Chitika: EME

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Bill:

I'll attach some pix of the feedhorn and LNA for you.

The importance of circular feeds is that as a linear wave passes through the ionosphere, it undergoes Faraday rotation. So it may arrive at the station you are talking to having been twisted 90 degrees. This is a slow progressing process and on all bands except 23cM, may cause EU for example to be locked out for hours at a time for linear stations.

With circular polarity, Faraday is a non issue. The feedhorn almost all of us use is a VE4MA that has separate TX and RX probes. The circular polarity is synthesized as the linear wave propagates down the circular waveguide and encounters sets of capacity stubs. The exact opposite occurs for waves entering the waveguide. The result is we get CW and CCW without having to use any relays (loss) and phasing lines (loss).

My LNA has a noise figure of under 0.24dB and uniquely connects to a protection relay with no cable or adapters (loss).

The position of the feedhorn and its scalar ring is tediously adjusted by measuring the difference between sun noise and cold sky. W4SC developed a very accurate and repeatable process that uses an SDR RX for this.

I use a modified C band satellite drive system known as a polar mount so I only need one motor drive to track the moon.

Anyway, hearing my own echoes off the moon was and still is the highlight of my amateur career.

The photos are the feedhorn + LNA, My first water cooled 500W tube amp, my previous 400W solid state amp (mounts right at the dish). My current design is 600W solid state and will also mount at the dish.

BTW, that little circle in the middle of the tube amp is a paddle wheel that turns as long as water is flowing. A tachometer on the wheel sounds an alarm and shuts down plate voltages should the wheel stop turning.

I'll keep you up to date on my BB RX progress- thank you again Bill.

Dale W4OP

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htmOur coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmokeOur Book Store: http://astore.amazon.com/contracross-20

Years ago I bought a Barebones Superhet from Dale Parfitt on E-bay. Several years after that, having forgotten who I bought it from, I was asking questions about how to get it working on 17 meters. Dale jumped in with some very helpful e-mails. It took us both a while to realize that I was working on the receiver that he had built. Dale is active in a really wide range of ham radio activities, everything from QRP to EME. Check out his homebrew projects here (I really like his Solid State Drake 2-B!) http://www.parelectronics.com/par-homebrew-projects.php
And his vintage projects here: http://www.parelectronics.com/vintage-radio-restoration.php
And here's what Dale has been doing with the Moon (that's his 15 foot dish in the picture):

Hi Bill,

I thought of you today when I won a Bare Bones Barbados RX on eBay for $5. I am going to team it with a DDS VFO and a matching TX.Some parts are apparently missing, but i have a huge junk box and also know how to order from Mouser should the junk box fail me.

Right now I am putting my solid state 650W 1296MHz EME amp , Power Supply, meters etc. in its waterproof cabinet so I can mount it right at the dish and not incur any feedline losses.

1296 is probably the best EME band. Power is getting easier and easier to acquire (although solid state is around $5/watt), dishes are fairly easy to acquire or build and perhaps most importantly, we all use circular polarity feeds with no relays/hybrids. Activity weekend can sound like 20M, with a number of stations just ragchewing on CW and SSB.

73,

Dale W4OP
for PAR Electronics, Inc.
http://www.parelectronics.com

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htmOur coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmokeOur Book Store: http://astore.amazon.com/contracross-20

Hack-A-Day ran a story on EME pioneer Zoltan Bay. In the comments section someone posted this memorable video about a moonbounce station in Central Kansas. Wow. Putting using naval gun as an AZ-EL rotor for the dish is really thinking outside the box. Then deciding to put the whole thing atop another tower... Great stuff.

Here is another moonbounce video. VE2ZAZ was using a smaller antenna (!) and JT65. FB.

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htmOur coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmokeOur Book Store: http://astore.amazon.com/contracross-20

The link below will take you to an amazing collection of QST articles describing the early days of EME or "moonbounce." Very interesting. I was really blown away when I found out that Ross Bateman, W4AO, (pictured above, on the left) did the very first amateur moonbounce work from the small suburban Washington town that I live in now -- Falls Church, Virginia!

I am trying to find OM Ross's old address or more info about him. If anyone has an old callbook, could you please look up Ross Bateman, W4AO, aka W4XNB? He worked at the National Bureau of Standards.

The moonbounce story is filled with interesting technology and characters and clubs. Sam Harris and his Rhododendron Swamp VHF Society sounds like our kind of group! Scroll through the OK2KKW web site and you will come across our esteemed Doug DeMaw and Bill Orr.

http://www.ok2kkw.com/eme1960/eme1960eng.htm

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htmOur coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmokeOur Book Store: http://astore.amazon.com/contracross-20

In March 1944, Bay recommended using the radar for scientific experimentation, including the detection of radar waves bounced off the Moon. The scientific interest in the experiment arose from the opportunity to test the theoretical notion that short wavelength radio waves could pass through the ionosphere without considerable absorption or reflection. Bay's calculations, however, showed that the equipment would be incapable of detecting the signals, since they would be significantly below the receiver's noise level.

The critical difference between the American and Hungarian apparatus was frequency stability, which DeWitt achieved through crystal control in both the transmitter and receiver. Without frequency stability, Bay had to find a means of accommodating the frequency drifts of the transmitter and receiver and the resulting inferior signal-to-noise ratio. He chose to boost the signal-to-noise ratio. His solution was both ingenious and far-reaching in its impact.

Bay devised a process he called cumulation, which is known today as integration. His integrating device consisted of ten coulometers, in which electric currents broke down a watery solution and released hydrogen gas. The amount of gas released was directly proportional to the quantity of electric current. The coulometers were connected to the output of the radar receiver through a rotating switch. The radar echoes were expected [11] to return from the Moon in less than three seconds, so the rotating switch made a sweep of the ten coulometers every three seconds. The release of hydrogen gas left a record of both the echo signal and the receiver noise. As the number of signal echoes and sweeps of the coulometers added up, the signal-to-noise ratio improved. By increasing the total number of signal echoes, Bay believed that any signal could be raised above noise level and made observable, regardless of its amplitude and the value of the signal-to-noise ratio.²⁶ Because the signal echoes have a more-or-less fixed structure, and the noise varies from pulse to pulse, echoes add up faster than noise. From: http://history.nasa.gov/SP-4218/ch1.htm

During the war, Zoltán Bay protected Jewish colleagues from Nazi persecution. In 1998, the State of Israel honored him as Righteous Among the Nations for his actions and listed his name at Yad Vashem.

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htmOur coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmokeOur Book Store: http://astore.amazon.com/contracross-20

I think the really cool thing about this is the "self echo." Listen carefully when the operator in the video turns it over to the G station. At first I thought they were doubling, or perhaps another station was on frequency. But then I realized that when he releases the push to talk, the first signal he hears is his own signal, bouncing back from the Moon! c is real!

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htmOur coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmokeOur Book Store: http://astore.amazon.com/contracross-20

Chitika

Circular Polarity and The Water Wheel in Dale's Moonbounce Amplifier

W4OP -- Earth-Moon-Earth and Another Barebones Superhet

Naval Gun Turret as EME Dish Mount (VIDEOS)

Knack-to-the-Max! Early Moonbounce

Zoltan Bay and his Chemical Moonbounce Detector

Earth-Moon-Earth!

AHMED HASSAN MOHAMMED

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