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Thursday, February 4, 2016
A Probable First: First Ever Radio Contact Using Unijunction Transistor as the Transmitter
AA1TJ writes:
I spent most of a week working to raise the RF output power from my unijunction transmitter to nearly 1mW. I was rewarded this evening with two contacts.
Jim/W1PID exchanged (599/449) signal reports with me from Sanbornton, NH (112km) at 2210z!
Dave/K1SWL did the same (589/229) from Newport, NH (95km) some four minutes later!
I should think these were the first-ever radio contacts made using a unijunction transistor as the transmitter.
FYI: my receiver was comprised of a single 1N34a germanium diode mixer followed by a single 2N35 germanium transistor audio amplifier. Great signals on this end.
Wikipedia on Unijunction Transistors: https://en.wikipedia.org/wiki/Unijunction_transistor
Saturday, January 30, 2016
RESISTANCE IS FUTILE! Diode Tunnels in Germany and Vermont
Michael Rainey AA1TJ's work with tunnel diode rigs has provided much grist for the SolderSmoke mill over the years, as has the tunneling of Peter DL3PB:
http://soldersmoke.blogspot.com/search?q=tunnel+diodes
They are back at it!
Michael updates Peter (and us!) us on his efforts of this week:
Grüss Peter!
Mike, your plan on how to increase output-power sounds reasonable – yes, a few dB could really help, to make reception a bit steadier and thus allow a QSO.
Well, I thought we had already talked about the ZnO TRX attempt, but obviously we didn’t. The reason is dead simple - It didn’t work.
[ The ZnO TRX is a minimalist 80m band transceiver with a homemade tunnel-detector-diode as the only active device – based on Nyle’s K7NS experimentshttp://sparkbangbuzz.com/zinc-
Three days in a row after Xmas I tried for several hours each, I had announced the activity on QRPSPOTS and the German QRP Forum. Thus several guys
within the right distance were really trying hard to copy. I used different temporary antennas, mostly verticals, but also a sloper dipole - nada, niente , nothing.
One or two OMs reported weak CW signals on the scheduled QRG, but too deep in the noise, to even make out, whether it was me or someone else.
Yes, power is more or less comparable, actually it’s 0.5mW +/-3dB depending on the day’s form of the homemade tunnel-detector, but I guess all my antennas are
some dB behind a full-size dipole, so at the end it’s pretty much the same.
Folks were very cooperative during the test itself, but after it was clear, that it had not worked, the usual trolls showed up to explain, why that never could have worked...
I plan another test within the coming week e.g. during the PA-contest next weekend ( I’m only 30km from the dutch border ) with a base loaded 15m vertical –
be assured, you’re the first to hear about any success in terms of QSO or just being heard anywhere.
What would we go for, if everything works as expected and/or right from the beginning – or as Jim said it : What fun...
Peter/DL3PB
Friday, January 29, 2016
AA1TJ's 150 Microwatts Heard at 112 Kilometers -- "To Boldly Go Where no Unijunction Has Gone Before."
Breaking news from W1PID... "Mike! I just copied the beacon. I got 'VVV de AA1TJ 150 uw' and it faded out. 2146Z on 3551.95MHz" That's it! Jim copied a message produced by a lowly unijunction at a distance of 112km. How's that for cool! In a nutshell... the unijunction runs as an R-C relaxation oscillator at ~500kHz. A quartz crystal at the emitter frequency-locks the sawtooth waveform to 507kHz. The 7th harmonic is admitted to the antenna via a bandpass filter. The RF output to DC input conversion efficiency is all of 0.1%. Heat-sink? Check! Mission statement:
"...to boldly go where no unijunction has gone before." Cheers,
Mike, AA1TJ
I think the really cool thing is that EM waves are once again flying out of the Vermont Hobbit Hole, propelled into space by the poet laureate of QRP.
Thursday, January 28, 2016
QST de AA1TJ -- Please listen for Mike's Microwatts!
I've a 150uW transmitter built from a single unijunction transistor currently running as a beacon on 3552kHz. If my New England amateur radio pals would be so kind as take a listen for it I'd be most appreciative!
Thursday, December 17, 2015
Modulated Michigan Mighty Mite?
Hi Bill,
Your recent Soldersmoke thoughts re. MMMites have been niggling my imagination; I think radio should be fun, educational, simple and cheap, to encourage young folks to get a license and "appliance users" to melt some solder.
Mike Rainey (AA1TJ) and Jim Kearman (KR1S) have done superb work in reducing RF circuits to a functional minimum... so egged on by a certain Mr. Bill Meara, I'm looking at modulating a MMMite Tx on 80m and building the simple Rx to go with it. I chose 3615kHz as it's a frequency UK VMARS (Vintage Military Amat Rad Soc) use for A.M. - the SSB kilowatt nerds who think the sky will fall down if A.M. corrupts the ionosphere have accepted a few enthusiasts firing a watt or ten of A.M. skywards. I
See how this sounds: modulate a MMM by inserting an electret mic capsule (2 terminal type) between the transistor base and ground, not forgetting the RF choke from the electret capsule output to the base bias 10k resistor, to avoid the xtal feedback signal being absorbed in the electret...
Yep, that's it: job done, the MMM now produces A.M. as the base current, fed by 10k from the +ve rail in the original MMM, is now partially shunted to ground by the electret capsule. I'll adjust the base bias resistor to get 50% "no speech" carrier and good mod. depth. I'm trying to avoid a mic amp stage; keeps it simple & sweet. If I can get 500mW in total, that's ~ 100mW in each sideband - on a good day with a following wind, on 80m that should go a mile or twenty.
Which leaves a drop dead simple Rx to design - somebody has done similar, HERE, You got it: an LM386 audio amp as a regen Rx. I had considered the ZN414 TRF Rx, or it's modern equivalents, but they are nowhere near as common as an LM386, or as cheap. IF it works on 80m...! Or, I could try an xtal controlled regen Rx, as per Mike / Jim's designs. Either which way, I'm sure I can find a cheap, simple and effective Rx - but if you know of any.....?
Cheers Bill, TTFN!
Peter Thornton G6NGR
Friday, September 11, 2015
Kids Homebrewing in Japan in the 1920s
Wednesday, December 10, 2014
Mahalo! WH7TT's Hawaiian Mighty Mite
This is our western-most MMM. Edward took one of the 3.579 rocks and, using a Radio Shack breadboard (much used by Michael Rainey AA1TJ) built his version of the Mighty Mite. When I saw the long clip leads to the coil I was apprehensive, but obviously it works. Great job Edward and thanks for sharing with us your island rig. Mahalo! (I like saying that!)
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Monday, October 20, 2014
Has AA1TJ Joined the FMLA?
I have learned that esteemed homebrewer Michael Rainey, AA1TJ, recently whipped up a 56 MHz, quarter-wave, helical coaxial resonator (BTW: the spoon is also homebrew). Hmm, 56 Mhz. Or perhaps we should say MegaCYCLES? Michael claims this device is for a low phase- noise VFO, but I find the frequency selection highly suspicious. The last time I heard of that frequency it had to do with an underground group set up by the late (or not so late) Frank Jones.
Here is all the info on Frank's Five Meter Liberation Army.
http://www.sunflower.com/~brainbol/frank/
A man of the '30s awakens one night in the '90s (episode 13) with a new mission: recapture 56-60 mc. He forms a Five Meter Liberation Army from his mobile home in a Barrio trailer park run by Tom Joad of Steinback's Grapes of Wrath (episode 9), and soon draws a decidedly uncolorful bodyguard (episode 7). A six foot tall half Mexican stockbroker named for Ayn Rand makes him rich and a demonic white ferret and a half-siamese cat become his familiars. (episodes 10 and 9). The leader of all this, called only "Frank," settles down in the narrator's basement to be joined by Maj. Armstrong (episode 8), Hiram Maxim (episode 23) and one-time pals Carl and Jerry from the 1950s Popular Electronics (episode 25). His huge 1940s sedan, with contemporary plates, is immune from police (episode 13 et seq) and his breadboarded electronic creations recall those distant days when a ham built his own rig and could "fix a radio." Of course all this is crazy. No one builds anything anymore and the other things Frank stands for, like self- reliance, tolerance and a generally Boy Scout viewpoint are simply out of step. Frank knows that too (episode 20), but he does not care. If you're standing in the middle of the road and see a big brown Frazer coming at you, you better jump - one way or the other.
VIVA EL FMLA! VIVA!
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Tuesday, April 15, 2014
AA1TJ Crosses the Pond with 10 milliwatts
From a Facebook Post by Mike, AA1TJ:
Made 7 contacts with this tiny transceiver on 20m CW today with an RF output power of 10milliWatts. Five were stations in Georgia (GA QSO Party). The 6th was a regular QSO with a guy in Mississippi.
I answered a DX station calling CQ at 2230Z. Hearing nothing in response, I sent my call sign a half-dozen times anyway. More silence. As I was reaching for the knob to QSY he suddenly returned my call! ...Carlos, CT1BQH northeast of Lisbon, Portugal (that's him in the second photo). I was only 329 on his end but we kept it going for three minutes!
Gosh, that was fun!
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Thursday, February 13, 2014
Back to the W7ZOI/W7PUA Power Meter
The last time I used it I remember thinking that a digital readout would be nice. But I didn't feel like going back into the world of Arduinos and LCD screens. So I came up with a real Kludge solution: I had cheap little DVM that I wasn't using, so I just velcroed it to the side of the power meter. That little connector above the BNC is the output for a DVM. I might work on calibration later today.
Wes has some very interesting info follow-up info on the meter on his site: http://w7zoi.net/qststuff.html
I really like the part about how the meter is so sensitive that you can see the thermal noise in the input circuit and can actually measure the strength of signals from your antenna.
I think I might need a low pass filter at the input of the meter. There are strong FM broadcast transmitters in this area (some of you may have listened to them in the background of early episode of the SolderSmoke podcast!). I notice that just bringing my fingers close to the input causes the meter and the DVM readout to swing up. That's not good.
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Saturday, April 20, 2013
AA1TJ Crosses the Pond using an Electric Razor!
http://aa1tj.blogspot.com/2013/04/talking-to-france-via-my-electric-razor.html
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Wednesday, March 27, 2013
AA1TJ's Latest QRPp Rig
I called CQ on 20m CW for a couple of hours yesterday afternoon with no response. With the cadence of my own Morse tugging at my eyelids, I was suddenly shaken awake by a brisk signal returning my call and signing CU2BV. I snapped out a 579 report and turned it over. The dits and dahs in my headphones told me it was Fernando; operating from São Miguel island in the Azores. He reported a weak but solid copy (529) of my fifty milliwatt signal.
Here's the radio that I used yesterday. The one-transistor transmitter is to the left of the red relay on the top board. The single transistor is a germanium surface-barrier device made by Philco in August of 1958. To the right of the relay is a two-transistor time-delay circuit used to switch the antenna between the transmitter and the receiver. My receiver on the lower proto-board is a reproduction of my first shortwave receiver: a $7 Japanese kit that I bought at Radio Shack when I was 13 years-old.
Fifty milliwatts is some twenty-four times less power than was used by an old double D-cell flashlight. I later learned that my signal was nearly simultaneously picked up by an automated receiver located just west of Dusseldorf, Germany.
Snowy Vermont to the lush Azores - some 1500miles off the coast of Portugal - with less power than is consumed by a beeswax candle...is it any wonder that I love radio? ;-)
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Saturday, March 16, 2013
Vanguard!
Wow, Vanguard even looks like a QRPp satellite.
I suspected that something was up: I noticed that Mike Rainey, AA1TJ has recently been crossing pond with a QRPp Germanium rig... Then Steve "Snort Rosin" Smith clued me in: The next period of Vanguard QRPp Activity Days begins tomorrow. "Club 72" has a nice write up, and a nice collection of pictures of the Vanguard rigs that have been built around the world:
http://www.club72.su/vanguard.html
Go Germanium! Go Vanguard!
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Friday, November 2, 2012
The Hobbit Hole of QRP
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Wednesday, July 4, 2012
AA1TJ -- As always, in the Vanguard
----------------------------------------------------
From AA1TJ:
Wahoo...Dale, you amazing!
You are my first QSO with the Vanguard 1 reproduction satellite beacon transmitter. My circuit is a fairly close copy of the one shown on the lower left-hand corner of the 1959 CQ Magazine article (notice the output signal pick-off shown in this schematic is incorrect, or at least incomplete). My circuit uses link-coupled output impedance matching, which is similar to the only other documentation that I was able to dig up. The attached image "Early_Microlock_Bcn.jpg" was snipped from an original NASA report on the transmitter used in early airborne and sub-orbital tests leading up to the Vanguard flights.
Yes, you heard correctly. I'm using a Philco 2N504 surface-barrier transistor, but please let me back up a bit.
Roger Easton (a native Vermonter...and still resides here!) was at the helm of the communications development for the Vanguard/Minitrack project. Of the Vanguard "grapefruit" satellite beacon transmitters, he wrote in the May 2008 issue of High Frontier magazine
"We tried subminiature tube transmitters first. They worked marginally. Finally, Bell Telephone/Western Electric developed a very nice transistor for the task, and the problem was solved."
However, that leaves out a small detail. They first tried Philco surface-barrier transistors, which worked fine on the bench, however two problems were discovered. They were found to be too temperature sensitive; the RF output power from the one-stage transmitter dropped excessively at elevated temps. Secondly, there was some issue with the packaging that produced erratic operation when the transistor was rotated positionally. The Western Electric devices proved better on both counts.
The WE transistor appears to be "unobtainium" these days. That, plus the fact that my circuit won't be flying up to space anytime soon, prompted me to settle on a Philco 2N504. Although my device was manufactured in September of 1959 (Vanguard TV-4 - re-Christened "Vanguard 1" - first orbited on March 17, 1958), the 2N504 was an off-the-shelf item on the launch-date.
The only other obvious difference is the Vanguard 1 beacon circuit operated on 108MHz, whereas mine is presently working on 14.0596MHz. I recently had it running as a beacon on 10m for 48 hours but I had no luck given present band conditions.
The receiver is a simple, 0-V-0 regenerative set using a single Raytheon QF721 (fabricated in February 1953). I heard little activity on 20m when I started up my auto-keyer this morning. I had it looping 3X1 CQs whilst I worked on another project. To make matters more difficult, the exhaust fan was running in my shop and it happened to be raining heavily when you called. Worse yet, the receiver had drifted off my calling frequency by the time you called. I barely discerned a high-pitched CW "1" or "J"...which prompted me to quickly switch off the fan and re-tune. You were subsequently a solid 579.
Of course my heart jumped when I heard you calling me...how I love that feeling! And it was a fabulous QSO so far as I'm concerned. Following our contact I opened my metal index card file box and pulled out the QSL that you sent to me following our "Code Talker" QSO. To think I now have another happy memory to add to that one! Thank you once again, Dale. It figures you'd be the one to pick-off my unannounced presence on the 20m QRP calling frequency with 25mW. Well done, OM.
Also, you might enjoy this video of the actual launch, including some interesting control room audio banter. It may be found here: http://www.nrl.navy.mil/vanguard50/index.php. The way at least one of them nervously repeats, "Keep going baby!" gives some indication of the pressure these guys were under...having failed so spectacularly on two previous occasions.
All the best,
Mike, AA1TJ
Hi Michael,That was fun!I first heard you on my SG-2020 rig, but did not have a paddle handy, so I fired up the K3. I don't ever recall having QRN on 20M, but it was bad. Without it, you were 579 and even with it, 569 towards the end of the QSO.I just happened to be QRV on 060 listening when I heard your CQ's. Not bad for a 25mW signal from (I think you said) a Philco transistor.73,Dale W4OP
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Wednesday, May 2, 2012
Kick Panel Progress; Podcast Delay
I'm kind of behind on podcast production, but once again I have a good excuse: I've been melting solder. I decided to finally finish the Kick Panel DSB rig that I started building back in London. It is built on a kitchen cutting board purchased in a Dyas store in Windsor. The cabinet is fashioned from an aluminum kick panel for a door (a pub door!).
I originally intended this to be just a transmitter (for use with my trusty Drake 2-B) but it is so easy to add a direct conversion receiver to a DSB rig that I just threw together a version of the NE-602 LM386 Neophyte receiver and hooked it up to the 75 meter VFO. It sounds great. I love DC receivers. They seem to connect you directly to the ether. And now I'll have a complete 75 meter DSB station in one box.
This morning I tested the balanced modulator (singly balanced with two diodes). DSB is being generated. All I have to do now is put a little 6 db pad between the modulator and the amplifier chain, then work on the antenna a bit and I should be on 75. The amplifier chain dates back to the period when Mike, KL7R, and I were using LTSpice to design amps....
I was very pleased to include in this rig a part that Michael, AA1TJ, sent me: I have a little 10.7 MHz IF can in the front end of the RX. A cap allows it to tune in 75 meters. Thanks Mike!
I hope to get a podcast out this weekend (if the computers cooperate -- the Sony Vaios "light bulb-repaired" laptop finally gave up the ghost last weekend.)
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Thursday, February 9, 2012
The Parasaki: DL3PB's Amazing All Diode Transceiver
Hi folks,
The low impedance of the high peak-current tunnel diodes make it very difficult to built a really crystal controlled oscillator rather than an LC-oscillator, synchronized by the crystal more or less, at least on the higher SW-bands. The Parametric VXO provides a crystal-stable, chirp-free signal on expense of an output power of two milliwatts only instead of ten, but with an amazing spectral purity, no need for a low pass filter or such. Of course it sounds pretty cool making a QSO with a 'bunch of diodes' and a parametrically excited crystal, but believe me or not, I'd preferred to bring that full ten milliwatt into the air - on the other hand that approach allowed to tune the rig a bit ( ~ 5kHz/per xtal), which turned out to be much more valuable than a few milliwatts more while being 'rock-bound'.
Thanks for the bandwidth, OMs, won't bother again you with such mails, unless I make a cross-pond QSO with that rig ( not that likely ) or any skywave QSO with homemade semiconductors ( probably impossible )...
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
Saturday, December 17, 2011
"The Little Sweetheart" Receiver
http://www.cryptomuseum.com/spy/sweetheart/index.htm
With more info here:
http://antiqueradios.com/forums/viewtopic.php?t=96007
And here:
http://antiqueradios.com/forums/viewtopic.php?t=96057
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
Tuesday, August 30, 2011
Russia, Vermont, Sputnik, Old Parts
Fellas,
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
Tuesday, July 19, 2011
Royal Order of the Sputnik Clone Chasers
From the Chief Designer (AA1TJ):
Fellas,
I came across an online blurb for the recent book, Sputnik: The Shock of the Century, by Paul Dickson; a worthwhile read, judging from the introduction and first chapter.
http://www.sputnikbook.net/intro.php
"Someone brought out a shortwave radio, and soon a beeping noise filled the room. A Russian scientist, Anatoli Blagonravov, confirmed it was Sputnik. "That is the voice," he said dramatically. "I recognize it." John Townsend Jr., one of the scientists at the party, recalled watching Blagonravov: "I knew him quite well, and I could tell that he was a little surprised and quite proud. My reaction was 'Damn!'"
And so an abstraction now had a voice. It also had a name - Sputnik.
Many of those at the party adjourned to the Soviet Embassy's rooftop, attempting to view Sputnik with the naked eye. Several of the American scientists drifted over to the American IGY headquarters in Washington, where they began speculating on what impact the satellite would have. They feared that the American people would be disappointed.
It also dawned on them that they had better start tracking the satellite's orbit. They got in touch with the American Radio Relay League in West Hartford, Connecticut, asking its 70,000 members-all "ham" radio operators-to lend a hand and help track the Sputnik. In less than twenty-four hours, reports on the satellite were coming back to the National Science Foundation, where a temporary control room had been established. Eventually, these hams and other amateur and professional trackers would consider themselves part of a great international fellowship known as ROOSCH, or the Royal Order of Sputnik Chasers."
That's right guys...ROOSCH...the Royal Order of Sputnik Chasers. And to think that fifty four years later a second great international fellowship would rise from the ashes...ROOSCCH, or the Royal Order of Sputnik Clone Chasers! ;o)
(BTW, October 4, 1957 is an important date in American history for a second reason. On that evening the first episode of Leave it to Beaver made its debut.)
I thought we should also at this point remember the intrepid lads of the Kettering Group, pictured above. (Some of those dudes look like they would have been right at home in "Leave it to Beaver.") For more info on their amazing Sputnik adventures go here:
http://www.svengrahn.pp.se/trackind/getstart/oldcyts.htm
and here
http://www.svengrahn.pp.se/trackind/trackin1.htm#KEttrack
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http://soldersmoke.com/book.htm