Sporadic Reflections

Hams of Bletchley Park

2008-07-22T01:13:00.002-04:00

Two cool items from Boing Boing:

RepRap

2008-04-07T19:39:00.002-04:00

Not RF related, but homebrew of the finest kind.

RepRap

The goal of the RepRap project is to build a machine
that can reproduce itself. RepRap has recently selected
the Arduino to be the computer building block of choice.

RepRap on Wikipedia

Sources of parts for home-brew

2008-04-02T11:30:00.002-04:00

Sources of Electronic Mechanical and Surplus Parts is an
extensive list of links to suppliers of goodies that
can be used in home-brew projects.

Part of an interesting site on classic electronics kits:
Nostalgic Kits Central

ESR Meter

2008-03-04T09:44:00.002-05:00

Some of the first components to go south in your aging electronics
are the electrolytic capacitors. One way to test them in circuit
is with an ESR meter.

Homebrew ESR meter

Kit ESR meters

DIY Triode

2008-01-02T23:14:00.000-05:00

Claude Paillard, F2FO, has put together a fantastic video of
making a homebrew triode vacuum tube. See the video at the
bottom of this page.

OK, he has a few pieces of equipment you don't find in every hamshack,
like a simple spot welder and laboratory glass blowing gear.
After you watch this video, you will probably crave the little
spot welder for all sorts of projects.

It seems like making vacuum tubes (valves) might be a lot
simpler (at least possible) compared to a homebrew transistor.

Sprat on CD

2007-12-14T17:42:00.000-05:00

Yesterday, I received my copy of "Sprat on CD" from the GQRP.
"Sprat" is the quarterly technical magazine from GQRP.
The current Sprat on CD contains issues 1 - 132 which brings you
right up-to-date. Each issue of Sprat is in a separate PDF file
and the navigation on the CD is via HTML files. Therefore,
the CD can be used on any computer that has a PDF reader and a browser.

To order Sprat on CD
Sprat home page

The Sprat home page contains a link to a PDF with the table of contents
of all the issues of Sprat. Enough projects to last a life-time.

LilyPad Arduino

2007-12-12T00:12:00.000-05:00

The LilyPad is an arduino board that is meant to be stitched
into an item of clothing. The little pads are to be connected
to conductive thread that would run to sensors, leds, etc. elsewhere on
the clothing. There must be a ham application jut waiting for this
technology. Perhaps a wearable PSK rig with a wristwatch display.
LilyPad Arduino description from arduino.cc
Sparkfun LilyPad Arduino
Wearable + Arduino

Arduino Revisited

2007-11-14T19:47:00.000-05:00

Some months ago, I submitted an item on Arduino.
Recently, Brian N1BQ, gave a presentation at an NJQRP meeting
and provided a kit.

Steve, K9ZW has also gotten interested and posted several
items on his "With Varying Frequency" blog.

Arduino is a very capable platform. Cheaper than a Basic Stamp.
More powerful than a PicAxe. The Arduino folks provide a development
environment that runs on Windows, Mac and Linux. It seems that
it will only be a matter of time until there are ham related applications.

Arduino Tutorials:
Brian, N1BQ
arduino.cc
Arduino playground
Arduino Sound
Lady Ada

Overviews & Amazing Collections:
freeduino universe
MAKE: Blog: Arduino Archives
Make Podcast
The World Famous Index of Arduino & Freeduino Knowledge
Wikipedia

Vendors:
AdaFruit
Modern Device Company
SparkFun
wulfden

30 Contesting tips in 30 days

2007-10-15T00:40:00.000-04:00

Scot, K9JY posted a contesting tip each day in September.
He summarized them and provided links to all 30 in
30 Days -- 30 Ham Radio Contesting Tips.

If you want to improve your contesting skills, that
is a great place to start.

HamAVR

2007-09-15T00:17:00.000-04:00

HamAVR -- a site containing a plethora of ham-related projects using the Atmel AVR processor.

Station X

2007-09-13T21:21:00.000-04:00

Gary, KF9CM is creating a replica of the rigs used at Station X at Bletchley Park.
Station X was the base station that communicated with SOE and French Resistance
agents who used Paraset suitcase radios. Gary describes the project here.

If you click on the key in this picture, you can see a blowup of the key that
Gary recently completed for the project.(In Safari, the picture is already expanded.)

Gary describes the key thusly:
"After fighting with the collectors on eBay trying to purchase a key for
my replica "Station X" I give up. So what is one to do?.....Build one.
So after googling patents for different straight key, I came up with a
design myself. I used all over the counter parts. The pivots on the
center block use the roller bearings out of an old hard drive. The
armature is made from 5/16" key stock and the center block is made from
an aluminum tie-down anchor used on pick-up trucks. "

Computer Monitor Recyling

2007-08-07T13:07:00.000-04:00

Hans Summer, G0UPL, has an interesting page on
recycling the parts from a discarded computer monitor.
The monitor he disassembled had an amazing number of
useful parts. I often see discarded monitors sitting on the curb.
A cheap way to fill your junk box.

The downside is you will have to properly dispose of the CRT
after you have stripped the monitor.

http://www.hanssummers.com/misc/recycling/monitor/index.htm

Throw Bags

2007-07-13T19:27:00.000-04:00

I have always been a little leery of using a sling shot
to send a line over a tree to raise an antenna.
My accuracy is not what I would hope and the occasional
ricochet is a little too exciting for me.

John Kalotai, N1OLO, wrote an excellent article for
the ARS Sojourner about using a throw bag.
Throw bags are used by professional arborists to get
a light line over a tree limb so that, they can then pull
up a heavier rope. The braided polyethylene rope
they use is a big improvement over mono-filament for me.
It pull through the tree very easily and does not tend
to wrap around a branch or itself.

You can get a throw bag and slick line from N1OLO.
Other sources:
Bartlett Arborist Supply
Sherrill - search for Item Number:"SET90"

Sideswiper-Cootie-Speed Keys

2007-07-09T23:58:00.000-04:00

I recently came across a page from France on "sideswiper" keys
written by F5SWN. Someday, I would like to master the art of the sideswiper.

A gallery of cootie keys.
How-to: The Art of Sideswipery

Expanded Electromagnetic Spectrum Chart

2007-06-08T16:28:00.000-04:00

A very interesting Electromagnetic Spectrum Chart.

I always wondered what happened to the Aether.

FDIM Potluck Winner

2007-06-07T23:42:00.000-04:00

The FDIM Potluck Contest was a challenge to build "something"
with a bag of fairly common parts kitted by Diz, W8DIZ of kitsandparts.com.

NT7S created a 40M CW transceiver of very impressive specification
with this $25 bag of parts. His description of the project can be found
here: FDIM Potluck Winner

The original QRP-L announcement of the contest:
[QRP-L] FDIM 2007 Design/Building Contest

Some very interesting schematics and a spreadsheet of the parts
allowed in the Potluck challenge can be found at the Potluck Repository.

Bothy Bags

2007-05-18T19:53:00.000-04:00

I recently received a link to SOTA videos on YouTube.

http://www.youtube.com/groups_videos?name=sota

SOTA stands for Summits on the Air, and the videos are
quite interesting and the Hams who activate some of these
summits are very intrepid. One of the videos contained a
term that was unfamiliar. What is a Bothy Bag?

A bothy bag is a sort of survival bag or group shelter.

Bothy on Wikipedia

A survival bag of this sort would be excellent for your go bag,
for any time or place, where the weather might surprise you.
For instance, on the Appalachian Trail. Something the Ninja QRPer,
WB3AAL might need.

Low-cost Band Pass Filters

2007-05-12T00:49:00.000-04:00

At Thursday night's AARC meeting, Tim Ikeda, KA1OS brought a
printed copy of this neat article from NVARC on a do-it-yourself
scheme for low cost band pass filters.

The NVARC “Ugly” Filter Project

They look like just the ticket for avoiding interference between
multiple stations at Field Day.

Cutting Formulas Considered Harmful

2007-05-02T21:51:00.000-04:00

W4RNL, L.E. Cebik goes full tilt at those magic numbers
we have all seen for cutting common wire aerials to length.

Blunting the Edge of Cutting Formulas

“Reflections”, by Walter Maxwell

2007-04-14T00:23:00.000-04:00

At the Antenna Modeling presentation, WA1JXR mentioned that the
book "Reflections" by Walter Maxwell, W2DU was available on-line.
There are several sources of material from "Reflections".

For a very brief summary, you might want to start with the review [PDF]
on W8KEA's web site. (A very brief summary: High SWR is not so bad;
high SWR and coax is very bad.)

Walter Maxwell's site, Home of the Reflections Series contains
many chapters from the books. Apparently "Reflections 2" is out
of print and a new version "Reflections 3" is being prepared.

The ARRL has a collection of "Reflections" articles that appeared in QST.
They are available in the members-only section: Another Look at Reflections [PDF]
A related QST article by Steve Ford, WB8IMY is The SWR Obsession [PDF] is
not restricted to members-only.

Antenna Modeling

2007-04-12T23:53:00.000-04:00

Tonight I went to a presentation on Antenna Modeling
by Greg Algieri, WA1JXR at the April meeting of the
Algonquin Amateur Radio Club.

The presentation led you to believe that it doesn't take
a "Rocket Scientist" to do antenna modeling with EZNEC.
(An on-line Antenna Modeling presentation by WA1JXR}

EZNEC Antenna Software - free demo software
NEC software for Mac OS
MMANA Antenna Modeling Program Tutorial
Antenna Modeling with L. B. Cebik, W4RNL
Cebik on Some Antenna Modeling Programs

MOXON Antenna Project

2007-04-10T12:28:00.000-04:00

Wow! I don't know how I missed this one for so long.
I have long been interested in M3KXZ, Pete Millis's experiments
with a vertical Moxon set up at the beach.

The MOXON Antenna Project site is chock full of design and
construction information and the experience of quite a number of hams.

Atlanticon 2007

2007-04-04T15:05:00.000-04:00

Atlanticon is the best bargain in Amateur Radio.
The registration fee is traditionally $10. When you
register, you are sent a kit to build for the conference
that is worth more than $10. So once you register, you
are ahead of the game.

Attendance was down this year (approximately 110), but everyone
who showed up had a great time. Since there are already excellent
posts covering all of this year's Atlanticon,
I will refer you to them:

George Heron is one of the NJQRP leaders who helps
create Atlanticon every year. Here is his recap.

K3OQ did a good job blogging this year's Atlanticon.
See his blog, starting with Friday nigh t.

There are two things that I didn't see covered anywhere else.

First is the jewel-like Manhattan construction of Larry Przyborowski, K3PEG.
Larry has developed a technique of using elaborate layout drawings
that he glues to the copper pcb substrate and then does the Manhattan
construction on top of the drawing. You can't get a true idea of
how pretty the results are from a photo.

You've probably heard the expression: "When life hands you lemons,
make lemonade". Well, the NJQRP suffered a glitch on the first production
run of boards for the Rookey Kit, which was the 2007 Atlanticon kit.
The rev. 1 boards were produced without a ground plane. After some
consideration, the NJQRP team turned these "worthless" boards into
the "lemonade kit" which were on sale at Atlanticon. They created a
Koch style Morse Code trainer using the bad boards, some extra wire runs
and the PicAxe microprocessor. Brilliant!
(Joe Everhart on the "lemonade" project.)

Try not to miss Atlanticon 2008.

BITX Construction Notes

2007-03-07T23:46:00.000-05:00

Several items of good news on the BITX front:

Doug Hendricks of qrpkits.com is planning a kit version
of the BITX20.

Leonard, KC0WOX has made several very interesting
videos of the test and debugging process for a BITX20
he is building. They are available at:
http://golddredgervideo.com/bitx20/

Arv Evans, K7HKL who has contributed many postings
on the BITX Yahoo group is blogging his construction
of one of Doug Hendricks's prototype kits.
http://arvevans.livejournal.com/

Sunil, VU3SUA has started a shared blog, CQ BITX,
so builders can share their experiences building
the BITX.

Electroluminescent Receiver

2007-03-06T20:56:00.000-05:00

I have had my eye on the "The Electroluminescent Receiver Kit"
for quite some time. The kit was mentioned on the Mail Bag
section of SolderSmoke #48, the most recent edition.

The kit is interesting because it results in a high performance
receiver that uses large printed circuit boards for those tired eyes.

"The interconnections are infrared and there are 21 functional
LEDs that add to the circuit, not just tell you when it's on."

I recently came across KC5WA's site, where he is documenting
his build of the Electroluminescent Receiver. He also documents
a variant he calls the Super Luminescent Receiver.

More info

Sporadic Reflections

Hams of Bletchley Park

Hams of Bletchley Park

Bletchley Park kicks...

RepRap

Sources of parts for home-brew

ESR Meter

DIY Triode

Sprat on CD

LilyPad Arduino

Arduino Revisited

30 Contesting tips in 30 days

HamAVR

Station X

Computer Monitor Recyling

Throw Bags

Sideswiper-Cootie-Speed Keys

Expanded Electromagnetic Spectrum Chart

FDIM Potluck Winner

Bothy Bags

Low-cost Band Pass Filters

Cutting Formulas Considered Harmful

“Reflections”, by Walter Maxwell

Antenna Modeling

MOXON Antenna Project

Atlanticon 2007

BITX Construction Notes

Electroluminescent Receiver