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Friday, August 9, 2013
Who Invented the Transistor?
http://www.beatriceco.com/bti/porticus/bell/belllabs_transistor1.html
I dunno.... Roswell? Really? But I find myself attracted to anything that involves the use of iron pyrite and cats' whiskers in radio. Mike, KL7R, sent me a bunch of fools gold from Alaska and it turned out to be better than galena as a detector.
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
Friday, January 11, 2013
Il Fido -- A Simple Receiver from Italy
This one is a simple crystal receiver with one stage of AF amplification. It covers the AM broadcast band, the HF bands, and (apparently) VHF using a switch and three different coil/capacitor combinations. You could make it a lot simpler by just building it for one band. Looks to me like a nice rig for an Altoid tin.
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
Sunday, March 13, 2011
Podcast QRM Culprit Found: WBIG-FM 100.3 MHz
The mic cord is just about 1/2 wavelength. That would put the high voltage nodes at the ends, right? I notice that the interference drops noticeably if I wind up the cord, and increases a lot if I stretch out the cord.
I can hear some other stations in there also (one country station). It may be that there are multiple FM stations broadcasting from that antenna site. I can see the tower's red lights blinking from my front lawn.
Thank you Peter Frampton!
Sunday, March 6, 2011
Crystal Radio Sleuthing
But here's a surprise: These are NOT the stations that are getting into the podcast! With the crystal radio in operation, I did some audacity recording and then quickly checked to see if the breakthrough sounded like what they were playing on WFAX and WUST. NO! The breakthrough was ZZ Top! I'm guessing that the breakthrough was from an FM broadcaster. I note that the length of the cord to the microphone would seems like it would be a nice antenna for the FM broadcast band... What do you guys think?
Whatever the source, I think I have taken care of the problem. I got big ferrite toroid core and wrapped about ten turns of the mic cable through it. No more broadcast breakthrough.
Monday, February 7, 2011
Audio Blues
Thanks for all the comments. Even for the bruising ones. They gave me some additional insights. Most of the problem is clearly at my end of the fiber optic cable. But I think part of this problem has to do with the fact that people are listening to the show with a wide variety of equipment: some are using car sound systems, some are at home using computer speakers (fed by all kinds of different sound cards). A very wide variety of headphones and earbuds are in use. Also, there are big differences in our ears! I, like many listeners, have some serious high frequency hearing loss.
But never fear, SolderFans! The quest for the perfect podcast audio continues. I have turned one corner of the radio shack into a roadkill sound studio. I have worked on several new (and several old) microphones. I have visited (and have actually read) several websites about podcast audio quality.
There may be a "name that mic" contest in our future...
Saturday, November 6, 2010
Homebrew Transistors!
None of those store-bought parts for Jeri Ellsworth! Once again she makes us all look like a bunch of pathetic appliance operators. I like the "harvesting of Germanium" from a 1N34. And I found very interesting her comment about "early hobbyists" cracking open 1N34's and turning them into transistors by adding phosphor-bronze collectors.
This all makes me want to fire up my Fool's Gold crystal radio. WFAX is right down the road...
BTW: I'm very pleased to report that Jeri is currently reading "SolderSmoke -- Global Adventures in Wireless Electronics." I hope she likes it. She definitely has "The Knack."
SolderSmoke Podcast 127 is almost ready.
Tuesday, January 12, 2010
AA1TJ: Reggies Rule! Diode Amps! QRP to the Max!
Whenever I find myself in need of some radio-inspiration, an e-mail from Mike, AA1TJ, seems to pop up in my inbox. This morning's message and the associated video (above) were especially inspirational. Mike was e-mailing Steve, WA1HFF.
Hi Steve,
Thanks for the message and the great QSO! I was running my one transistor transceiver that I call the Reggie. You can read about it on my webpage at
http://mjrainey.googlepages.com/reggie
My antenna is nothing to write home about; just an end-fed half-wave wire bent into an "EL" at 35 feet.
I've made just over 240 contacts with my Reggie in a little more than a year's time; working 19 states. My best (and only) real DX was the Bahamas. All of these contacts were made with no receiver gain on this end; just a pair of diodes fed by a one-transistor BFO, and onto the headphones.
A couple of fellows have built their own Reggies, so you might run into one on 80m now and then. I've made three Reggie to Reggie QSOs thus far.
Steve, last night I was trying something new; I ran a loudspeaker from an audio amplifer connected to my Reggie. What's unusual is that my audio amplifer was made from three, common power supply rectifiers (1N5401's). I'm not kidding! It's a nearly forgotten circuit from 1954 that I (re)stumbled upon a couple of weeks ago. It uses the phenomenon of PN junction charge-storage to produce amplification.
Last week I used two diode gain stages for a total power gain of 48dB to drive my headphones. Yesterday, I added a third diode gain-stage and connected it to a loudspeaker for shack-filling audio volume.
I made a video of last night's setup (the same setup I worked you with). You can see it at
http://www.youtube.com/watch?v=3DA07A6BLDg
Thanks again for the nice contact last night, Steve. You were armchair copy here! :o)
Best wishes,
Mike, AA1TJ
Here's a question for Mike: Can you build that kind of amplifier with homebrew point-contact diodes? If so, you'd be opening up the possibility of a homebrew solid state receiver with homebrew solid state devices. Oh man, this stuff makes me feel like such an APPLIANCE OPERATOR.
Monday, January 11, 2010
DXing with Crystal Sets
http://www.antiquewireless.org/otb/dxxtal.htm
The link for the Antique Wireless archive (another treasure trove for us) is:
http://www.antiquewireless.org/otb/archive.htm
Tuesday, September 8, 2009
Early Crystal Set in Altoids-like Box
Even way back then, British homebrewers had an affinity for Altoids-like boxes!
David, M0VTG, sent me the above pictures, and this description:
I enclose some pictures of a kit produced in the early to mid 1900s of crystals and a holder for use in a crystal radio; unfortunately the cats whisker is missing! The box is marked:
Wednesday, August 12, 2009
VE7NSD: The Knack, personified
I started playing with radios in Roseburg, Oregon when I was ten. My Dad’s prospecting buddy Cliff, had been a Radioman in the USN and turned me on to building a crystal set using a Gillette Blue Blade for the detector. I built it but had no headphones and ordered some from the Allied Radio catalog. I felt like it took about 6 years for them to arrive, but it was probably more like 6 weeks. When the headphones finally came the xtal set didn’t work and so I started learning troubleshooting. Eventually, it worked fine and I experimented with a hunk of galena my Dad had in his rock collection.
From there Cliff gave me circuits for regenerative receivers and I built a few but none of them ever produced a usable output. All of my SWL listening had to be on the big console radio in our living room.
I can’t remember how I came to have an Arc 5 receiver for 80M, but that was my first real radio. It was probably a gift as I had no money except what I got from my paper route and all of that went to pay for the bike I used to deliver the papers. I started going to local ham club meetings and Bob Reese, W7TUI, became my mentor.
I read a copy of How To Become a Radio Amateur and started collecting parts to build the single 6V6 transmitter on the orange crate slat chassis. All of my parts had to be scrounged from the radios, TV’s and other electronic gear that was given to me. I built the power supply on a home bent chassis. I got it to work on out-of-band xtals but it had a mean chirp. W7TUI showed me how to add a VR to the power supply to feed the screen grid in the 6V6 and that cleaned up the chirp.
I was licensed as WN7VTZ in 1952 at age 12. My first QSO was with Beaverton, Oregon, with less than 10 watts input and feeding a random wire with no ATU. I suspect that there wasn’t much radiated power from that lash-up. Another buddy in Roseburg was licensed at the same time I was and we contented ourselves with cross-town QSOs.
I was the only boy in my grade 9 typing class. But, I was glad I learned to type. I could copy CW quite fast, much faster than I could write. The first time I sat down to my typewriter, put on the headphones, and put my fingers on the keys it was like magic. When my ear heard a di dah, my left little finger pushed a key. Di dah dah dah and my right index finger pushed a key. I could just sit there and watch the message appear on the typewriter paper. No effort required!
Read the full story on his QRZ.com page: http://www.qrz.com/detail/VE7NSD
And check out his Wilderness Workbench site (complete with a real moose skin):
http://www.qrpedia.com/book/200812/wilderness-workbench-ve7nsd
Tuesday, June 23, 2009
The Xtal Set Society
There is great stuff in the catalog, and the newsletter seems like gold mine of technical info.
Check it out: http://www.midnightscience.com/index.html
Tuesday, June 16, 2009
Gregorian Chants on a Crystal Radio
I live very close to Vatican City (see above), but I think their AM transmitter is out of town, to the North of Rome. I visited the Wiki on Vatican Radio. Very interesting. Turns out that the Jesuits run the radio stations. Go here for a virtual tour:
http://www.vaticanradio.org/museo_tecnico/it/gal_fot_24.asp
It took me a few minutes to hook up the 4 parts of my crystal receiver; it seemed kind of fitting (and a bit eerie) to be rewarded with the faint sound of Gregorian chants.