SolderSmoke Daily News

Sunday, February 8, 2015

Glowing Blue Numerals! A Frequency Counter for the BITX17 (VIDEO)

These little frequency counters from China have a lot of potential. And they add a dash of digital color to an otherwise bland analog hamshack. I got mine on e-bay.

My BITX17 has now been "accessorized" with
1) A rotatable Moxon antenna (big improvment!)
2) A 120 watt Communications Concepts Linear amplifier (another big improvement) and
3) This digital frequency readout.

What next?

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Saturday, February 7, 2015

DuWayne's Scalar Network Analyzer -- In an Altoids Tin!

DuWayne (KV4QB) has done something very cool here. He's taken an Arduino Nano, a cheap AD9850 DDS board, a small screen, and a couple of log detectors, and he has built IN AN ALTOIDS TIN a scalar network analyzer that lets you see the bandpass of a filter. (We posted an earlier version of this here: http://soldersmoke.blogspot.com/2015/01/duwaynes-ad9850-arduino-tft-swr-scanner.html ) Wow. I've been doing this by hand, changing the input freq at 100Hz increments, measuring the output, putting the results into a spread sheet, converting to log (db), creating a graph... DuWayne makes it a lot easier. DuWayne is being encouraged to write up the results, possibly for QRP Quarterly.

Hi Guys
Started playing around with the SWR scanner that I had been working on. Waned to see how hard it would be to make a very simple scalar network analyzer out of what I had. Really wanted something small to use for checking bandpass other filters. Hoped to get about 30 db. of range ,which should be enough for most filters. I have a couple of 8307 log detectors, but was afraid that it would be a pain getting it working and shielded in an Altoids tin along with the rest of the circuitry. Went with something even easier than the resistive SWR bridge I already had. Replaced the bridge with two basic diode RF probes, and changed the amplifiers so I could adjust the gain. I use one to measure the direct output of the 9850 DDS module, and the other for the output of the device under test. Kept the same control function as in the SWR scanner. A short push on the encoder button starts a sweep of the selected band. Holding it down for over a second cycles through the bands. Once a scan is done you can use the encoder to scroll through the sweep. I display the frequency and iDUT value in db relative to the output of the DDS module. The USB connector is available and different start and stop frequencies can be entered if needed when working with IF stages.

Well it worked much better than I had expected. After a simple adjustment of the amp gains with the output looped directly to the input, I was getting nearly 50 db with the loopback removed. Just using some standard value resistors, in a pi attenuator I got a very nice looking sweep that was within a couple db of the 40 db i had built it for. Since I only used standard value resistors, I though this was good enough.

Then I used ELSIE to design a 14mhz lowpass filter, again used standard values for L and C that I had on hand . Really happy with the results I got.

Finally I grabbed 3 crystals out of a bag without checking frequency or other parameters, I threw together a basic crystal filter. Used the USB interface to set the sweep range, I was really really really pleased with the results I was able to obtain.

The software still needs a little tweaking and a couple of additional functions I want to add, but I think this will be a very nice tool. Plan on giving it a try when I build Pete's Lets Build Something transceiver. Amazing what you can stick in Altoids tins, even if you have to stack two so you can include a battery pack .

Attaching some pictures of the progress so far. As you can see that with what I used to build the test fixtures, I am amazed that they even worked at all.
73 DuWayne

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Friday, February 6, 2015

A De-Soldering Primer By Wayne Burdick

A De-Soldering Primer

Wayne Burdick, N6KR

Removing resistors and other parts from double-sided boards is easy and

fun. After years of careful analysis of my own technique I have documented

the process. I start with technique #1, below; if that doesn't work, I try

#2, etc. Good luck!

1. Turn the board over. With one hand behind your back, a wry smile, and

the confidence of a pet surgeon, simply heat the lead in question and

listen for the pleasant sound of the component hitting the work bench.

2. Well, that *would* be too easy, wouldn't it. Staying with the solder

side for now, locate a large solder sucker (the larger the better; it

should frighten smaller pets when brandished). Heat each joint and deftly

suck out the solder with a single satisfying Thwop! Listen for the part

hitting the bench.

3. Didn't fall out, eh? No problem: rummage in that tool bin for a shiny

new roll of solder wick. Crack open a beer, too, and take a generous swig.

Wedge that wick in between the lead and pad, heat until you see the solder

flow nicely onto the wick, and pull it out of the way just in time to see a

beatiful, black annular ring around your component lead. Nudge each lead

with your iron and keep your fingers crossed.

4. OK, so you've got a tough customer: small lead, hole just barely

larger, and a bit of off-color solder that can't be bothered with any of

the usual techniques. Have another sip of that brew. Vigorously flip the

board back to the component side. Now grip the lead professionally with

your most elegant long-nose pliers and hold on tight. Give it a playful

yank, then pray. Should pop right out.

5. Damn. Finish the beer and get out your brutal, 8" electrician's

long-nose. Grab the component with gusto this time, buster, then tip the

board up at a 45. Turn up your soldering station to max and heat that baby

up on the backside. Pull down hard with the pliers.

6. No go? Hmmmm -- let's get serious. Put the board up directly on its

edge and hold it in place vertically with your chin. Since your iron is

suspect by this time, test it for several seconds on the nearest exposed

skin. (Doing it by accident is just as effective.) Heat the joint with

*feeling* this time. Lunge and parry. Don't worry about the pad, traces,

or other parts--this is war! With maximal chin pressure exerted to hold

the offending board in place, pull the lead out, out, Out!

7. OK, so you "...couldn't get hold of it...," blah blah blah. Fool!

You must risk everthing at this stage. Insert a small screwdriver under

the part, and white-knuckle that soldering iron on the obverse. Pry and

heat until it pops. (Note: It is important to keep in mind the concept of

"kick-back" should you succeed at this. PC boards are likely to

wobble, flop, slip, then fling out of your grasp once the offending little

monster finally lets go, taking test leads and soldering station with it.)

8. So, what kind of inept dweeb are you, anyway? Give up! Clip the part.

Leave some lead to grab onto and repeat #6 and 7. If your face has turned

red it is best to shield the work from veiw with your body, then steal a

quick look behind you to be sure noone is suppressing a giggle as they

watch this humiliating display.

9A. The lead came out but you STILL have some solder left in the hole?

Gads. Find another part that you can sacrifice. Press its helpless

lead into the depressingly small pit you made in the center of the pad.

Heat the base of the lead until you achieve Punch-Through. Yank and Heat,

Yank and Heat. Evetually the solder will give up in disgust and the

sacrificial component lead will slide smoothly, signalling victory.

9B. To your left is a hand drill; to your right is a #60 bit. You know

what you must do.

10. Now—you brute!— now that you've overheated the pad, broken the trace,

cracked the component, gouged the board, pitted the tip, blistered the

skin, wasted a beer, and irrefutably proven once and for all that you

should have taken up gardening instead, NOW maybe you'll learn the color

code!

;)

N6KR

Thanks Wayne! Been there! Done ALL that! This brought to mind the time I soldered in a 16 pin logic chip on a double sided board... UPSIDE DOWN. TRIBAL KNOWLEDGE MY FRIENDS.

Thursday, February 5, 2015

K8GZ's Towering Tea Tin Ohio Mighty Mite

Here is a very innovative approach to the Mighty Mite. The compression cap atop the coil form gives it a towering appearance. Pete and both liked the button key. The Te Tin is very nice and marks another example of the long ham radio tradition of bringing kitchen items (breadboards!) into radio projects. E-mails from K8GZ appear below.

Podcast 171 is fantastic, loaded with
Information and inspiration. Your
podcasts continue to lead me down
the road of home few. I'm trying to
get the demons out of a regen that
will companion my MMM.
I have attached photos of my MMM,
complete with on board key. A ceramic
trim capacitor fills in for the air cap.
A reverse polarity diode helps to keep
electronic smoke in precious components.
Thanks for the crystal and inspiration.
The MMM emits a stable signal whether
it is powered by 1.5 or 12 volts.
73
K8GZ
Kaye Hartman

Thank you for the crystal that arrived on

Sat. the 13th. I was hoping for a

"Plug-N-Play" since the MI Mighty Mite

was assembled, waiting for a crystal.

However, Noodleing was required.

Several salvaged transistors were tried

with the winner being an unmarked one

with a low hfe of 21. It draws 120 ma. at

12 volts and 4 ma. at 1.5 volts. I added a

cap across the key to soften the key

clicks (per Pete). Also I added a reverse-

protection diode (to protect myself from

additional moments of stupidity).

I live in an environment that is not

antenna friendly, so no air time yet.

I must try some portable operation

to get the MMM on the air.

Thanks for the crystal. It really makes the

project extra special.

Pictures will follow as soon as I figure out

how to send them. Time to have a tech-talk

with my grandchildren.

73,

Kaye Hartman, K8GZ

Lancaster, OH

Wednesday, February 4, 2015

Mama Mia! N2HTT's Regen Receiver (Video)

I am fairly certain that Pete Juliano will take pride in N2HTT's success on this project, and will attempt to attribute it, in part, to the Italian ancestry that they share. The Tarantella background music will definitely encourage that kind of thinking.

In presenting this nice video, we continue with our "rigs not yet in a box" theme. There is something especially nice about the sound of receivers that are not yet boxed up.

Mike has some great information on the construction of this receiver (and other projects) on his blog:

http://n2htt.net/

Bravo Michele!

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Monday, February 2, 2015

Video of Colin's First Contact with his Homebrew Scratch-built BITX20

I love this video. Colin finished his BITX a week or so ago and has been waiting for an opportunity to test it. Over the weekend he braved the winter of Northern England and, with his son, set up his new rig out in his snow-covered garden. Appropriately for a first contact with scratch-built rig, the circuitry was unencumbered by any kind of case or box. That's the way it should be done! Well done Colin! You are well and truly a member of the International Brotherhood of Electronic Wizards, and the diagnosis of "The Knack" has been confirmed (a severe case, it appears).

Hi Pete and Bill,

It's been a lovely fine day here in West Yorkshire, so I took a table out into the garden and set up my BITX circuit on it. I set up my SOTA dipole on a 9m fishing pole.

I heard a strong German station calling CQ, so I gave him a call and hoped for the best!

How amazing to contact someone in another country using a rig and mic you've made yourself! Do I qualify as a REAL radio ham now? Do I have a confirmed case of the knack? :-)

Although I may appear underwhelmed in the video, (besides the air punches!), I did really get a kick out of the QSO.

73 and huge thanks to both of you for the encouragement and support.

Colin, M1BUU

Brian's Mighty Mite

Bill,
All the parts finally arrived from China so the MMM lives :)
Good to finally join the CBLA!!

It made for a very enjoyable Saturday afternoon while the snow fell!
I left some room between the antenna connector and the coil for the low pass filter I'm going to build if the caps ever arrive.

Thanks for the crystal and the inspiration to get busy and build something; it brought back a few childhood memories of building things for the homebrew contest at the local hamfest.

73,
Brian
KA0PHJ

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