From the trade magazines: capacitors, inductors, radio architectures

May 22, 2013 by Leave a Comment

Temperature and voltage variation of ceramic capacitors. Read the data sheet! This tutorial explains how ceramic capacitor type designations, such as X7R and Y5V, imply nothing about voltage coefficients. You must check the data sheet to really know, how a specific capacitor will perform under temperature and voltage.

Circuit measures capacitance or inductance. You don’t need a fancy LC meter to measure capacitance or inductance. This short article show you how to do it with a function generator, multimeter, frequency counter, and an oscilloscope. Hmmmmm. By the time you get that all lashed up, it might have been quicker to just buy one of these LC meters from China.

Understand Radio Architectures. This is the first in a series of excerpts from the book RF Circuit Design, 2e by Christopher Bowick. Even though this appears in an engineering trade magazine, some of this is pretty basic stuff. You even get a schematic for a crystal radio!

Filed Under: Electronic Components, Electronics Theory, Test Equipment

Yet another Heathkit?

May 21, 2013 by 2 Comments

heathkit-screenshot-20130521

 

Twitter is abuzz with news that someone is trying once again to revive Heathkit. The image above was taken right off the Heathkit home page.

Even more amusing is the online customer survery. It’s quite an extensive survey and very heavy on the amateur radio questions. GB Hoyt (KB4GVL, @kb4gvl on Twitter) has an interesting take on what it will take for them to succeed on his blog.

Take the survey and tell me what you think. Can Heathkit be resurrected?

 

 

Filed Under: Building/Homebrew, Kits

From my Twitter feed: future of SDR, Dayton review, fritzing

May 19, 2013 by Leave a Comment

K9ZW
The Future of SDR – Fat-Pipe vs. Thin-Pipehttp://t.co/u6WpGGv6ML

 

ke9v
Dayton in the Rearview Mirror | Smoke Curlshttp://t.co/PI25XUisGR #hamr

 

g6avk
This looks like an interesting and easy to use PCB package - http://t.co/xsL7rY2t7n

Filed Under: Building/Homebrew, Circuit Design, Hamfests, Software-Defined Radio

Amateur Radio Tip of the Day: Keep your soldering iron tip clean

May 13, 2013 by 3 Comments

To make good solder joints, you need to keep the tip of your soldering iron clean from any oxides and dust or dirt. A clean, well-tinned tip will transfer heat properly and help you avoid cold solder joints. Many solderers use wet sponges to clean soldering iron tips, and many solder stations have troughs to hold these sponges.

soldering_iron_tip_cleaner

An alternate method is to use a wire cleaning pad like the one shown above. You stick the iron into the pad and then draw it back out. The wire scrapes the oxides and dirt from the tip as you do this. Proponents of this method claim that this method increases the life of the tip as it avoids the rapid temperature changes that using a wet sponge cause.

73!

Dan

OUR FIRST WINNER!
Larry, KB8QJE, is this week’s winner of one of my e-books. His name was randomly selected from the subscriber list.

SUBSCRIBE
Tips like this one are sent out every day by e-mail. To subscribe to the list, simply click here and fill out the form. Every week, I’ll select a random subscriber and give them one of my books.

GOT A TIP?
Do  you have a tip that you’d like to share with other radio amateurs? E-mail it to me. If I use your tip, I’ll send you one of my books.

Filed Under: Building/Homebrew, Tip of the Day

Solder: 60/40 or 63/37?

May 10, 2013 by Leave a Comment

File this under  ”You learn something new every day.”

A 1-lb. roll of Kester 44 solder with a 63/37 tin-lead formulation is $22.96 from AllSpec Industries. Kester 44 with a 60/40 formulation costs only $21.06.

A 1-lb. roll of Kester 44 solder with a 63/37 tin-lead formulation is $22.96 from AllSpec Industries. Kester 44 with a 60/40 formulation costs only $21.06.

A couple of days ago, someone on the HamRadioHelpGroup mailing list asked, “So I’m about to put up my first antenna and I need to solder the connectors to the coax. I know learned this in the book but I can not find it, so what kind of solder should I be using?”

Pat, K7KBN, replied, “Rosin core, 60/40 lead/tin (63/37 is better).  Don’t use any acid core or acid flux solder, and avoid the no-lead junk.  The diameter of the solder depends on your taste and experience.  Connector work requires more solder than circuit board work in most cases. And for connectors you need an iron with a massive tip that won’t cool off when you touch the body of the connector like a typical gun tip will.”

So, of course, I had to ask, “Why is 63/37 better?”

The answer? “The 63% tin/37% lead solder alloy is “eutectic” (Google it).  Basically it has NO ‘plastic range.’ It changes instantly from liquid to solid.”

Mark, K5LXP, ever the practical ham, added, “For anything hams solder you would be hard pressed to discern the flow, hardness or durability difference between any of these lead alloys. Hams being hams, 60/40 is usually the cheapest. That makes it ‘better’ right there!”

Filed Under: Building/Homebrew

From the trade magazines, impedance matching, EMI basics, open-source hardware

May 2, 2013 by Leave a Comment

elelctronic-design-logoBack to Basics: Impedance Matching. electronic design editor (and amateur radio operator) Louis Frenzel is the author of this short e-book on impedance matching. Note: this e-book was intended for engineers and does use a fair amount of math, but nothing you can’t figure out if you work at it.

EMI Basics. This article  comes from the book Signal Integrity Issues and Printed Circuit Board Design by Douglas Brooks. I like the discussion of how twisted pair wire helps prevent radiation.

Interview With SparkFun’s Director Of Engineering. Peter Dokter is director of engineering for SparkFun, one of the major suppliers of open source hardware. SparkFun designs and sells things useful and interesting to the aspiring electronics tinkerer, including microcontroller boards, Bluetooth, GPS, Wi-Fi, LCD displays, e-textiles components, robots and robotic parts, motors, motor drivers, buttons and switches, tools, and books.

Filed Under: Books and Magazines, Electronics Theory, EMI/RFI, Gear/Gadgets

From my Twitter feed: kits, cool transmitter, new CW book

April 24, 2013 by Leave a Comment

MW0IAN
Tim Walford G3PCJ does a nice bunch of radio kits and accessories http://t.co/ZgIdxUc2aj

 

This brings new meaning to “having a cool one.”

kc5fm
“A new “Cool Transmitter” from W5IG.”http://t.co/vtxAwfsWar #ARRL #hamradio

 

The ARRL stole my idea! (just kidding)

ke9v
NEW book from the @ARRL – Morse Code Operating for Amateur Radio ~ Don’t Just Learn Morse Code, Master It!http://t.co/kzlgAQJSUN #hamr

 

Filed Under: Books and Magazines, CW, Kits

From my inbox: 1, 2, 3-tube radios, cheap cap tester, cheap frequency synthesizer

April 3, 2013 by 1 Comment
  • Build a radio with three tubes or less. This article lists radios that you can build with three tubes or fewer. In general, this is a very cool website. (Thanks to Brad, AA1IP, and the Glowbugs mailing list.)
  • Cheap capacitance tester. The Glowbugs mailing list also recently had a discussion of cheap capacitance testers. I just bought a fancy, new Keithley DMM  that measures capacitance, but some of the instruments mentioned in this thread also measure inductance. The consensus seems to be that while they’re not as accurate as a “real” test instrument, for $20 or so, how can you go wrong?Brad, AA1IP mentions the article, “A Low Cost Automatic Impedance Bridge” by Dr. George Steber, WB9LIV, that appeared in the October 2005 QST. Brad says, “This arrangement uses a PC’s sound ports, a dual-section op amp, a few components and some software to deliver reasonably precise RLC measurements along with a graphic screen display.”
These frequency-synthesizer boards use the AD9850, and can be purchased on eBay for as little as $5 each.

These frequency-synthesizer boards use the AD9850, and can be purchased on eBay for as little as $5 each.

 

  • Cheap AD9850 boards. The AMRAD mailing list has a thread on these inexpensive signal-generator modules. One of the AMRAD guys has been experimenting with using them with an Arduino to make frequency control easier. They’re only $5 each and generate 0 – 40 MHz.On the Glowbugs list, they talked a little bit about these boards, too. One guy gave a link to the article, “An Improved VFO Driver Amp for Tube Rigs.” This article describes a circuit that allows you to easily use the AD9850 boards (or any other digital synthesizer, for that matter) as the VFO for a tube rig.
Filed Under: Building/Homebrew, Circuit Design, Tubes

From my Twitter feed: old book, HAMcurmudgeon, mountain topper radio

March 30, 2013 by 2 Comments

ke9v
Really? Everything? I somehow doubt it.http://t.co/3CKO04H3pO

Screen shot 2013-03-30 at Sat, Mar 30 - 10.06AM 1

What Jeff is referring to is the book above, All About RADIO and Television. I love books like this and tweeted Jeff about that. Being the great guy that he is, he actually bought the book and sent it to me. THANKS, Jeff! If I see you at Dayton this year, I owe you a beer….Dan

HAMcurmudgeon
U might be a HAM if when U tell your wife that 20 meters is dead she sighs & asks, “How much will that cost to fix?” #hamradio

W2MDW
First blog post in a while. My MTR arrives!http://t.co/ABZCKSU9oH

 

Filed Under: Books and Magazines, Kits

Ads of note from the April 2013 QST

March 22, 2013 by 3 Comments

I couldn’t sleep this morning, so rather than just lie in bed, looking at the ceiling, I got up and made myself a (very) early breakfast. Whilst eating my eggs and cantaloupe, I scanned the ads from the latest QST. Here’s what caught my eye:

The TT1A costs $129, and that doesn’t include the 200 V power supply. Yipes!

  • YouKits (page 128). YouKits is offering a new kit this month – the TT1A two-band, two-tube CW transmitter. It’s very cute, but according to the YouKit website, it costs $129 (plus $29 shipping), and even at that, you have to buy or build a 250V supply to power the thing. Call me crazy, but I think that’s a bit much for a 4W transmitter, don’t you? I think I’d rather spend that money on the Funk Amateur SDR kit (see below). TenTec is YouKits U.S. distributor, but I don’t find this kit on the TenTec website yet.
  • Mosley Electronics (page 132, 153). Mosley has been making quality antennas for many years. In the April 2013 QST, they are running a very small ad on pages 132 and 153. I guess they have such a good reputation that they really don’t need a big ad. You’d think that I’d be more familiar with their products (since I’ve been a ham for many years), but I’m not really. Their ad prompted me to go to the Mosley website, where I found out that they not only made beam antennas, but verticals and dipoles as well. In addition to information about their products, there is information about antennas in general. I particularly liked the short article on “SWR-itis.”
  • Funk Amateur (page 147). A lot of amateur radio operators are funky, but “funk” in this case is German for radio. This German company is offering two kits: the FiFi SDR kit, which is a 0.1 – 30 MHz SDR receiver for $169, and a voice keyer kit for $55. Both prices include shipping to the U.S. I’m going to contact them and see if they’re going to be at Dayton. If not, I might just pop for one or both of the kits.
Filed Under: antennas, Kits, QRP
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