Rohde & Schwarz EK 071
manufactured by Rohde & Schwarz, Munich.
Parallel to the general coverage receiver EK070, Rohde & Schwarz launched the EK071 in 1979. Designed for fixed-frequency operation, the reception frequency is set by means of BCD switches, 50 frequencies can be stored even over a time of power failure.
- Principle: Double conversion superhet, IF 81.4 MHz / 1400 kHz
- Operation modes: A1 with BFO, USB / LSB, AM (A3)
- Frequency range: 10 kHz - 30 MHz
- Frequency display: Digital display, 10 Hz, via BCD switch
- Frequency memory: none
- Signal processing: RF gain, AGC fast/slow
- Sensitivity: CW up to 0.3 μV, SSB < 0.75 μV, AM (A3) < 2 μV / Selectivity: 150/450 Hz, 0.3/0.75 kHz, 0.6/1.5 kHz, 1.5/3.75 kHz, 3/7.5 kHz, 6/15 and 12/100 kHz and + and - 3.1 kHz SSB (-3/-60 dB).
- Mains operation: 110 / 120 and 220 / 240 V
- 483 x 132 x 515 mm, weight 23 kg
The Rohde & Schwarz EK 071 was sold in a desktop cabinet or as a 19 inch rack mount unit. As a rack mount unit it measures 48.3 x 13.2 x 51.5 cm and has a weight of 23 kg.
The receiver can be operated with different mains voltages of 110 / 120 and 220 / 240 V.
The front panel of the commercial set has a very straightforward structure, as usually found in Rohde & Schwarz sets: At the top left, you find the signal strength instrument, at the top right the monitor speaker, in between the LED chain for tuning FSK signals and the BCD switches for the BFO frequency, the frequency memory channels and the operation frequency. A tuning knob is not provided on the set, if you need that, you have to look around for an EK070.
In contrast to the EK070, the lower row of controls has conventional switches instead of touch buttons: on the far left is the rotary switch for the various IF filters. The EK 071 has a wide selection of narrowband CW filters and the bandwidths 3, 6 and 12 kHz, which are suitable for AM reception. For SSB reception, one 3.1 kHz filter each is provided for the lower and upper sideband, but before purchasing a set, check whether these filters are fitted. Below the LED line for displaying FSK signals is the operation mode switch, to the right of which is the switch for remote operation, memory recall and storage and manual operation.
Further to the right is the witch for the RF gain control; in addition to AGC with short and fast decay time and manual control MGC, combined control is also possible; this only starts after a certain signal threshold is exceeded. On the right is the control for the radio frequency Gain and the volume (AF Gain).
The monitor speaker can be switched off, and the mains switch is located in the upper right corner of the front panel.
After connecting mains and antenna, the operation is uncomplicated: switch on the receiver at the top right, select operation mode (CW (A1), SSB (USB/LSB) or AM), for CW reception it is recommended to select a narrow, for AM reception rather a wider IF filter. Depending on the intensity of adjacent channel interferences, it is possible to change from 3 to 6 or even 12 kHz. For the AM mode, a fast AGC time should be selected, otherwise the slow AGC. Now the frequency can be set with the BCD switches, the last two digits for the 100 and 10 Hz digit can usually be left in the O position when receiving broadcast stations.
Like the EK070, the receiver is highly stable, very sensitive, selective and, as usual with Rohde & Schwarz, the occurrence of mirror frequencies and other „ghost“ signal is not be expected: you are sitting in front of an absolutely professional receiver.
The EK 071 is similar to the EK070 in the fact that it is an excellent general coverage receiver that covers all the usual operation modes even in its standard configuration. However, due to the tuning with the decadic BCD switches and the lack of a tuning knob, it is far more suitable for fixed frequency reception than for search reception.
The stability of the EK 071 is excellent, there is also nothing wrong with the sensitivity and the usual IF filter selection is suitable for practically all situations; the set was also available with various special filters for special modes or, depending on the intended use, with cut-down filter selection, before buying it is worth checking all the built-in options.
The prices on the second-hand market reflect the fact that the EK070, which is better suited for search reception on the bands, is offered less frequently (more people tend to keep their set) and the EK071 is usually traded at a lower price, if one can ever speak of „low-priced“ at Rohde & Schwarz.
Technically, after a switchable attenuator, the signal first passes through a low-pass filter (< 500 kHz), a band-pass filter 500-1500 kHz for medium wave or a high-pass filter for frequencies above 1.5 MHz.
First, the antenna signal is converted to 81.4 MHz and passes through a 12 kHz crystal filter. After conversion to the second IF of 1400 kHz the signal passes the filter bank. After the IF amplifier stage, the signal is fed to a diode demodulator for AM reception, for CW reception the BFO is activated, for F1 / FSK reception the signal is amplified, and then is feed to a limiter stage and phase demodulator. The FSK demodulator controls the FSK tuning display and can directly drive a teletype machine.
The set is solid state.