SolderSmoke Book "Pirate Day" Sale! 15% off

Looks like Lulu is running a 15% off sale for "Talk like a Pirate Day." Apparently you just have to write "AHOY" when they ask for a promotional code. Here is what Lulu says:

Enter coupon code 'AHOY' at checkout and save 15% off any purchase (up to $100). Discount cannot be used to pay for, nor shall be applied to, applicable taxes or shipping and handling charges. Coupon codes cannot be applied to any previous orders. No exchanges or substitutions allowed. Only one valid promotional code may be used per account. Orders must be in U.S. Dollars. Offer expires on 09/20/09 at 11:59 PM GMT. Lulu.com reserves the right to change or revoke this offer at any time. Void where prohibited.

Knack on a Bike: Steve Roberts Video

Oh man, this is great! The Winebikko! Gizmology! He even had an Oscar 13 satellite station on the bike. You guys are gonna love this:

SolderSmoke: The Book NOW ONLY $19.99

I found a way to bring down the price on SolderSmoke -- The Book.
It is now $19.99 plus shipping. Check it out:

http://www.lulu.com/content/paperback-book/soldersmoke---a-global-adventure-in-radio-electronics-%28ships-from-a-us-printer%29/6743576

This all has to do with paper availability, so this version ships only from U.S. printers. This will be a good deal for most buyers, but for buyers in Europe and Asia shipping costs might make this version too expensive. I will put up a standard version that ships from Lulu printers in Europe in a day or so.

Ponticelli QRP Station Gets New Antenna

At the country place I now have a table on the front porch for the HW-8 and assorted gear. In the picture above you can see the Trastevere Flea Market Pi Section antenna tuner (upper left), a Japanese SWR meter (also from the flea market) , HW8 and Radio Shack speaker, Volkswagen Solar Cell, 12 Volt gel cell, key and cans...
I had been using a piece of wire just thrown up in the trees, but I thought I could do a bit better. I had some TV twin lead in the shack, and there was this useful-looking center connector... I had some AC line cord. Next thing you know I had a sorta-doublet antenna supported by a Roman Pine in Sabina (pictures below).
And it gets out! Worked IT0ULN in Sicily on 40 meters. Then I spoke to another QRP station, 2W0NNN in Wales, on 20. Also UU4JDD/P on Tuzla Island. Finally E53AX in Estonia.
Ioan, 2WONNN, sent this report:

Hi Bill, thanks for the email, I look forward to seeing the pics on your blog too. Very interesting reading, same goes for your QRZ page too. I had to laugh at your DX with an astronaut on Mir!!!

Your HW-8 and doublet is certainly working well; I remember you were completely readable with a good signal about 90% of the time, it was only the QSB that made it difficult. To be honest I was surprised to have a QRP QSO with someone in Italy. I was using my FT-817 with a new Par End Fedz that I'd catapulted over a tree. The top was about 15m high but oriented as a sloper to the north west. I've had a fair number of QSOs with East coast US stations so I thought I'd go for an over-the-pole route to the West coast... there in Italy you're pretty much spot on the opposite direction so I'm not sure it's all that directional!

73 and hopefully speak to you again for more QRP/QRP!

Ioan,

2W0NNN

Armadillo Aerospace Video

SolderSmoke Podcast #115

http://www.soldersmoke.com
Camping in Sabina
Michelangelo's late start
Anniversaries: Internet, SolderSmoke, Hack-A-Day
From Kitty Hawk to the Moon 
Carrington flares and childhood aurora
Calculating speed of light (using cheese)
Mythbusters
Hubble Space Telescope, Sliding Spring Observatory 
Europa
Transistor Museum
Understanding Mixer products
FALL SALE AT SOLDERSMOKE CAFE PRESS STORE! 
MAILBAG

Mixing it up

OK, enough of the pretty pictures from outer space, now it's time to go back to mixer math.

In the podcast, on this blog, and in the SolderSmoke book I have chronicled my efforts to understand how mixer circuits REALLY work. For some of us, the trig is just not enough. We want intuitive understanding. Ya' gotta draw us a picture. Mike KC7IT, and Dennis W6DWF, both alerted me to a good one. It is from a new book "RF Front-End: World Class Designs", Edited by Jane Sullivan Love. The chapter on mixers is available online here:
http://i.cmpnet.com/rfdesignline/2009/08/C0429pt1.pdf

I really like figure 9.6 (above). You can really SEE how the switching action that is driven by the LO kind of "chops up" the RF signal and produces the complex waveform that is the IF. The neat thing about the IF waveform in this drawing is that you can clearly see both the sum freq (the smaller squiggles) AND the difference freq (the overall movement inside which the smaller squiggles are present). Go ahead, count them up! Sums and differences!
This is a special kind of mixer: a polarity-reversing switching mixer. When the LO is negative, it inverts whatever is at the RF port. From this you can see why mixers are described mathematically as "multipliers." This mixer is multiplying the instantaneous value of the RF input by +1 (when the LO is positive) and then by -1 (when the LO is negative).
I think it is quite a bit harder to "see" the genesis of the sum and difference freqs when you are working with non-switching mixers, but this diagram is, I think, really useful in gaining an intuitive understanding of what goes on in the mixing process.

Hubble Space Telescope: New and Improved!

I know, I know, it is not exactly ham radio, but look at it this way: electromagnetic waves from far, far away! REAL DX. And some very cool gear to receive the signals. And some recent repair and modification work... So you see, this is really not so far afield after all.

I've been a big fan of the Hubble Space Telescope for a long time. When I was closer to the equator (in Santo Domingo) sitings of the HST were quite common. I'm glad to see that the recent repairs and mods worked out so well. Here is a really nice video on the new and improved Hubble: Hubble Space Telescope Video

Saving the world, finding comets....

Well I guess the hours are not great, but how about the job satisfaction! Rob McNaught works at the Sliding Spring Observatory about 400 km from Sydney, Australia. The observatory searches for comets and asteroids that could do to us what they may have done to the dinosaurs (see below). A significant fringe benefit of this job is that Rob gets to discover new comets. He recently set world record by finding his 50th. Congrats Rob!

The mission of the Siding Spring Survey is to contribute to the inventory of near-earth objects (NEOs), or more specifically, the potentially hazardous asteroids (PHAs) and comets (PHOs) that may pose a threat of impact and thus harm to civilization. The identification of the iridium anomaly at the Cretaceous-Tertiary boundary (Alvarez et al., 1980) and associated Chicxulub impact crater (Hildebrand et al., 1991) and perhaps recently the Australian Bedout crater (Becker et al., 2004) associated with the Permian- Triassic "great dying" (although the presence of shock metamorphism has not yet been adequately demonstrated), strongly suggests that impacts by minor planets play an important role in the evolution of life. These are a natural result of the accretionary process that formed the Earth and planets. Indeed, the 1994 impact of D/Shoemaker-Levy 9 on Jupiter provided tangible evidence of this. Although the collision frequency is much lower than in the past, the question is not whether there will be other impacts, but when.

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:

Front: NEUTRON Back: Neutron Ltd

Trade Mark Sicilian House

Wireless Crystal Southhampton Row

1/6 Phone Museum 2017

Catswisker and

Directions Enclosed

The 1/6 refers to the price (one shilling and six pence) pre-decimalization and converts to seven and a half pence today (although the half pence has been dropped thorough inflation). I should add that the box measures about an inch and a half in length.