As always, a very illuminating presentation by Alan. I wish my oscillators were that stable! And I couldn't help thinking how much simpler this circuit is in comparison to the DDS devices we've been talking about.
This one is not about radio or electronics, but over the years many SolderSmoke listeners have written in saying that they liked the opening "travelogue" portion of the podcast. This book may appeal to them. It might also be of interest to spouses who've been hearing about these "soldersmoke people." This would be, I think, a good "beach book."
The title is: "Us and Them -- An American Family Spends Ten Years with Foreigners"
Here's the description:
What happens if you take an American family and send them to Europe for ten years? In the summer of 2000, Bill and Elisa Meara, accompanied by 2 year-old Billy and 4 month-old Maria, left their home in the suburbs of Washington, D.C. and moved to the Azores. There they experienced the highs and lows of diplomatic life on a small distant island. After three years in the Azores, they spent four years London and three years in Rome.
Overseas they lived in two houses and two apartments, went to five schools, used four different health care systems, experienced one earthquake, 9-11, the terrorist attack on London, tea with the Queen, the election of Barack Obama… and all the ordinary things that families go through.
They lived mostly with the locals, learned Portuguese, Italian, and a bit of Cockney, and made many friends (foreign friends!) They returned to the United States in 2010 with a changed view of the world. This is their story.
In print form is available from Amazon and from Lulu:
Bert, WF7I, was recently struggling to get his BITX 20 going and he asked some good questions about carrier suppression. I realized that I hadn't really paid much attention to this. Perhaps as a result of my long experience with DSB, I was happy as long as I was able to null out MOST of the carrier.
I fired up the scope and took a look at the output from the BITX 2040 on 40 meters. Here's the test setup: Coax from the antenna terminal to a 50 ohm resistive load at the Rigol O'scope probe. Just keying the transmitter (no mic connected), carrier was at 980 millivolts rms or about 19 milliwatts. I then connected an AF sig generator into the mic in connector and pumped in some 1000 Hz sine wave. Peak output was 20.7 volts rms, or about 8.6 watts. That puts the carrier about 27 db down. I felt I should be doing better.
I took a look at the shape of my crystal filter and the frequency placement of my carrier oscillator. I noticed that the carrier oscillator freq was fairly close to the bandpass portion of the crystal filter -- fairly high up the skirt, only about 9 db below the passband level. I figured that if I just moved that carrier oscillator up around 300 Hz, I would get around 10 db of additional carrier suppression.
Sure enough, with the carrier moved a mere 300 Hz further away from the passband, the residual carrier dropped to 346 millivolts rms, or about 2.4 milliwatts. Now peak output was 20.9 volts rms, or 8.7 watts. 36 db of carrier suppression.
I guess I could do better if I moved the carrier up another little bit, but I like the sound of it now. I may have been able to better if I'd fiddled with the balanced modulator diodes a bit more. But what do you guys think? Should I worry about 2 milliwatts of residual carrier? Heck I once ran a CW rig (W1VD' VXO 6 watter) that kept the oscillator running on key up, producing about 15 mw of "backwave." No damage was done, few noticed, no one complained.
Oh yea, is this the way to measure carrier suppression?
While doing all this, I pulled out my trusty copy of EMRFD. The index led me to the balanced modulator section on page 6.56. There I spotted a familiar call: W6JFR!!! That's Pete Juliano, N6QW! Pete is credited with a mod to the SBL-1 mixer that adds a balance control pot to the device. Wow, actually being IN EMRFD fully confirms Pete's homebrew guru status.
SolderSmoke 162 is now available at http://soldersmoke.com/soldersmoke162.mp3 June 21, 2014 Part II of our interview with Pete Juliano, N6QW -- Bill's Moxon Monstrosity -- Amplifiers and Exorcisms (See slideshow link below) -- Varactor tuning -- Polivaricon capacitors -- The challenge of building small rigs -- Heat, layout, components and VFO stability -- "No frills" as a building philosophy -- The future of Bill's Heathkit HW-101 We still have a lot more to talk about. Stay tuned for Part III!
That, my friends, is the look of exhausted contentment that comes after you have FINALLY gotten your new homebrew rig to work, and were rewarded by crossing the mighty Atlantic on your first call. Congrats Bert! Details here:
I'm not a big collector of QSL cards, but this one has been kicking around in boxes and on various hamshack walls for more than 20 years. I like the bit of Confucian wisdom that arrived in Santo Domingo all the way from Hyderabad. I was running my trusty HT-37 and Drake 2-B.Anyone know OM Kab, VU2BK?
The solar flux index was only 151 this morning, but grey line conditions to Japan were very good. Yoshi, JA1OJJ, was booming in on 17 meters. We had a nice chat. He said I was 55. His 5 element quad helped a lot!
I've been put together a fishing pole MOXON antenna for 17 meters. It will be used with my 5 Watt BITX rig. I need something to spin it around. I know that many of the cheap TV rotators don't hold up very well. I had one die quickly out in the Azores. There seems to be several brands out there, but the rotators and the control boxes look suspiciously similar.
Is there any brand out there that is more robust and reliable than rest?
I came up with a pretty cool way of affixing the corners of the antenna elements to the fishing poles. That coil-like thing is the wire part of a bungee cord. It fits nicely into the end of the fiberglass pole.You have to be sure to get the pole length and the element dimensions properly proportioned, with a sufficient amount of bend in the poles.
I'm sure many of you are, like me, impressed with the enclosures that Pete Juliano has been using with his rigs. Here's an e-mail that he sent yesterday to Bert.
You have a ready source of material right there in Seattle and they will cut it to size. Check out On-Line Metals. The transceiver project has a 4 x 8 inch base plate I bought from them and the front and back are pieces of single sided copper PC Board. The support material is 1/2 inch aluminum angle stock (Home Depot). Interesting use of round aluminum pillars. The front and back are stabilized using 1/4 inch threaded aluminum spacers that were fitted inside of small diameter hollow aluminum tube I bought in a hobby shop. A dab of Gorilla Glue holds the spacers inside the tubing and it forms a rigid support structure.
The subject of mechanical construction is a good one and perhaps Bill would like to cover that in a future podcast. That said I do have a bench top 3 axis manual milling machine and a 3 axis CNC milling machine (that one cost me about $250K). The cost was not in the machine but the cost of sending my youngest son to WSU where he got an ME degree. He designed and built the machine for me.
Boeing Surplus (now gone) in Kent used to sell aluminum plate by the pound and a lot of my stock (now all gone) came from there. As a retired Boeing employee I used to get a discount.
And here is a slide show illustrating Pete's technique:
This arrived from Paris, from our friend Rogier, PA1ZZ KJ6ETL. "Men are like computers: one never knows what's going on inside." But it looks to me like the OM in the picture knows EXACTLY what's going on inside that rig. So I guess this is commentary on the perils of black boxes, and the benefits of an analog, discrete component, Hardware Defined Radio approach. I'm with you Rogier! Merci!
I enjoyed the interview with Pete N6QW very much. So many main points were covered and I kept nodding in agreement, especially some of the stuff about the ease of doing homebrew that we have these days. Like you, or similar to you I'm guessing, I have memories as a kid staring at the pages of an ARRL handbook, saying "huh?" These days almost any question can be answered with a Google (and if not, an appropriate book overnighted via Amazon). You guys both nailed it too with the comments about the free design software that is plentiful and the cheap crystals (I still need to order some "bags" of these!). When I started out it seemed crystals were a big expense. I guess not so much now. It's really a great time to be a homebrewer.
I was trying to think of more questions for him for the second half of your interview but most of what I could come up with was too pedestrian probably or already covered. I am curious about amplifiers but I believe he's going to talk about that next anyway. Nothing was said about using varactor diodes in VFOs (unless I missed it) and I'm a little curious about his experiences with them. And whether he still uses air variables or not (and if he has an opinion on these more compact "polyvaricons", one of which is in the Hendricks version of the Bitx-20 I'm building). It sounds like most homebrewers these days are pairing up their VFOs with digital architecture of one type or another for stability and the display. I guess you can't argue with the price of some of the needed parts. But like you I feel like I'm not wanting to jump into the complex digital too far, the simplicity and ease of understanding of the simple circuits is really refreshing and fun for me. The moment you have to rely on software for something I feel that the project is lessened a bit, not as robust in a way, kind of like having to rely on cholesterol-lowering meds so that we can keep eating cheeseburgers (had to slip in a food reference somewhere).
Something else dawned on me a few weeks ago, soon after I'd built my 40m direct conversion rig ("mrad-40") -- does anyone consider the audience on the band they're designing for??? I'm only partly joking! There are some rude and coarse dudes on 40m. It takes a little bit of luster off the whole "first light" experience of a new homebuilt radio when you turn it on and hear some drunks arguing politics or making fun of a YL ham on another frequency! Probably not a suitable question for Pete!
I also really enjoyed the FDIM edition. As always, it's one of the best of your podcast series. My favorite was the interview with the ham near the end, I think he was 2nd to last. He seemed to really sum up the entire homebrew motivation and experience. I don't remember his name offhand. But his description of sitting there with store-bought radios and the sort of transactional nature of appliance operating ("telephoning strangers") perfectly describes how I felt about a dozen years ago. I'd migrated towards DX chasing and 6m grid collecting but that too can get pretty stale after awhile. I'm getting closer to having a station that is all home-built, but I'm not sure I'll ever sell my commercial rigs as he did (although it would free up money for more test equipment!).
Maybe one final comment for Pete or just in general. Since I've been a ham I feel like there's always been this pressure to build/design something that is in some way "cutting edge" or new. In today's landscape that would be along the lines of the FDIM guy turning an Android phone into a ham rig. I'm wondering if others feel some sort of peer pressure to "push the envelope" in some way with what they're doing, to establish bragging rights of some kind or to somehow feel that what they're doing is important or relevant. I've never been clever enough to succumb to this pressure and invent something ingenious! And I find doing lots of software coding incredibly boring and I know I'm not very skilled at it.
So...I guess the question or point is, should we all in some way as "responsible" hams feel obligated to break ground in some new technical aspect of the hobby somehow, especially as builders and homebrewers (and hams)? In other words, should I be riddled with guilt if I decide to devote the rest of my life to building regens and not SDRs? Do you know what I mean here? There seems to be a mindset among some hams that the hobby was founded on experimentalists pushing the boundaries of what was known, and in some way we all carry that torch. For me, I've always pretty much seen it as a hobby, and if it felt like work I didn't do it! Any thoughts on that?
Eduardo, EA3GHS, sent this to me. It looks like a wonderful bilateral SSB rig for 17 meters. They said they wanted a "daylight" rig (for a daytime band) because in Spain the religious pilgrims walk all day and are tired at night. Hence 17 for Los Peregrinos!
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!)