Fixing the Hubble Space Telescope

Gentlemen, NASA TV is the place to be this week. They have the Hubble Space Telescope in the payload bay of the Shuttle and soon they will be going outside to do the kinds of repairs that Knack victms can relate to. (Update: I'm watching a space walk live through the helmet-cam of Astronaut Grunsfeld. They are now lubricating some bolts on the doors of the telescope.)

Here is the NASA description of the repairs.

Two of Hubble's instruments are in need of repair. ACS, which partially stopped working in 2007 due to an electrical short, is the "workhorse camera" responsible for some of Hubble's most spectacular images. STIS is a spectrograph that sees ultraviolet, visible and near-infrared light, and is known for its ability to hunt black holes. While COS works best with small sources of light, such as stars or quasars, STIS can map out larger objects like galaxies. STIS suffered a power failure in 2004 and was put into hibernation to preserve the possibility of its repair.

Astronauts plan to fix both – a challenging prospect since these repairs are beyond the scope of Hubble’s serviceable design. Hubble’s creators envisioned astronauts swapping out components, not performing delicate surgeries during spacewalks.

An interior electronics box of ACS that supplies power for ACS detectors, contains equipment affected by an electrical short. However, its location makes it inaccessible to astronauts. So instead of trying to reach the problem area, astronauts will attempt to bypass those power-shorted components entirely.

The failed power supply is connected by cables to a series of electronics boards, which are within reach but have no power because of the damaged box. Astronauts will install a new power supply to a handrail on the ACS outer enclosure, remove the electronics boards and install different ones that are compatible with the new power supply, and connect them to the new supply with exterior cables. The arrangement simply cuts the damaged box out of the equation.

Innovative tools for the repairs are designed and developed by Goddard engineers and tested by the astronauts for refinements. STIS needs a new power supply circuit board. The repair would be relatively easy but for the electronics access panel, which was never meant to be opened and is attached to STIS by 111 small screws. The screws are hard to grasp with the astronauts' gloved hands, and could create problems if they were to escape and float around the electronics. So engineers have created a "fastener capture plate" that fits over the top of the panel. When the astronauts remove the screws, they will be trapped in the plate. Astronauts will then switch out the power supply circuit board and close off the open electronics with a new, simpler panel that attaches easily with two levers.

3 Kids, 3 Cesium Clocks, Mt. Rainier, Time Dilation

He may not know it, but this dude has a bad case of The Knack. From his web sites:

In September 2005 the kids and I took several very accurate cesium atomic clocks from home and parked 5400 feet up Mt Rainier (the volcano near Seattle) for a full two days. The goal was to see if the clocks actually gained time, even if billionths of a second, as predicted by Einstein's general theory of relativity. Does gravity really alter time and can this weird phenomenon be detected with a family road trip experiment?

Ten years ago I wanted to build a LED digital analog clock that would be accurate to better than one second per year -- so I would have the fun of adjusting it when a leap second occurred. This simple goal resulted in a most interesting journey into electronics, horology, astronomy, test equipment, quartz oscillators, rubidium and cesium atomic clocks, hydrogen masers, frequency counters and phase comparators, GPS, Loran C, GOES, and WWV / WWVB radio receivers. That makes me one of the Time-Nuts. By now I've exceeded that goal by a factor of a million: the best clocks in my collection (active hydrogen masers) are accurate to better than one microsecond per year. Excluding national government laboratories, my home time lab now has the most accurate clock in the world.

For info on the Rainier Time Dilation Road Trip: http://www.leapsecond.com/great2005/tour/
For a more general discussion of this madness: http://www.leapsecond.com/

Hey, but who are we to talk, right?

SolderSmoke Podcast #107

http://www.soldersmoke.com

On SolderSmoke 107:

SolderSmoke -- The Book!  ON SALE NOW!
Get it here: SolderSmoke: A Global Adventure in Radio Electronics

Orbits II reborn via a VK6 junkbox
NA5N's Amazing Atlanticon 2002 article
WSPR madness:
20 mw across the Atlantic.
K1JT picks up my sigs
WSPR generates interest on Hack-A-Day
Linux: Ubuntu gets SolderSmoke Thumbs-up
Somerset Supper Report
Diode Ring Mixers
Solar conditions
AA1TJ, Chloroform, and HB transistors
ET's rig
Have fun at FDIM!
MAILBAG

SolderSmoke -- The Book! On Sale Now!

SolderSmoke is the story of a secret, after-hours life in
electronics. Bill Meara started out as a normal kid, from a normal
American town. But around the age of 12, he got interested in
electronics, and he has never been the same.
To make matters worse, when he got older he became a diplomat. His
work has taken him to Panama, Honduras, El Salvador, the Spanish Basque
Country, the Dominican Republic, the Azores islands of Portugal,
London, and, most recently, Rome. In almost all of these places his
addiction to electronics caused him to seek out like-minded radio
fiends, to stay up late into the night working on strange projects, and
to build embarrassingly large antennas above innocent foreign
neighborhoods. SolderSmoke takes you into the basement workshops and
electronics parts stores of these exotic foreign places, and lets you
experience the life of an expatriate geek. If you are looking for
restaurant or hotel recommendations, look elsewhere. But if you need to
know where to get an RF choke re-wound in Santo Domingo, SolderSmoke is the book for you.
SolderSmoke is no ordinary memoir. It is a technical memoir. Each
chapter contains descriptions of Bill’s struggles to understand (really
understand) radio-electronic theory. Why does P=IE? Do holes really
flow through transistors? What is a radio wave? How does a frequency
mixer produce sum and difference frequencies? If these are the kinds
of questions that keep you up at night, this book is for you.
Finally, SolderSmoke is about brotherhood. International,
cross-border brotherhood. Through the SolderSmoke podcast we have
discovered that all around the world, in countries as different as
Sudan and Switzerland, there are geeks just like us, guys with
essentially the same story, guys who got interested in radio and
electronics as teenagers, and who have stuck with it ever since. Our
technical addiction gives us something in common, something that
transcends national differences. And our electronics gives us the means
to communicate. United by a common interest in radio, and drawn closer
together by means of the internet, we form an “International
Brotherhood of Electronic Wizards.”

http://www.lulu.com/content/paperback-book/soldersmoke/6743576

Homebrew Transistors? Careful with the Chloroform!

I suppose it was inevitable. After years of pushing the envelope with the tunnel diode, it seems like Michael, AA1TJ, is moving toward homebrewing his own transistors. Michael writes:

Hey, I found a Yahoo Group of kindred spirits late last night, 2N1150_Down; where the interest is centered on early Germanium semiconductor devices. I downloaded a book from their files that, until now, I'd only heard about. Practical Transistors and Transistor Circuits, by J.S. Kendall, first appeared in the U.K. in 1954. Believe it or not, the subject of the book is how to make the "practical" transistors referred to in his title! Of course, these are point-contact devices built from a pair of cat's whiskers on a slab of "P-type" Germanium salvaged from diodes. I especially like where he writes, "Great care should be exercised owning to the anesthetic properties of the chloroform vapour...the constructor may not be aware of the danger until he is almost on the point of collapse." Oh brother!

Better yet, I found an article in the group's files taken from the March and April, 1954 issues of The Short Wave Magazine, by G3HMO. This fellow not only made his own transistor, he used it to build a one-transistor, 160m, transmitter and then went on to make contacts with it up to a distance of 30miles! He writes, "There is nothing impractical about making a point-contact transistor at home." Oh baby, crack me open a bottle of chloroform and let's get to it!

The photo above is, of course, the original point contact transistor from 1947. It looks do-able.
In searching for the picture I came across this interesting article from the author of the wonderful book on this subject "Crystal Fire" : "How Europe missed the Transistor"

Big Solar Flare -- End to the Minimum?

From a WIRED article today: "Solar flares rise and fall on an 11-year cycle, and last year marked what scientists thought was the solar minimum. But through the beginning of 2009, the sun stayed unusually quiet. That changed yesterday, when a major sunspot appeared on the backside of the sun, where it was captured by NASA’s STEREO instrument."

The NASA stereo images were nice, but the amazing picture above was taken from a backyard in Buffalo, New York by solar photographer Alan Friedman.

It seems like the effects of this new prominence will be felt here on earth on May 8. Woo Hooo! Maybe my WSPR signal will cross new oceans!

Inside a Mini-Circuits Mixer, and the Dissing of DSB

I'm not crazy about using integrated circuits, especially the really complex ones for which true understanding of how they work is impossible. The Mini-Circuits mixers are not, of course ICs, but for me they too have always had a whiff of the "black-box" about them. Thomas, OZ2CPU, pulls away the veil with this photo of the innards of an SBL-1.

I came across Thomas's very interesting web site when I was installing in my QRSS beacon rig the SBL-1 mixer sent to me by Jim, AL7RV. That poor SBL had died suddenly during testing. Thomas alerted me to the cause of death: In his caption for the picture of the innards, he notes, "I was unlucky to kill this one during my first transmit experiment. The IF input can NOT accept more than +20dBm audio level."

Joop and I have been discussing diode ring mixers, and I've been reading an article about them by Paul, NA5N. It looks to me like the designers of the SBL mixers weren't really thinking of balanced modulators when they created these things. Just look at the schematic above. In a normal receiver application, LO energy goes in from the L port, your RF goes in R, and your IF (or, in a DC receiver, your AF) comes out from the I port. But when we use these things as balanced modulators, we have to put the Audio INTO the I port. You can see how too much voltage on that port would quickly release the smoke from those little hot-carrier diodes.

The data sheets are oriented to the standard application (RF into R, LO into L, IF output at I). We are told to keep the LO level at +7dBm and that the 1 db compression point for the RF input is +1dBm. But at what level should you put the AF input to the I port if you are using this thing as a balanced modulator in a weird WSPR DSB rig? Similarly, the data sheets give SWR data across a wide frequency range for the L and R ports... but not for the I port. DSB is getting dissed!

K1JT Spots My DSB QRPp WSPR Signal

2009-05-03 16:42	N2CQR		-29					K1JT		7035	4371
2009-05-03 16:38	N2CQR		-24					K1JT		7035	4371

I got into WSPR because I wanted the gratification that comes from seeing a map readout indicating that my QRP signal has crossed various oceans. Well, yesterday I crossed the pond for a second time, but this time the receiving station heard the signal more than once, so the rx station callsign appeared on the display (if the signal is heard only once, you get the line showing the path, but NOT the rx station call). And what a fine callsign it was: K1JT, Joe Taylor, Nobel Prize winner and the inventor of WSPR.

In the last SolderSmoke I got Joe's name wrong (I called him John). It must have been too early in the morning here. Anyway, I was gently corrected by Wes, W7ZOI, and I promissed to make ammends. Sorry Joe! (Thanks Wes).

The Dover Construction Club

Last night there was a meeting of the Dover Construction Club (discussed by Nigel, M0NDE, in Solder Smoke #194). For the first time, the members agreed to be photographed.

Above, in the foreground, Merv checks the main board of his softrock, Ian explains to Paul how a mod to an old FT101ZD will work, and Nigel is seen using the microscope and observe to Merv he has not soldered all the IC legs down on a SMD board. He says he knows. grin!!

Ian Keyser, G3ROO, host of Dover Construction Club. At his bench in a separate part of the workshop where he has test equipment to diagnose the inevitable faults. Here he is working on the RAMU featured in a past edition of Sprat.

In a corner of the garden a brick arch leads to the workshop door, behind the brown door hides the secret world of the amateur radio constructor. Obviously, this is something of a clandestine operation.

Tony, sitting at the other end of Ian's test area, taking down some CW.

In this workshop club members have bandsaw, milling machine, lathe, and pillar drill.

Wow! That's the kind of club that we'd all like to be part of -- Nigel's comments on SS 104 generated a lot of envious e-mail . Thanks a lot guys!

WSPRing Across the Mighty Atlantic

You have to look carefully, but in the picture above you can see a little green line stretching from Rome to Maine. That's my 20 milliwatt WSPR signal crossing the Atlantic. W1CDO's receiver picked me up at 0452 UTC yesterday.

Date	Call		SNR				W	by	loc	km	mi
2009-04-29 4:52	N2CQR		-22				0.020	W1CDO	FN43ou	6541	4064

The day/night terminator was in the mid-Atlantic at that time, so I think I had a bit of a tailwind from the gray line! But still, not bad for 20 mw in Maunder Minimum II. K1JT's software and W1CDO's receive system did the heavy lifting. Antenna here is just an end-fed wire among the buildings of central Rome.

Goats Go QRP to the Field!

Another great video from Steve and the goats.

The Flea at MIT

Nick LaPointe sent along this nice virtual tour of the famous flea market (it includes four videos):
http://eepromeagle.dyndns.org/Pick/gallery/v/mitswapfest090419/

Nick also points us to the very interesting web site of Stephanie Maksylewich (VA3UXB): http://planetstephanie.net/

Thanks Nick!