KNACK IN THE SHACK: N5ITU

Jeff, N5ITU, clearly has The Knack.

The mug and the bumper sticker are available at the SolderSmoke Cafe Press store: http://www.cafepress.co.uk/SolderSmoke

Jeff is in Texas. We had a feeling that this particular bumper sticker would appeal to those the Lone Star State.

Reverse Polarity Protection -- Words of Wisdom from K7QO

Words of wisdom from Chuck Adams, K7QO:

Wednesday, February 24, 2010 12:11 AM

From:

"chuck adams"

Add sender to Contacts

To:

qrp-l@mailman.qth.net

This posting due to the traffic on the SST reverse
voltage application.

Here is what I do. There is a diode, the 1N5817,
a Schottky Diode. Will take 20V peak reverse voltage,
will handle 1A continuous with 25A surge and has only
a 0.45V forward drop and the reverse current is 500uA.

I put one of this in series with the 12V line input of
every electronic device I build. If the designer used
a 1N4001-7 in series, I replace it.

I am not a fan of the diode across the voltage input
line and having it short out when reverse voltage is
applied. What if the applied voltage is a gel-cell
without a fuse? You blow the diode and you blow the
rig. IMHO is this not an ideal way to do it. Should
be using fuses too, but I don't. Haven't found a way
to use the flat auto fuses with gel-cells in a handy
low-profile way and inexpensive parts. I'd appreciate
the education, if someone has film and photos of great
arrangements.

I buy the diodes from Mouser.Com for about $26 per 250.
For a dime a rig it is a real cheap way to protect your
equipment from yourself and others.

With the limit of 1A at 13.8V, it is well within the
QRP operating limits. And why do you need more than
1A anyway?????? :-) And the low forward voltage
drop means that the finals (which are usually fed
direct from the B+ line anyway) don't lose much
in applied voltage and you get pretty much the
same output as without the diode. And you protect
those expensive parts for a dime. A quarter if you
buy just one diode from Mouser.

Hope this helps. Just the way I do it, and I'm
not always right. But I've only lost a few parts
and that was before I started using 1N5817's on
everything.

The 1N4001 through 1N4007's are fine if you are
feeding 9-12V to a 78L08 regulator.
FYI
chuck
--
chuck adams, k7qo
http://www.k7qo.net/
chuck.adams.k7qo@gmail.com

F8CKH: The Knack, 747s, and Homebrew QRP

Here is some further evidence that The Knack is a global phenomenon. I'm sure our readers will find Antoine's story quite familiar. Looking at his QSL (below) we can see that he has a special reason to be interested in QRP: After a full workday of operating a very high-powered rig (!), a simple little QRP rig must represent an appealing contrast. And even if that 747 is very QRO, I think we will all agree that Antoine has the kind of job that most knack victims dreamed about when they were kids.

Hi Bill,

I have been listening to your podcasts for a while now after I heard about them in one of the Amateur Logic TV shows. I picked up one podcast randomly and I got to say that I really enjoyed the tone and content of your talks. Very informative and interesting. I like also the fact that your amateur radio experience is based on homebrewing and experimenting. Back in 1997, I earned my French amateur radio license at the age of 16 (extra and big CW lover). I have been always amazed by what we could do with very little and go very far. My family is Hamradio friendly: my grandfather was F8KE back in 1930s and he has been around the hobby for most of his life. At 7 or 8 I remember times where we were at his place and I would ask for permission to leave the table early to go upstairs and visit my grandfathers shack. Everything there was homebrew and I was really pleased to see that the magic of Radio was achievable with only few components, homebrew antennas and a bit of luck. He encouraged me to learn the Code and at 12 I was already up to 20 wpm! My dad used to be 6W8FC while he was in the service and he gave me the passion for weak signal and DXing. Technically speaking, I HAD to become a Ham Radio operator.

I am really fascinated by your level of dedication to homebrewing and also that you share that we us, fellow operators addicted to -soldersmoke-. Just like you, I have been all over the place since I am an Airline Pilot qualified on the Airbus and Boeings... UK, New Zealand, US, I got a chance to operate from couple of places and something got the pleasure to be behind the scene and become the reason of a pile up. Operating from down under from Kiwi lands was a wild and exciting experience, indeed!

Finally I am about to move permanently to the US, in Pennsylvania. I applied for a Vanity Callsign (NY3G) and hopefully I will hear from the FCC soon.

I wanted to mention also that I got rid of almost all my regular Yaesu, Kenwood rigs to start from scratch. My project? To design, build, operate an HF station from scratch. No more commercial rigs for me! Well I will try! I am really happy to finally make use of a workbench that I just cleaned at home. I will set up a blogspot account to illustrate my projects... I think that would be great to make QSO with you Bill, sometime!

Thanks again for bringing some much enthusiasm into this fascinating side of Ham Radio, Homebrewing.

Best Regards,

73

Antoine Pierre GAMET F8CKH

Homebrew QRP Contest... With DSB!

Walford Electronics Brendon 80m DSB kit

Hi Bill

I trust all is well and that the roadkill PCs are not fighting back. Thought you might like to hear about a new contest we are trying here in the UK. Having assisted lots of new knack victims to build their first rigs at the 3 Bath Buildathons we thought we should encourage them to get on the air - 30 QRP DSB rigs on 80m all at once - now that's what I call a contest.

We have opened it up to any QRP voice radio to cover the QRP appliance operators but homebrewers get extra points. Not sure how much support we are going to get but there is a £50 voucher for Walford Electronics kits up for grabs.

Hopefully this will be a fun contest with freindly extended exhanges rather than the all too common '599 1002 73 QRZ'. Picture is the Walford Electronics Brendon 80m DSB kit in all its glory.

73, Steve, G0FUW

Big Filament -- On the Sun

The WSPR system has become something of a personal solar activity detector for me. I know, there are lots of ways to detect solar activity: there's the internet, of course. WWV is also there. You could even set up a small telescope and (with the appropriate eye-saving screen or projection systems) watch for spots yourself. But I like using my 20 mW DSB WSPR signal. If I get up in the morning and see that my little signal has been received during the night in Norway by LA3JJ (1950 km) I know that something different is going on with Old Sol.

LA3JJ was detecting my signals all night long last night. And other stations in Europe were picking up U.S. and Israeli stations throughout the night. So, what was happening on the sun? It may have had something to do with the filament pictured above. For more info on this kind of solar event, take a look here:
http://www.ips.gov.au/Educational/2/4/1

QRP Quarterly -- Winter 2010

Lots of great stuff in the latest edition of QQ from QRP ARCI:

Mike Czuhajewski's "Idea Exchange" column has been sending out great ideas for many years now. In this edition he opens with a piece from Wes, W7ZOI, that originally appeared on the EMRFD mailing list. It deals with diode ring mixers, specifically the power requirements for the local oscillator. What do they really mean when they specify 7 dBm? Wes explains: "If we say that the LO power is +7 dBm, what this really means is that a signal generator is attached to a power meter or spectrum analyzer and adjusted to deliver +7 dBm at the desired frequency to the 50 ohm instrument. Once the power is set, the cable is disconnected and reattached to the mixer." I'd always wondered about how to measure that. Thanks Mike! Thanks Wes!

Preston Douglas, WJ2V, has a nice article on our latest craze: WSPR. Preston also discusses SDR radios -- his encouraging comments may help me get out of my current luddite curmudgeon rut. Preston mentions recent efforts to use a BITX-20 for WSPR and concludes that this would be "a tall order for any analog rig." This comment lessened my feelings of inadequacy about my SDR SMT problems, because I recently used my ancient Drake 2-B to receive WSPR sigs (see earlier blog entry). Luddites Rule! But Preston is right -- it's not easy! But -- at least for a little while, before drift takes you out of the band -- it can be done.

Ward Harriman, AE6TY, writes of a "homebrew" SDR project. In his opening paragraph, he tells us what the term "homebrew" means to him: "homebrew design, homebrew assembly, homebrew programming, homebrew in a wide range of disciplines both familiar and untried." That's pretty hardcore! FB Ward!

Jim Osburn, WD9EYB, has a nice article on "circuit stickers" and how they can be used to simplify project construction using a variety of circuit boards and breadboards. I really liked Jim's description of old Electronics Illustrated projects in which they pasted a diagram to a wood base and then put finishing nails at specified points. Components were then soldered to the finishing nails. When the thing works, you can say you "really nailed it!" (Sorry!) Cool technique.

Thanks to the folks at QRP ARCI for another inspiring edition of their wonderful magazine. If you are not a member, you are missing a lot. Sign up for the club and the magazine here:
http://www.qrparci.org/

Solar Rocket Destroys a Sun-dog

Continuing with our solar theme, here is a neat little video taken on Feb 18 by a thirteen year-old kid. It shows the Atlas rocket carrying NASA's new Solar Dynamic Observatory crashing through a "sun-dog" and obliterating it with the rocket's shock wave. Obviously an auspicious beginning for this mission.