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 with
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
Page updated 19-Sept-2017 by Lars Petersen, OZ1BXM.