Chitika: moonbounce

Showing posts with label moonbounce. Show all posts

Somehow this seems appropriate for Pi Day (3-14). I guess it is because the antenna is circular.
Thanks to David GM4JJJ for sending this to us. There is no audio. Kind of fun to watch the lads struggle with the big antenna while wearing coats and ties!

David writes:

Hi Bill,

Just watched the video of the progressive receiver and immediately noticed the old Eddystone drive and dial.

My first general coverage receiver was an Eddystone 840C in about 1969 I guess, so it brought back fond memories.

I also had (much later) an Eddystone 770R VHF receiver, which I used to listen to transatlantic 50MHz on during the sunspot peak a couple of cycles ago now. That was before we were allowed to transmit on 6m over here.

Incidentally if you saw the recent film "The Imitation Game" about Alan Turing, you might have spotted the 770R in it, which was actually a mistake as the receiver was not produced until after the war.

Now something to break your heart, and mine actually:

This old rig which was given to me sometime in the 70's by another ham, was stored the attic of my previous house now used by my brother, and a couple of years ago I had to clear the attic of the "junk" that I had left when I moved out. I didn't have any more room to store quite a lot of things and I made the decision to take a few things that I never thought I, or anyone else, would need. They went to landfill. :-(

As you can probably see there is an Eddystone drive and dial driving a VFO which originally had insulation material around it for thermal stability. I think it may have been mixed or multiplied up to 144MHz judging by the scale on the dial. Looking back now I should have tried to save it, but I just felt at the time it would just probably lie in my new attic until I departed and then someone else would have to throw it out.

I don't know exactly who made it, I was given it by Andy GM3IQL(SK), but I vaguely recall him telling me that it was made by Fraser Shepherd GM3EGW(SK) who I did not know as he died tragically young, but was a brilliant constructor. It could equally possibly have been made by Jimmy Priddy GM3CIG, and I could contact him as he is still around in his 80's now. At least I had the sense to take some photos.
Now a couple of semi related video material that I put up on YouTube.

http://youtu.be/dqTLVLmz5ro

This is a (silent 8mm) film made in the 1965s about the first moonbounce attempts from Scotland and Jimmy CIG made the film. My Elmer Harry GM3FYB(SK) is in it.

Another one this time 1965 field day!

http://youtu.be/UjYyaS1Fkao

Bill, I really enjoy SolderSmoke podcasts etc, I am returning to ham radio after about a decade, got the bug again....

The KX3 is in the shack, and I have the parts here now to build a QRP WSPR beacon by Hans Summers also.

I like QRP, having previously worked with George GM3OXX back in the 70's when we went out portable with wideband FM QRP 10GHz (3cm) gear using Gunn diode oscillators. Just a few mW and we could work several hundred miles with small 2 foot dish antennas in the right conditions over water by super refraction. The receivers were just mixers, no active RF amplifiers in those days.

I think the best I did was 322km with my 10mW from Scotland to Wales on 10GHz. A couple of decades I built up a real SSB transverter with surplus MOSFETs for 10GHz and with greater power (250mW) and SSB bandwidths I could work non line of sight paths on that band from home.

I also like QRO for such things as 2m EME (moonbounce) and am in the course of replacing my old 8877 W6PO design 1500W amp for 144MHz with an Italian manufactured LDMOS 1kW amp that is a fraction of the size and weight, who would have imagined a single solid state device would be able to do that at a price amateurs could afford?

Anyway enough of my ramblings.

Hope you don't mind me taking up so much of your time, I will let you get back to whatever you have on your workbench!

David Anderson GM4JJJ

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

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

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

Chitika

Happy Pi Day! Scottish Moonbounce in 1965, Eddystone Dials

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

AHMED HASSAN MOHAMMED

Popular Posts