Inhaltsverzeichnis
EKV (Single Sideband - Shortwave - Communications Receiver)
Manufactured by RFT / VEB Funkwerk Köpenick, VEB Kombinat Nachrichtenelektronik, Köpenick.
The EKV single sideband shortwave receiver was used primarily by East German intelligence and government agencies and was manufactured in various models and configurations by VEB Funkwerk Köpenick in the early 1970s. The set was fully transistorised and, with its mechanical IF filters, ISB demodulator, antenna diversity and the FSK demodulator, matched the state of the art in communications technology at the time. After the reunification of the two German states, numerous sets appeared on the second-hand market.
EKV 01: Basic unit in small cabinet, no MW / LW - coverage
EKV 02: Basic unit in small cabinet
EKV 03: Basic unit in small cabinet
EKV 10: Basic unit, DM031 A3B(ISB) demodulator NF 250 - 6000 Hz
EKV 11: Basic unit, LZ031 long wave add-on, AAD 02 antenna diversity, DM011 FM demodulator 1 channel
EKV 12: Basic unit, AAD 02 antenna diversity, DM023 FM demodulator 2 channels, DM032 A3B demodulator NF 300 - 3400 Hz
EKV 13: Basic unit, LZ031 long wave add-on, AAD 02 antenna diversity, DM023 FM demodulator 2 channels, DM031 A3B demodulator NF 250 - 6000 Hz
EKV 14: Basic unit, AAD 02 antenna diversity, DM023 FM demodulator 2 channels
EKV 15: Basic unit, AAD 02 antenna diversity, DM011 FM demodulator 1 channel
In the following I will only describe the basic receiver „Single Sideband - Shortwave - Communications Receiver EKV 01“.
Technical data
- Frequency range: optional LW, MW; SW (1.6 - 30 MHz)
- Frequency display: mechanical digital display, 100 Hz
- Frequency memory: none
- Sensitivity: SSB < 0.5 μV / Selectivity: ±75 Hz, ±250 Hz, ±700 Hz, ±1.5kHz. ±3kHz, SSB +6 kHz, +2.7 kHz (-6 dB)
Power supply
- Mains operation: 110/127, 220 V
- Batteries: 24 V DC
Dimensions
- 530 x 415 x 410 mm, weight 52 kg
Accessories
Operation
The EKV of the model series 10 - 15 with a grey metal cabinet measuring 53 x 41.5 x 41 cm with carrying handles on the sides. Depending on the model, additional plug-in units (diversity, ISB demodulator) are located above the basic unit. In the EKV 01 - 03 model series, only the basic unit with different IF filters and with / without coverage of the longwave range is built into the somewhat smaller cabinet. When buying a set, it is important to check whether the medium- / longwave range is really covered. The set can be operated with 110/127 and 220 V AC from mains or 24 V DC (from a vehicle battery).
On the front panel of the basic unit, the switches for mains operation, the quartz oven - which can remain switched on continuously to improve frequency stability - and battery operation are located at the top right. Below that, the fuses are accessible.
At the top left is the grill of the monitor speaker, which is activated by pulling the volume control located right next to it.
With the adjacent rotary switch, the appropriate IF filter can be selected from several CW, SSB and AM filters, which varies depending on the receiver type; the mechanical filters are characterised by their steep skirt factors. The switch to the right is used to tune the internally generated auxiliary carrier for SSB reception (BFO), the following rotary switch for mode selection. In turn, you can select from A1 (CW, Morse), A2,3 (AM reception with manual HF control, fast and slow AGC), A3J/A3A (SSB reception with suppressed or reduced carrier, manual and fast or slow AGC control). (SSB reception with suppressed resp. reduced carrier, manual and fast resp. slow AGC control), A3J/A3A with additionally trimmed AF frequency response 1.85 kHz and F4 (fax reception), i.e. Operation mode AM / SSB / CW as well as the AGC are set with this switch. Further to the right is the display instrument which, with a switch below it, can be used not only to display the HF and AF signal strength but also to check the supply voltages and other reference voltages.
The lowest row of controls includes the preselector group, the RF gain control and the tuning. The preselector tuning knob is located above the headphone sockets; with the preselector range switch next to it, this assembly can either be switched off (position 1.6 - 30 MHz) or the corresponding shortwave or MW / LW segment can be selected; when receiving with activated preselector, the left rotary knob must be used to peak for signal maximum. To the right of this is the control for the RF amplification; in the MGC setting of the operating mode switch, the HF and IF amplification is set completely manually; in automatic mode, the AGC takes care of this. In automatic mode, when the button is pulled, it is possible to leave the control of the 3rd IF amplifier to the automatic system, but to control the RF and IF1 amplification manually.
Further to the right are the tuning controls; the first two knobs switch the MHz digit and the 100 kHz digit respectively, the large tuning knob is responsible for the last digits. The frequency is displayed mechanically digitally with an accuracy of 100 Hz. With a small knob, the tuning can be mechanically blocked. At the push of a button, a calibration oscillator signal becomes audible at MHz intervals.
In practical use, the receiver is not easy to operate, or reception can be made impossible by operating it incorrectly. The receiver is switched on by pressing the yellow-orange power button. If the volume control is pulled out, a hiss should now be audible. For AM reception, the IF filter switch should be in the upper middle position at +/- 3000 Hz and the operating mode switch should be set to A2.3 Automatic 0.2 (seconds decay time). The preselector is first bypassed in the 1.6 - 30 position, the HF gain controls should be switched off or to the left stop. After setting the reception frequency 06 (MHz) with the first rotary switch and 1 (100 kHz) with the second rotary switch, the large tuning knob is cranked to 55.0, Radio Oesterreich International from Vienna should now be audible on 6155 kHz. In position UZF the measuring instrument shows the field strength as S-meter. If nothing is audible yet, make sure that the telephony demodulator TFA and the antenna 1 are selected and that the input signal is fed to the correct antenna input.
After these first steps, the operation of the various gain control modes, the characteristics of the IF filters and the preselector can be tested in various more difficult reception situations, and the EKV will prove to be a very selective and sensitive receiver, especially in the SSB mode. The sound from the small monitor speaker, however, remains tinny, a tone control or a notch filter are not provided, a connection with a NF notch filter can make a lot of difference here.
According to the analogue technology, the owner of an EKV has to do without the possibilities of digital frequency memories or clock/timer functions. On the other hand, the EKV with a second demodulator unit can be used for ISB reception (independent side band, different information is transmitted in both side bands, e.g. two voice channels), and the FSK demodulator can be used for radioteletype reception in Operation modes that are usually reserved for professional sets.
You can recognize the fully equipped EKV-13 from its a built-in LW/MW module (which can be recognized by the fact that the preselector ranges go down to 14 kHz) and various modules at the top: on the left the antenna switch / diversity add-on AAD 02, in the middle the SSB/ISB demodulator DM 032 and on the right the FSK demodulator DM 023 with options for radioteletype decoding.
Technical principle
Triple superhet with mechanical digital frequency display.
Components
The set is solid state.
