AEG / Telefunken E 1900/3
VHF - UHF Receiver E 1900/3; manufactured by AEG - Telefunken, Ulm. Telefunken also developed a VHF / UHF receiver for the E1800 receiver family: the E 1900 covers the frequency range from 20 - 500 MHz and with an option also 500 - 1000 MHz.
- 433 x 132 x 465 mm, 15 kg
- HT-1600 U2/2 frequency range extension up to 1000 MHz
- DZ-1610 add-on for broadband demodulation
- BT-1900 self test (BITE)
- Interfaces SER 1610 (serial), PSE 1800 (parallel), IEC 1810 (IEC bus)
The E 1900/3 receiver is housed in a 19„ rack mounting unit or a corresponding cabinet made of impact-resistant plastic.
At the top of the front panel there is a row of LED displays.
Below this, from the left, are the keys for controlling the memory and scan functions, and the numeric keypad for direct frequency entry.
Below the digital frequency display (which shows the working frequency to within 10 Hz) are the keys for storing and recalling memory, for setting the tuning speed and the tuning knob. To the right of this is the bandwidth display and the two buttons for selecting the wider and narrower IF filter, and below this the monitor speaker.
At the top right are the LED bar displays, the left one can be used to display the signal and the carrier (marked red), the right one shows the HF or LF signal strength. Below are the buttons for selecting the Operation mode, the modes A1, A3, J3E (SSB), P0N, F3 (FM) and A3E+F3E can be accessed directly.
A row of buttons below switches between automatic and manual RF control (AGC), activates squelch, etc. - The button on the far right activates the monitor speaker.
Below that are the rotary controls for volume control (AF Gain) and HF gain (MGC), and the STANDBY switch at the bottom right is the main switch. When the set is switched on, an internal self test runs first. If a key is pressed in the first two seconds, a key test is activated, each key press is followed by a corresponding number on the left display. Press the CLR key to exit the key test.
With the function COR, a carrier operated relay is switched on, when a signal is audible in the speaker, the contacts 37 and 49 in the 50-pole connector are connected, thus an external set, for example a tape recorder, can be controlled.
The HF signal from the antenna socket first passes through electronically switched band-pass filters in the HT 1610 module, which protect the following stages against overload and mirror frequency reception. After a multi-stage HV amplifier, the signal is converted to the first IF of 681.4 MHz in the first mixer. After passing through a bandpass filter and amplification, the signal is converted to 21.4 MHz in the second mixer. The main selection is carried out in the filter module FI 1610; there are seven switchable filter positions. The filter assembly has two automatically switched inputs for the HF part HT 1610 and the optional HF part HT 1600 U2/2 for the optional frequency range 500 - 1000 MHz.
The second IF is passed on to the DE 1610 demodulator module, part of the signal is amplified and regulated and is available for further processing at the „IF output 21.4 MHz, regulated“.
The HF is now controlled automatically (AGC, electronically controlled) or manually (MGC). In the Operation mode „automatic control with squelch“, an increase in gain activates the squelch function („SQ“ key) for very weak or missing signals.
For the reception of A2 (telegraphy tones, i.e. amplitude-modulated Morse code) and A3 (amplitude-modulated telephony) an envelope detector is used, for reception of A1 (CW, unmodulated telegraphy) and J3E (single sideband reception) a product detector. FM signals are demodulated in a frequency discriminator, all demodulated signals are then fed to the low frequency stage. The AF drives the internal monitor loudspeaker or a 600 Ohm output.
For F1B / F1C (teleprinter by frequency shift keying) an FSK demodulator is used, the signal can be taken off at the corresponding output for further processing.
Frequency processing is done by a PLL circuit in the SO 1900 and OZ 1610 boards, which prepare the variable oscillator frequency of 701.4 - 1181.4 MHz of the VCO and provide the 10 MHz signal as output signal for the second oscillator.
The BF 1900/3 control panel consists of the BEO 1910 control panel card and the BFT 1810 control panel driver card, which controls the LED indicators of the numerical displays and the keys. The microprocessor control processes the control signals from the operating elements, the displays on the front panel and the management and scanning functions of the 100 memory locations.
For reception of the 500 - 1000 MHz range, the signal is switched between the standard RF section and the optional HT 1600 U2/2 module via a coaxial relay. After amplification, it passes through three switched low-pass filters of 660 MHz, 830 MHz or 1000 MHz to avoid mirror signals and is then mixed down to a first IF of 181.4 MHz. After the second mixer, the second IF of 21.4 MHz is created, which is further filtered in the IF section and fed to the demodulation stage as described above.
The demodulator add-on DZ 1610 for broadband demodulation provides corresponding audio and also video signals for visualising a frequency section and also has a pulse extension circuit to make short radar pulses audible.
The set can be retrofitted with serial and parallel interface cards as well as an IEC bus interface.
The set is completely solid state.
The Telefunken E1900 was developed as a VHF / UHF receiver to the family of the VLF /HF receiver E1800 in the late eighties.