Kw. E. a

(Kurzwellenempfänger a)

 

The type Kw.E.a is a high-grade Heterodyne receiver, widely used with heavy transmitters, employing the following controls:

  • on/off switch
  • Tp - Ts switch
  • band switch
  • Vernier tuning control within the band selected
  • Antenna and ground connections
  • Antenna matching adjustment
  • Antenna selection switch with two positions (one, a straight connection to the first IF stage and the second, a coupled circuit tuned by "Ankopplung" to provide further selectivity if needed)
  • A separate switch for AVC
  • Voltmeter switching arrangement

For the pre-1943 version of the Kw.E.a, this switching arrangement consists of a row of push buttons that switch the meter from one circuit to another and permit eleven different readings to be taken from the same meter without removing the receiver from its chassis. There are neon tubes near the HF tubes to protect the tuning coils nearest the antenna from large voltages induced by comparatively nearby transmitters. The set should not be worked without these tubes. The receiver is in a reinforced wood container with two collapsible handles and removable lid. It has a 5-strand connector cable 49 inches long for power supply connection.
 
 
Specifications
 
YEAR INTRODUCED :
1938
   
MANUFACTURER: Telefunken
   
FREQUENCY RANGE:

0.98-10.2 MHz in 5 bands as follows:

  1. 0.98-1.61 MHz
  2. 1.56-2. 2.55 MHz
  3. 2.47 - 4.06 MHz
  4. 3.94 - 6.395 MHz
  5. 6.205 - 10.2 MHz
NUMBER OF CRYSTALS:
Two, used in BFO at approximately 1800 KHz separation. The one used for calibration works from bandwidth 1-7.
PRESET FREQUENCIES:
None
ANTENNA:
High, low, roof, ground or auxiliary.
TUNING:
Crystal. Tuning is accomplished by control marked "Anpassung".
SENSITIVITY:
na
SELECTIVITY:
Variable -- receiver controlled by "Bandbreite" which is graduated from 1-8, 1-4 being for telephony and 4-8 for telegraphy.
POWER SOURCE:

Filament: 2 volt DC from batteries or rectifier unit at 1.8 Amperes. Plate: 90 volts from battery converter unit EU-d or rectifier NA6 / NA6a at 20-25 mA.

SIMILAR SETS
German long-wave receiver type (Lw. E. a), American BC-342, BC-344
POWER OUTPUT:
na
TUBES (TYPE and NUMBER):

11 x RV 2 P 800 (pentodes), employed in the following stages: 2 RF amplifiers, one local oscillator, one mixer, 3 IF amplifiers, one heterodyne, one detector, one IF amplifier, and one for AVC.

2 x TE30 neon lamps

USE:
For stationary and semi-mobile heavy Army and Air Force stations and for stationary Naval stations.
TYPE OF SIGNAL:
CW, tone and voice.
RANGE: (MILES)
na
TO COMMUNICATE WITH:
Heavy transmitters -- 120W.S. and 70 W.S.
TO REPLACE IN PART:  
   
TRANSPORTATION:
Fixed or semi mobile (in vehicle)
 

 
The front panel. Some of the control knobs had surface "zink-pest" that I cleaned up and subsequently protected the knobs.

 

 
The front panel from another angle.

 

 
The year of manufacture is 1943. Based on the manufacture dates stamped onto the coil turrets, this radio was made in October 1943.

 

 
Attention, no more than 2 Volts of filament current!

 

 
Antenna connection controls, antenna connector, ground connector and one of the unlocking screws to remove the receiver from its housing.

 

 
Other controls.

 

 
The other disassembly screw, along with the tone filter switch. The on/off switch is below.

 

 
The coil turret drum. Notice the paint seals on all of the screws. Only properly trained staff with the correct diagnostic equipment was capable of correctly tuning this receiver. Any unauthorized field repairs were easily detectible by broken paint seals. The other purpose of these seals was to prevent the screws from loosening from vibration.

 

 
The TE30 Neon tubes to protect the receiver from antenna lightning strikes.

 

 
The coil turret drum is moved from one position to the next by means of a Maltese cross mechanism shown in this photo on the extreme left of the turret. But before the coil turret drum starts to rotate the contact fingers are lifted from their partners on the coil turret by means of a camshaft in front of the turret. When the turret has come to rest in the new position, the contact fingers are lowered onto the turret again. The fingers make a slight wiping movement when pushed onto the ring shaped contacts on the turret, thereby removing possible dirt deposits.

 

 
When I received the first images of this receiver, I noticed that the vacuum tube on the bottom right of the above image was different from the rest, and suspected a reworked system.

 

 
When I got the unit, the above contraption was pulled out of the first socket.....

 

 

An RV 12P 2000, which is a tube with a 13 Volt filament current, completely unusable in the Kw. E. a.