VHF - UHF monitoring receiver ESUM, BN 15076/5/P; manufactured by Rohde & Schwarz.

The VHF/UHF monitoring receiver ESUM consists of a basic unit in which frequency plug-in units for the corresponding frequency ranges are inserted. Several plug-in units can be selected directly from the receiver when they are installed in the „Standby Unit for ESUM“. The ESUM receiver is part of the PA004 direction finding system, which was used in Switzerland as ULPE.

• Principle: Superhet, IF
• Operation modes: A1, AM (A3), FM (F3)
• Frequency range: 30 - 1300 MHz in four ranges (25 - 230 / 160 - 470 / 460 - 900 / 850 - 1300 MHz)
• Sensitivity: AM (A3) / Selectivity:

• Mains operation: 220 V

• mm, kg

• In the Standby Unit for ESUM, three additional frequency units can be controlled directly from the main receiver.

The receiver is housed in a sturdy metal cabinet, the Standby Unit for ESUM for direct control of the additional frequency ranges has the same dimensions.

The frequency unit for the lowest frequency range 25 - 230 MHz is inserted on the right-hand side of the front panel and can be pulled out after releasing two locks.

The small monitor loudspeaker, the centre display instrument for displaying the signal centre and the signal strength instrument are located at the top left of the front panel.

Below this are the other controls in two rows and, at the bottom, the pushbutton unit with the four buttons for selecting the four frequency ranges or frequency units.

In the bottom row of controls is the mains switch on the far right, next to it the volume control, pulling it activates the internal monitor speaker. To the left is the operation mode switch for A1, A3 and F3 operation and, further to the left, the squelch control with the corresponding squelch threshold control.

In the top row of controls, from the right, you find the measuring instrument switch, the switch for the AFC (automatic frequency correction), the control for the IF bandwidth of 25 and 120 kHz and the controls for automatic and manual RF gain control.

The VHF / UHF monitoring receiver was developed by Rohde & Schwarz at the end of the 1960s and was used as an main receiver for the PA004 direction finding system.

In Switzerland, two PA004 direction finders were used as ULPE direction finders by the air force at high-altitude locations.

• Rohde & Schwarz ESUM on the website of www.radiomuseum.org