Ham Radio Stations
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Club and Contest Station DF 0 UD
The HFT departement runs the club and contest station DFOUD on the roof of building BB (12th storey) at a height of 55m with activities
in Shortwave (SW), VHF and Microwave Bands.
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| Generell View of Building BB |
| Equipments: | Short wave |
| | SW-Transceiver Yaesu FT902DM / FT101ZD |
| | Self-designed SW-Power amplifier with QB5/1750 |
| Antenna: | 80/40 Dual-dipole |
| | 3 Element SW-Beam FB33 |
| 2 m |
| Kenwood TS770 |
| Self-designed Pre-amplifier with 0.5 dB noise factor |
| Self-designed Power amplifier (student thesis) with two 4CX250B |
| Push-pull amplifiers, 750 W Output Power |
| Antenna: 9 EL Tonna |
| 70 cm |
| Kenwood TS770 |
| Self-designed pre-amplifier with 0.4 dB Noise factor |
| Self-designed Power amplifier with 4CX250B |
| 400 W Output Power |
| Antenna: 19 EL Tonna |
| 23 cm |
| Kenwood TS770 |
| Self-designed Transverter with 0.5 dB Noise factor |
| Self-designed Power amplifier with 2C39BA |
| 60 W Output Power |
| Parabolic dish Antenna, Diameter: 1.6 m |
| 13 cm |
| Self-designed Transverter with 0.6 dB Noise factor |
| Power amplifier with 2C39BA |
| 40 W Output Power |
| Parabolic dish Antenna, Diameter: 1.6 m |
| 9 cm |
| Self-designed Transverter, 0.5 dB Noise factor |
| Power amplifier with YD1060 and 2C39BA |
| 50 W Output Power |
| Parabolic dish Antenna, Diameter: 1.6 m |
| 6 cm |
| Self-designed Transverter, 0.7 dB Noise factor |
| Power amplifier with YD1060 |
| 3 W Output Power |
| Parabolic dish Diameter: 0.7 m |
| 3 cm |
| DB6NT-Transverter, Pre-amplifier with PHEMT, 0.8 dB Noise factor |
| Power amplifier with MGF2430 |
| 3 W Output Power |
| Parabolic dish Antenna, Diameter: 0.7 m |
| 1,5 cm |
| DB6NT-Transverter |
| 10 mW Output Power |
| Parabolic dish Antenna, diameter 0.3 m |
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Microwave-Beacon DB 0 GW.
The department operates since July 1986 the Beacon-Transmitter DB 0 GW in Duisburg.
The Beacon-Transmitter was developed and built by OM Jürgen Schulz (DL6EAV) for his diploma-thesis at the HFT department.
(Block diagram of the Beacon-Transmitter).
The frequency of the DCF 77 - Transmitter is taken as reference. For the reception of the DCF 77 - signals a special receiver has been developed,
which is able to process and clean-up the frequency signals from the DCF 77 - transmitter using a tracking filter.
If a failure of the DCF 77 - transmitter occurs, receiver-internal memories maintains the frequency stability for up to some hours.
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Frontal view of the Plug-in unit, the DCF 77-Receiver-Module on the left,
the two Beacon-Transmitter-Module on the right |
The transmitter systems (1 Watt output power each) are separated into an active part, which produces a precise frequency in the range of 480 MHz with high power,
and a passive part, which contains a frequency multiplier with varactor diodes close to the antenna. A control loop maintains the stability of the output power.
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View of a Power amplifier mounted on a Heat-sink |
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View on the top of the Synthesizer |
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Frequency Multiplier for 3.4 GHz |
The suppression of spurious and harmonic frequencies of the output signal is achieved by special microwave inter-digital filters, integrated in the frequency multiplier above,
which satisfies the requirements. The equipment has an emergency power backup.
SHF-Beacon DB 0 GW in Duisburg
| Call sign: | DB 0 GW |
Location:
| JO 31 JK
51° 25' 36'' Nord
6° 47' 24'' Ost |
| Height above S.L: | 55m |
| Harmonic signal suppression: | better than 80dB |
| Modulation: | A 1 A |
Send out:
| Call sign, Location, Frequency
2 Minutes CW |
Frequency precision:
(DCF77 synchronised) | Long time stabilised: 1 E-13 / h
Short time stabilised: 2 E-9 / h |
| Frequency: |
2320.85 MHz |
3400.85 MHz |
1296.95 MHz |
5760.85 MHz |
10368.85 MHz |
24192.85 MHz |
| Output Power: |
1 W |
1 W |
100 mW |
500 mW |
100 mW |
50 mW |
| Antenna: |
Double Helix antenna, horizontally polarised, omni-directional |
Waveguide Slot Antenna with 2 times 8 Slots, horizontally polarised, omni-directional |
| Gain: |
approx. 7 dBD |
approx. 9 dBD |
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Double Helix Antenna for 2.3 GHz und 3.4 GHz |
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Repeater Radio Station DB 0 DR
Since 1991 our department operates an amateur radio transmitter station for the 70 cm band, which was built by radio amateurs, members of the staff and students.
The automatic transmitter station serves mobil and portable radio stations to communicate with each other intra-city.
The transmitter signal is frequency modulated and radiates through a vertical polarized omnidirectional antenna at the top of our building BB.
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| Relais-Antenne auf dem Dach |
| Specification of the Repeater Radio Station |
| Output Power Level: |
P = 10 W |
| Location: |
Building BB of Area Bismarckstrasse 81 (55 m over Ground) |
| Range: |
approx. 30 km |
| Output Frequency: |
439,35 MHz |
| Input Frequency: |
431,75 MHz |
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Waveguide Slot Antenna with Horizontal Polarization and Omnidirectional Pattern
Vertically installed omni-directional Antennas are developed for the operation of the beacon
and the ATV-relais in the range of cm-wavelength on the basis of rectangular waveguides with arrays of slot radiators in one or both broad walls.
A QBasic code was developed for the design and dimensioning of antennas. You can download the latest version HLSSA54.bas.
It includes comments and references to publications on the basic design data in UKW-reports 1/91 (S. 50-55) und 2/91 (S. 71-77)
as well as the IEEE Antennas Propagation Magazine december 1991 (Vol. 33, No. 6, pp. 45-47).
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Photo of a 13-cm-Antenna with
9 Slotted-Pairs | |
Measured Omnidirectional Radiation Pattern
of a 23-cm-Antenna with 12 Pairs of Slots |
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Inverted-V Wire Yagi Array with Switched Beam Rotation for Frequency f=14MHz
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Inverted-V wire switched beam array antenna on the roof platform.
For better visibility, the dipole wires have been colored. |
The antenna utilizes six wires sloping under 30° elevation angle from the top of the roof platform tower in 7 meter height.
Using a switch unit, two wires are selected for the active dipole and are connected to the feed cable;
two wires are selected as parasitic elements and are connected to a capacitor as reactive load. The remaining two wires are left idle.
By cyclic interchange of the selected wires, we create six different combinations with radiation patterns separated by 60° in azimuth and covering 0 - 360° of pattern rotation.
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| Six wire arrangement of the switched beam array. | |
Sketch of principal patterns created by six selections of wires. |
The switch unit employs signal relays on a printed circuit board and the relays are remotely controlled by the operator using a digital circuit board with a 6-position rotary switch:
Changing beam pointing direction is practically without inertia.
The antenna was realized by our student, Ashraf Abuelhaija, as part of his Master thesis in 2010.
His thesis is available on request as a PDF document from the department.
A paper with detailed information on the design and performance was published in QST, December 2011, pp 34-37!.
Amateur Radio Links
Responsible / Contact
Please write to Mr. Rolf Küppers.
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