July 15, 2016

So where did the name Google come from?

Q: So where did the name Google come from?

A: While at Stanford, Larry Page and Sergey Brin explained the origin of the name Google in their famous paper, "The Anatomy of a Large-Scale Hypertextual Web Search Engine".

"We chose our system name, Google, because it is a common spelling of googol, or 10100 and fits well with our goal of building very large-scale search engines."


Good DX and 73, NJ2X

July 8, 2016

A Radio Palindrome


"I, madam, I made radio! So I dared! Am I mad, am I?”

— Spider Robinson - a palindrome.

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 24, 2016

Design your own language...

"If you decide to design your own language, there are thousands of sort of amateur language designer pitfalls." -- Guido van Rossum

June 23, 2016

Field Day 2016 is here!

ARRL Field Day is the most popular on-the-air event held annually in the US and Canada. On the fourth weekend of June, more than 35,000 radio amateurs gather with their clubs, groups or simply with friends to operate from remote locations.

ARRL Field Day 2016 logo showing a boot tread with the ARRL logo enbedded next to "FD16".
ARRL Field Day 2016
The objective of Field Day is to work as many stations as possible on any and all amateur bands (excluding the 60, 30, 17, and 12-meter bands) and to learn to operate in abnormal situations in less than optimal conditions. Field Day is open to all amateurs in the areas covered by the ARRL/RAC Field Organizations and countries within IARU Region 2. DX stations residing in other regions may be contacted for credit, but are not eligible to submit entries.

Field Day is always the fourth full weekend of June, beginning at 1800 UTC Saturday and running through 2059 UTC Sunday. Field Day 2016 is June 25-26.

Hope to hear you on the air.

Good DX and 73, NJ2X

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

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

June 17, 2016

Learning Python is a lot easier than C, C++, or Java

"Now, it's my belief that Python is a lot easier than to teach to students programming and teach them C or C++ or Java at the same time because all the details of the languages are so much harder. Other scripting languages really don't work very well there either." -- Guido van Rossum

June 11, 2016

Backpacking Amateur Radio Power: Alternatives

In our prior post (Backpacking Amateur Radio Power: Requirements) we discussed our requirements for powering our electronics in the backcountry including an HT and an iPhone.  We defined our requirements in the form of a user story with acceptance criteria.

USER STORY: As a backpacker, I need a way to use my TH-F6A radio and iPhone 6 during my backpacking trip and not run out of battery before the end of the trip so that I can have fun with the devices during the trip and have them ready for use at any time during the trip in the event of an emergency to call for help.

ACCEPTANCE CRITERIA:
  • Must allow the backpacker to use the device a little or a lot as needed.
  • Must be flexible enough to allow the backpacker to use the solution regardless of duration (our typical backpacking adventures range from from 1 night to 15 days).
  • Must not add significant weight to the pack (i.e. < 1.5 lbs / 0.68Kg).
  • Must be able to maintain power for an iPhone via the USB connection (5Vdc USB power).
  • Must be able to maintain power for a Kenwood TH-F6A via the 12Vdc connection.

In today's post, we will explore potential alternative solutions and compare them against our requirements.

Option 1: Conserve the battery

Pros
  • Practical approach
  • No cost
  • No added weight
Cons
  • Conserving the battery means using the devices sparingly over the trip.  For the iPhone it means leaving the device powered off during the hike and powering it on when needed.  Not very convenient for snapping photos while trekking.  Keeping the HT powered off is a bit more feasible.  However, we like to use the radios in our backpacking group to keep the front and rear in communication as we go to since we tend to string out a bit.
  • This approach doesn't meet our acceptance criteria of being able to use the devices as much or as little as needed during the trek.

Option 2: Pack extra batteries

Pros
Cons
  • On longer trips, one set of extra batteries may not be enough.
  • Some conservation of battery power is still required.

Option 3: Pack a portable generator: BioLite Wood Burning Campstove

Pros
  • Claims to provide portable power (USB).
Cons

Option 4: Pack a portable generator: K-TOR Pocket Socket Hand Crank Generator

Pros
  • Possible to recharge both USB and 12Vdc batteries.
  • The weight is under the limit per our acceptance criteria (1.0 lbs/0.45Kg < limit of 1.5 lbs/0.68Kg)
  • Cost is reasonable at $54.00 on Amazon.com
Cons
  • The K-TOR Pocket Socket Hand Crank Generator had mixed reviews on Amazon.com.  From the reviews is sounds like hand cranking is laborious and takes a long long time to recharge.  This is a material consideration since backpacking can be physically exhausting.  Having difficulty imaging cranking for hours after a day of backpacking 16 miles with elevation changes.
  • Requires packing the transforms for iPhone and HT.  This adds additional weight.

Option 5: Pack a solar panel: Goal Zero Nomad 7

Pros
  • Recharges USB devices.
  • Recharges 12Vdc devices.
  • Lightweight at 1.4 lbs/0.64Kg which is less than our acceptance criteria limit of 1.5 lbs/0.68Kg.
  • Easy to use and requires no physical effort to generate power.
  • Cost is reasonable at $77.31 on Amazon.com
  • Solid reviews on Amazon.com.
  • Well made and durable.
Cons
  • Need direct sunlight to recharge.  We have sunshine in abundance here in California so this isn't a material concern.

Option 5: Pack a solar panel: Goal Zero Nomad 7 is the clear winner among our alternatives.  It fits the requirements very well.  We are looking forward to putting it to the test.


In our next post in this series, "Project: Hacking the Nomad 7 Solar Panel for Amateur Radio Use" we will show step-by-step how we modified our Nomad 7 to make it more convenience to use with our Amateur Radio setup.

We will review how well the whole setup worked on a challenging backpacking backcountry adventure in our final post in the series.


Good DX and 73, NJ2X


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

June 10, 2016

Light is electromagnetic waves...

"light is electromagnetic waves: the speed of electromagnetic waves experimentally agrees with the speed of light in a vacuum, and neither experiment depended on the other view." -- J. C. Maxwell