EME station for 144 MHz
|Yaesu FT-847||1 kW SSPA||4 x 6 element yagi (click picture to enlarge)||Sequencer|
Station configurationMy station
configuration is show in fig. 1. The 1 kW SSPA
is connected to the antenna array using 22 meters of Ecoflex
low-loss coax cable. The loss in this piece of Ecoflex
15 is 0.75 dB and that equals 160 W when running 1 kW.
Remaining cables are standard low-loss coax cables.
The four 6-element yagi
antennas are PA144-6-2 from the company Dual (YU1CF, antennas-amplifiers.com). Each antenna has 9 dBd gain, and the 4x6 array is about 15 dBd. The power-splitter is from the same company.
is a 250 W coax-relay (Tohtsu CX-140), and Relay2 is a 1 kW
coax-relay (Tohtsu CX-600). The bias-T is from Wimo.de and the sequencer is homemade.
The preamp is Extra-2 with typ. 0.5 dB NF (HA8ET).
Fig. 1. Station configuration for 144 MHz EME.
Fig. 2. Antenna array for 144 MHz EME.
array is 4x6H which is 4 stacked 6-element yagi-antennas PA144-6-2
horizontal polarization. The stacking distance is 2.40 m horizontal and
2.20 m vertical. All four antennas are mounted on an H-frame made of
1½" galvanized steel tubes. The power splitter is fitted using a
homemade clamp. The box closest to the antenna
rotor contains a coax-relay (Relay2). The other box contains the preamp.
You can view my rotor system in fig. 3. The antenna
is turned horizontally with a Yaesu G-600 rotor (6a),
and elevated with a Kenpro KR-550 (6b). Both rotors are controlled
by the ERC-3D rotor controller (4) which interface the 2 control boxes (5a
and 5b) using relays. The controlling software is PSTRotator (2).
It has a separate window dedicated to Moon tracking (1). The
interface between the PC and the Rotor Controller is a
USB-to-serial converter (3).
Fig. 3. How rotors are controlled.
Earlier EME antennasSummer 2017
used an 8 element horizontal yagi (11 dBd gain)
and elevation. My sked with HB9Q (monster
station) was not successful. I tried
with another big station. He used horizontal polarization
first, and then vertical polarization; no signal was heard.
I used a 2 meter long ash tree cross-boom with 2 x 6
element yagis. This array was light and the wind
resistance was low. The two 6-element yagis were PA144-6-2 from the company Dual
(YU1CF). Each antenna has 9.2 dBd gain and a pair provides 12 dBd gain with vertical polarization. I heard
the Graves radar (143.050 MHz) and a few powerful EME stations using
these yagis. No QSO. I decided changing from vertical to horizontal
polarization in order to hear and
Distance to the MoonThe
distance from the Earth to the Moon is not constant; it varies between
362.600 km to 405.400 km. The below photo was taken from the
OSIRIS-REX satellite, about 3 million miles away, dated Oct 2, 2017.
The Earth-to-Moon distance on this day was 390.000 km
(242,000 miles). The photo was posted by Mike Cooper in the
Facebook group Earth Moon Earth (EME) Radio Communications.
The Moon 390.000 km away from Earth.
Latest update 06-April-2018 by Lars Petersen, OZ1BXM.