|The MicroWave contacts we made|
While being very far to set new records, we had great fun with every single contact we tried. Even at the first test from a corner of a room to the opposite one, you feel the challenges of being a microwave operator. Everything can go wrong when your key equipments are homemade, and non-extensively tested. But the first difficulty, here in Sicily, has been to find other hams active on 3cm. That's why we have setup two complete 10GHz rover stations to make our experiments on this band.
Here we keep a Log of the 10GHz contacts we have been able to establish with our equipments, together with a photo gallery and some comments we like to share with you.
1. This was our first true 10GHz contact and first on-air verification of our stations, just after completion of Andrea's transverter that, at that time, had not the GPS lock circuit yet. The locations chosen were perfectly LOS, with easy eye-aiming, and in fact the contact was done easily with strong signals also in FM and with low-gain antennas. But we didn't know yet that our equipments would work! This first experiment was so smooth and encouraging that, immediately after, all our doubts disappeared and we both felt that those 41Km weren't that much at all. Our thanks to IW9CRG that has offered the large terrace of his penthouse located on the south side of Etna volcano, and to IW9GUR who, despite of his his leg recovering from a surgery, has actively participated with his experience from DX-peditions and field-days.
2. This very successful long-range contact was not "scientifically"
programmed. Andrea's location was simply the highest place close to the
town in Campania where he and his family were spending Easter vacations.
Without any experience, we did not know exactly where to look for the
Sicilian location, so we made our best guess identifying a site on
the highs of Monti Nebrodi with a good visibility of the Tirrenian coast,
with Eolie Islands at the horizon. According to the simulations we did,
about 140Km of sea would be below LOS, but we have been positive-thinking...
and lucky. This time Andrea had a dish to increase the antenna gain, and
also the GPS frequency lock was implemented in his transverter. But
unfortunately GPS signals were jammed in his location, therefore also this
time we had to play for a while to find each other. The
FT817 has been a big help in this task because it is able to send
continuously a Dih-Dah sequence with a simple trick: just set it in CW
mode with the internal auto-keyer enabled, and afterwards short to ground both dot
and dash pins of its paddle jack (or simply insert a stereo earphone that practically acts a a short). By continuously transmitting
and slightly moving the dish, one station got better chances to be caught
by the other.
3. Just a summer exercise from our respective holiday locations, but with a little bit of risk because we both were at sea level and LOS slightly obstructed by headlands in two points. Nevertheless, the direct path contact has been done easily, plus an interesting and successful experiment using as a reflector the large rocky hill of Taormina, about 1Km NE, behind Andrea's location.
4. Also this year Andrea moved to I8 for his Easter vacations, so it was time to try again the big jump... Both transverters were significantly upgraded in power, and oscillators were locked to an internal OCXO to avoid bringing the extra load of the GPS disciplined references. To make things less easy, this time Andrea drove his car to I0 to set his equipment on the beach of Terracina (LT), just few meters above the sea. Johnny went again to the location in Monti Nebrodi at 1200m. QRB was slightly below 400Km, and the forecast of tropo index in the south Tirrenian sea was 2 (fair). Despite of that, signals were very strong also this time, and the QSO has been like talking at the telephone, also in FM. Sporadic, deep fading was observable, but the communication has never been lost. The OCXOs, previously tuned in the lab with the GPS reference, have been proven very stable, and fine tuning has been rarely necessary. We had the time also to stop the QSO and make an on-the-air check of the CW beacon recently built by Johnny, running 150mW in a low gain sectoral horn antenna. The beacon was transmitting from Johnny's location in Monti Nebrodi and was received 5/5/9 by Andrea in Terracina. Here is a short video of this QSO.
5. First QSO with stations outside Italy (and different from Andrea IW9HJV!). The contact was done easily at first try (QRB is not challenging) but this contact has been important to test a new 80cm dish and to learn more microwave DX techniques from a new /P location.
What we learned...
Apart of the common-sense rules you may easily imagine, like
"bring also a spare battery and don't forget to charge both the
night before", there are a few lessons we learned during our few
experiences as 10GHz ham operators, and we like to share them with you.
- Cellular phones can also be a good (even while expensive) back-channel for longer ranges, but not rely too much: there could be no GSM coverage where you are going to operate
- Plan in advance one or two microwave frequencies to operate on, and store the corresponding IF frequencies in both IF radios: this avoids calculations and/or misunderstandings when on-site. You will have many other things to think about.
- Study in advance and bring a note of the azimuth values from both locations, and don't forget a good magnetic compass (yes, is common sense, but is so important...).
- When outdoor, you normally run with batteries and your lab is not with you. A very useful thing we have put in our transverters is a simple meter to check the battery voltage and the TX power: if you are building a transverter don't consider it as an accessory gadget.
- Similarly, on the field, you might need to check if the transverter is able to receive correctly. When no beacons are in range, ground noise/sky noise can theoretically help, but we noticed that by ear is a very thin difference to catch. Without the antenna, it is much easier instead to hear the noise difference between terminated/unterminated antenna port: bring a 50ohm termination with you.
- Setup a system to continuously transmit a characteristic signal. You can use a looped voice recording in your MP3 player, or a CW keyer with memory. A PC needs a lot of power, space, and it's the very last tool we would suggest. Bottom line, if you have an FT817, use a 3.5mm-plug stereo earphone (read above).
If you are interested to get more details or to arrange a sked, feel free to drop an e-mail atour e-mail address
|The projects presented in these pages are our own design and have been tested and verified by ourselves at the best we can. However, they might be inspired by concepts, ideas, solutions coming from known-art or free resources on the Web. We provide them as reference designs to skilled hobbyists and technicians who are willing to reproduce them for non-commercial use. Your results might be different from ours and we cannot be considered responsible for that. Similarly, we are not responsible for any damage or injury you might incur while building, assembling or using the equipments, projects or ideas presented in these pages. The firmware embedded in our projects is our property unless differently stated and when available in the Download Area it is license-free only for non-commercial purposes.|
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