Balun replaced, dipoles repaired

Heavy winds destroyed the N-connector of the elderly balun feeding our 40m/80m/160m triple band dipoles during December 2016. Foto of the newly installed balun and the corresponding VSWR measurement below. GDX de Stefan OE1ABU and Chris OE1VMC




X-Band Scatter-Link via Schneeberg

On Dec. 29, 2016, interesting microwave QSOs were in the air: Mike, OE3MZC was on air as OE16YOTA on the 3cm band from Buchbergwarte (Locator:JN78xe). Gerald, OE1GAQ and Stefan, OE1ABU activated OE1XTU (QRG 10.3681 GHz, 250mW, 16dBi horn antenna) on the roof of the Institute of Telecommunications, see fotos below. Other stations heard by OE1XTU: OE1TGW/1 and OE4WOG/p. Below you see Gerald, OE1GAQ and Stefan, OE1ABU while listening to OE16YOTA in SSB using the Schneeberg as scattering object. Although OE1YOTA was clearly heard, a QSO with OE1YOTA was not accomplished. At least one QSO with Gerhard, OE1TGW/1 was completed. Next time better using directive antennas with significantly larger gain.

Short Wave Radio classes

During the Winter Term 2016/2017 four groups of 2-3 students participate in the short wave radio classes (LVA 389.030). After the lectures on HF propagation and antennas, radio block diagrams, modulation and coding, we enter the OE1XTU shack for gaining some real-world experience. We demonstrate J3E (aka SSB), A1A (aka CW), and various digital communication forms. The foto below shows Angelika and Valentin practicing their CW skills with the paddle: CQ CQ DE OE1XTU …


X-Band activity on Dec 18, 2016

Today was the last microwave activity day of the year. Vienna was cold and somewhat foggy. Nevertheless, OM Gerald OE1GAQ, Taulant, and OM Chris OE1VMC withstood the creeping cold on the institute’s roof for two hours and OE1XTU made three SSB voice contacts on the X-Band at 3 cm wavelength (10368.1 MHz +/- 6 kHz, H-Pol.) using 0.25W Tx power and 16dBi horn antennas. The OE1XTU transceiver was identical to the setup used on Sep 18 and yields 40 dBm EIRP.

Below left, you see the original paper log and on the right-hand side, the QSL card from OM Gerhard OE1TGW.


Storm damaged the DB36

During the night from Thursday Dec. 01 to Friday Dec. 02, there was heavy weather with wind speeds up to 120 km/h. Unfortunately, the resulting torsional oscillations of our pneumatic BigLift mast caused too strong forces for both the mast itself and the fiber glass tubing. The mast is now leaking air and the SteppIR DB36 reflector element cracked at two places near the end of the boom. Likely, the copper-beryllium tape is undamaged because the SDA100 controller was set to 14.100 MHz. Thus, the crack in the tubing was far away from the CuBe-tape. Currently, we are preparing the repair of the reflector element and replacing the broken mast, but it will take at least until summer 2017.

Diese Diashow benötigt JavaScript.

Welcoming first year EE students with the PIXIE 2

imageAt TU Wien, all first year EE students take the introductory course „EE?“ with lab tours in small groups through several institutes of the faculty. This year, Günther (OE1UBU) suggested to doodle around with the cute and tiny Pixie 2 transceiver for 7,023-7,026 MHz. So we got hold of a couple of do-it-yourself kits for two groups of EE students. It’s just two bipolar transistors and the famous LM386 integrated circuit for audio amplification. If only we all were proficient in Morse telegraphy

X-Band activity on Sep 18, 2016

On Sunday morning, Sep. 18, 2016, the Radio-Amateur Club of TU Wien participated in the ÖVSV microwave activity contest and the first three contacts were made in the X-Band: with OE3WHU/p, OE4WOG/p, and OM3KII. We used just 250 mW of transmit power which were fed directly into a WR90 horn antenna with 16 dBi gain. Doing the math, this amounts to 10 dBW equivalent isotropic radiative power (EIRP). The experimental setup is shown below: two separate horns are used: one for RX and the other for TX. This way, we don’t need any RX/TX coax relay. The setup was erected on the satellite antenna platform at 5m above the institute’s roof. Antenna height roughly 37m above ground level.



Prototype Setup for 3cm Band

OK, let’s give it a try on the 3cm band. The OE1XTU prototype setup consists of a YAESU FT-817ND QRP transceiver that is used to excite a Kuhne Electronic MKU 10 G3 432 Prof. 3 cm transverter (from 432 MHz to 10.368 GHz). Two separate horns are used for transmission and reception. No Tx/Rx coax relais in the feeds and we rely on the 16dBi gain of the horns alone: no dish for now. OE1XTU (Locator: JN88ee) goes on air on Sep. 18, 2016 for the OVSV microwave activity contest. 73 de Chris


Rotation of SteppIR DB36-Yagi controlled via StationMaster

During July and August 2016, Matvey and Arpad, OE1SZW, redesigned the motor control which rotates the BigLift mast carrying the  SteppIR DB36-Yagi. Analog feedback of the beam steering is provided to the StationMaster by a 10-turn 10kΩ potentiometer. Only one-and-a-half rotations in azimuth are tolerated in each orientation to spare the cables. The fotos below shows Matvey puzzling with the StationMaster’s interfacing and the two-relais circuitry reversing the single-phase AC motor.