, with Morse code tone toggle. Tonsel. (Tonselektion)mit/ohne means Audio filter on/off, the switchable 1000Hz filter for CW.

Feedback control knob, used to clarify either Morse code or voice signals.

Tone control knobs and fine frequency adjustment knob.

Vacuum tube test meter. This meter test both the heater and anode voltage of every vacuum tube in the receiver.

Headphone / Speaker connectors. Above them is the lid for the display light of the console.

The manufacturer's data indicating the serial number 714, and the year of manufacture being 1942

This is the internal power supply which has been converted from 240 volt to 120 volt AC to wok with US outlets.

Another example of superior German engineering showing contact blades used for the external antenna connection.

A photo from the manual showing the lo6k39a mounted on a shock-absorbing bracket.