March 14, 2021

Amateur Radio Computer Clock Synchronization

Weak signal work with modes such as FT8, FT4, and JT65 all require software running on a computer with its time synchronized.  The consequence of running a computer with its internal clock substantially out of sync is to neither be able to decode signals nor have your signals decoded by others.

You may have noticed hearing strong stations that were not decoding.  It is likely that their computer’s clock was substantially out of sync with yours.



With the WSJT-X application, synchronization is measured by the DT value (time-differential).  Small DT values are necessary for effective communication.  If you happen to see an abundance of FT8 signals on the waterfall yet few decodes, or a distinct bias of negative DT values on decode, these are indicators that your computer’s clock is in need of synchronization. 

Curious about your computer's clock synchronization?  Use time.is to get a measurement of your computer's clock against a standard.

On Windows 10, it is fairly easy to manually sync the computer's clock.  Though it is also easy to forget to do this periodically which can lead to the computer's clock becoming unacceptably out-of-sync resulting in lost QSO's.  Computers are supposed to do this type of work for us humans anyway!

Fortunately, there is a handy little utility called NetTime that takes the work out of keeping your computer's clock synchronized within a millisecond.  NetTime is a Simple Network Time Protocol (SNTP) client and it is easy to install and configure.  The only real change I made to the default settings is setting the update interval to 15 minutes.  15 minutes happens to be the most frequent update value possible in the application.



Hope this helps you make more digital contacts.  See you on the air.


Good DX and 73, NJ2X

February 15, 2021

Ten Terms and Abbreviations Every New Radio Amateur Needs to Learn

Amateur Radio, like any other area of interest has its own vernacular.  Fortunately, there are an abundance of resources available to help decode what these terms mean.  Here are ten terms that every new ham needs to learn with links to the associated Wikipedia page.


Good DX and 73, NJ2X

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

February 6, 2021

Completed the ARRL 17m Digital Worked All States Award from California

Thanks to Robert (N7QT) in the great State of Washington, I completed the ARRL 17m Digital Worked All States Award this afternoon from California.  Robert and I made an FT8 contact on 17m with ease.  17m WA contacts had proven difficult in the past for me.  There seems to be a narrow window that my signal would propagate into WA on 17m.  I believe this has to do with the orientation of my antenna and take angles.  Robert's excellent station made all the different in the contact.

Washington State Flag



Good DX and 73, NJ2X

January 22, 2021

Collection of vintage amateur radio books and magazines

I stumbled on a fascinating collection of links to vintage radio frequency books and magazines.  It contains some really useful amateur radio relevant material.  While browsing, I found several outstanding books on antennas that inspired ideas for future projects.  If you have an interest in radio, this site is definitely worth checking out.





Good DX and 73, NJ2X

January 18, 2021

Martin Luther King Jr. Day 2021

Martin Luther King Jr. Day is a federal holiday in the United States marking the birthday of Martin Luther King Jr. It is observed on the third Monday of January each year. King's birthday was January 15, 1929.

I have a dream that my four little children will one day live in a nation where they will not be judged by the color of their skin but by the content of their character. I have a dream today. -- Martin Luther King Jr. August 28, 1963

Martin Luther King, Jr.



January 17, 2021

Completed the ARRL 20m Digital Worked All States Award from California

Thanks to Karl (N8NA) in the great State of Delaware, I completed the ARRL 20m Digital Worked All States Award this morning.  Karl and I made FT8 contacts on 20m and 15m with ease.  15m was in poor condition with only a couple of other stations being decoded at the time.  Regardless, we managed to make the contact work.  We tried 10m out of curiosity and the band wasn't open.



Good DX and 73, NJ2X

January 10, 2021 Radio Scavenge Around Field Exercise

On January 10, 2021, I had the opportunity to participate in the Santa Cruz County ARES Scavenge Around Field Exercise with my family and we had an excellent time.  A radio scavenge around exercise is a fun activity designed to maintain safe social distancing while improving participant's amateur radio skills and knowledge of local County geography and repeater coverage.

Santa Cruz County FEMA Map

The scavenge around exercise was a three-hour event.  It started with participants checking into a SAFE Resource Net and being assigned a SAFE tactical net from one of three other area repeaters.  Participants then changed frequency to their assigned tactical net and checked in for tasks.  

The tasks involved driving to a location which was either an intersection or a address and answering a question that was given as part of the task regarding what you observe at the location.  The task assignments often involved the participant driving to a distant and possibly unfamiliar part of the County.  This made the task interesting for participants.

After completing a task, the tactical net control operator would ask each participant if they would like another task assignment.  Toward the end of the exercise, participants checking into their tactical nets would be asked to contact the resource net control to demobilize.  After demobilizing, the final check-in was when the participant had arrived home safely.

It was a beautiful day for driving and our family enjoyed this activity very much.  We are all licensed hams though we only used one call sign for the check-in and tasks since we were travelling together in one vehicle.

Good job Santa Cruz County ARES!  We are looking forward to joining in another ARES Scavenger Around Field Exercise again soon.

Good DX and 73, NJ2X

January 8, 2021

The great teacher inspires...

This quote echoes the EDGE method - Explain, Demonstrate, Guide, Enable.

‘The mediocre teacher tells. The good teacher explains. The superior teacher demonstrates. The great teacher inspires.’ ― William Arthur Ward




Good DX and 73, NJ2X

January 3, 2021

Provide the conditions...

"I never teach my pupils; I only attempt to provide the conditions in which they can learn." – Albert Einstein

Albert Einstein 1921




Good DX and 73, NJ2X

January 1, 2021

Configuring WSJT-X with a Kenwood TS-480SAT and SignaLink USB

Communicating on HF using various digital modes is a ton of fun.  There has been a significant shift in the popularity of digital modes toward FT8 over the last couple of years.  PSK31, JT65, and other digital modes have nearly disappeared from the bands.  This means hams need to join in the FT8 craze if they want to operate digital modes and actually make contacts.  WSJT-X is my preferred software for JT65, FT8, and FT4.  In this post, I will share how I have configured my station for WSJT-X digital HF communication.

Station Control

I use a Kenwood TS-480SAT that is capable of 100W on HF and 6M.  The TS-480SAT is interfaced to the computer for radio control through the radio's serial port through a Keyspan USA-19HS USB adapter.  The radio's audio is interfaced to the computer from the TS-480SAT's data port through a SignaLink Integrated USB Sound Card.  I have used this configuration for years with excellent results.

Kenwood TS-480SAT

SignaLink Integrated USB Sound Card

WSJT-X Settings Configuration

Radio
  • Cat Control - Serial Port: COM3
  • Serial Port Parameters: Baud Rate = 57600
  • Data Bits: Default
  • Stop Bits: Default
  • Handshake: Hardware
  • Force Control Lines: DTR and RTS are both blank
  • PTT Method: CAT
  • Transmit Audio Source: Rear/Data
  • Mode: USB
  • Split Operation: None
Audio
  • Input: USB Audio CODEC - Mono
  • Output: USB Audio CODEC - Mono

TS-480 SAT Configuration

Menu 56 Com Port Parameters = 57600
Menu 60 VOX Operation With Data Input = Off


Be sure to check out my article on setting up WSJT-X for automatic logging with Ham Radio Deluxe.


Good DX and 73, NJ2X


Other related articles:





December 28, 2020

Teach them to dream...

“You will teach them to fly, but they will not fly your flight.
You will teach them to dream, but they will not dream your dream.
You will teach them to live, but they will not live your life.
Nevertheless, in every flight, in every life, in every dream,
the print of the way you taught will always remain.” -- Mother Teresa



Good DX and 73, NJ2X

December 27, 2020