My best terrestrial DX on 3 cm !!!

X band terrestrial communications, best QRB hitherto:

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My best DX on 10368 MHz so far was a 451 km QSO with OM Karl, SM3AKW back in 1996 (Status change - see below - MF, 23.05.2000). This was the Finnish record for this band until May 1999 when OM Pertti, OH2AXH ( KP20OK ) worked SM1HOW (JO97LK) - just barely some kilometers longer ;-). My QSO with Karl took about a week of regular skeds to accomplish. We attemped the contact every morning and evening during a belt of high pressure and hot, still weather. Finally one morning Karl came through on CW just about as loud as if he were in the neighbourhood. Of course also SSB was readily copiable too. The propagation mode was a combination of tropospheric scatter, ducting and also propably ducting over the sea path (almost half of the path was over sea). The OH2AXH/SM1HOW QSO was more like a regular troposcatter virtually over a sea path.

Here is a photograph of my 120 cm dish on my balcony. The RF was fed via a 1 m length of RG214 believe it or not at 3 dB loss at 10 GHz. Here is an image of OM Pertti, OH2AXH (current record holder since May 1999) and myself pointing towards the horizon in the direction of SM3AKW. This is a picture of SM3AKW and myself when OM Karl visited me later the same year. And finally an image of my current setup that virtually eliminates the losses between the RF equipment and the dish feed by using a section of high quality flexible/twistable waveguide.

Post scriptum:

On May the 9th SM1HOW and myself succeeded in breaking the current Finnish record. The distance was 525 km with fairly good signals. My station consisted of a new DB6NT based rig driving a homebrew 8 W SSPA. Since this record breaking QSO I have also added a NE32584C P-HEMT preamplifier also designed and manufactured by DB6NT. The purpose of this is for future EME plans using a 4 m dish. My antenna was my smaller portable 60 cm (105 k) dish mounted on a Manfrotto camera tripod. The complete station is rucksack portable except for the power (12 V/10 A !!!). I ran the station off my car battery at a local hilltop.

Lars was using a 35 * 40 cm offset dish and running 400 mW at the transverter output. His dish is fed over 0.5 m of semirigid cable. This contact was about three kilometers longer than the previous record of 522 km. Why overdo it ;-)

To give you an idea of the path, here is an image (20 k) of the non-line of sight path as seen by Roger Hedin's marvellous piece of software, Great Circle Maps, version 2.3.

Two contacts were made; initially on CW with good raports and then also on SSB for a longer chat. Lars' signal had a very deep and slow fading characteristic going from 57 all the way down into the noise. The conditions in Finland were entirely normal, but from Gotland northwards there was apparently a local lift. The conditions were so unusual at Lars' end, that our talkback contact on 900 MHz GSM was almost impossible, but 10 GHz was close to excellent ;-)

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Updated 28.05.2000