Beautiful Videos from the Space Station

http://eol.jsc.nasa.gov/Videos/CrewEarthObservationsVideos/

The link above takes you to a really spectacular collection of videos taken recently from the International Space Station. Great stuff. Be sure to check out the aurora. And the stars as they become visible over Canada. The St. Lawrence seaway is very apparent in the Mexico to New Brunswick video. In that one you can also see where the Rockies really start to rise (not so many lights). Over the Great Plains you can see where the main North-South and East-West highways are (straight lines of lights!).

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Knacktivity in the White House: The Mashmallow Cannon

I thought this was a lot of fun. And in another video I saw that the kid was using an Altoid tin to hold the batteries that power the trigger.

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The Parasaki: DL3PB's Amazing All Diode Transceiver

JBOD! FB!

Hi folks,

I'd like to share with you a long-cherished dream, that recently came true, forty years after I came to read about hams using tunnel diodes to make QSOs when I was aged twelve or so:

Finally I managed a first skywave QSO with my PARASAKI-transceiver, an 'all diode' rig: Christophe/F8DZY replied to my very first call on 20m band in REF-contest last weekend. I was running 2mW into a temporary vertical dipole on my balcony. Distance between us is 918km - obviously OM Christophe has excellent ears.

Those interested in the cruel details of my circuit, please find attached a schematic and a photo of the pretty ugly setup. The circuit is designed straight-forward with exception of the parametric VXO, derived from Mike/AA1TJ's famous Paraceiver design. (see http://fhs-consulting.com/aa1tj/paraceiver.html )

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'.

The receiver in its 'gain-less' version works fine for strong signals - while listening to QRP(p) stations, the moderate gain of the audio amplifier helps a lot. A comfortable frequency shift between receive and transmit is realized by the 5µH inductor at the LO-port of the mixer, with little effect on sensitivity.

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 )...

72!

Peter/DL3PB

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Building a Wright Model D

There is a lot of Knack-like activity in this project. I think you guys will like this show. I'm not sure the Hulu link will work outside the U.S.

http://www.hulu.com/watch/23333/nova-wright-brothers%E2%80%99-flying-machine

There is also a lot of good background info here:

http://www.pbs.org/wgbh/nova/wright/

And as long as we're talking about Knack-related aviation, here's a great article about an avionics engineer who has made a big difference in the world:

http://seattletimes.nwsource.com/html/businesstechnology/2017426408_bateman05.html

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SolderSmoke Podcast #141

http://www.soldersmoke.com/soldersmoke141.mp3

February 5, 2012

Recording on repaired computer
RG-174 shield wires: "Murphy's Whiskers"
"The Radio Art"
"Non e radioamatore se non gli fuma il saldatore!"
Does soldering a soldering iron disturb the universe?
HCJB: Home of the Quad, but DX Party line is over
Butane, Loctite, Scotchbrite, Velcro, and Gorilla tape
Getting the 17 meter SSB station going -- trials, tribulations, triumph! MAILBAG

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QROoooooooo!

Here's a rig that will never be featured in SPRAT or QQ! Welcome to the Gates HC-114: http://www.transmitter.be/gat-hc114.html
(Stephen, G7VFY, sent me this, so blame him if this exposure to QRO causes any psychological trauma.) I note that the rig does have a five element low-pass filter.

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The Knack, defined

Of course, our British cousins will have some problems with this. (We already have some lexicon problems there -- I can sense many of them wincing every time I say "SodderSmoke"!) But I'm sure they will be understanding here. And indeed, the Knack can sometimes leave you Knackered! (BTW: I currently have an annoying little soldering iron burn on the tip of my right finger.)

Hi Bill,

Maybe I'm not the first to think of these two words, but here goes:

Knacking v/n. as a noun, the act of artfully and cleverly designing, building from scratch, or repairing devices using, usually electronic in nature, specifically amateur radio related...not related to hacking As in: "My knacking was a success and I finally got my Drake 2B working on 30 meters" Somewhat redundant, since knacking IMPLIES extreme cleverness, knacking ALWAYS has a successful result, by definition!

as a verb (as in "Googling") to artfully and cleverly design, build, or repair a device, normally electronic in nature as in "I was knacking my JBOT amp yesterday and successfully added a new low pass filter" Implies high level of cleverness and determination and a modicum of luck


knacker n. one who artfully and cleverly designs, builds or repairs electronics, especially amateur radio related, implies high level of accomplishment and can be used by knackers to describe themselves without embarrassment or outright bragging. Knackers do not need formal training in electronics to fully qualify. Knackers always know who they are and can be identified by burn scars on their fingers from soldering accidents.

Keep your great blog and podcasts going.

73

Steve Silverman
KB3SII

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Hard Core! Wisdom and Ideas on Toroids

Gerard ZS5AAC

This morning the BITX20 mailing list has an interesting discussion of toroidal cores. I especially like Gerard's use of the cores from old CFL bulbs. Farhan wraps it up with a great explanation of why we use ferrite cores in broadband transformers:
------------------------------
Over the years I built quite a few BITX's. In the beginning I used the
toroids salvaged from CFL lamps. These worked quite well for the mixer
coils. For the filter coils I used 6mm bakelite slug tuned coils that were
stripped from old PYE radios. Wonder if anybody else experimented
along the same lines. I build my BITX's Manhattan style and they work from the start with few minor tunings. Happy BITX'ing, Gerard, ZS5AAC.
---------------------------------------
Bob
The purists may attack us on this, but what you propose is very
possible. I have been using a wooden-core toroid for several years as part of an antenna tuner.

http://qrp.webhop.net/Pictures/Webcam-1293651325.jpeg

http://qrp.webhop.net/Pictures/Webcam-1295140555.jpeg

I'm also using small plastic and wooden beads as toroid cores for
several other projects. Half inch long sections cut from thick-wall (schedule-40 or schedule-80) PVC pipe also makes good toroidal forms. Beauty of using non-metallic cores is that the core can be split to allow winding wire through the slot without having to thread it through the hole.

http://qrp.webhop.net/Pictures/Webcam-1289957121.jpeg = 1.4 uh

Bending an inductor back on itself in toroidal form concentrates the
magnetic field in the center, whether the core is metallic or non-metallic. This gives you similar self-shielding properties when using either type core material.

With non-metallic cores you no longer have to worry about core saturation, so running high current finals is not a problem.

Key to doing this is being able to measure inductance of 5 turns, 10 turns,
and 20 turns, so you can calculate and plot the effective AL of your wooden core toroids. Once you know this value you can make up a chart to tell how many turns are required for a specific inductance.

Twisting wires together to make a transmission-line for bifilar or
trifilar windings is interesting because the impedance of that transmission line might affect performance of your transformer. It may require a bit of experimentation with an SWR bridge to tell when you have the best balance between twist pitch, wire diameter, and insulation thickness.
Arv - K7HKL
---------------------------------------------

Robert, Arv,
There are two types of coils used in the bitx - the broadband
transformers and the RF coils in the bandpass filter and oscillators.
You could easily substitute the rf and vfo/bfo coils with just about
any kind of coil - as long as you are hitting the same inductance and
Q. But there is a catch : a few years ago, I finally got down to
measuring the Q of the nylon tap washers that I had originally used.
The q was quite modest at 70. Wes made independent measurements with similar results (his paper is on www.w7zoi.net under technical stuff). In short, for good performance use good old air coils wound on a
cylindrical formers if you don't use toroids.

About the broadband transformers. These need a material that has very
low loss, very high permeability. The reasoning is like this :
1. We need an transformer's inductance such that the reactance is
at least 200 ohms at the lowest frequency. This puts the inductance at
around 30uH at 4MHz.
2. If we achieve 30uH through lots of turns (say 100), each turn will
exhibit capacitance with it's neighbor and the large number of turns
will add up the capacitance so that the coil will provide enough
self-capacitance to resonate at an unintended frequency in HF leading
to pretty bad mixer performance.
3. The only way out would be to achieve the required reactance with
lower number of turns. This means using ferrites.
- farhan VU2ESE

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Success on Seventeen Sideband!

Wow, sometimes scratch-built homebrewing can be a frustrating masochistic activity. Who among us at one point or another hasn't sat back from the bench and wondered why he didn't take up stamp collecting? But then sometimes the radio gods are smiling on you, the smoke stays inside the components, the antenna rope doesn't break, oscillators osc and amplifiers amp and all is right with the universe. I had one of those days yesterday.

The RF feedback measures I described earlier took care of that problem very nicely. Conditions on 17 were not that good yesterday, but as soon as the sun was up I started hearing stations. I called Phil, K5ACR, in Oklahoma and he came right back to me. He said the signal sounded OK, but he thought I might have been driving it a bit too hard. I backed off a bit and he said it sounded very nice.

Our weather was really disturbingly pleasant yesterday (we're not supposed to be out in T-shirts on January 31). I took advantage of it and went out with my fishing pole and sling shot (the neighbors love it) and got a line over just the right branch. This allowed me to turn my low-to-the ground 17 meter inverted Vee into a proper dipole, up about 15 meters or so.

Back to the shack and K5USI said I was booming into Mississippi's Gulf Coast. I turned off my 20 watt linear and he could hear me just fine barefoot. Then I worked K2BQ in Florida. All stations report that the signal sounds very nice.

I remembered that I did a QST article about this transmitter a few years back. I can't find it on the web, but here is an old page that describes it as it was in the last solar cycle:
http://www.gadgeteer.us/17SSB.HTM

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SolderSmoke -- The Book 20% off. And available for Ipad and Nook

Save 20 percent through February 3. Through the Lulu site you can get the book in the print or e versions.

The book is also available from Kindle, the Ibook store, and for the Barnes and Noble Nook.

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Some Audio Shielding

As I was aligning my "23/24 Re-cycle" 17 meter SSB rig, I noticed the tell-tale sounds of RF getting into my audio. (I guess I should be pleased -- my amplifiers are now producing enough RF to cause some trouble!) So this morning I went in and battened down the hatches in the AF part of the rig. Lead lengths were reduced. Unshielded cables were replaced with RG-174 (with due attention to "Murphy's Whiskers"). A ferrite bead was placed on the wire that carries voltage to the op-amp chip. I wrapped some foil (actually some of that conductive tape used to protect windows in alarm systems) around the plug on the D-104). And finally I cut out two pieces of PC board and made a shield for the whole AF section (see above). I think all this has had the desired effect. The audio sounds clean. I have the day off today, so if there are no Coronal Mass Ejections I hope to make some contacts on 17. Stay tuned!

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My .02 KW Linear Amplifier

Once again, die-hard QRP guys should probably look away at this point...

My Cycle 23/Cycle 24 refurbishing project continues. The JBOT amplifier in the 17 meter SSB rig is now working nicely, but unfortunately just as I got ready to make some contacts, the Coronal Mass Ejection hit us and conditions on 17 deteriorated badly. Looking for something to do, I noticed that in some pictures of my old Azores station, sitting alongside the SSB transmitter there was a small cabinet with a QRO/QRP switch on the front panel. Ah yes! My Ramsey Kit linear amplifier! This is a MOSFET-based device. Mine was designed for 20, but I changed the low pass filter and put it on 17. Later, in Italy, it went on 20 meters and for some reason I went back to the 20 meter low pass filter.

Yesterday I blew the dust off this thing, pulled out the 20 meter LP filter and replaced it with a filter that will let my 17 meter RF reach the antenna. Today I fired it up. Wow! 20 Watts! Look out 17 meters!

I really like the QRO/QRP switch -- it gives me the opportunity to lean back and say (just like the big guns) "Wait a second Old Man, let me turn on my LINEAR!" I even have a little fan in the box that you can hear when I go to the QRO position. Unfortunately it doesn't make the lights flicker. But we can dream...

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