Congratulations to the Indian Space Research Organization. They put a spacecraft into Mars orbit on their first attempt, and they are getting back some spectacular images. I also like the banner on their web site:
Thanks for the kind words Thomas. Be sure to have someone do a video of your presentation. You truly have The Knack -- proof of this is your reaction to your wife's departure for field research in Senegal: "IT'S SOLDER TIME!" That's the spirit!
Too bad about the chickens, but hey, they died for a good cause... Dear Bill, I have been listening to your podcast for about a year now. I think you were right to say that one episode a month is a reasonable limit to avoid listeners getting addicted. At some point in January I was listening to you every morning and every evening in my car, a very serious case of addiction. This is also the time that Farhan chose to announce the Minima and my wife to go to Senegal for 3 months for a field study (she is doing a PhD in Sociology). I think it took me less than a week to run to the shop, get most of the parts and start melting solder! In two weeks from today I will present the project and my build at Pacificon. I would really appreciate if you could mention this on your blog because I am sure there are other listeners who will be there and curious for some homebrewing-materials. I hope to delight them! For your own pleasure there are some pictures and videos on my blog: http://www.sarfata.org/ham/minima/ Pacificon Schedule: http://pacificon.org/ (My talk will be at 10:45 in the Portland room) My presentation will retrace my journey building the minima. From the first smokes on the crystal filter when I was not even sure how to test it, or what results to look for ; to the amplifier where I am still battling some oscillations (by the way, if you had not talked so much about them, I would never have understood what was going on!). This project has taught me that radio is a lot less black magic than I thought. It bridged the gap between the maths that I can understand but not really "see" and the sound coming out of the amplifier. It made me realize that once split into stages, a radio is much better understood and testable. Without a doubt, this has been my most ham-enriching experience and I hope to convince more people to build a minima, preferably Manhattan style! (In this public setting, I will probably not discuss killing chickens to exorcize my amplifier but I thank you for the tip ...) I got pulled back from homebrewing by life and work this summer but I kept the last three episodes of Soldersmoke on my phone. They were my safety parachute and I listened to them last week on the way home to give me the extra boost that gets me to melt solder or fix bugs until 3 in the morning on a tuesday. I don't think I will ever be able to express my gratitude for all that I have learnt reading the book and listening to you but I would like to start here: Thank you! Please keep the podcast going! I have really enjoyed the new format with Pete. 73, thomas kk6aht / f4hdq
For the past month or so I have been wondering about a strange echo that I've been hearing on the 31 meter transmissions of Radio China International. I first noticed it on my "Kings Speech" regen receiver. Then I heard it again on my "Off the Shelf" regen. For a while I thought that what I was hearing was a propagation effect: Perhaps the very strong RCI relay station in Quivican,Cuba was sending north a signal so strong that it was travelling around the earth along the grey line and coming back to me about .133 seconds after the original reception. This sounded plausible (and it does happen sometimes). But there were reasons for skepticism: Why wasn't anyone else hearing this? Why wasn't the effect showing up on signals from Radio Havana Cuba? Pete Juliano had suggested that perhaps I was getting signals from TWO different RCI transmitters. I had quickly checked the RCI schedule and didn't see them transmitting on the same frequency at the same time from multiple transmitters, so I kind of put that idea aside. Hey, the round-the-world idea was just more appealing! But then I remembered something strange about the echo: It seemed to disappear when I tuned close to the center frequency of the RCI signal, but then appeared when I tuned off to one side. Hmm.... That was an important clue. I've long been wary of regen receivers and for a while suspected that I was dealing with some weird regen effect. Regen and Echo seem to go together, right? Well, as it turns out, no. But I was right about this being an effect of the nature of my receiver... Last night I was listening to RCI English service at around 0030 UTC on 9570 kHz. Nice clear signal. No echo. At 0100 UTC the program changed, and the echo started. A very strong echo. I went to the RCI schedule. Here I found the answer: At 0030 they were transmitting from their relay station in Cerrik, Albania on 9570 kHz. At 0010 they switched programs, frequencies and transmitters. At 0100 Cerrik shut down, but the Quivican, Cuba relay came on on 9580 kHz. At the same time the RCI transmitter in Kasi Sabagh in far-off exotic Western China, in Xinjiang, fired up on 9535 kHz. Both transmitters were carrying the RCI English service. You see, my little regens are not very selective, and the RCI transmissions are quite strong. So if I have my receiver tuned to around 9560 kHz, I'll be hearing BOTH the signal from Cuba AND the signal from Xinjiang. That would explain the echo. To try to confirm this, last night I fired up my old Hammarlund HQ-100 receiver to see if I could discern the two different signals. I could. And the echo appeared when I tuned BETWEEN the two. You can hear this in the video above. There is one remaining question here: Is the echo caused by the RADIO path difference between the two transmitters? Or are we just seeing the effect of the programming being transmitted at slightly different times, perhaps with this delay caused by INTERNET latency? Anyone know how RCI gets its signals from its Beijing studio to its distant transmitters? I calculate that the path difference is about 10,000 km. With c at 300,000 km/second, that would yield an echo of only about .03 seconds. The echo we are hearing sounds longer than that, so I suspect we are hearing a difference in studio-transmitter transmission time. What say the SWL RF gurus? BTW: I think the same phenomenon may explain the echo on Brother Stair's "Overcomer" signal. I see that starting at 2200 UTC he is on BOTH 7570 kHz and 7730 kHz from RMI transmitters in Florida. Perhaps they are not synched up. I think this is all very cool. Think about it: Here I am, sitting in Virginia in 2014, listening to the Albanian, Cuban, and Xinjiang relay stations of Radio China International on a receiver first built by some guy in England during the 1930s. And I'm trying to figure out if the echo I hear is caused by the limits imposed by the speed of light and the size of the earth, or by the time it takes packets to move through sub-oceanic fiber optic cables.
Edwin did a beautiful job on his BITX. This is an excellent example of stage-by-stage construction. This is his THIRD BITX. On the second one he got all the parts from an old television and a washing machine. That's the true BITX spirit! I want an S Meter! There is more information on his blog: http://pa1ed.blogspot.nl/
Thomas, K4SWL, has a really impressive shortwave listening blog. Yesterday he was kind enough to post an article about my latest obsession: the echoes on China Radio International: http://swling.com/blog/ Even more impressive is Thomas's work on behalf of poor people in the Third World. He is the Director of Ears to Our World, a charity group that provides innovative, simple and appropriate technologies to schools and communities in remote, rural and impoverished regions of our world. Here they are: http://www.earstoourworld.org/ They distribute radios to people who would no other regular technological contact with the rest of the world. They are also involved in an intriguing project called the HumanaLight: "Dead" AA batteries power lights that can make a big difference for people living in areas that have never been on any grid. Here it is: http://www.earstoourworld.org/humanalight/ Ears to Our World is looking for Donations to help them bring light and radios to people who really need them: Here is where you can help: http://www.earstoourworld.org/donate
This is clearly a very appropriate charity for radio amateurs.
Here in Northern Virginia, it is not all that unusual to run into friends and have them say things like, "We're moving to Antananarivo." Here is a report from Jack, AI4SV on his new location. That garage seems to have real potential as a workshop Jack.
Greetings from Antananarivo, Madagascar!
I thought I'd turn the tables and give you a bit of travelogue and radio news.
The only radio-related item in our air freight was my toolbox, which I thought was justified. I lugged along the rest of the station in my carry on, an FT817 (with post-market Collins mechanical filter), magnetic palm paddles, a winkeyer, and the 40/20/10 end-fed LNR halfwave dipole, plus some mason line. I also brought a very compact 240V recharger that I had picked up in Sweden.
The day after I got here, the dipole was hung using the time respected coke bottle on a string method, which greatly entertained the guard assigned to the house. A couple days later, I clambered up on the roof to raise the feed end another ten feet. Since then, I've worked about 240 stations with my QRP rig (all but three CW). I don't have any way to upload to LOTW right now, but my rough estimate is that I have worked something like 45 DXCC entities.
The location is probably not as ideal as Azores in terms of having a nearby salt water ground plane, as we're 100 miles to either east or west coast, and the local noise here can be very high in our tightly packed appliance-heavy diplomatic neighborhood. On the other hand, we're on the central highlands, almost a mile up and Madagascar is a very desirable DX location. When propagation smiles on me, I can work runs of 30+ stations before I disappear again into the ionospheric mist.
Before I got here, I talked with a bunch of US, UK, and German hams who had held 5R callsigns, and they gave me the lay of the land. Phil, G3SWH became my QSL manager and put me in touch with Albert, 5R8GZ, who has been a huge help. Prior to arrival, Albert was able to put through my paperwork with OMERT, the local equivalent of the FCC, so I could get on the air as soon as I arrived. He has similarly assisted quite a number of visiting hams and dxpeditions and is a big proponent of ham radio in scouting here.
There's no ham club here, but there are so few active hams that in my three weeks here, I've either met or been introduced by email to about half of them.
It will be another month before our main shipment hits the docks here, and meanwhile management has given me the thumbs up to install a tower in the backyard to support a hexbeam. Between the K3 and the hexbeam, I think I'll be in good shape to do some serious operating, although I think that a couple months of operating QRP has been not only a character-building experience, but has given me a much better understanding of propagation patterns.
We have a large, empty garage and I think it's destined to become the workshop. I am curious about how dry it will stay in the rainy season and how many mosquitos will visit me there, but it has electrical power and plenty of wall space for shelving. Packing out my workshop took me about as much time as the rest of the house combined. So many little parts...
My toolbox arrived last week and the soldering iron was put to immediate use to build a dipole for six and then 15 meters. I've captured the moment of "first smoke" in the new location for your viewing pleasure.
So, please look for me on the air in future months and point your moxon over here when you can. I'm putting updates about the station's status on its qrz page.
Keep up the podcasts! I've enjoyed the series with Pete Juliano - kind of a return to the original format. Also, I've listened to the icq podcast for years, so it was great to hear the "very special crossover episode" with you and Martin.
Pete Eaton sent us links to an old article from the New Zealand magazine "Break-In." So many good, simple rigs come to us from New Zealand! Who can forget ZL2BMI's DSB rig? This one is the work of Fred Johnson ZL2AMJ. It is especially interesting and is in some ways similar to Peter Parker's "Knobless Wonder." It uses the phasing method of sideband generation. No crystal filters in this one. You need TWO balanced modulators. You have a 90 degree phase shift network for the RF (from the carrier oscillator) and a second 90 degree phase shift network for the AF from the mic amplifier. When you combine the signals from the two balanced modulators -- viola! -- one of the sidebands disappears. The balanced modulators take care of the carrier, and an SSB signal is launched. That is how my old HT-37 works, and similar ideas seem to be at work in modern SDR rigs. G3TXQ has the complete set of Break-In articles (it includes a VFO): http://www.karinya.net/g3txq/temp/tucker_tin/ Here is a Canadian article on the rig. A "Tucker Tin" is apparently what the Kiwis call a lunch boxes (shades of Benton Harbor...).
Several people have e-mailed me suggesting that the weird echo I have been hearing on shortwave broadcast stations is in fact one of the fabled "Long Delayed Echoes" that radio amateurs have been hearing intermittently since about 1927. I was skeptical at first, but -- at least in the case of the Radio China signal -- I think LDE caused by the signal going around the globe several times does explain what I've heard. Each trip would add a delay of about .133 seconds, and that seems to match what we hear in my recording: http://soldersmoke.blogspot.com/2014/08/strange-echo-on-china-radio.html Compare that with what K9FIK recorded on 10 meter SSB (thanks Stephen!): http://swling.com/blog/2013/10/hearing-the-speed-of-light-dx-double-echo/ (you can listen to the audio on this one). It sounds very similar. If this is in fact LDE, I'm lucky -- this is pretty rare. And it is a eerie that I first heard it on on Regen receiver from the 1920s! Above is a picture of the regen used to study the FIRST LDEs. See: http://folk.uio.no/sverre/LDE/
Here is the two tube SSB transmitter that Pete was telling me about. This would be a nice companion to the "Mate for the Mighty Midget" receiver that I built a long time ago. Another Benton Harbor Lunchbox may have to be sacrificed...
You know that you are dealing with a broad range of technology when you find yourself discussing how to power an Arduino microcontroller from the 12V AC voltage on a vacuum tube filament line. Thanks Pete.
There is only so much that can be said in 1 hour and 19 minutes so maybe here is some stuff for the blog.
The 1st thing on the list when working with the Arduino when it is not connected to the computer is to have a proper power supply. My research as indicated that 9 VDC “raw” is a good starting point to power the Arduino boards so here are two supplies that will provide that power.
I did find that it was necessary to have an isolated supply when working with the “toob” radios and even to isolate the RF into the radio using a ferrite core transformer –some more tribal knowledge.
One supply takes an 8 VDC regulator and boosts its output to 9 VDC. The second uses a switching regulator and the beauty of the second is that the input can be either 12 V AC or DC. This is ideal for use in toob radios where you can sample the 12.6 VAC filament string.
I was able to pick up the podcast with excellent audio quality. It is quite true that regenerative receivers are very much in use even today... for example many if not all of the automobile RF keys opening and closing the cars doors rely on a superregenerative receiver circuit !!!
The radio that you copied at the blog works very well indeed but it would be good idea to include a 5 kilo ohms volume control.... Very easy to do indeed.
But let me tell you that my favorite regenerative receivers are the classic ones, using vacuum tubes, and operating them at voltages not higher than 50 volts... As a matter of fact many tubes work very well at the 24 volts DC voltage level. Using the classic Hartley circuit , there is no need for a hard to find throttle capacitor required by the Armstrong circuit, because the regeneration control works very well by using a potentiometer to change the screen grid voltage of the detector.
I agree that using an RF stage ahead of the detector is always a very good idea.... In my tubes regenerative I use a triode connected 6AK5 clone.... as a grounded grid stage....another 6AK5 clone ( the 6ZHE1P Russian tube ) is the detector and I use another 6AK5 clone as the first audio amplifier then feeding an audio output pentode all provided from a very simple basic 70 volts DC power supply. BTW, using regulated DC on the filaments of the detector stage, although a luxury by my standards is very helpful to reduce hum .... 7805 regulator recycled from a bad motherboard, with one 1N4007 from broken Compact Fluorescent Lightbulb inserted in series with the regulator ground pin, produces a nice 5.7 volts regulated DC that with a brand new tube is more than enough... with old 6ZHE1P recycled from Russian TV sets, you add another 1N4007 to obtain 6.4 volts regulated DC....
As said in the podcast, it is very important to do a very good mechanical engineering job, place the main and bandspread tuning capacitors away from the front panel, use isolated shafts between the capacitors and the dial mechanism and make the front panel of a a thick steel plate if possible.
There is a Dutch Cascode Regenerative radio that several Cuban radio amateurs have built... it was designed with the amateur bands in mind so the information about the tuning coils and capacitors lets you obtain a very excellent bandspread on the ham bands. I can send you that circuit that uses very common 12AT7-ECC81 and Russian equivalent double triodes.
Keep up the good work amigo and always tell us when the next podcast is available. BTW it lasted for almost an hour !!!
73 and DX
Your amigo en La Habana, Cuba Arnie Coro CO2KK Host of Dxers Unlimited radio hobby program Radio Havana Cuba
SolderSmoke Podcast #165 is available: http://soldersmoke.com/soldersmoke165.mp3 September 13, 2014 Workbench Update: Bill's "Off the Shelf" Regen, Pete's Boatanchors Mysterious Echos on Shortwave Signals. Solve the Mystery. Please. Microcontrollers -- What they can do for you. Small world: As a kid, Pete was neighbor of "Digital Dial" N3ZI NEWS FLASH: Arduino creator Massimo Banzi was a ham! Born in a bar, cheaper than pizza: The Italian origins of Arduino Arduino CW generators No coding skills needed Arduino + AD9850 = Signal Generator or VFO Arduinos in the Minma What the heck is a Shield? SolderSmoke Mailbag
Tony, VE7JUL, wrote in asking for a schematic on the "Off the Shelf" regen. Here you go Tony. Nothing fancy or new here. All the credit goes to Howard Armstrong, Charles Kitchin and Jay Rusgrove!
Even though they seem much simpler than other receivers, I think regens are in fact more of a challenge than, say, a Direct Conversion receiver. Be prepared to do a lot of fiddling around with the coil and the tuning and regen capacitors. Think of that detector stage as a VFO, a VFO that you want to be able to smoothly take out of oscillation.
Here's a tip on regen debugging: Once you have it built, hang a high impedance 'scope probe off the drain of the FET and watch the scope/counter as you move the main tuning cap and the regen control. This will give you a visible indication of where (on the regen control) the stage is going into oscillation. A freq counter (I have one inside my Rigol 'scope) will let you know what frequency range you are operating on. You may end up having to make adjustments to the coil, adding or taking away turns to get into the proper frequency range, or to the desired level of feedback. Pay attention to the phasing of the coil turns. You may also find yourself adding capacitance in series with the regen and main tuning controls (to reduce their tuning range) or adding capacitance in parallel with the main tuning cap (to lower the entire tuning range if necessary).
Build it solid and strong! It is, after all, an oscillator. Be prepared to do a lot of "noodling"
This receiver with just 4 transistors and no chips looks really interesting to me. Do you have a schematic that you could either flip to me or point me to? Getting my hands on some air variable caps may be a challenge, but I can 'noodle' something out on that.
Love the podcast, blog and really enjoyed the SolderSmoke book - thanks for your continuing efforts to share with the amateur radio community.
the little red dot at Coquitlam, British Columbia on what used to be the Clustr map (but is now a Revolver map)
A few weeks ago I noticed a strange echo on Radio China International's signal. If you scroll down a bit you can see my YouTube recording of the problem. On one of the SWL lists, there was speculation that this problem was the result of a flaw in the RCI digital studio gear. But then a few days ago I heard it again on RCI -- surely the tech-savvy Chinese would not have let this kind of problem persist for weeks. Today I heard the same effect on a very different SW station -- this one an the 24/7 fire and brimstone broadcast that appears at many points on the dial. The effect is very similar to what I heard on RCI. So OK all your shortwave gurus: What is going on here?
I call it the "Off the Shelf" Regen because the base on which it is built is scrap lumber from a recent shelf building project. Also, all the parts came out of the junk box. 6-10 MHz, AM, CW, SSB, Data. 4 transistors, no chips.
Colin and Martin of the ICQ Podcast were kind enough to invite me in for an interview. I really enjoyed our talk. We covered a lot of ground, everything from podcast history, to regens and BITXs and Arduinos. I think SolderSmoke podcast listeners will enjoy this. Thanks Martin! Thanks Colin! Here it is:
I've been building shelves for my wife. So I end up with all these nice pieces of pine, just the right size for the base of a breadboard receiver and a very sturdy cabinet to surround it. Then I find in the junk box two nice variable caps and this old pill bottle coil (with tickler!) that I wound in 1998; I figure they will resonate from around 5 - 15 MHz. Then Jeff Murray, K1NSS does that poster about Dave Richards, AA7EE (scroll down) in which he mentions the virtues of a National Velvet Vernier reduction drive -- I have one of those too. And then there is the copper-clad board (from AL7RV/W8NSA) that would be perfect for the front panel. You see where this is going, right? My friends, I am once again on the road to shortwave regeneration. It will have an Armstrong detector with throttle cap.
Oh man, when I saw this I just had to put it on the blog. The artist is Jeff Murray, K1NSS, the genius behind Dashtoons. Dave Richards AA7EE is, well, the OC! So not only have we learned that regen receivers are NOT demonic, we now see that they have health enhancing properties! Like all that antioxidant stuff! This is great. I'm feeling younger already. Regen on my friends!
In response to popular demand, "SolderSmoke -- Global Adventures in Wireless Electronics" is now available as an e-book for Amazon's Kindle.
Here's the site:
For the print version:
For shipping from a printer in the U.S. (probably better for N. American buyers) Click here: SolderSmoke USA Version
For shipping from a printer in the UK, Spain, or the USA (probably better for UK and other European buyers)
Click here: SolderSmoke EU Version
The two versions are identical, except for a minor difference in the paper used. That's why the prices are a bit different.
Bill's OTHER Book (Warning: Not About Radio)
Click on the image to learn more
W4HBK's QRSS Grabber: The Amazing Pensacola Snapper (Live!)