In spring 2004 the local club decided to expand the duration of the traditional august fieldday weekend. We rented the hut for a week in order to do something different this year. Our usual activities include HF, 144MHz meteor scatter and some other more digital stuff as provided by the club members.
The hut is located in the vineyards close to the „German Wine Road“ (JN49BD) in southwestern Germany. It is mainly used for barbecue parties in the summer. However, the distance to the next village and the availability of 3 phase 400V AC makes it very suitable for all radio activities.
So we decided to go for the 432 MHz EME challenge!
Tom, DL2IAN and Daniel, DL3IAE used to be very active on 144 MHz EME in the early nineties but due to other circumstances, neither of them was still QRV and all antennas were down. Daniel had began to work on a 70 cm GS35b amplifier some years ago. The cavity was finished but ended up in Tom’s cellar for a five year rest. The plan was to reactivate the metalwork and build a reliable power amplifier around it.
DL3IAE had built many DL6WU / DJ9BV style yagis for various bands with good results, so their latest designs were picked to get an optimum overall efficiency.
We ended up with 4 x 8,5 wl yagis on a 6m boom (BVO II). None of us had worked with open wire feed systems before, but the articles in DUBUS where very promising, so we went for it.
Matti, DH7PM assisted by making the 4:1 centre balun, which worked right away and could easily handle the power levels required for EME.
Daniel and Tom finished the antennas and the metal frame work within a week, but the feed system was not checked before we went on site in august.
Out of DL3IAE’s reservoir came the old FT736 and a driver amp (2 x 2C39 tubes).
We used Tom’s KR500 for vertical rotation of the array, and a modified CD45 for azimuth.
The preamp was built, using an MGF1302 and a BFP 196 as second stage (YU1AW style). There was no NF- meter available, so “ear tuning” was the only choice. We could never reach the performance given in the articles however. At this years Weinheim Radio Fair, it was measured at 0,8dB NF / 30dB gain and retuning did not improve it much.
Meanwhile Matti and Stefan, DH0SP provided a wlan link for our internet connection (luckily there is a radio amateur in the nearby village who runs an access point) and Andy, DD8IL had the great idea to get a webcam going. We had visitors from all over the world watching us working moonbounce.
With the availability of the internet on site we could announce our activities in the cluster, moon - net and activity loggers.
We found some sked partners and managed to work HB9Q (the PA went bang right before the QSO, so we used only 150 W from the driver!), DL9KR, SM2CEW, KU4F, F6KHM, G3LTF and VK4AFL. There was no random activity besides SV1BTR who did not hear us.
We heard our own echoes at a level we never expected. It all proved that our system was working!
With the ARRL EME contest coming up in October, DH0SP and DL3IAE decided to do some more activity in order to check the systems performance under “real” conditions.
We did some minor changes on the mechanical support and it took about 4 hours to get the station running.
Stefan provided the computer setup. This time we also used a Timewave DSP filter.
The team was partly supported by Matti, DH7PM (Wlan and mechanics) and the club’s chairman Elmar, DJ1UO.
Our own echoes were just at the SSB level and we worked 23 stations, EA3DXU with his 2 yagi setup being the smallest.
Due to time limitations we will not take part in the second leg of the contest, but please check our website regularly, DL0GER will be back!
Special thanks to everybody at K23 for the support (and understanding) and to DF8SEM for the internet link.
QSLs please via DL3IAE
Mail to Daniel DL3IAE