December 31, 2012

Project: PAiA P60 Regulated Power Supply Kit

Over the  years, we have built a number of electronic devices that require a 9v DC power source.  We typically keep a box of 9v batteries on-hand though more often then not we find our cache of batteries depleted.  During a recent trip to the local grocery store we were shocked to see name-brand 9v alkaline batteries selling for nearly $5/each.  This inspired us to build a dedicated 9v power supply for use on the bench with goal of reducing our use of overly expensive 9v batteries in the coming year.  Perhaps that is a worthy New Year resolution for us all.

Regulated or unregulated?
An unregulated DC output power supply (e.g. most common wall-warts) delivers voltage without voltage control.  The DC output voltage is dependent on a couple of factors: 1) the voltage reduction transformer; 2) the amount of current used by the device receiving the power (also called load).  An easy way to identify if a wall-wart is unregulated is to simply measure the voltage without a load.  If the voltage is several volts higher than the rated voltage on the device then it is unregulated.  The typical wall-wart is often also unfiltered making it unsuitable for radio related projects.

A voltage regulator controls a power supply such that it delivers a constant voltage output over a variety of load currents (up to a maximum load).

We have a junk box full of transformers and could have had an unregulated power supply for next to nothing.  However, the ability of delivery exactly 9v for our creations was appealing and not very costly ($10 to $25 depending on the kit).  The cost of building a 9v regulated power supply is quickly recovered by simply avoiding the purchase of a few 9v batteries.

Linear or switched regulator?
Regulated power supplies can be built with linear or switched regulators.  We decided we were indifferent regarding this question.  Either would work fine for our simple needs.  We did a quick search of various kit makers to see what was offered in the way of regulated power supplies.

PAiA P60 Regulated Power Supply Kit
As a youth in the 1980's we had always enjoyed looking through the PAiA catalog of kit electronic musical instruments.  In our eyes, PAiA had the coolest looking gear hands down; though we lacked the means necessary to buy and build it.  So during our search of kit manufacturers, we were delighted to find that PAiA is still in business offering a variety of electronic kits.  A quick review of the PAiA website is all it took to find a low-cost little regulated power supply kit that fit our needs perfectly: PAiA P60 Regulated Power Supply Kit

The P60 kit provides a circuit board and all components except for the 3-pin (TO-220 package) voltage regulator.  This allows the builder to select the specific regulator / voltage that meets his needs (5v to 24v).  Input voltage can be either AC or DC and needs to be 2v or 3v higher than the target output voltage (depending on the regulator chosen).  We liked the fact that terminal blocks were provided for both input and outputs.  This would make it very easy to connect and disconnect from various projects.  We also appreciated the on-off switch and power-on LED indicator.  The power supply is rated for up to 1A which would be more than enough for our 9v projects.  We had a couple of 7809 voltage regulators on-hand so this kit would be a perfect fit.

The kit was a breeze to assemble following the guidance provided by the kit product sheet.  We decided to substitute a blue LED for the one that came with the kit out of personal preference.  We are Anderson PowerPole connector enthusiasts so it was natural to wire up an Anderson PowerPole to the input block.  This would make it easy to connect the to our 13.8v DC Astron RS-35M power supply that we use in the shack or in the car using our home-brew car power to Anderson PowerPole adapter.

On the output block we connected one of our home-brew 9v battery clips.  This would make it easy to connect to our electronic 9v creations.  To use a battery clip as a power source (simulated battery) requires reversing the polarity.  That way when two clips are married together the voltage polarity will be correct. 

The power supply has worked flawlessly in our shack since it was built.  We really appreciate the convenience and economy of powering up our 9v creations free of the hassle and expense of 9v batteries.  We are using our 9v power supply at the time of this writing to power KC2VSR's 3D Xmas Tree which gives a little holiday charm to the shack.  We haven't mounted it in a case so far.  Looking for something that is both free and suitable to repurpose.

By the way, we found an excellent resource for power supply terminology.  It is interesting to browse through the page.

Good DX and 73, NJ2X

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© Michael W. Maher and NJ2X.COM, 2012. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Michael W. Maher and NJ2X.COM with appropriate and specific direction to the original content.

The Passing of the Year by Robert Service

The Passing of the Year

By Robert Service, RHYMES OF A ROLLING STONE, 1912

My glass is filled, my pipe is lit,
My den is all a cosy glow;
And snug before the fire I sit,
And wait to feel the old year go.
I dedicate to solemn thought
Amid my too-unthinking days,
This sober moment, sadly fraught
With much of blame, with little praise.

Old Year! upon the Stage of Time
You stand to bow your last adieu;
A moment, and the prompter's chime
Will ring the curtain down on you.
Your mien is sad, your step is slow;
You falter as a Sage in pain;
Yet turn, Old Year, before you go,
And face your audience again.

That sphinx-like face, remote, austere,
Let us all read, whate'er the cost:
O Maiden! why that bitter tear?
Is it for dear one you have lost?
Is it for fond illusion gone?
For trusted lover proved untrue?
O sweet girl-face, so sad, so wan
What hath the Old Year meant to you?

And you, O neighbour on my right
So sleek, so prosperously clad!
What see you in that aged wight
That makes your smile so gay and glad?
What opportunity unmissed?
What golden gain, what pride of place?
What splendid hope? O Optimist!
What read you in that withered face?

And You, deep shrinking in the gloom,
What find you in that filmy gaze?
What menace of a tragic doom?
What dark, condemning yesterdays?
What urge to crime, what evil done?
What cold, confronting shape of fear?
O haggard, haunted, hidden One
What see you in the dying year?

And so from face to face I flit,
The countless eyes that stare and stare;
Some are with approbation lit,
And some are shadowed with despair.
Some show a smile and some a frown;
Some joy and hope, some pain and woe:
Enough! Oh, ring the curtain down!
Old weary year! it's time to go.

My pipe is out, my glass is dry;
My fire is almost ashes too;
But once again, before you go,
And I prepare to meet the New:
Old Year! a parting word that's true,
For we've been comrades, you and I --
I thank God for each day of you;
There! bless you now! Old Year, good-bye!

December 28, 2012

Project: Anderson Powerpole Polarity Checker

Ward Silver's (N0AX) article, "Hands-On Radio: Experiment #120: Power Polarity Protection", in the January 2013 issue of QST included a circuit diagram for a 12v polarity checker.  Inspired by the diagram, we headed to workshop on a Friday evening to fire up the soldering iron and fabricate our own Anderson Powerpole polarity checker using junk-box parts.

Schematic of a polarity checker with a 1k Ohm resistor and two LED's one red and one green
Powerpole Polarity Checker Circuit Diagram
From Hands-On Radio: Experiment 120: Power Polarity Protection, January 2013 QST; copyright ARRL

We are big fans of Anderson Powerpole connectors and recabled our radio gear with the connector sometime ago.  A polarity checker would be a very useful item to have around the shack and in a go-kit.

Step 0: Round up the parts and tools

A well-stocked junk box and workshop will likely yield all the necessary parts needed to build the polarity checker.  A few minutes of scrounging around our workshop is all it took to find the parts for this project.
  • Green LED
  • Red LED
  • 1k Ohm resistor 1/4W
  • Pair of Anderson Powerpole connectors
  • Junk box plastic part to turn into an end-cap
  • Hot glue gun
  • Soldering iron
  • Shrink wrap tubing (small diameter)
  • Wire snips

Step 1: build the circuit on a solderless breadboard

We find it helpful to first build a circuit on a solderless breadboard prior to assembly and soldering.  This approach helps confirm the junk-box parts are still functional, the circuit works as advertised, as well as verifying the orientation of parts having polarity (e.g. the LED's in this project).  This circuit is very simple.  The key is to make sure the LED's are wired together in opposite polarity.

Anderson PowerPole polarity checker circuit being tested on a solderless breadboard prior to assembly.
NJ2X first built the polarity checker on a solderless breadboard as a test

Step 2: Prepare the end-cap

We found some sort of plastic cap in our junk box that would marry up perfectly to the back side of a pair of Anderson Powerpole connectors.  We drilled four small holes in the top of the cap to pass the LED's leads through.
Anderson PowerPole polarity checker cap - four holes being drilled for the LED wires to pass through.
NJ2X drills four holes in a small cap for the LED leads

 Step 3: Solder the components together

Insert the leads of the two LED's on the top of the cap.  Solder the leads and resister together per the wiring diagram.  Use shrink wrap tubing to insulate the leads from each other to prevent a short.  Solder a short red wire and back wire to the leads.  Again use shrink wrap tubing to insulate the connections.  Solder the Anderson Powerpole connectors onto the wire ends.  Be sure the Powerpole positive and negative are tied together in the correct configuration, "Red Right Up".  Test the circuit to confirm it is working before proceeding with final assembly.

Anderson powerpole polarity checker in a vice while be fabricated
NJ2X testing the soldered polarity checker prior to final assembly

Step 4:  Final Assembly

Fill the cap with a generous amount of hot glue.  You want enough glue to assure a solid mechanical connection and prevent the wires from moving or being stressed during use.  Press the wire and Anderson Powerpole connectors into the cap and hot glue.  Let the glue cool and harden.  Test again to confirm the circuit is functional with both correct and reversed polarity.  We used a label maker to add our call sign to the outside.

Fully assembled Anderson PowerPole polarity checker.
NJ2X's Anderson Powerpole polarity checker fully assembled

We shared a picture of the finished product with N0AX and he pointed out that it looked a little like a rabbit.  My son, KC2VSR gave the polarity checker a funny bunny face to really set off the effect.  We had a good laugh and decided to call the polarity checker, "Bunnicula".  Ham radio is really a wonderful hobby to share with kids.

fully assembled Anderson PowerPole polarity checker with a cat-face drawn on it for humor.
NJ2X's Homebrew Anderson Powerpole Polarity Checker

Voila!  There is our build of a very handy 12v Anderson Powerpole polarity checker.  Use the polarity checker before plugging into an unverified Anderson Powerpole connector.  This simple test may save your equipment from damage.  A lit green LED denotes correct polarity and lit red LED indicates reversed polarity.

There are at least a couple of potential failure modes that would cause the polarity to be reversed on a pair of Powerpole connectors.  One potential failure is that the red wire terminating at the power supply was accidentally connected to the negative terminal.  Another possibility is that the Powerpole connectors were snapped together with the incorrect orientation.

For example, when volunteering during an emergency and you need to recharge your HT's battery from the HQ emergency power via a Powerpole.  If you plug into it without checking polarity you may end up with a dead HT if the cable was wired incorrectly to the supply.

Not all cars are wired so the center of the cigarette lighter connector is positive.  If you use an Anderson Powerpole to Cigarette Lighter adapter on an unfamiliar vehicle you may be in for an unpleasant surprise when you connect your rig and the reversed polarity causes damage.

An additional use of the polarity checker is a quick power cable or connector continuity checker.  We plan to put our polarity checker to good use in the shack testing all new cables and Anderson Powerpole connectors that we build for mechanical contact, continuity, and polarity.  In the past, we have simply used a multimeter which didn't confirm that the connector makes proper electrical contact when connected mechanically to another Powerpole.

Good DX and 73, NJ2X

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December 23, 2012

Learning Morse Code Online

We have been thinking about Morse code and how to approach learning it.  There is interest in our local Boy Scout troop to learn Morse code in pursuit of the new Morse Code Interpreter's Strip.

We recently discovered an interesting website to help people learn Morse code online called Learn CW Online.

Early Morse Code Training Course
One of the attractive aspects of this site is that all lessons are accessed via a web browser without requiring a download or installing software.  A complete Koch CW course is available on the site via the browser - for FREE.

The Koch method is a popular teaching method and named after the German psychologist Ludwig Koch.  The Koch method teaches at the full target speed from the outset, first with just two characters (K and M).  Once a student has mastered the first two characters by being able to copy at 90% accuracy, an additional character (letter, number, or prosign) is added, and so on until the complete character set is mastered.

Example: CW Course results from lesson 1 showing we are ready for lesson 2.

We really like how the CW course is organized into lessons and how feedback is provided so you can see how you are doing.  There is even a recommendation provided indicating when you are ready to move to the next course and learn a new letter, number, or prosign.  This is a fun and easy way to learn Morse Code.  We recommend for anyone interested in learning CW (Morse code).

Once you have mastered the character set, an excellent (and free) resource for improving your code recognition speed is by listening to the regularly scheduled code practice broadcasts by the ARRL's station W1AW on shortwave.

These free resources could very helpful to Boy Scouts interested in earning the new Interpreter's strip for Morse code.  The strip would certainly be a very impressive addition to one's uniform:

The Morse Code interpreter strip designates those who are proficient in Morse Code and denotes their availability for emergency communications and other types of supporting communication for Scouting and the community. Youth and adults may wear this strip if they show their knowledge of Morse Code by:
  1. Carrying on a five-minute conversation in Morse Code at a speed of at least 5 words per minute.
  2. Copying correctly a two-minute message sent in Morse Code at a minimum of 5 words per minute. Copying means writing the message down as it is received.
  3. Sending a 25 word written document in Morse Code at a minimum of 5 words per minute.

Requirements #1 and #3 imply that the scout will need to also learn how send Morse code with a key.  Scouts will need to either buy or have access to a Morse code key and a code practice oscillator.  The PicoKeyer Plus is an inexpensive and easy-to-build kit that can be used a small self-contained code practice oscillator (just add a key).

Our local amateur radio club (Skyview Radio Society) offers Morse code practice nights using the club's repeater for discussion and transmitting morse code on a 10m frequency.

There is no one right way to learn something.  Each person is different in how best they learn a new skill or language.

The ARRL has an excellent webpage, Learning Morse Code.

Good DX and 73, NJ2X
Press play to hear my salutation in Morse code:

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December 22, 2012

DX Technique: Taking A Break = Opportunity For A Modest Station

Working DX with a modest station or QRP (5w of power or less) is an interesting and challenging endeavour.  DX'ers regularly experience having more powerful stations with 1500W amplifiers, impressive towers, and beam antennas punch through to the target station and block the lower-power stations.  To succeed, low-power stations must use skill - brains over brawn.

Here we share a useful technique to help log that DX station when operating with low-power.  This is the scenario, the DX station announces that he must take a break (i.e. take a phone call, dog needs to go out, bathroom visit, refill coffee cup, grab a snack, answer the door, ...) and will be return. 

This represents an opportunity for the savvy lower-power station since this announcement will cause the pile-up size to immediately diminish.  Time (and human nature) is on your side since the longer the DX station is off-the-air the fewer people will stay tuned to the frequency.  Why?
  • As soon as the station stops calling, many people will leave the frequency in search of DX stations that are on-the-air.
  • Reported spots for the DX will start to age off and no new spots will be posted.
  • People tuning up-and-down searching for DX will not stop on the frequency since there is no DX calling.
The savvy DX'er will wait and listen and be ready to pounce when the DX station returns from his break.  Patience, listening, and being ready is the key to success.  You want to be the first station (without interference from a pileup) to respond and be heard.

We have used this technique with success and it can help you too.

Good DX and 73, NJ2X

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December 21, 2012


It is a paradox of modern life that pseudoscience thrives amidst accelerating scientific knowledge, widespread literacy, and powerful teacher's unions.  As you are reading this, The-End-Is-Near-Nuts-V2012 are now licking their collective wounds that resulted from the world having not come to an end on December 21, 2012. Their great disappointment in our continued existence is a small source of pleasure for many of us (as well as a few good jokes on late-night shows).

As with the prior versions of The-End-Is-Near, the pattern will be for the spokesmen to make a few irrational-rationalizations explaining away their error.  Then some charismatic will start afresh with a new version of a peculiar brand of nonsense which will inevitably find a strong market with the media and a few true believers.

In the meantime, have a happy (and rational) New Year.



© Michael W. Maher and NJ2X.COM, 2012. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Michael W. Maher and NJ2X.COM with appropriate and specific direction to the original content.

December 19, 2012

DXCC Completed!

We are celebrating in the shack today on completing the requirements to earn the ARRL DX Century Club (DXCC) award. The DXCC award is a worthy challenge. To earn the ARRL DXCC award a ham must confirm 100 contacts each from a qualifying different DX entity. These entitities are defined in the DXCC list. To qualify, an entity must have some definable political or geographical distinctiveness.

Proof of a confirmed contact can be either a paper QSL card or a Logbook of the World (LoTW) QSL.  We are a big fan of the ARRL's LoTW so for an extra challenge we decided to we would confirm 100% of our qualifying DXCC contacts via the LoTW (and not use any paper QSL card confirmations).  This proved to be more of a challenge than we anticipated since we had to complete several contacts with many DX entities before locating a LoTW subscriber.

We also decided to make all of our contacts using transmitter power of 100W or less and with a simple wire antenna.  This meant we would not use amplifiers, towers, beam antennas for the DXCC contacts.  We were interested in demonstrating that the ARRL DXCC award is within the reach of hams with modest stations (like ours).

Today we filed our application when the 100th qualifying contact was confirmed in the LoTW.  Our award is #57,420.  What a great feeling!

Good DX and 73, NJ2X

PS: In 2012, the DXCC Desk processed 14,301 applications, comprising 1,491,661 QSOs.

© Michael W. Maher and NJ2X.COM, 2012. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Michael W. Maher and NJ2X.COM with appropriate and specific direction to the original content.

December 18, 2012

Edwin Howard Armstrong's Birthday December 18, 1890

The great American inventor and electrical engineer, Edwin Howard Armstrong was born this day - December 18, 1890.  Armstrong held 42 patents and invented the frequency modulation (FM) radio, hyterodyne radio, superheterodyne radio, and regengerative radio receiver.

December 8, 2012

Shortwave Program: WTWW 9480 KHz QSO Radio Show

Found an interesting shortwave broadcast today on 9480 KHz on WTWW in Tennessee, USA called, QSO Radio Show with Ted Randall.

The program was amateur radio oriented with an guest interview discussing 6 meters.  This was an excellent program.  This broadcast was ending at 21:00 UTC on 12/8/2012.

If you are looking for interesting shortwave programming in English then be sure to checkout 9480 Khz for QSO Radio Show with Ted Randall.

Yaesu FRG-100 Shortwave Receiver

Good DX and 73, NJ2X