Showing posts with label Soldering. Show all posts
Showing posts with label Soldering. Show all posts

April 5, 2017

Project: Anderson Powerpole Polarity Checker - W3OW's Build

W3OW (Bruce Patterson) shared his build of the Project: Anderson Powerpole Polarity Checker.  Bruce's design incorporated a bicolored red/green LED.  He repurposed a coax connector cover and added a hole for the LED with a touch of his soldering iron.

W3OW's Anderson PowerPole Tester

The resulting tester came out looking really terrific.  Well done Bruce!

Have you built your own?  Please send me an email with your build of the Anderson Powerpole Polarity Checker and I will post them here on my website.

Good DX and 73, NJ2X



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November 24, 2016

Anderson PowerPole Tip #1 - Correct configuration "Red Right Up"

Anderson PowerPoles black and red connectors can be connected together in two different ways.  One is the defacto standard the other will potentially ruin your day.  Remember the mantra, "Red Right Up" and your Anderson PowerPole contacts will be oriented correctly.


Correct configuration of Anderson PowerPoles: "Red Right Up"

Good DX and 73, NJ2X

July 2, 2016

Project: Regulating the 12v Output of the Nomad 7 Solar Panel

This article is in a series about using the Nomad 7 Solar Panel for amateur radio use on backpacking trips.  Our prior article was, "Project: Fabricating a Anderson PowerPole to 3.4mm dc connector for the Kenwood TH-F6A".

Something went wrong during field testing of recharging our Kenwood TH-F6A HT radio using the Nomad 7 Solar Panel.  Sadly, our TH-F6A stopped charging (lights went out) and would then no longer turn on.  This issue occurred within only a few minutes of charging in full sunlight.

There are a couple of possibilities for the failure:  
  1. The TH-F6A blew one or more of its three fuses due to the relatively high voltage (15Vdc) of the Nomad 7 Solar Panel in full sun.  The TH-F6A is rated at 10Vdc to 16Vdc though the radio's internal voltage regulator converts voltages greater than 10Vdc to heat.  It is possible the 15Vdc caused overheating and blew one or more of the fuses.  
  2. A fuse was blown when the 3.4mm connector was plugged into the radio with power applied to the connector (not supposed to do this per the manual).
  3. Other failure mode?  If you have an idea, please post a comment to this article.
We will post an update once the radio has been diagnosed and repaired by Kenwood.

In the meantime, we decided that adding a voltage regulator to bring the voltage to about 11 volts would be a prudent move.  We found an inexpensive ($1.75), lightweight, and low-power, adjustable DC-to-DC switching voltage regulator for sale on eBay that fit the need.   This regulator can be set to produce a stable 11Vdc with an input voltage between 5Vdc and 32Vdc.  The seller claims the MOSFET (LM2577 operating at 50KHz) switching voltage regulation design is 94% efficient.  This means more solar power directed to the battery and less lost to heat.

DC-DC Auto Boost Buck Adjustable Voltage Regulator with Anderson PowerPole connectors soldered to both the input and output.
DC-DC Auto Boost Buck Adjustable Voltage Regulator
Here is the specification sheet that came with the module:

Technical Parameters

  • Model Specification:DSN6000AUD Automatic Buck module
  • Module Properties:Non- isolated boost (BOOST)
  • Rectification:Non- Synchronous Rectification
  • Input Range:3.8V ~ 32V
  • Output Range:1.25V ~ 35V
  • Input Current:3A ( max ) , no-load 18mA (5V input , 8V output , no-load is less than 18mA. Higher the voltage , the greater the load current . )
  • Conversion efficiency:< 94% ( greater the pressure , the lower the efficiency )
  • Switching frequency:400KHz
  • Output Ripple:50mV ( the higher the voltage , the greater the current , the greater the ripple )
  • Load Regulation:± 0.5%
  • Voltage Regulation:± 0.5%
  • Operating Temperature:-40 ℃ ~ +85 ℃
  • Dimensions:48mm * 25mm * 14mm ( L * W * H )
To keep it flexible we went ahead and soldered on a pair of Anderson PowerPoles at the input and also the output.  Everything still fit nicely within the carrying pouch of the Nomad 7 Solar Panel.  We also modified our operating procedure so that we will only plug and unplug the 3.4mm connection to the TH-F6A when no power is applied.

There is a small brass set screw on the voltage regulator module.  Turning this set screw allows for very precise selection of output voltage.  We used our multimeter to monitor the voltage during adjustment.  Once set, we used a large piece of heatshrink tubing to encapsulate the module and electrical tape to seal the ends.  This will keep the module waterproof which is important on backpacking trips.

Testing

1) Measure the voltage output of the voltage regulator.  Our voltage regulator produced about 11Vdc which was exactly where we wanted it for use with the TH-F6A.

2) Charge the TH-F6A battery.  We used our second Kenwood TH-F6A for testing.  The battery was a little low so we plugged everything together and it charged perfectly.

3) Confirm that TH-F6A still functions after charging.  After charging the battery, we disconnected the radio from power.  We then turned on the radio and everything worked perfectly.


June 25, 2016

Project: Fabricating a Anderson Powerpole to 3.4mm dc connector for the Kenwood TH-F6A

In our prior post, "Project: Hacking the Nomad 7 Solar Panel for Amateur Radio Use", we explained how to replace the stock 12Vdc 8mm male connector with the more useful Anderson Powerpole connector.

In this post, we describe how to make a pigtail cable to connect the Kenwood TH-F6A triband HT to a 12Vdc power source via an Anderson Powerpole connector.  As our starting point, we purchased a Kenwood PG-2W cable from Universal Radio.  The Kenwood PG-2W cable comes with fuses already installed.

Kenwood PG-2W

Step 1: Slide on a short length of heat shrink tubing
  • Slide on a short length of heat shrink tubing over both the tinned ends of the PG-2W cable.
  • The tubing will be used to dress the cable and provide a little strain relief.
Kenwood PG-2W with heat shrink tubing slide on


Step 2: Solder on Anderson Powerpole contacts
  • Solder (or crimp) on the Anderson Powerpole contacts onto the tinned ends of the PG-2W cable.

Kenwood PG-2W cable with Anderson Powerpole contacts soldered on

Step 3: Install the Anderson Powerpole housing
  • The positive wire is clearly tagged on the PG-2W.
  • Install the Anderson Powerpole housing such that the positive contact is inside the red side of the housing.

Step 4: Test the cable
  • Using your voltmeter, confirm that the positive contact on the 3.4mm dc connector is connected to the red Anderson PowerPole contact

PG-2W cable back packaging label showing the connector polarity.  The center pin is positive.
Kenwood PG-2W cable - back of the package showing polarity of the 3.4mm dc connector


Voila!  That is how we fabricated our very own pigtail to connect the Goal Zero Nomad 7 solar panel to the Kenwood TH-F6A radio for the purpose of recharging the radio's battery.

The Nomad 7 solar panel with an Anderson PowerPole soldered on.
Nomad 7 with Anderson Powerpoles connected

The Nomad 7 solar panel in full sun charging a TH-F6A.
Goal Zero Nomad 7 V2 solar panel charging the Kenwood TH-F6A HT Transceiver via Anderson Powerpole cables

In the next article in this series, we share our project to regulate the 12v output of the Nomad 7 Solar Panel.


Good DX and 73, NJ2X

Other related articles on NJ2X.COM


© Michael W. Maher and NJ2X.COM, 2016.

June 18, 2016

Project: Hacking the Nomad 7 Solar Panel for Amateur Radio Use

In our earlier article, "Backpacking Amateur Radio Power: Alternatives" we explored various solutions to powering electronic devices (iPhone and an amateur radio HT) while backpacking.  The Goal Zero Nomad 7 solar panel met our requirements the best.

Goal Zero Nomad 7 Solar Panel folded up is about the size of a book
Goal Zero Nomad 7 solar panel

In this post, we explain step-by-step how we modified the Nomad 7 solar panel to make it more convenient to use in amateur radio applications.

Goal Zero has made a very handy little solar panel in the Nomad 7.  It provides power via a USB port and a 12Vdc port.  This makes it possible for us to recharge our iPhone (5V USB) and Kenwood TH-F6A (12Vdc) from the Nomad 7.  One of the great things about standards is how many of them there are. There are innumerable standards for 12v power connectors.  We prefer the Anderson Powerpole connector for our 12Vdc applications.  Unfortunately, the Nomad 7 provides 12Vdc via an 8mm connector.

Nomad 7 solar panel with its 8mm connector
Nomad 7 12Vdc via an 8mm connector

Nomad 7 with its built in USB port
Nomad 7 5Vdc via a USB connector
In order to connector our Kenwood TH-F6A to the Nomad 7 we would need to make a pigtail.  We considered purchasing Goal Zero's 8mm female to 4.7mm male pigtail assembly for $4.99 and then cutting off the 4.7mm connector and replacing it with an Anderson Powerpole.  However, this seemed like unnecessarily complex solution that would add weight and cost.  Weight comes at a high cost for backpackers.
Commercial 8mm female to 4.7mm male pigtail assembly.
Goal Zero's 8mm female to 4.7mm male pigtail assembly
After talking this over with our friends at Santa Cruz Electronics we came to the conclusion that the simplest, least weight, and lowest cost approach would be to simply cut off the 8mm male connector from the Nomad 7 and solder on an Anderson Powerpole.

Replacing the 8mm male connector with an Anderson Powerpole

Step 1: Cut off the 8mm male connector
  • Leave enough wire on the Nomad 7 to comfortably solder on an Anderson Powerpole connector.
  • Leave enough wire on the 8mm connector to solder on an Anderson Powerpole later if needed.
Step 2: Strip the coaxial cable
  • Carefully strip the black plastic sheath about 1 inch.  Take care not to cut any of the copper wire.
  • Twist the copper braid into a single wire for soldering.
  • Strip the white wire to the same length as the Powerpole connector.
  • Slide on a short length of heat shrink tubing over the coaxial cable.
Step 3: Verify the positive and negative contacts
  • Place the Nomad 7 in full sun and verify the positive and negative contacts using your volt meter.
  • Our Nomad 7 produced 15.15 Vdc in full sun (open voltage).  The Kenwood TH-F6A has a specification limit of 16V.
Nomad 7 open voltage of 15.15Vdc as displayed by a digital volt meter.
Nomad 7 open voltage (15.15Vdc)
Step 4: Solder (or crimp) on the Anderson Powerpole contacts

  • We prefer soldering the contacts to minimize resistance and assure good contact.
Soldering the Anderson PowerPole contacts



Step 5: Insert the contacts into the red/black Anderson Powerpole housing
  • Be sure to install the red side on the positive connector.
  • Use your volt meter or your Anderson Powerpole Polarity Checker to confirm that the red connector has been installed on the positive contact.
Step 6: Shrink the heat shrink tubing
  • Slide the heat shrink tubing up so it is snug with the Anderson Powerpole.
  • Using a heat source, carefully shrink the tubing so it tight around the wires.
  • This dresses the construction and provides some strain relief for the connector.

Voila!  The 8mm male connector has been replaced with a much more useful Anderson Powerpole connector on the Goal Zero Nomad 7 solar panel.  We can now connect our Nomad 7 to a wide variety of devices and cables that we have fabricated using Anderson Powerpole connectors.  This seems like such an obvious design choice it makes us wonder why Goal Zero didn't choose the Anderson Powerpole instead of the 8mm connector to begin with?  Come on world, it is time to rally around the Anderson Powerpole for 12Vdc applications.

Anderson PowerPole connectors soldered onto the Nomad 7 solar panel
Nomad 7 with Anderson Powerpole installed

In our next post (Project: Fabricating a Anderson Powerpole to 3.4mm dc connector for the Kenwood TH-F6A), we will build a pigtail for the Kenwood TH-F6A HT so we can recharge the radio's battery from the Nomad 7 via the Anderson Powerpole connector.


Good DX and 73, NJ2X

Articles in this series:

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© Michael W. Maher and NJ2X.COM, 2016.

November 8, 2015

Vintage Fender Champ Amplifier Restoration

We have been using a weathered looking vintage Fender Champ "silverface" guitar tube amplifier ever since it was given to us by a friend a few years ago.  It had acquired innumerable cosmetic warts and battle scars over the decades as well as a set of extremely dirty/noisy potentiometers and input jacks.  The issues all seemed manageable and we decided this great little amp was worthy of restoration.

Beat up Fender Champ Silverface amplifier
Fender Champ Silverface Front View (before restoration)
Top view of the beat up Fender Champ
Fender Champ Silverface Top View (before restoration)
Beach up Fender Champ amp side view
Fender Champ Silverface Side View (before restoration)

Beat up Fender Champ amp side view
Fender Champ Silverface Side View (before restoration)

Planning the Restoration

Our objective for the restoration was to return the amplifier to its original function and beauty. We made a list of the restoration work that we intended to perform:

  • Replace electrical power plug - connector pulled away from the outer insulation
  • Replace speaker grill - original color had faded, dirty, punctures
  • Clean the Fender logo - minor corrosion, dirty
  • Clean the knobs and panel face - dirty
  • Replace the black Tolex - dirty, several large damaged areas
  • Clean all hardware - corrosion and dirty
  • Clean inside of cabinet - dust bunnies and layers of dirt
  • Replace all three potentiometers - super noisy and intermittent
  • Clean both input jacks - noisy and intermittent
  • Replace carrying handle - original handle was missing

Sourcing Parts

We ordered the parts we needed from Antique Electronic Supply including:

  • Black Tolex - we ordered extra in case we made a mistake cutting a piece
  • Original Fender amp carrying handle
  • 250K Ohm audio potentiometer (qty 2)
  • 1M Ohm audio potentiometer

We purchased a 207g spray can of 3M Super 77 Multipurpose Adhesive at our local ACE Hardware.  We used nearly the entire can for the project.  The spray on application worked perfectly for adhering the Tolex to the cabinet.  We had replacement grill cloth on-hand so we didn't need to order it.  We also had a good supply of staples, tacks, and an replacement electrical plug in the workshop.  The total cost of all the parts and materials was about $80.00 USD.

Preparation

  1. Photograph all sides of the amplifier.  Photographs are excellent reference resource during any restoration.  Photographs can answer questions that your memory cannot, such as, "So where did this do-hicky go?"
  2. Unplug the amplifier from the wall and let it discharge the capacitors which carry potentially dangerous voltages.
  3. Cut the power plug off and discard.
  4. Unscrew the back panels.  Save the screws and panels for reuse.
  5. Remove the grill by prying it off.  It is held in place by heavy Velcro.
  6. Unscrew the Fender logo from the grill.  Save the logo and screws for reuse.
  7. Unplug the speaker.
  8. Remove the speaker.  Store with care to protect the delicate cone.
  9. Remove the metal feet.  Using a flat head screw driver and tack hammer, carefully pry up the feet.  Save these for reuse.  Straighten any points that are bent during removal.
  10. Unscrew the hardware holding the amplifier module in place.  Hold onto the amplifier module case to prevent it from falling to protect the delicate vacuum tubes.
  11. Seek qualified help to remove the amplifier module.  Beware of the capacitors that are potentially storing deadly voltages.  Don't touch anything inside.  Photograph the wiring so you have a reference for how the potentiometers are wired. Store the amplifier carefully out of reach of anyone.
  12. Carefully remove the staples holding an aluminum shield to the inside top of the cabinet.  Retain the shield for reuse.  Discard the old staples.
  13. Remove the knobs and store for reuse.
  14. Vacuum the dust bunnies from inside the cabinet.
  15. Carefully peel the old Tolex off the cabinet.  Try to pull each section off whole if possible since these can help you by providing a template for cutting and reapplying new Tolex.  Save for later reference.
  16. Sand the wood surfaces smooth and clean.  Remove the old adhesive and Tolex residue.  This step also helps remove small nicks and dings in the wood.
  17. Fill any major damage (divots, deep abrasions, missing slivers ...) to the wood and sand smooth.
  18. Vacuum and wipe all surfaces with tack cloth to remove dust and dirt.
  19. Remove and discard all the old staples that were used on the grill cloth and Tolex.

Restoration

You will need a box cutter with a new blade and scissors for cutting the Tolex and grill cloth.   An electric stapler is very handy.  You will also need flat head and Phillips head screw drivers, a hammer, a roller, and a square.
  1. Gently clean all the hardware and logo using alcohol and cotton swabs.  Use Never-Dull to remove any light corrosion.
  2. Using cotton swabs and alcohol gently clean the input jacks contacts.
  3. Cut a piece of grill cloth about the same size as the original.  Install in the frame using an electric stapler.  Four hands are helpful with this step.  Two hands for stretching the fabric while the other person staples.
  4. Install the Fender logo.
  5. Using the old Tolex panels, cut new pieces.
  6. Apply the new Tolex panels in the following order: left side, right side, top, bottom
  7. To apply each piece, you must spray the surface with adhesive where the Tolex piece will be applied as well as the Tolex itself.  We found a liberal coating of adhesive on both worked best.  Avoid spraying areas that you are not working on since it only makes the job messier than needed.  Take care not cover up the Velcro strips.
  8. Use the roller to smooth out the fit and remove air bubbles.
  9. Using the box cutter and scissors, cut and fit each piece following the old Tolex as a template / guide.  We found it more effective and precise to make the cuts with the piece in place for the purpose of optimizing the fit.  Use your hands to make sure that each corner it good and tight.
  10. Once all the Tolex is in place, let it dry and harden for awhile before proceeding.
  11. Using a small sharp screw driver, poke holes through the Tolex where each screw is supposed to go.
  12. Install the aluminum shield.  Carefully align the shield holes with the cabinet holes.  We used brass flat head tacks instead of staples using the holes left by the old staples.
  13. Install the feet by tapping in gently with a hammer.
  14. Install the handle.
  15. Replace the potentiometers one at a time.  Take care to wire exactly as original.  Inspect visually when complete to make sure there are no cold solder joins or shorts between leads.
  16. Gently clean the amplifier face and knobs with cotton swabs and alcohol.
  17. Install the speaker
  18. Reinstall the amplifier module into the cabinet.
  19. Reconnect the speaker.
  20. Install the speaker grill.
  21. Install the back panels.
  22. Install a replacement power plug.
  23. Test the amplifier.

Results

We were very pleased with the outcome of our restoration work.  The restored amplifier looked just beautiful.  It was a wonderful experience to be able to adjust the potentiometers silently.  All the intermittent issues went away as well.  The amp was quiet and sounded warm and wonderful.  Plugging and unplugging the amplifier from the wall was no longer a scary task.  We were also delighted to find that all the materials we had purchased were perfect for the job.

Beautifully restored Fender Champ amp front view
Fender Champ Silverface Amplifier - front view (after restoration)

Beautifully restored Fender Champ amp side view
Fender Champ Silverface Amplifier - side view (after restoration)

Rear view of the restored Fender Champ amp
Fender Champ Silverface Amplifier - back view (after restoration)

Restoring the amplifier helped us see just how well Fender designed and built the Champ.  With a little tender loving care the amplifier still sounds great after a having endured decades of considerable apparent hard use.

We would like to extend a special thank you to our friend who gave us this little gem-in-the-rough of a vacuum tube amplifier and the opportunity for a wonderful father-and-son restoration project.

Good DX and 73,

NJ2X & KC2VSR


© Michael W. Maher and NJ2X.COM, 2015. 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.

October 4, 2013

Using your multimeter: Continuity Test

One of the most basic uses of a multimeter is to test if there is continuity in a circuit. Testing for continuity means to verify if a circuit, wire or fuse is complete with no open. A switch in the off position will be "open" and no continuity.  A switch in the on position "closed" and has continuity between its contacts.

Digital Multimeter

Audible continuity means the multimeter produces a tone that you can hear when a circuit is complete.  Audible continuity testing is very handy since it allows you keep your eyes on your hands and the circuit you are testing.  You can hear if continuity is present without looking at the meter.

Never try to test continuity with on a circuit that is energized.  The meter may be damaged and you risk injury.

The basic procedure for a continuity test:
  1. Make sure the circuit is not energized.
  2. Set your multimeter to continuity test.
  3. Touch the two probes together.  You should hear a tone which indicates the continuity test is working.  If you don't hear a tone then the multimeter you must stop and resolve the issue. Likely problems: the meter is not set to continuity test, the meter's fuse is blown, or the multimeter is damaged.
  4. Place the two probes across the two conductor you are testing for continuity.
  5. If you hear a tone, continuity is present.  If you don't hear a tone then the circuit is "open" and there is no continuity.
Typical uses in amateur radio:
  • Confirm there is no electrical connection (short) between the center conductor and shield on a piece of coax
  • Confirm that there is an electrical connection between the center conductors on both ends of a length of coax
  • Confirm that there is an electrical connection between the shield on one end to the other end on a length of coax
  • Testing DC power cable assemblies.
  • Testing fuses
  • Test if a switch is working properly
  • Test if the multimeter's own internal fuse has been blown
There are an endless number of uses for a basic continuity test and it is a great feature to have in a multimeter and on your bench.


Good DX and 73, NJ2X

Check out our other related articles on NJ2X.COM:
Quick Guide To Common Multimeter Symbols and Abbreviations






© Michael W. Maher and NJ2X.COM, 2013. 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.

September 27, 2013

Quick Guide To Common Multimeter Symbols and Abbreviations

Ever wonder what all the symbols and abbreviations mean on your multimeter?  Here is NJ2X's handy quick reference guide to help you decode some of the more common symbols and abbreviations appearing on multimeters.

 Capacitor
Diode
AC Alternating current or voltage
~ Alternating current or voltage
•))) Audible Continuity
DC Direct current or voltage
Direct current or voltage
V Volts
mV Millivolts (1 x 10- 3 volts)
A Ampere (amps). Current
Fuse
Ground
mA Milliampere (1 x 10-3 amps)
uA Microampere (1 x 10-6 amps)
nS Nanosiemens (1 x 10-9 siemens). Conductance (1/W)
Ω Ohms. Resistance
Kilohm (1 x 103 ohms). Resistance
Megohm (1 x 106 ohms). Resistance
Hz Hertz (1 cycle/sec). Frequency
kHz Kilohertz (1 x 103 cycles/sec). Frequency
mF Microfarads (1 x 10-6 Farads). Capacitance
nF Nanofarads (1 x 10-9 Farads). Capacitance
- Negative
+ Positive


Good DX and 73, NJ2X


Other related articles on NJ2X.COM:
Using your multimeter: Continuity Test
What is the schematic symbol for a ferrite bead?



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© Michael W. Maher and NJ2X.COM, 2013. 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.

March 22, 2013

Solder Smoke Night March 2013

This past week NJ2X and KC2VSR attended the "Solder Smoke Night" held by our local club Skyview Amateur Radio Society.  What can be more fun than building a kit?  Building a kit with room full of friends - that is what.

NJ2X's build of a dual voltage linear power supply


KC2VSR built this neat Velleman Water Alarm

KC2VSR's build of the Velleman Water Alarm kit
KC2VSR discovered the kit was a little more involved than expected since a hacksaw was required to cut the circuit board into two parts.  One part for the detector circuit and the other for use as the remote sensor.  Fortunately, the club's workshop was well equipped with both a hacksaw and vice to hold the board secure.  With a little help from a fellow ham a perfect cut was quickly made.

While experimenting with the completed circuit, KC2VSR found that his water alarm kit could be triggered by simply placing a finger across the sensor plates (without water).  With just a touch, he then demonstrated that it doubled nicely as a Morse code practice oscillator.  Fun!


Good DX and 73, NJ2X



© Michael W. Maher and NJ2X.COM, 2013. 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.

March 2, 2013

Project: Wheel Of Fortune Kit (Velleman)

We are big fans of the Velleman mini kits.  They are low-cost, fun to build, and fun to play with.  At the same time they help kids learn valuable lessons for themselves:
  • Soldering technique
  • Discrete electronic component identification
  • Learning how to properly orient parts on a circuit board
  • Problem solving (when things go wrong)
This month, KC2VSR built the Velleman, "Wheel Of Fortune" kit.  Once built, this circuit simulates a spinning wheel.  A button is pushed to "start the wheel" causing an LED to light up randomly momentarily.  The lit LED then appears to move around and around as each LED lights momentarily in succession.  The spinning effect starts off fast and then slows with time much like a real wheel until stopping on one of the LED's.

Velleman Wheel Of Fortune Kit Package
As with our other favorite kits, there is something special about LED's - adds a real "fun factor".  The kit components are all through-the-hole type (i.e. no surface mount components).  This is really an important factor when selecting a kit for beginners.  Through-the-hole components are largers and easier to handle and more forgiving when soldering than the surface-mount type.  Stick to kits with through-the-hole for beginners.

Velleman Wheel Of Fortune Kit Parts
KC2VSR won this really great "third hand" at the Skyview Radio Society annual banquet this past January.  This build gave us the chance to try it out.  It was a perfect helper for this kit.  The built-in magnifying lens helped with seeing the small parts during placement and soldering.


Kit being soldered as viewed through magnifying glass

The "third hand" with magnifying glass really help with build process


Velleman Wheel Of Fortune Kit Built
The build turned out perfectly and was great fun giving it a spin.  Check out this short video to see the full "spin" effect.


We highly recommend the Velleman, "Wheel of Fortune" kit for a young person (or anyone else) interested in electronics and building simple fun circuits.


Good DX and 73, NJ2X


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© Michael W. Maher and NJ2X.COM, 2013. 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.

February 17, 2013

Project: PicoKeyer Plus Kit

Back in 2010, we built the PicoKeyer Plus (V3.8) kit from HamGadgets (N0XAS Dale).  We really enjoyed building and using this kit and wanted to share our experience and a pictures of the finished product.

What is a PicoKeyer Plus?

The PicoKeyer Plus is a diminutive Morse code memory keyer that comes in kit form.  The PicoKeyer Plus is available fully assembled too.  This photo provides a little perspective of the relative size as compared to a Hamkey.

NJ2X's finished PicoKeyer Plus connected to a Hamkey

Why the PicoKeyer Plus?

There are a fair number of keyers on the market.  We choose the PicoKeyer because it fit really well with what we were looking for.  Namely:
  • Value - Hard to beat this much keyer for under $20.
  • Code Practice Oscillator - The built-in speaker was attractive since the keyer could be used for learning Morse code.
  • Kit - There is nothing quite as satisfying as building your own device and then using it.
  • Appearance - We really like the quality looking finished product with its attractive and durable case.
  • MCW - The small size, self-contained power, and built-in MCW mode makes this a very attractive way to explore Morse code on FM HT's or mobile rigs.

The PicoKeyer Plus Kit

This is a very straightforward kit.  The kit comes with easy step-by-step instructions and an operations manual.  All the parts are through-the-hole so soldering is a breeze.

PicoKeyer Plus Kit

All the parts are mounted directly to a silk-screened board.  The board is easily fit into a nice black project case by drilling four holes and securing two screws.  Drilling templates are provided which makes hole placement easy.  We used clear tape to secure the templates to the face and end plates.  This worked perfectly the first try.


Templates secured to the face and end plates with clear tape
Face and end plates after drilling with templates still in place


PicoKeyer Plus board soldered prior to mounting in the case

PicoKeyer Plus Fully Assembled

We really like the how our finished kit turned out.  It looks great in its enclosure.  The quality is everything we had hoped for.  The board is held securely in place and is protected by the case.  There is no play in the controls or connections.  The knob on the front panel is used to adjust the Morse code speed.  The button is used for programming purposes.

NJ2X's fully assembled PicoKeyer Plus (front)

The PicoKeyer Plus can work with paddles or straight key.  It can even automatically detect when a straight key is plugged in during power up.

NJ2X's fully assembled PicoKeyer Plus (rear)

The code practice oscillator feature is very handy.  The audio volume is adequate when practicing in a quiet environment.  This is as expected considering the small speaker.  We haven't found the need to connect to an outboard audio amplifier so far.

If you enjoy kit building or are in the market for an excellent keyer do give the PicoKeyer Plus consideration.  All-in-all, it is a fantastic bargain.  We highly recommend the kit and N0XAS (Dale) is great to work with.

We hope to eventually interface our PicoKeyer Plus to our Kenwood HT and give MCW a try.  Stay tuned to NJ2X.COM for a future article.

Good DX and 73, NJ2X



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© Michael W. Maher and NJ2X.COM, 2013. 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.

February 2, 2013

What are common-mode currents?

You may have heard of common-mode currents in reference to transmission lines, baluns, common-mode chokes, SWR, RF in the shack, and a long list of other RF-evil.   So it is clear common-mode currents are to be avoided but what the heck are they?

The key to a basic understanding of common-mode currents is to recognize that the word "common" is used to describe currents flowing in the same (common) direction on both transmission line conductors.  This is in contrast to the optimal situation (with no common-mode currents), where transmission line conductors will have currents flowing in opposite directions exactly balanced.

Common-mode currents appear on transmission lines due to asymmetry in the antenna system.  For example, common-mode currents appear when feeding a balanced antenna such as a dipole with unbalanced feed line (coaxial cable).


Good DX and 73, NJ2X

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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© 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.