Marine "Gustav"

1. Purpose

The Lo 70 KL 40 device (also known as the naval small transceiver or Marine-Gustav) performs radio communications between ships and from ship to shore stations. It operates on both long and short waves.

2. Mechanical construction

The device is comprised of five main sections:

  1. Control block
  2. Transmitter
  3. Receiver
  4. Antenna block
  5. Power supply

The control block, transmitter and receiver are inserted into a metal case and are fastened with screws. Exhibit 1 shows these device blocks. The receiver is on the left, the transmitter on the right and the control block is below. The antenna block is on the far left. The combined set sits on rubber feet. To remove the devices from the case, one must loosen the screws with the red ring around them. The vacuum tube removal screw must be removed from the receiver to re-insert it into the case. The electrical contacts are connected when the blocks are inserted into the case. A picture of the reverse of the case shows where the cabling and connection box. In exhibit 2 and 3, the individual blocks are shown separately. The power supply may either be hanging or stand on a flat surface and be attached. There must be a minimum clearance of 60 mm around the power supply to allow the free flow of air. The antenna block can be connected as a separate device or be connected directly to the transmitter. It is connected by a special construction to the backplane of the case. Current is provided by two cables. With a feature of the device block, the antenna block with case can be removed from the inserted devices that are fastened to the case. The normal mode of operation has the antenna block and case connected to the rest of the unit.

3. General internal (inter-block) connectivity

The internal connectivity of the blocks is shown in exhibit 8. The control block, transmitter and receiver are connected through male/female connectors on the back of each block and on the backplane of the case. These connectors provide the voltage for each block as well as signals. The utility power supply can be exchanged for an Umformer. The inter-block connectivity does not need to be modified.

4. Frequencies

300 to 600 kHz and 1,5 to 7,5 MHz. Identical frequencies for the transmitter and receiver are divided into the following ranges:

Range I ---300 to 600 kHz (identifying color RED)
Range II --1,5 to 2,5 MHz (identifying color BLUE)
Range III -2,5 to 4,3 MHz (identifying color BLUE)
Range IV -4,3 to 7,5 MHz (identifying color BLUE)

With ambient temperatures between +15 °C and +40 °C within the transmitter block, frequency errors of ±400 Hz in the long wave range, and ±2 kHz in the shortwave ranges may occur.

5. Operating modes

  1. Radiation-free tuning
  2. Telegraphy (A1) - without tone
  3. Telegraphy (A2) - with tone
  4. Telephony (A3)
  5. Hellschreiber transmit
  6. Hellschreiber receive
  7. Frequency control

6. Power

The power output of the transmitter from the antenna circuit is 70 Watts ± 20% for all frequency ranges. In the operating modes of telegraphy with or without tone, power can be reduced to 1/10, 1/100 or 1/1000 of full strength. Sensitivity of the receiver in operating mode of Telegraphy without tone (tonlos) is 1.0 µV for 1 Volt of output voltage.

7. Schematic

The transmitter is designed with two stages

a) Self-regulating master oscillator stage
b) Power amplifier stage with two parallel-connected vacuum tubes

The receiver is of a heterodyne type with the following seven stages:

aa) First HF stage, 1 tube RV12P2000
bb) Second HF stage, 1 tube RV12P2000
cc) Mixer, 1 tube RV12P2000
dd) First IF stage, 2 tubes RV12P2000
ee) Second IF stage, 2 tubes RV12P2000
ff) Third IF stage, 2 tubes RV12P2000
gg) LF stage, 1 tube RV12P2000

The device is equipped with the following vacuum tubes:


7 a) 1 tube LS 50
7 b) 2 tubes LS 50


Same as 7 aa) to 7 gg), further 4 oscillating and 2 rectifier tubes RV12P2000 so 16 tubes total.

Also included in the receiver's inventory:

1 glow lamp Te 30
1 stabilizer StV 150/20
1 scale illumination lamp Osram 12 volt, 5 Watt

The control block also has 4 tubes RV12P2000

8. Antennas

The same antenna is used for both receiving and transmitting, and is switched when keyed internally. Its capacitance, including the feed line, must be between 330 pF and 1100 pF. When operating with long waves, a different antenna capacitance must be established (see paragraph 68). For the short wave ranges, make sure the feed line does not exceed 21 meters.

9. Power supply

The device can be operated with the following power supplies:

a) with utility power of either 110 or 220 Volts
b) with DC power of either 110 or 220 Volts
c) with a 24 Volt battery

The power supply device in scenario a) is a utility power device, and in scenarios b) and c) is an Umformer. They produce the following voltages:

a) Filament voltage 12,6 Volts
b) Anode voltage 800 Volts = for the transmitter
c) Screen grid voltage of 250 Volts = for the transmitter
d) Anode voltage 200 Volts = for the receiver
e) Negative grid bias voltage -400 Volts =
f) Auxiliary voltage 24 Volts = (for relay)

With AC utility voltage the outlet voltage can be -15% to +10% and DC can vary from -18% to +7% from nominal voltage. With battery operation, Umformer input voltage may vary from 23 Volts to 28 Volts. Power consumption can be approximately 550 VA with AC utility voltage and 660 Watts with Umformer operation.


Translated from "Die deutschen Funknachrichtenanlagen bis 1945 - Band 2 "Der Zweite Weltkrieg" by Fritz Trenkle

Lorenz created the new 40/70 Watt SW/LW radio station called the FuG 10 which was an improvement over the older 40/70 Watt FuG IIIaU station (1927-1930 construction). The company received a contract for the development of an appropriate naval version Lo70KL40 "Marine Gustav" with 70 Watts of antenna power in frequency ranges of 300-600 kHz (for air navigation services) and 1,5 - 7,5 MHz for tactical communication. In contrast to the airplane device FuG 10, which had separate transmitter and receiver for LW and SW band, here a transmitter, a receiver and an antenna tuner were provided which handled the tuning for both frequency ranges, therefore simultaneous reception on SW and LW was not possible. The two-stage transmitter has one LS50 tube as the master oscillator, and two LS50 tubes as power amplifiers connected in parallel. The reciever has two HF stages, mixer and local oscillator which are switchable between 4 frequency bands, and also with a three-stage IF section with a telegraph heterodyne for use with low or high intermediate frequency to LW or on HF. There were the IF detector, AGC stage, audio pre-amp and power amp stage, and a frequency test signal generator. These circuits were used during operation over all four frequency ranges. The receiver used 16 x RV12P200 vacuum tubes. The control block contained the tone generator, the three-stage modulation amplifier (all 4 x RV12P2000) and the operation mode switch with settings: "Radiation-free tuning / Telegraphy (A1) - without tone / Telegraphy (A2) - with tone / Telephony (A3) / Hellschreiber transmit / Hellschreiber receive / Frequency control". The sensitivity of the receiver is approximately1µV for 1V of output voltage, and the frequency drift of the transmitter is about 0,3 %.

Allegedly, only six prototypes were built (after the war, however a larger number said to have been converted to other frequency ranges ???). The reason for the non-introduction of this advanced device may have been bottlenecks in the production of radios.

Telegráfia Praha-Pardubice

This set was designed by the Lorenz, Berlin company and manufactured by the Telegrafia Praha-Pardubice company. The Telegrafia company was founded in 1919 to manufacture radio equipment for the civilian market. They also ran several large broadcasting stations. Forty percent of Telegrafia was owned by its employees, and sixty percent was owned by the Czechoslovak government. In 1938, when Germany invated Czechoslovakia, Telegrafia was repurposed to manufacture military radio equipment. The Lo70KL40 set was one of the products manufactured for the Kriegsmarine. In 1946, Telegrafia was absorbed by the Tesla firm, which operated until 1990 since it could not compete well globally with other electronics companies.

From Radiomuseum.org

The company Telegrafia was founded on 18.10.1919 as a public limited company. 60% of the shares were owned by the state, 40% belonged to the workforce. The first operation was located in the municipality Roztoky near Prague. The ensuing flood of orders from the post office and also by private customers prompted the Board of Directors in 1920 to incorporate a number of small suppliers who were also created after the second world war soon always forcing new orders for telephones and telephone exchanges, which in European countries such as the Turkey, Bulgaria, Yugoslavia etc. exported for company expansion. Not infrequently orders before German and Austrian companies were able to be obtained. Looking for a suitable operating site, which could also accommodate the construction of housing for the workforce, were discovered in 1922 on the not quite finished shoe factory Zeisl in the city of Pardubice, about 130 km east of Prague. Between 1922 and 1923, this factory was completed, 323 employees were working there. In the continued operation in Prague 488 people were employed at that time. Despite the rapidly evolving telephone industry, the company management decided to enter into the development and manufacture of radio equipment. From 1923 the first units came under the brand name "RADIOLA" on the market. The further development of Telegrafia was delayed by the Great Depression in the 1930s. After that, the production of radios increased strongly: Annually several models came onto the market, up to the occupation by the German Wehrmacht, there were 38 during the second World War II had the company Telegrafia work for the German armor, while you got there, new materials and technologies, such as know-molded from lightweight metal chassis for radios, completely new, the production of picture tubes was for radar equipment of the Luftwaffe. The end of the company Telegrafia came on 31.12.1945: According to the government decree on the nationalization of major industrial plants it was incorporated in the state Group TESLA. There ended up also including companies such as Philips, Siemens, Lorenz and Telefunken. Misik By Georg freely translated from Czech. Source:http://cb.cwal.net/cbmuseum/historie2/.

This radio set belonged to amateur radio operator Erwin Greiner, who's personal documents may be viewed on this page.
MANUFACTURER: Telegrafia, Praha (design by Lorenz)

300-600 KHz, 1.5-7.5 MHz in three bands.

1 - for frequency calibration


Compatible wire antenna. Direction-finding loop with special direction-finding attachment.

(MO OR CRYSTAL) master oscillator

Sensitivity of the receiver in operating mode of Telegraphy without tone (tonlos) is 1.0 µV for 1 Volt of output voltage.



Utility power: S-80-4348-C power supply. 110 V or 220 V AC input; for output see above

24 Volt battery: Umformer - 660 Watts total power consumption; for output see above

FuG 10 for the Luftwaffe

70 Watts. (can be switched to provide 1/10, 1/100 or 1/1000 the output)


Receiver: 15 x RV12P2000, 1 glow lamp Te 30, 1 stabilizer StV 150/20

Transmitter: 3 x LS50

Control block: 5 x RV12P2000

Power supply (utility): 1 x AZ12, 2 x RG62

Ship to ship, and ship to shore stations

A1, A2 and A3


Other ships and naval shore stations

Other known Lo70KL40 units in collections:


The Lo70KL40 transceiver. All blocks were completed in 1944. The blocks are in the following order from left to right: receiver, transmitter, antenna matching. At the bottom is the main transceiver control block.



The receiver block



Transmitter block



Antenna matching block.



Antenna galvanometer.



Antenna matching control. The two red sections on top represent the long-wave frequency bands. The other sections represent the medium-wave and short-wave bands.



Connector section of the control block. There are sockets for two headphones, a telegraph key, microphone. Additionally, this transceiver can receive and transmit Hellschreiber messages through the "Typenbild-Empf." and Typenbild-Send" sockets respectively.



Control section of the control block. From left to right: main mode selection switch; volume of control-block headphones; transmitter power control; power switch.



Antenna connector on top of the set.



Power cables which connect to a socket at the rear of the power supply.



Power supply for utility power.


























16 Tubes RV 12 P 2000
1 Glimmlampe T30 Fl 26624
1 Stabilisator St V 150/20
1 Soffitte 12V 5W






























The manufacturer label on the control block.