[Moon-net] 10 Ghz EME from Cincinnati, Ohio, USA

[mmurphy at triumph-eng.com]

Gentlemen...

 On March 30th, around 01:30 GMT, Jim, N8ECI and myself were finally able to receive our own echos 
at the old Voice of America shortwave transmitting site located just north of Cincinnati, Ohio.  
The echos were about 10 db above the noise as seen on Spectran (thanks I2PHD!) and we heard the 
signals by ear as well...  

 The station consists of a 24 ft (7.2 meter) commercial dish (F/D = .3) with Cassegrain optics and 
corrugated horn feed.  Six feet of 3/4 inch copper pipe acts a circular waveguide from the feed 
horn, making an abrupt transition to rectangular guide at a waveguide switch.  The receive chain 
consists of a transition feeding a DB6NT pre-amp (0.6 db NF), followed by an RG-405 jumper and a 
Down East Microwave two-stage preamp.  The signal then enters a Down East Microwave transverter in 
which it is heterodyned down to two meters where it is received on an old Icom IC-251A.  Audio is 
sent to a PC running Spectran.  A G4NNS noise indicator (built by G4HUP and N8ECI) provides a 
signal that aids in trimming antenna pointing using moon noise.

 Transmitted signals begin in the IC-251A, are heterodyned up to 10 kMc in the Down East 
transverter. Then the signal is amplified in a 10 mW to two watt Down East amp that feeds a two to 
eight watt Down East amplifier.  From there the transmitted signal hits a transition at the 
waveguide switch, finally heading up the water pipe and out the horn to the sub-reflector.  
Currently we are limited to 7.5 watts output power, and the transmit chain has not been 
optimized.   A sequencer won at the '04 EME conference in New Jersey controls all switched sub-
components.

 The dish and mount was built by Vertex/RSI in '90, and it was removed from service and abandoned 
in position in '94 when the short wave station closed.  VOA personnel removed various components, 
including the drive motors and control system that moved the dish.  Actuation is now provided by 
three-phase motors and computer controlled, variable frequency drives via pointing data generated 
by the W9IP tracking program "Nova".  Jim, N8ECI, wrote software to control antenna pointing.

 Unfortunately, the mount is a degenerate alt-az system that can only point between 120 and 240 
degrees azimuth.  This severely limits our moon visibility, especially at high northerly 
declinations.  The EME station is located near 39.10 degrees north lattitude and 84.51 degrees west 
longitude. Station call is "WC8VOA"...

 Photos and additional details can be seen at www.wc8voa.org

 Not sure of our schedule possibilities at this time, but we are somewhat flexible and can try when 
we can see the moon with our limited azimuth window.

 Thanks to many, including G4HUP, I2PHD, W5LUA, W1GHZ, WA3ZKR, the Engineering Department at 
Vertex/RSI in Kilgore, Texas as well as all the great EME men who came before.  Guys like W2IMU, 
W8JK and the other pioneers around the world have been a great inspiration...

 The moon looks different to me tonight!!! 

73...

Mike Murphy
KA8ABR