Nice Ham Radio Documentary from Montana

Thanks to Thomas K4SWL for alerting us to this.  The 25 minute film is well-done, using modern film techniques and editing. It is a bit appliance oriented (but so is ham radio, unfortunately).  The EME stuff is interesting.  And I think the film captures the friendly, fun spirit of ham radio.  

Some Initial Thoughts on FT-8

 -- This is really interesting technology.  Three cheers for Joe Taylor and colleagues.  This mode would obviously be very useful for fast, weak signal contacts as are needed on meteor scatter or EME. 

-- FT-8 does give you the chance to work DX that would have been difficult on other modes. 

-- Chinese hams showing up on FT-8 -- more than other modes. 

-- I think FT-8 is good for hams who just want to have a lot of "contacts." It is definitely not for the rag-chewer. 

--  I find it it kind of cold and antisocial.  More like a computer game than ham radio. A bit like sending  short text messages on a cell phone. 

--  I think FT-8 contacts are in some ways more meaningless than a "59!" contest exchange -- unless you look, you don't even know the report you got,  nor do you know the report you sent. 

--  For me it is more impersonal than CW.  But at least we let the technology decode the characters instead of having to memorize dot and dash sounds.  In a phone contact you can hear the other person's laugh.  In a CW QSO, you hear him key "HI HI."  FT-8?  No laughter at all. 

-- With PSK Reporter, FT-8 gives you a good feel for how propagation changes during the day. But it is kind of like 2-way WSPR.  As with WSPR, it is -- at first -- fascinating, but then it loses its charm. Yes, everyday you are heard in Belgium. 

-- It seems to be getting kind of crowded.  The passband for FT-8 contacts is often full, and it is hard to find an open space.

-- There is little opportunity for the homebrewer.  I hooked it up to my homebrew transceivers and had a small bit of fun using a 2N3904 as a switch triggered by the RTS signal for T/R.  But that's about it. 

-- I get the sense that the ham himself is not really needed in FT-8.  This mode seems like it could easily be automated or run by an AI.  Just tell it to go out there, make a lot of contacts and log them.  Maybe prioritize the DX you "need."  Has this already been done? 

--  After a session with FT-8, I had a really nice 17 meter ragchew SSB QSO.  That SSB contact left me happy.  The FT-8 session was a bit like spending time on social media or a video game.  It left me edgy.  FT-8 made me appreciate phone even more.

But hey, to each his own.  A lot of people really like FT-8.  I hope they have fun. 

SolderSmoke Lexicographer Worked on Earth-Moon-Earth Laser

Hi Bill

A ham, well known to us, actually me, was very involved in the very first laser reflector experiment.  I was a new EE graduate and was hired by the University of Maryland Physics department to design and build the control system for the laser experiment.

The first reflector was placed on the moon immediately after Apollo 11 landed.  And the equipment on Earth to use it was in place and ready to go to work.

Here is how it worked.  A very powerful laser was installed at the McDonald Observatory in west Texas.  It pointed into the viewing end of the telescope and had 5 Joules of energy.  When it was fired, a control system made from discrete logic chips was used to control an electronic shutter in front of a very sensitive photomultiplier tube.

In order to prevent stray photons from impacting the photomultiplier tube, the shutter was opened just microseconds before the reflected photons were expected to arrive from the moon, a round trip of about 2.5 seconds.  Then the photons were collected from the laser's pulse.  Only between 1 and 10 photons were collected from each shot and were statistically analyzed to get the best transit time to determine the distance to the moon.

Similar systems were set up on other continents in order to triangulate the distances between the telescopes to determine continental drift.  In addition, the outward shift of the lunar orbit was also determined.

Because the moon's orbit varies by about 10% and is easily predicted, the control system used thumbwheel switches to set the time of transit to open the shutter at the right time to keep out photons that were not from the laser.

The control system also sent the trigger pulse to the laser's gigantic capacitor bank to send trillions upon trillions of photons to the moon. So a 5 volt pulse triggered this massive release of stored energy into the lens of the telescope.

And here is the coolest part,  the astronauts could see the laser pulses from the telescopes when they were fired.

I had no idea that these reflectors were still in use and that their efficiency has degraded likely due to lunar dust. 

73

Steve

KB3SII ... .. ..

------------------------

See also: http://soldersmoke.blogspot.com/2020/08/earth-moon-earth-with-lasers.html
and
https://www.smithsonianmag.com/smart-news/scientists-shot-lasers-moon-decade-then-one-bounced-back-180975585/

Earth-Moon-Earth -- With Lasers

https://www.nytimes.com/2020/08/15/science/moon-lasers-dust.html

Thanks to Chuck KE5HPY for alerting us to this very interesting article. 

Moonbounce on 40

Well, we were talking about it on 40.   This just proves that there is more to 40 meter SSB than the never-ending quest for audio "brilliance," "presence," "body"  and "sparkle."   I was working at the bench yesterday when I heard Frank NC1I telling another fellow about his 35 years of experience with moonbounce.  Wow, you don't hear that kind of talk on 40 every day.  Frank also said that the contact I was listening to was one of very few HF contacts that he has made in recent years.  I just had to jump in to encourage him to get on 40 more regularly.  He seemed impressed with my BITX40 Module (which I was using).  I warned him of the buffoonery that can be found on the band, but told him not to be deterred by it -- there are a lot of FB hams on 40.

Above you can see Frank's amazing antenna farm.  The dish is for 23 cm EME. Behind the you can see his 70 cm array.  That is 48 (FORTY EIGHT!) end-mounted Yagis, aimed into space. 

Check out Frank's QRZ.com page:  http://www.qrz.com/db/NC1I  He has some great pictures of his shack.  In case you are wondering why he has so many rotator control boxes, remember that the dish and the Yagi array need two each (azimuth AND elevation).

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

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.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

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

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.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Naval Gun Turret as EME Dish Mount (VIDEOS)

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.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Knack-to-the-Max! Early Moonbounce

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.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Zoltan Bay and his Chemical Moonbounce Detector

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.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Earth-Moon-Earth!

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.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Laser QSO and Visual EME with laser!

Bob, Kd4EBM, sent me some really good info on laser safety. Bottom line: For the time being anyway, Billy will be limited to the <5mw href="http://www.earthsignals.com/Collins/0036/index.htm">http://www.earthsignals.com/Collins/0036/index.htm
Their rig is pictured above.

And here is one that is really mind blowing: A while back we discussed the laser reflectors left on the moon by the Apollo astronauts. Well, apparently there is an intrepid amateur out there who has been shooting his own lasers at the Sea of Tranquility, and seeing reflections come back. Visual EME. Check it out:
http://www.k3pgp.org/viseme.htm

Thanks Bob!