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.
On November 23 and 30, two groups of first year EE students soldered their Pixie 2 do-it-yourself kits. The photo below gives an impression of soldering fun. Then they listened to live CW transmissions at 7.023 MHz in the 40m band using the rooftop antennas at the Institute of Telecommunications: the 40m/80m/160m fan-dipole and the 4 element SteppIR DB36 Yagi-Uda. Dah-di-dah-dit / dah-dah-di-dah / dah-di-dit / dit / …
At 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…
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.
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
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.
During July and August 2016, Sam and Chris, OE1VMC, redesigned the remote antenna tuner. The wooden base of the homebrew design, is replaced by aluminum. The whimsical plastic gears for rotating the massive inductor are replaced by a toothed belt. First QSOs in JT65 mode on 160m using the brand-new OE1XTU Triple-Band Inverted-V (which is not yet fine-tuned for 160m) showed that the new design works fine.
Finally, today, the second passive element for the 6m band is mounted on the boom of the SteppIR DB36 Yagi antenna. This first passive element was mounted in October 2015. This modification promises 12.8 dBi gain and 27 dB Front-to-Back ratio. TNX to Matvey and Sam.
Well in-time for the Perseids meteor shower which will be at its maximum on August 12 this year.
This event promises some spectacular meteor scatter QSOs in the 6m band. Proceed with fingers crossed…
Do you think there is not enough space for a good top band antenna in downtown Vienna?
On July 7, 2016, we extended the previously existing Dual-Band Fan-Dipole in Inverted-V configuration for 80m/40m to the „top band“ (160m). Roughly 80m of copper wire span a bent dipole in Z-shape due to the space limitations on the roofs of the EE buildings of TU Wien. We were lucky, it was a beautiful sunshine day and had a lot of fun. More details follow. For now, just enjoy the team photo: Andreas OE1AJW, Stefan OE1ABU, Max OE1HXC, David, Sam, Lukas OE1LZW, Matvey, Shrief, and Chris OE1VMC.
With support from Arpad, OE1SZW, and Gregor, OE1GLC, the homebrewed remote antenna tuner came to life this week. It is really just a piece of minimal art: a variable inductor and a variable capacitor, both are operated by DC motors and controlled from the shack. The remote antenna tuner is installed on the rooftop near the vertical antenna’s base.
Remote Antenna Tuner