The Overview Effect

OVERVIEW from Planetary Collective on Vimeo.

Every once in a while, it's a good idea to step back and consider the big picture.

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Fabio's Direct Conversion Receiver

Fabio, IK0IXI, is an electronic wizard from Civitavecchia, near Rome.   Check out his very nice DC receiver. Note that wonderful direct conversion sound.   Very cool that has it atop our beloved SPRAT.   Below you can hear the effectiveness of the audio filter.   Bravo Fabio!



Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

A Ham Radio HackerSpace

Bill -  Enjoyed your conversation regarding seeing the Maker guys at a recent hamfest.  Thought I'd let you know that, at least on a small scale, we've created a ham hacker space in our club by organizing a "Builders Group" as an adjunct to the Williamsburg Amateur Radio Club (WAARC) here in Williamsburg, VA.  I volunteered my QTH as a meeting place and the majority of projects have been either QRP or test equipment related.  Folks select their own project and bring their own tools to use.  These projects have included the Hendricks tri-band QRP transceiver, NorCal FCC-1 frequency counter, N3ZI digital dial, Tuna Tin II transmitter and others.

I corralled two friends in the club to act as "mentors" to assist less experienced builders with soldering and construction.  Once builders complete their projects my workbench upstairs is available to verify correct operation or troubleshooting as required.

Here are a couple of pix of the guys having fun melting solder.

73 - Dino KL0S

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Richard's Rip-Van-Winkle Barbados Rig

Dear Bill,

Thank you for taking a few minutes to read my email. I recently found your blog and enjoyed reading the entries.  However, the most interesting and exciting article I discovered was your "Homebrew Radios in the Age of the Internet." The article reminded me of a project started 30 years ago this month and placed in a box in the attic to wait until I could return to it.
Thirty years of health care management work filled the interim.

The project is the 8P6 Hamcation rig by W1FB from QST of June and November 1982!

I searched through the cob webs in the attic and found that all the boards are completed and I even fabricated a case. The original QST's were there too! In response to a (somewhat strong) suggestion from my wife to "get a winter project going", the rig is back on my retirement work bench. Wahoo.

Progress to date has been instructive and fun. The boards are all cleaned, checked, and 95% wired together in the case and working. I attached 2 photo for your pleasure because you wrote specifically about the receiver in some blog posts.

This is where I am scratching my head. As you say in the article, "receivers are tough". I am confused and a bit frustrated about the correct procedure and sequence to correctly align the Barebones superhet. I can already hear stations and the noise level is acceptable. But I am not quite sure how to proceed in peaking up the receiver (hit a plateau?) Any suggestions for a newly retired ham now with the time to get back to the bench?

Thank you very much for your kind comments and interest in my project.

73's
Richard
WB2PEF
Cherry Valley NY

Wow, what a cool resurrection project!   I recognize both the receiver and transmitter boards.   The RX is clearly DeMaw's Barebones Superhet on a FAR Circuit board.  I am listening to one of those AS I TYPE.  Mine was put together by Dale, W4OP, and currently inhales on 17 meters.   The TX board is what became known as the VXO 6 Watter.   It was (I think) designed by W1VD, and appears in the ARRL book "QRP Classics."   This was my first really successful homebrew rig -- I built that transmitter in the Dominican Republic  in 1993.   I still have most of the board, and the 20 meter Barebones RX that I used with it.   Richard's message makes me want to put this old gear back on the air. 

I hope Richard will send us an update on his Barbados revival project.

I'm sure Doug DeMaw would be very pleased to know that his projects are still providing radio amateurs with a lot of fun and inspiration.


Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

SolderSmoke Podcast #150

http://www.gadgeteer.us/PORTABLE.html

SolderSmoke Podcast #150 is now available:

http://soldersmoke.com/soldersmoke150.mp3

March 6, 2013

-- SolderSnow!
-- Winterfest Hamfest report
-- N2CQR WINS ARRL INTERNATIONAL DX DSB CONTEST!!!!
-- Homebrew Direct Conversion RX meets PSK-31 and FLDIGI
-- Kludge Controversy II
-- More Q Killing
-- Fixing up old cassettes
-- Pat Hawker, G3VA, SK
-- Mailbag




Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

VE7BPO on "Killing Q"

I'm still scratching my head a bit about HOW the resistor prescribed by Edgardo, LU1AR, cured the 250 kHz oscillation problem that was plaguing the JBOT amplifier in my 20 meter DSB rig.   Earlier I'd posted an excerpt from a CQ article in which Doug DeMaw talks about swamping and Q killing.   Last week I got a very thoughtful e-mail from esteemed homebrewer Todd,  VE7BPO.  Here is an excerpt :

Thoughts and Considerations
Let’s discuss squashing low frequency oscillations in a QRP transmitter; say at 200 KHz or so. A low value resistor across the coil (12t -- FT37-43) often works well to stop these.
Oscillations come from the transistor: gain versus frequency isn’t linear, nor is impedance at transistor ports. We’ll often add negative feedback and such to stabilize an amplifier towards unconditional status. In my Tx circuit that oscillated, no feedback was applied. 
 In the case of an inductor wound on a FT37-43 or FT50-43, the Q is already low (say 8- 15 or so). Obviously a resistor in parallel with such a coil is not going to lower Q since Q is already quite low. That R will reduce the inductor impedance and thus may serve to decrease the low frequency gain of the RF amplifier to stop any low frequency oscillations. This might not work so well with a way-high fT transistor where decoupling might be hampered if UHF oscillations are singing. 
Doug DeMaw often referred to the parallel resistor as a Q-killer. If we examine the equations describing parallel, or series resonant circuits -- if the Q of a tank is high enough, we can practically ignore the effect of resistance at resonance. Conversely if we add a resistance and make it high enough, we might even obliterate the resonant frequency or “kill the Q”. Engineers have long placed an R into a parallel-tuned circuit to drop Q and stop oscillations — they refer to it as damping. 1 example might be in old TV sets where a variable resistance was added to peaking coils to prevent a tank from ringing at a frequency determined by the coil L and distributed C. This applies to higher Q inductors and not our FT37-43 inductor. 
Decoupling
Our teacher, Wes, teaches us in EMRFD that coupling often occurs along the DC power supply lines.  Further, he’s taught us to decouple AC by placing high impedance in this path.  Often the impedance is a low-pass filter with series element(s) of a high Z and shunt element(s) with a low Z.  The filter must present a simple short circuit (or perhaps just a resistance) at low frequency so DC flows to the amplifier.    
Final 
Oscillations should likely be identified and treated according their frequency. This topic looks advanced and all RLC networks deserve more attention from us.
Todd, VE7BPO --- Feb 27, 2013  

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Three Great Videos from Alan W2AEW

Bill:

While not really homebrew, they do deal with QRP and RF.  The first two are walk-throughs of the schematics of two QRP transceivers, and the last is a discussion of how diodes can be used as RF switches.  I thought you'd find them interesting.

MFJ-9340 QRP Cub CW Transceiver kit schematic review:

http://www.youtube.com/watch?v=2QSwXv2RJzw

 

Heathkit HW-9 schematic walk-through:

http://www.youtube.com/watch?v=rPM1vvGorTo

Using diodes as RF switches:

https://www.youtube.com/watch?v=YBNIq_d56sA

73,

Alan
Http://www.youtube.com/w2aew

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

QRO Problem, and THE KLUGER

Hi Bill,

I've been enjoying your podcasts for a couple of years now and have read both of your books. Please keep up the good work it is much appreciated. In fact, as I can now have both your books and your podcasts on my iPod they are quite literally held close to my heart.

Inspired by your "Kludge Controversy" - enclosed are a couple of photos that I took while on Mount Wellington in Tasmania.


THE POWER OF RADIO

Mount Wellington is a high mountain and is a good launch point for radio waves over the city of Hobart. The visitor lookout has this fantastic warning sign "Electronic disturbances to your vehicle" warning that the transmitter on the mountain can seriously interfere with your car and it may not start, the doors may not open, and the immobiliser may permanently immobilise it. The advice is "A metallic sunshade may reflect radio waves away from the vehicle" and allow you to start it. I'm sure your QRP rigs need no such dire warnings!

WHAT WERE THEY THINKING

And in the very same car park I see this car called a Kluger. In what flavour of English is that a good idea? I know the Brits and Yanks differ over a few phrases but I've never before come across an Oz word that means the exact opposite.

Thanks again for all your many inspiring "broadcasts", and may the Magic Smoke (http://en.wikipedia.org/wiki/Magic_smoke) always stay where it should!


Steven
G6VRD


Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

73 -- The BEST Number

My kids watch this show.   This appears to be one of the only interesting comments to come from it:

"The best number is 73. Why? 73 is the 21st prime number. Its mirror (37) is the 12th and its mirror (21) is the product of multiplying, 7 and 3. ... In binary, 73 is a palindrome, 1001001 which backwards is 1001001."

-Dr. Sheldon Cooper, (Jim Parsons), "Big Bang Theory"

"Just to invite your attention to "73" in Morse code--also a palindrome."

-W9JEF

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Kludge Controversy Continues

Forget about the sequester!  The real issue facing our country is the proper pronunciation of the word Kludge.   Several visitors to the SolderSmoke table at last weekend's Winterfest weighed in on this issue.   SolderSmoke Lexicographer Steve Silverman wrote to inform me that I had totally misinterpreted his e-mail -- he is in fact rather firmly in the Klooge as in Stooge camp.  I, however, am sticking to Kludge as in Fudge.  It just feels right.  And I may use the awesome power of the SolderSmoke media empire to actually CHANGE the way people pronounce this word.

Check out the California Kilowatt ad.  In retrospect, probably a poor choice of brand name.


Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

SolderSmoke Podcast #149

Podcast #149 is now available:  http://soldersmoke.com/soldersmoke149.mp3

17 February 2012

IGY intro
Cappuccio turns off TV on New Year's Eve
Pre-inaugural day on the National Mall
The importance of audio bandwidth in DSB rigs
On 15 meters with the HT-37 and the Drake 2B
Q Killing and Swamping
Adding a Filter the Mighty Midget Receiver
Italian lessons via Echolink
Billy and the Raspberry Pi -- Three Cheers for Ada Fruit
Translate Button on the Blog page (upper right)
C.F Rockey SK
Mailbag: Kludge or Klooge?  

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Carl Sagan, Astronomy, and the Zen Pencil

We presented Carl Sagan's beautiful "Pale Blue Dot" quote back in September 2011, along with a nice video.    This week a friend in Kathmandu sent me a link to a web site called The Zen Pencil.   This fellow takes great quotes and draws cartoons to accompany them.   I liked his cartoon for The Pale Blue Dot:

http://zenpencils.com/comic/100-carl-sagan-pale-blue-dot/ 


Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20