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Einheits - Verkehrsempfänger EKV - 13

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überarbeitet am 22.10.2010

The standard communications receiver EKV has been in use by military and governmental services in the former German Democratic Republic and has been produced in different configurations by VEB Funkwerk Köpenick in the seventies. The receiver is completely solid state and represented the state of the art with it's mechanical i.f. filters, ISB demodulator, antenna diversity module and FSK radioteletype demodulators
After the merger of the two German states, many of these sets have been faded out and were sold to the public for a moderate price. hergestellt.

EKV 01 Base unit in small cabinet,
EKV 02 Base unit in small cabinet,
EKV 03 Base unit in small cabinet,
EKV 10 Base unit, DM031 A3B(ISB) demodulator NF 250 - 6000 Hz
EKV 11 Base unit, LZ031 Langwave adaptor, AAD 02 antenna diversity, DM011 FSK demodulator 1 channel
EKV 12 Base unit, AAD 02 antenna diversity, DM023 FSK demodulator 2 channels, DM032 A3B demodulator NF 300 - 3400 Hz
EKV 13 Base unit, LZ031 Langwave adaptor, AAD 02 antenna diversity, DM023 FSK demodulator 2 channels, DM031 A3B demodulator NF 250 - 6000 Hz
EKV 14 Base unit, AAD 02 antenna diversity, DM023 FSK demodulator 2 channels
EKV 15 Base unit, AAD 02 antenna diversity, DM011 FSK demodulator 1 channel

In the following text, I only refer to the basic receiver of the Einheits - Verkehrsempfänger EKV - 13:

Triple conversion superhet, I.F. 37,8 - 38,3 MHz, 3,2 MHz, 200 kHz

mechanical digital display, resolution 100 Hz

AM, USB, LSB

Sensitivity at 5 MHz SSB < 0.5 uV

Selectivity -6 dB
+6 kHz, +2,7 kHz, +/- 3 kHz, +/- 1,5 kHz, +/- 700 Hz, +/- 250 Hz, +/- 75 Hz

RF Gain, two speed AGC, antenna diversity, ISB demodulator

The receiver EKV in model variants 10 - 15 comes with a huge metal cabinet of 53 x 41,5 x 41 cm with carrying handles on both sides, above the receiver itself, there is room for another three modules (diversity adaptors, special demodulators).
With the model variants EKV 01 - 03, only the basic receiver with different filters and coverage of the longwave band is built into a smaller steel cabinet.
The receiver can be powered from 110/127 or 220 V mains or from 24 Volts DC from a vehicle battery.

On the frontpanel of the basic receiver, You find in the right upper corner the switches for mains operation, the quartz oven which will heat the main oscillator's crystal to keep a constant temparature and reach very high frequency stability, the switch for battery operation and the fuses.
In the left upper corner, You find the monitor speaker, it is activated, when the volume control knob right next to it is pulled out.

The rotary control at the right let's You select the i.f. bandwidth filters, according to the different model variants, You will find a slightly different filter selection. There are all mechanical filters with steep filter skirts for optimum selectivity.
Now for the upper row of controls, the ones next to the monitor spekaer: The slightly smaller control is used to control the BFO beat note in CW / A1 mode, next is the reception modes switch. You can select from the following modes: A1 (CW, continuous wave morse code transmissions), A2,3 (AM reception with manual R.F. gasin control or automatic gain control with slow and fast AGC decay time), A3J/A3A (single sidedanb transmissions with suppressed or reduced carrier, with manual or fast / slow automatic gain control), A3J/A3A single sideband reception with reduced audio frequency passband up to 1,85 kHz and F4 (Fax reception) - You see that this switches combines the reception mode and MGC/AGC, as found in the Telefunken E1500 receiver, too.
The instrument can be set with the knob just below to display not only the R.F. and audio frequency levels, there are positions to control several voltages in the receiver.

The bottom row of controls consists of the preselector group, the R.F. gain and the frequency switches / tuning knobs. The preselector tuning knob is located just above the headphones sockets, select the preselector waveband with the rotary control next to it, with the position 1,6 - 30 MHz, the preselector is bypassed in the complete shortwave range.
At the right, You find the R.F. gain knob to manually adjust the R.F. gain, in AGC modes, the gain is controlled automatically. When the knob is pulled out, the gain of the third i.f. stage is controlled automatically, You can manually control the R.F. gain and the gain of the first I.F. amplifier.
Further right, You find the frequency selectors. The first two rotary knobs select the MHz and the 100 kHz decimals and the big main tuning knob the 10 and 1 kHz decimals of the reception frequency, the frequency is displayed with an odometer type digital display with a resolution of 100 Hz. A small knob lets You mechanically block the the tuning mechanism. A pushbutton operated 1 MHz oscillator lets You control the dial calibration.

In practical use, the receiver is not that straightforward to operate - or You can end with very poor results when the controls are not set correctly.
Press the yellow - orange button to switch on the receiver. When You have pulled out the volume control and have to volume turned up half way, You should hear a noise from the speaker.
For reception of an AM shortwave broadcast signal, select the +/- 3000 Hz filter, the modes switch should be on A2,3 / Auto(matic) 0,2 (seconds AGC decay time). The preselector is first bypassed in switch position 1,6 - 30, the R.F. gain controls should be switched off resp. turned counterclockwise. After You set the MHz control to 06 (MHz) and the 100 kHz selector to 1 (100 kHz), You can use the main tuning knob to tune to 55,0, now You should hear Radio Austria from Vienna on 6155 kHz. In position UZF, the instrument will act as signal strength meter.
If You can't hear anything, make sure that the telephony demodulator TFA (telephony channel A) and antenna 1 is selected, the R.F. signal should be fed into the correct antenna connector (should be ANT 1).
After these first steps, You can try the different I.F. filters, the different gain controls and the preselector under more difficult reception conditions (select the correct preselector range and tweak for signal maximum). The EKV is a stable and sensitive performer also in SSB modes.
The audio quality out of the monitor speaker is quite poor, You can improve it quite much when you connect the receiver to a good external speaker and maybe add a A.F. noise filter.
As the EKV is a completely analog radio, You have to do without electronic frequency memories, a clock or timed operation.
In connection with additional modules as an ISB demodulator (independant sidebands, i.e. on one frequency, two different informations or programs can be transmitted simultaneously, one in the upper and one in the lower sideband), an FSK demodulator for radioteletype and data / fax transmissions and antenna diversity, the EKV gives You possibilities only found on spezialised commercial receivers.

weitere Lektüre:
d: CD mit Scans der Betriebs- / Serviceunterlagen des EKV erhältlich unter Ronny_Kunze@gmx.de

© Martin Bösch 10.10.2010