Inhaltsverzeichnis
Rohde & Schwarz VHF/UHF measuring receiver ESU
VHF/UHF measuring receiver ESU, BN 150021/2, manufactured by Rohde & Schwarz, Munich.
This measuring receiver was developed by Rohde & Schwarz in the 1960s; the set was supplied with different frequency adapters for the different frequency ranges.
Technical data
- Frequency memory: none
- Signal strength indicator: calibrated S-meter
Power supply
- Mains operation: 115, 125, 220, 235 V
- Batteries: 12 V
Dimensions
- 430 x 300 x 440 mm, weight 30 kg
Accessories
- Frequency adapters RF I (25 - 230 MHz), RF II (160 - 480 MHz), RF III (460 - 900 MHz), RF IV (850 - 1300 MHz)
- R&S supplied a wideband dipole antenna BN 1500202 and a logarithmic-periodic antenna BN 1500203 as antennas
- Mains cable part number 15001-4.42 and battery cable SN 15001-4.43 with two battery terminals, the pins for the mains cable and battery supply are wired differently on the coupling side, which is screwed to the front of the set, so if there are battery terminals on the cable, do not apply mains voltage!
- Panoramic display ESUP
- Frequency band recorder FBS to use in monitoring of band ranges
Operation
The VHF - UHF measuring receiver ESU with the BN 150021/2 in its robust metal cabinet weighs 30 kg and has four frequency adapters to cover the entire VHF/UHF range.
The frequency adapters are inserted into the set on the righthand side, with the antenna input on the bottom left, which, as like typically found in older R&S sets, comes in the Dezifix standard.
Using different power supply cables, the set can be operated from 220 V mains voltage or 12 V battery voltage, for example for field strength measurements in the field.
The set can be used as a measuring receiver for radio monitoring, for field strength measurements and also as a selective microvoltmeter. For field strength measurements, the average field strength value is displayed for amplitude and frequency modulation, the peak value for pulse-modulated transmissions and, in addition, the RMS value in the synchronisation peak can be displayed for field strength measurements of television transmitters in accordance with CCIR.
The receiver can demodulate FM transmissions (bandwidth ±60 kHz for voice modulated transmissions and ±12.5 kHz for carrier measurements), AM transmissions and also unmodulated carriers A1 audible by means of a built-in BFO.
The switches for the FM-AM-A1 and AFC operation modes are located below the row with the input socket and the intermediate frequencie sockets.
A synchronised calibration generator allows voltage calibration at all frequencies, and the levels can even be printed out on recording paper during registration.
At the standard voltage output (Rohde & Schwarz uses the typical Dezifix plug of the 1960s), the calibration voltage can be taken at a level of +90 dB above 1 μV (31.6 mV) after performing the calibration procedure CALIBRATION I.
The set is connected to the power supply using the appropriate cable for the voltage and switched on using the ON/OFF switch. For the frequency ranges 25 - 230 MHz / 160 - 480 MHz / 460 - 900 MHz / 850 - 1300 MHz, separate frequency adapters have to be used; the corresponding frequency is set on the spiral dial using the tuning knob.
To listen to the programme content, either headphones or a 15 Ohm loudspeaker can be connected to the corresponding sockets; the volume control above the sockets regulates the listening volume.
The antenna signal is fed into the decifix plug at the bottom left, the input impedance is 60 Ohm. The correct frequency adapter is plugged in and the set is switched on. Press and hold the Contr. calibration I button at the bottom left of the measuring instrument and use the calibration I level control at the bottom left of the frequency plug-in unit to set the instrument to full scale.
In the calibration II operating switch position, with the instrument switch in the black marked calibration II position, the calibration generator is set to maximum display on the instrument using the CALIBRATION.NEXT control at the bottom right of the frequency adapter. Now use the CALIBRATION II control below the instrument to set it to full deflection.
For measurements using the logarithmic range, the operating switch is now set to calibration III and this is set to full deflection using the calibration III control below the instrument. The calibration process is now complete.
For signal measurements, the frequency with a bandwidth of 60 kHz (12.5 kHz only for measuring very low voltages) is selected. The measuring switch is in the MEASURE position and the display is set to LIN 20 dB. Now, for high field strengths, switch to the 40 dB and 60 dB LOG ranges marked in red; the red dials on the instrument are much less accurate to read.
For normal audio signals, the average value measurement is selected and the dB level switch is now moved to a position with a clearly visible deflection below full deflection. The field strength in dB now results from the sum of the value displayed on the instrument + the dB value of the dB level switch position, which are added.
The reference value for 0 dB is 1 uV. To convert to the voltage, 10^(measured value/20) is calculated, i.e. if 14 dB is displayed on the instrument and the level switch is set to 20 dB, the calculated voltage from 10^(34/20) will correspond to 50.1 μV. Depending on the antenna used, any antenna gain must be added; this is not necessary for broadband dipoles.
The measurement of interference field strengths and harmonics is described in the manual.
For long-term observations, the automatic frequency correction (AFC) can be switched on to prevent the receiver from drifting over time.
Technical principle
Double conversion superhet with frequency adapters with spiral analogue dial.
Components
The VHF / UHF measuring receiver is largely equipped with tubes, some functions are realised with semiconductors.
