Showing posts with label Home Brew. Show all posts
Showing posts with label Home Brew. Show all posts

February 7, 2021

40m Skywire Loop Antenna Experiment

I have been curious about skywire antennas since becoming a ham.  I first learned about skywire antennas initially from a contacts made with hams operating on skywire loop antennas.  Over the years I have received many recommendations to give one a try.

I decided it was high time to build my own homebrew skywire loop antenna with the goal of constructing it from various pieces-parts available in the shack.  There is simply no better way to spend a Sunday than making something in the workshop with the HF transceiver running.

A full wavelength skyloop antenna has a nominal impedance of 120 ohms depending on various factors.  The ideal antenna impedance is 50 ohms which would match a 50 ohm coaxial cable and 50 ohm transceiver.  A skywire antenna would work more efficiently with a 2.5-to-1 balun to transform the antenna impedance to more closely match the 50-ohm coaxial cable.  

A balun is an electrical device that converts between a balanced signal and an unbalanced signal. There are many different types of baluns including those that transform impedances.

Unfortunately, I didn't have a 2-to-1 or 2.5-to-1 balun in the workshop.  I did have a 1-to-1 balun and a box of type-43 ferrite beads.  I decided using a 1-to-1 balun and ferrites would be close enough and help keep common mode currents off my coaxial cable.  I also had an unused coaxial antenna center conductor, a spool of wire, and a few insulators.  These were enough parts to give the 40m skyloop a ago!

A skywire loop antenna is exactly as it sounds a single wire in the shape of a circle (ideally) some other shape such as a square, rectangle, or triangle and suspended horizontally.  To calculate resonance of #18 wire, the following formula can be used:

Length in feet = 1005 / frequency in MHz

For example, at the FT8 40m calling frequency a resonant skywire = 142 ft. = 1005 / 7.074 Mhz

Skywire Loop Antenna Bill of Materials
  • 136 ft of Poly-STEALTH 18 gauge wire from Davis RF
  • qty 11 type-43 ferrite beads 1/2" snap on
  • CE-1 Deluxe Dipole Antenna Center Feed from Spi-Ro Manufacturing
  • 1-to-1 Balun Designs Maxi Choke Balun (5kW) dual core model 1115du
  • qty 3 "dog-bone" type insulators
  • Self-sealing silicon tape
  • 3M electrical tape
  • Stuff - dielectric water proofing filler for coaxial connectors

CE-1 Deluxe Dipole Antenna Center Feed

1-to-1 balun connected with LMR400 with ferrites connected to the antenna center feed 

I used trees to support my skywire loop antenna.  Two of the corners were up around 40ft and the other two were on the low side at around 20 ft.  Not ideal but good enough to tune up and work some DX.  I used floating insulators when hanging the antenna.  Floating insulators allows free movement of the insulators and antenna wire while adjusting the antenna.  It allows provides freedom of movement due to tree sway.

The goal in hanging a skywire loop antenna is to maximize the enclosed area of the antenna.  Given infinite hangers, a circle would yield the maximum enclosed area.  Fortunately, the skywire doesn't require perfection.  A rectangle with four hanging points works very well too.

The Poly-STEALTH antenna wire from Davis RF is wonderful to work with - strong, light, and nearly invisible.  136 ft. of #18 wire weighed only 0.136 lbs. which is much less than my multiband fan dipole.  The insulators and rope weighed more than the entire antenna.

Initial Results

I was delighted to find that I my Kenwood TS-480SAT's build-in antenna tuner would tune the skywire on 40m, 20m, 17m, 15m, 10m, and 6m effortlessly.  This is a great way to begin testing a new antenna - no tuning or trimming.  Next I fired up FT8 and worked 20m and 40m contacts as the grey-line passed on into the evening.  The signal-to-noise ratio seemed improved as compared to my fan-dipole antenna.  I quickly made contacts with stations near and far including:
  • 40m KN4APP, NV - 203 miles
  • 40m AB6ZQ, CA  387 miles
  • 40m KE7JBK, AZ - 597 miles
  • 40m N7DBO, UT - 600 miles
  • 40m KF7UGG, OR - 618 miles
  • 40m K7EAZ, AZ - 694 miles
  • 40m KS7TU, WA - 792 miles
  • 40m KG5ZZB, TX - 1460 miles
  • 20m KB0BRO, MN - 1565 miles
  • 20m W9RF, IL - 1797 miles
  • 20m KH6AN, HI - 2353 miles
  • 40m N3MK, VA - 2527 miles
  • 20m JA9DJX, Japan - 5286 miles
  • 20m LU8DN, Argentina - 6597 miles
  • 20m ZL1IA, New Zealand - 6732 miles
The 40m Skywire experimental antenna was a huge success.  The antenna worked perfectly the first time I tuned it up.  It is remarkable how flexible the antenna is using just a build-in antenna tuner.  No adjustment or fine tuning was required to get on the air on multiple bands.  It also performed very well at the bottom of the sunspot cycle.  Overall, I am pleased with the outcome and would recommend a skywire loop antenna to anyone with suitable supports, a few inexpensive parts, and a Sunday to experiment.  It is a surprisingly good antenna for very little cost.

I am looking forward to trying out the new skywire antenna on 17m, 15m, 10m, and 6m when the bands are open.  I am also looking forward to a future experiment with an 80m skywire loop antenna.

Good DX and 73, NJ2X

July 5, 2020

Backpacking Hack: Packing Duct Tape

I recently returned from a wonderful backpacking trek in the John Muir Wilderness located in the Sierra Nevada Mountains of California.  The John Muir Wilderness is rugged and exceedingly beautiful.  It is also challenging backpacking country with high altitude and difficult terrain.  The trek tested our group's skills, readiness, and fitness.  Fortunately, we were well prepared and able to handle every test mother nature presented us.

John Muir Wilderness Marker
One item in my pack proved its usefulness over and over again - duct tape.  Duct tape is not just for air ducts or home repairs.  Here are just a few uses of duct tape while backpacking:
  • Repair a pair of shoes by re-affixing a delaminated tread with duct tape
  • Repair a tear in a tent stuff-sack with duct tape
  • Patch a puncture in a water bag with duct tape
  • Secure a moleskin pad with duct tape to prevent it from rubbing off while walking
  • Cover a hip abrasion caused by a backpack with duct tape to prevent further injury
  • Wrap a sprained ankle with duct tape to support the join and prevent further injury
  • Whip an end of rope to prevent fraying
  • Patch a torn tent bag
If you aren't carrying duct tape in your pack then you will inevitably find yourself wishing you had.  Fortunately, you don't have to bring a bulky and heavy roll of duct tape to benefit from this miracle material.  Several feet of tape will do.

A helpful method of packing duct tape is to roll several feet onto a plastic medicine bottle.  The width of the duct tape fits perfectly on the bottle and adds very little weight or volume to a pack.  This hack also provides you with a waterproof container for medicine or small items.  Later, when a length of duct tape is needed, simply peel off the desired amount from the medicine bottle.

You don't need to pack the whole roll

I hope this article has inspired you to add duct tape to your backpacking kit and try rolling it onto a plastic medicine bottle for convenient packing.

Several feet of duct tape rolled onto a plastic medicine bottle

Happy trails and 73, NJ2X

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© Michael W. Maher and NJ2X.COM, 2020. 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 6, 2013

Project: Home Brew 9 Volt Battery Clip

The Eveready company introduced the 9v battery type in 1956.  The familiar 9v battery utilizes a snap or clip to connect to its terminals.  Home brewers, DIY enthusiasts, makers, and kit builders all routinely use 9v batteries or battery-packs that are equipped with 9v terminals to power their projects.  All these battery powered projects require 9v battery clips to attach the battery to the circuit.

Commercial 9v battery clips are of course readily available.  The commercial 9v battery clips are rather pricey ($2.69/each at a local electronics retailer) and lack somewhat in quality.
Why buy an overpriced and inferior component when a superior version can be fabricated for FREE from readily available recycled components?  Here is how we make our own 9v battery clips using parts recycled from dead 9v batteries.

9v Battery

Tools and parts used
  • A dead 9v battery
  • Needle nose pliers
  • Soldering iron
  • Electronic solder flux
  • Electronic solder
  • Hot glue gun and glue stick
Step 1: Open 9v battery case
There is a crimped seam that runs the length of the 9v battery case.  Using a pair of needle nose pliers, carefully open the 9v battery case starting at the bottom of the case at the seam.  It takes a little practice, patience, and hand strength to complete the operation.  Be sure not to damage the six LR61 size cells cells inside.  Haven't you always wondered what was inside a 9v battery?  Now you know.
9v Battery Case Opened At Seam
Step 2: Remove top and bottom from the 9v battery
Complete remove the cover once the case seam has been opened the full length of the battery.  The top of the battery is soldered / welded to two leads.  Break the welds by gently pulling the top away from the battery.  The bottom falls away from the battery on its own.  Keep the top and bottom.  They will be used to make the battery clip.  Properly recycle the remaining battery cells and case.
9v battery top and bottom removed from recycled 9v battery
Step 3: Solder leads to the battery top
We apply a thin coat of flux to the battery top inside metal.  The flux cleans the metal and helps the solder to flow and form good solder joints.  The red lead goes to the positive contact.  The black lead goes to the negative contact (the smaller circular contact on the clip).  The clip will be wired so that when connected to a 9v battery the positive wire is connected to the positive terminal.  Carefully solder the leads assuring good quality solder joints.
Red and black leads soldered to inside of 9v battery top
Step 4: Use hot-glue to affix the battery bottom over the soldered leads
The final step is to seal the battery clip using hot-glue and the 9v battery bottom.  Once the glue is dry, use a sharp knife to carefully trim the excess glue.

Step 5: Test your new clip
The purpose of this test is to both confirm you have correctly wired the leads to the clip and the clip is conducting power from a battery.  Connect the battery clip to a good 9v battery.  Connect your volt meter across the battery clip terminals by connecting the positive meter lead to the red wire and negative meter lead to the black wire.  If your meter shows approximately 9v then you have successfully fabricated a 9v battery clip.
Voila!  The home-brew 9 volt battery clip is complete in four easy steps.  Below is a photo comparing a commercial clip (left) with our home-brew version (right).  The home-brew clip has a much more durable look and feel.  Another obvious difference is the quality of the lead wires.  For this project, we used wire we recycled from a dead computer power supply which is heavier gauge and more durable.

Flimsy $2.69 Commercial 9v Clip on Left versus $0.00 cost home-brew 9v Clip on Right
We make several of these at a time to keep on-hand for future projects.
So why build when you can buy?
  • This is a fun and easy project.
  • This project can save you money (savings $2.69/clip).
  • This project would make an excellent group activity such as a boy scout troop electronic night.
  • Great way to make a 9v clip if ever in a tight spot (ala McGiver or repairing equipment during a disaster or emergency).
  • The quality of the end result is superior in several ways to the commercial off the shelf 9v clip.
Good DX and 73, NJ2X

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March 30, 2013

The Altoid tin: a nearly perfect DIY enclosure

The Altoids tin is one of the very favorite enclosures of the DIY / home-brewing electronic enthusiast / ham radio experimenter.  For small electronic projects, the Altoids tin is nearly a perfect fit for purpose.

    Photograph of an Altoids tin at an oblique angle
    Altoids Tin
    Photograph by Michael W. Maher
  • Free (after you eat the excellent peppermints)
  • Recycled / reused
  • Durable (its metal)
  • Hinged lid
  • Light weight
  • Size can accommodate a small circuit board, 9v battery, and mounting jacks, knobs, and such. 
  • Outside dimensions:
    • 3-13/16" (9.68 cm) length
    • 2-7/16" (6.19 cm) width
    • 3/4" (1.91 cm) height
Happy home-brewing!

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.

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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February 23, 2013

Built to trash: the totally defective HT clone cable

I admit it.  I like to save money and I love to home brew, repurpose, and recycle.  Ham radio seems to fit really well with this way of thinking.  A ham radio project is simply more fun when you are engaged with your own two hands and applying your own creativity.  Some my call it being "thrifty" but it really goes well beyond the dollars and cents.  Fundamentally, it is the human need to create that is at work here.

However, occasionally the home brewing and repurposing (and money saving) goes awry.  Case in point: the totally defective HT clone cable. 

I had an idea for a project that involved interfacing our Kenwood HT audio-in and push-to-talk switch.  I mulled over various approaches including buying and soldering 3.5mm and 2.5mm jacks.  Using two jacks would certainly work and was easy-enough but the result would not looks as nice as the commercial dual-prong moulded connector used on the HT's headset.

I happened on a super-cheap eBay listing for Kenwood HT clone cables and decided to buy one.  This cable would give a dressed appearance on the HT side for our home-brew the interface.  The cable arrived and went into a box (along with the month-balled project) for several months due to a relocation.

Super cheap Kenwood HT Clone Cable from eBay

Skip forward to the present... I dug the project out of its mothball status and pulled out my Kenwood technical documentation, solderless breadboard, capacitor, resistors, digital multimeter and got to work.  However, no matter what was tried I could not get the HT interface to work.  After a series of fruitless attempts with checking and double-checking the circuit I realized that something wasn't working as it should.

The next step was to isolate the fault.  The first step was to check all of the alligator clips.  We had run into a faulty clip-wire connection with a past project.  The clips and wires all checked out fine.  Next tested our ability to trigger the push-to-talk through the cable manually.  Strangely this did not work as expected so we decided to test the continuity of the cable itself using our digital multimeter.

The multimeter continuity testing immediately showed that only one of the six contacts had continuity through the cable.  That is a strange problem for a brand new commercial quality cable.  Caveat emptor (corollary: especially when buying through eBay).

The next step was to cut the cable in half and check for continuity between the wires and the two plug contacts.  If only one side was defective then the other could be salvaged for use in the project.  When the the cable was cut and wires exposed, only 4 wires were found. 

There are were six contacts on each plug and not all are needed during the "cloning" procedure (copying the memory of one HT to another).  Further testing showed that neither cable-end had electrical continuity to more than one of the wires.  This test eliminated the possibility of the defect being only one-sided.   The dissection again proved that this was a totally defective HT clone cable.

So what did we learn from this experience:
  1. If you buy a cheap cable through eBay, test it on receipt and return it immediately if it is defective.
  2. Often you can make a better cable than you can buy (though perhaps not cheaper).
  3. When faced with a home brewed roadblock, work the problem and isolate the fault.  Failure is the best teacher.
  4. Home brewing takes tenacity.  Don't give up.

Good DX and 73, NJ2X

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February 21, 2013

Home Brew 17 Tube Hoofus-Doofus

This 1929 Polymet ad gave us a chuckle.  Wouldn't you love to see the home-brew 17 tube "Hoofus-Doofus"?

1929 Polymet Ad

Good DX and 73, NJ2X

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.

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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January 29, 2012

Project: Anderson Powerpole to 2.1mm Connector Pigtail

When building our KN-Q7A Single Band SSB Transceiver Kit we realized after starting that we lacked the necessary power 2.1mm connector to supply 12v to the power jack.

From a design standpoint we decided to construct an Anderson Powerpole to 2.1mm connector pigtail.  This was a natural choice since we previously converted our radios and cabling to Anderson Powerpoles.  A 2.1mm connector to Anderson Powerpoles will give us maximum flexibility to move the radio from one power source to the next (e.g. battery, car power, shack power supply, bench power supply, ....).  The commercially available Anderson PowerPole to 2.1mm cable costs at the time of this writing about $5.00 plus shipping. 

We decided it would be more ecconomical and far more fun to build the pigtail cable ourselves.  A home-brew cable would also give us an opportunity to incorporate a few improvements in design over the commercially available cable.
One of the improvements we wanted to include on the cable was an RF choke.  We decided to add a ferrite (from the junkbox) to the pigtail to help minimize RF travelling over the power cable.  This would potentially be useful when running the radio from a car or other noisy source.

Pigtail construction in progress with ferrite bead
To protect the ferrite bead and assure the wire loop would stay nice and tight we added heat-shrink tubing around it.  We also added a section of heat shrink tubing to the end next to the Anderson Powerpole connector as a strain relief and to dress the cable nicely.

Finished 2.11mm to Anderson Powerpole Pigtail with ferrite bead for RF supression
After completing the wiring we ran a quick series of continuity tests with our multimeter to verify that the cable was fully functioning and without any shorts or other defects.  For our project, we needed the 2.1mm center to be positive.
The final product came out really looking and functioning perfectly and cost very little.  Having a completed cable enabled us to continue on building and testing our KN-Q7A Single Band SSB Transceiver Kit - Step 2: Audio Amplifier.

By Michael W. Maher (NJ2X)
Other related articles on NJ2X.COM:

© 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.

November 19, 2011

Soldering 101

Amateur radio is a wonderful hobby with so many different facets to explore.  One of the skills that most ham develop at some point is soldering.  This is because soldering is fun, useful, and arguably necessary.  Here are just a few things you can do with soldering:
  • Solder a power cable (see our article Project: Car power adapter to Anderson Powerpole)
  • Solder ends on coaxial cable
  • Build a commercial kit (radio, power supply, gadget, ...)
  • Make a home-brew device
  • Splice wires together
  • Repair or modify electrical equipment

If you would like to improve your soldering skill, spend the next 7 minutes with this excellent tutorial on the basics of soldering.  It will help you solder like a pro in no time.

A few safety precautions:
  • Never touch the element or tip of the soldering iron. They are very hot (about 400°C) and will give you a nasty burn.
  • Return the soldering iron to its stand when not in use. Never put it down on your workbench, even for a moment!
  • Work in a well-ventilated area. The smoke formed as you melt solder is mostly from the flux and quite irritating. Avoid breathing it by keeping you head to the side of, not above, your work.
  • Wash your hands after using solder.  Solder contains lead which is a toxic metal.
Now that you have learned how to solder it is time to practice.  A great way to start is to buy a simple electronic kit from Radio Shack, Fry's Electronics, Vectronics, or other electronic kit retailers

Elenco sells a nice Elenco Learn To Solder Kit that comes complete with a soldering iron, solder, circuit board, and components.

Alternatively, check out our simple, useful, and easy-to-build project, Project: Car power adapter to Anderson Powerpole.

Elecraft offers a useful Q&A on soldering called, "Ask Dr. Solder".  It is definitely worth reading.

We learned desoldering in our youth tearing apart old gear and salvaging parts. It turns out that desoldering is a common pattern among hams as a path to successful mastery of soldering technique.  In other words, desoldering an old piece of equipment and salvaging parts is a great way to learn how to handle a solder iron.   This is likely because the risk of damaging the circuit is ZERO (since it is already broken) which gives the freedom to make mistakes and learn.  Desoldering old equipment is also nearly free!  Be sure to check out our NJ2X.COM article, "Desoldering 101"

See our related articles:
Project: Wheel Of Fortune Kit (Velleman)
3D Xmas Tree Kit - Velleman
KN-Q7A Single Band SSB Transceiver Kit - New Arrival

November 11, 2011

Project: Car power adapter to Anderson Powerpole

Conservation is the act of preservation, protection, or restoration of the natural environment.  We hams are conservationists as we tend to be a thrifty lot and regularly re-purpose and reuse materials for our hobby.  Why throw something into a landfill when it can be made into something useful?  Through creativity and technical know how we conserve materials (and funds).  The smell of solder and a few minutes in the workshop is great fun too!
In this article we share a useful and simple project to convert an unneeded car power cable to an Anderson Powerpole adapter.  We cabled all of our radio gear for Anderson Powerpoles sometime ago and have been glad we did so ever since.  Anderson Powerpoles offer many compelling reasons for adoption:

Flat Wiping Contact System
  • Minimal contact resistance at high current, wiping action cleans contact surface during connection/disconnection.
Colored Modular Housings
  • Provides visual identification of proper mating connector.
Molded-in Dovetails
  • Secures individual connectors into "keyed" assemblies which prevents mis-connection with similar configurations.
Defacto Standard
  • Anderson Powerpoles have emerged as the defacto power connector standard in the amateur radio community.
  • This means it is easier to power your equipment at hamfests, club meetings, field day, emergency communications, ....
Unfortunately, vehicles provide power for passé "cigarette lighters" and not Anderson Powerpole connectors.  Come on Detroit, time to get with it and provide Anderson Powerpole outlets in your vehicles.  A boring solution would have been to buy a couple of  vehicle power to Anderson Powerpole adapters which typically sell for about $15.00 at ham fests.  However, a quick survey of our junk box revealed several unused vehicle power cables which could be readily adapted to Anderson Powerpole connectors for very little cost.

Materials and Tools
1 - pair of Anderson Powerpole contacts (black and red)
1 - 2-inch length of suitable heat shrink tubing
1 - vehicle power cable (AKA cigarette lighter power cable)
Wire cutters
Wire stripper
Soldering iron
Rosin flux
Electrical Solder

Step 1: Prepare the cable by snipping off the unneeded end.

Step 2: Strip both wires about 5/16 inches (7.9 mm).

Step 3: Brush on rosin flux and tin the wires.  Be careful not to apply too much heat and melt the insulation.  If you do melt the insulation a little, just trim up the exposed wires to maintain the 5/16 inch length.

Step 4: Slip the cable through the 2 inch length of heat shrink tubing.  This provides a nice dressed looking cable.  Additionally, the heat shrink tubing will provide strain relief.

Step 5: Melt rosin flux into the Anderson Powerpole connectors.  Solder the connectors onto the tinned wires.

Step 6: Using the multimeter, determine the vehicle adapter's center contact.  Install the red Anderson Powerpole's by inserting the contact and wire into the housing from the rear. Position contact and push forward so that contact slips under the barrier and snaps over the end of the retaining spring.  Tug slightly to make sure contact is locked in place.

Step 7:  Install the black Anderson Powerpole's by inserting the contact and wire into the housing from the rear.  Position contact and push forward so that contact slips under the barrier and snaps over the end of the retaining spring. Tug slightly to make sure contact is locked in place.

Step 8: Using the multimeter, confirm continuity of red contact with the vehicle adapter center conductor.  (and no continuity with the outer spring contacts).  Confirm continuity of the black contact with the vehicle adapter out spring contacts (and no continuity with the vehicle adapter center conductor).

Step 9: Dovetail the two connectors together and interlock the red and black Anderson Powerpole by slipping the keyed parts together as pictured above.

Step 10: Slide the heat shrink tubing forward as close to the Anderson Powerpole connectors as possible.  Use a blow dryer or other heat source to gently shrink the tubing until snug.  Avoid burning or melting the heat shrink tubing.

Voila!  That is all it takes to make a vehicle power / Anderson PowerPole cable adapter.  This is a fun and easy project that has the added advantage of saving money.

A few other considerations.
  • Since it is possible that vehicle manufacturers may reverse polarity of the power output, be sure to use your multimeter or Anderson Powerpole Polarity Checker to confirm that red Anderson Powerpole connector is indeed positive on your vehicle prior to using the cable.
  • We built our cable for use with low power devices.  Be sure to use a cable suitable for the current your device will draw. 
  • An in line fuse or fuse integrated into the tip of the vehicle power adapter is a good idea. 
  • Adding a ferrite bead or two can do wonders with keeping RF off the power cable (our junk box cable came with a ferrite already installed).

By Michael Maher (NJ2X)
See related articles on NJ2X.COM:

© Michael W. Maher and NJ2X.COM, 2011. 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.