Mariánske ostrovy (Northern Mariana Islands, DXCC prefix KH0) patria medzi tichomorské teritóriá USA, ktoré dlhodobo priťahujú pozornosť DX manov po celom svete. Tom Callas, KC0W, na týchto ostrovoch pôsobí už mnoho rokov ako jedna z mála trvalo aktívnych staníc z tejto lokality – a práve teraz prechádza jeho stanica významnou zmenou zamerania, smerom k prevádzke EME (Earth-Moon-Earth, odraz signálu od Mesiaca) na pásme 2 metre.
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KH0/KC0W on shortwave
Tom KC0W is an experienced traveling DXper – in the past he has activated Hong Kong as VR2/KC0W, Vietnam as 3W9CW, Brunei as V85/KC0W and American Samoa as KH8/KC0W. He has been operating in the Mariana Islands for a long time under the calls KH0/KC0W and KH0W (the second call belongs to the Saipan CW Club, which Tom manages). His station on Saipan is active on a wide range of bands including 160, 80 and 6 meters, and has long been known mainly as a CW operator.
Operating in this location is not without risk – the western Pacific is a typhoon-prone area, and Tom has lost his antenna equipment in the past during a storm. After similar events, he repeatedly rebuilds the station, with a view to larger and more powerful yagi antennas. According to his own words, reconstruction after such an outage usually takes about four to six months, during which he is at least dedicated to operating POTA from many parks on Saipan.
QSL politika pre KH0W je nasledovná: potvrdenie je možné výhradne priamo (direct) cez KC0W, LoTW aj byro služba nie sú k dispozícii. Pre DX stanice je poplatok 2 USD, pre stanice z USA sa vyžaduje SASE obálka. Stránku volacieho znaku KH0W na QRZ.com spravuje priamo KC0W.
Disaster is a part of life in the typhoon-prone western Pacific. Sometimes you win, sometimes you lose. (Tom, KC0W)
Transition and preparations for EME operation as KHØW
Tom remains active on the HF bands, his interest has shifted towards EME operation on 2 meters. Construction of the EME station is currently underway, with reception tests scheduled to begin in late August.
The entire EME station is located on the roof terrace of his house. The antenna consists of 16 elements on a 37-foot (11.3 m) boom. The current power amplifier has a power of 1 kW, while in December a 1.5 kW amplifier from the manufacturer W6QPL is due to be installed. The main operating mode will be Q65, but Tom is also keen to try CW connections with strong (big gun) stations. The antenna system's direction control (AZ/EZ) is provided by the Armstrong system - i.e. manual rotation.
The maximum antenna elevation is limited to 45 degrees for all stations. When the Moon sets towards Europe, the antenna scans directly over the ocean down to zero degrees of elevation. For North and South American stations, the Moon is available from an elevation of 6 degrees, as the view at its rise is obstructed by Mount Tapochau - the highest point on the island of Saipan. Tom is considering adding automated AZ/EL rotation and a second antenna during 2027. The radio is a heavily modified Icom IC-9700.
The preamplifier power supply solution is interesting. The total length of the Heliax cable from the radio to the antenna feed point is 29 feet (9 m). The preamplifier is located 1 meter behind the antenna feed point, on a robust telescopic fiberglass mast, the height of which can be changed from the ground. When the antenna is in the horizontal position, the telescopic mast is extended to its maximum. As the front of the antenna tilts upwards during elevation changes, the mast shortens to match the decreasing height of the feed point on the back of the antenna. This unusual solution allows the use of a very short, only 1 meter long coaxial jumper between the preamplifier (located on the telescopic mast) and the antenna feed point - thereby minimizing signal loss on this critical path between the antenna and the first amplification stage.
| Parameters | Value |
|---|---|
| Band | 2m (144MHz) |
| Antenna | 16 horizontal elements, boom 37 ft (11.3 m) |
| Amplifier (current) | 1kW |
| Amplifier (since December) | 1.5 kW, W6QPL |
| Main mode | Q65 (both test and CW) |
| Direction control | AZ/EZ, Armstrong system (manual) |
| Max. elevation | 45° |
| Min. elevation for NA/SA | 6° (obstacle: Mount Tapochau) |
| Radio station | Icom IC-9700 (heavily modified) |
| Heliax cable length | 29 feet (9 meters) |
| Preamp–antenna jumper | 1 m (on telescopic fiberglass mast) |
| Call sign for EME | KHØW |
Všetka EME aktivita bude prebiehať pod volacím znakom KHØWGiven the location of the Mariana Islands in the western Pacific and the previous absence of regular EME activity from this location, this will be a rare opportunity for VHF operators and EME enthusiasts around the world, especially for those who don't yet have the Mariana Islands on the 2m band in their diary.
Video: KH0/KC0W
Summary
Tom, KC0W, is among the radio amateurs who, despite repeated natural disasters at their Pacific station, continue to invest time and resources in improving the signal from the Mariana Islands. After years of activity on the HF bands under the calls KH0/KC0W and KH0W, his efforts are now directed towards the construction of a full-fledged EME station on 2 meters - with a 16-element antenna, a kilowatt (soon to be 1.5 kW) amplifier. Despite the limitations resulting from the terrain (Mount Tapochau blocking the low elevation at the moonrise towards North and South America), this is a promising project that can bring the Mariana Islands to the logs of EME operators around the world.
If you are an EME operator on 2 meters, follow the announcements about the construction progress of the KHØW station and prepare your station for the possibility of working this rare location via reflection from the Moon - reception tests are scheduled to begin in late August, with the main mode Q65 and openness to CW contacts with strong stations.