Tag Archives: DX

Why Ham Radio?

Fred's Truck Antenna
Fred’s Truck Antenna

Every so often, I drive Fred’s truck into work and people ask me what that big antenna on the back of the truck is for. I explain to them that it is for Ham Radio.  But the reply is usually, why ham radio – isn’t that outdated technology?  We have cell phones and IM, etc…what do we need Ham Radio for?  So I thought I would put down my thoughts as a relatively new Ham about why I enjoy spending so much of my time with Ham Radio.

Amateur Radio for Public Service

Public Service

The number one reason we still need Ham Radio along with all the other technology we now have is for public service.  When there is a disaster and cell phones, television, etc are all not working, Ham Radio operators provide the critical communication.

Ham Radio operators help locally to keep hospitals and first responders in contact with each other to help those affected by the disaster.

Hams also use our ability to communicate around the world on HF bands to help family members around the world to get in touch with loved ones affected by a disaster.

Ham Radio operators have been on the scene helping in every disaster from the earthquakes in Nepal to the recent flooding in California.

Amateur Radio Cube Satellites

Technology and the Maker Movement

I only became a Ham 5 years ago but many of my fellow Ham Radio operators got their license when they were in their early teens and used what they learned to launch their careers. Many have had very successful careers in STEM fields, all launched by their interest in Ham Radio at a young age.  As technology advances, so does the technology used in our hobby.   We even have a nobel laureate, Joe Taylor K1JT who is a ham. Joe has developed weak signal digital communication modes that let us communicate by bouncing signals off the moon!

As technology has advanced, so has the use of it in Ham Radio.   Most Ham Radio operators have one or more computers in their shack.  Many also have a software designed radio (SDR), where much of the radio functionality is implemented using Software, we use sound cards to run digital modes, which are a lot like texting over the radio, and we use the internet extensively as part of operating.  We can also make contacts through satellites orbiting the earth and even the International Space Station.

Most hams love do-it-yourself technical projects, including building a station, home brewing an antenna, building a radio or other station component.  In my day job, I am a program manager for software development projects, but its been a while since I have built anything. As a Ham I taught myself how to code in Python and about the Raspberry Pi and I built the DX Alarm Clock.

QSL Card from VK6LC in Western Australia

International Camaraderie

One of the coolest things about being an amateur radio operator is that you can communicate with other hams all over the world. Ham Radio is an international community where we all have something in common to talk about – our stations and why we enjoy ham radio.    The QSL card above is from a memorable QSO with Mal, VK6LC, from Western Australia, who was the last contact that I needed for a Worked All Zones award.  I must have talked to him for 1/2 hour about his town in Australia and his pet kangaroos!

Amateur Radio Map of the World

Geography Lesson

I have learned much about geography from being on the air and trying to contact as many countries as I can.  There are 339 DX Entities, which are countries or other geographical entities and I have learned where each one is in order to understand where propagation will allow me make a contact.  I have learned a great deal about world geography. Through exchanging QSL cards often get to see photos from so many areas of the world.

DXCC Challenge Award Plaque

Achievement – DXing and Contesting

DXing and Contesting provide a sense of achievement and exciting opportunity for competition. Many Hams work toward operating awards. You can get an operating award for contacting all 50 states, contacting 100 or more countries, contacting Islands, cities in Japan, countries in Asia, or anything else you can imagine.  Each of these operating awards provides a sense of accomplishment and helps to build skills.  Contesting builds skills through competition among Hams to see who can make the most contacts with the most places in 24 or 48 hours. Contesting also improves our operating skills and teaches us to copy callsigns and additional data accurately.

Teaching a License Class

Teaching Licensing Classes – Passing it On

Recently I have joined a team of club members who teach license classes to others who want to get licensed or upgrade their existing Amateur Radio licenses.  Teaching provides a way to improve my presentation skills and also helps me to really understand the material that we teach about Amateur Radio.  It is always a thrill at the end of the class to see so many people earn their licenses or upgrades.

There are so many interesting aspects of Ham Radio which is what makes is such a great hobby.  Getting your license can open up a world of possibilities.  Upgrading to a new license class provides more opportunities to communicate over longer distances.  Our club provides many resources to help you get your first license, upgrade to a new license class, and learn about the many aspects of our hobby.

Little Pistol DXing

For many years, I enjoyed chasing DX from my NH station with two towers, multiple beams, an 80-meter 2-element quad and a 160-meter Inverted L.  I got spoiled with the AL-1200 hammer I used almost constantly whenever a DXpedition came on the air to bag it quickly.  The setup allowed me to bust a contest pileup in just two or three calls.  Ah, the good ol’ days.

I’ve been in FL now for 18 months in a covenant-restricted retirement community.  I was fortunate to find a place with a fair amount of open property that allowed me to put up a couple of low inverted Vees and a multi-band vertical.  The wire antennas drape off a pole on the back of the house, out of sight of most of my neighbors.  The vertical is enclosed in a PVC flagpole with just the 80-meter “stinger” poking out the top.  It may be an ugly flagpole but it falls within the covenant permissible guidelines and, more importantly, keeps the village aesthetic vigilantes off my back. I have about 32 radials fed from the base of the vertical in a ¾ pie-shaped field with lengths varying from 55 feet to 10 feet.  While this is far from the standard practice of at least 100 radials of 65 feet or more (assuming 80-meter capability), it is better than nothing.

As one might expect, DXing has been a far cry from what I was used to.  Hearing stations is a chore, even with a K3 over my old FT-1000MP.  I often find myself irritated at the juicy spot reports from New England that I cannot hear.  Part of the problem is geography; I am at a lower latitude and I line near Ohio longitudinally so gray-line effects are different.  One might think the high threat of thunderstorms down here also generates a lot of noise but it has been dry and quiet during the fall and winter months when DX is most active.

So what is an old DXer supposed to do?  Answer: back to the future.  When I got my Novice license back in high school, I put up an end-fed long-wire antenna for 80 meters and a dipole for 40 meters, both of them much lower than 1/4-wavelength above ground.  The long-wire was fed with 300-ohm line.  Why?  Because that is what my Elmer and high school buddy told me to do.  I was clueless about matching, common-mode currents and RF in the shack.  I had a Hallicrafters S-38 reconditioned tube receiver that had a barn door-wide filter for CW.  You can understand why it was a thrill to work states west of the Mississippi.  If nothing else, I learned to appreciate a QSO and to be patient when trying to work someone.

My present station has the advantage of all the technological improvements in signal processing and automation that have mushroomed since the tube days.  Stations are still weak when I do hear them but I can work them if they aren’t too busy.  Contesting is actually better since many stations crank up the amplifier and plead for stations late in the contest.  Using an amplifier here is problematic.  My vertical is about eight feet from the shack so RF saturation would be likely.  Furthermore, I would need to run a 220 VAC line to the shack to avoid brownout when using 110 VAC with an amplifier.  The worse thing, however, would be EMP effects on the neighborhood breaker systems.  It seems building contractors have switched to breakers with a much lower RF tolerance than before.

So what a desperate DXer supposed to do?  The easiest thing I can do is put down more radials.  As I mentioned, my radial field is far from ideal, even if I had moist, loamy soil instead of sand.  An ideal radial field would be a copper sheet surrounding the vertical.  In the climate here, it would turn green in a few weeks so it would look like a California painted lawn, if it isn’t stolen first.  I decided to double the radial field I have to provide more return paths for the RF currents.  I have not modeled my antenna to see what kind of radiation pattern I have but it is a good bet that the so-called takeoff angle for bouncing off the ionosphere is 40 degrees or higher.  Conventional theory says that a takeoff angle should be 15 to 20 degrees, values usually achievable with yagis mounted 1/4-wavelengths or higher.  The hope is that I can pull down my takeoff angle enough to where I fall into the usual DX footprints.

When I installed my original set of radials, it was a time-consuming effort to work each wire down through the thick St. Augustine grass here.  I finally got smart one day when trimming the walkways with my weed-whacker set up vertically.  I found that I can lay out the wire and walk along it with the weed-whacker cutting a narrow slice through the grass.  I then drop the wire down into the cut, add a few staples and close the grass around the cut.  The cut will be completely grown over in about a month.  (This technique will work in New England if you have a manicured lawn; the rocks in a natural lawn tend to mess things up.)  To date, I have added eight radials so it is still a work in progress.

For those of you with a modest station, take heart.  With today’s transceivers, propagation predictions, and worldwide spotting it is possible to achieve DXCC on several bands in less than a year.  I have been fortunate to work them all when I was a “big gun”.  As a “little pistol”, I’ve managed to work 176 countries with 144 confirmed.

The chase continues…

Ed (K2TE)

The DX Alarm Clock – Part 1: Software

I have been a Ham for 5 years and my favorite thing to do is chase DX. As a new Ham it was always a thrill to work a new DXCC, but now that I have over 280 DXCCs and over 1000 band points, it is a little more difficult to find a new one. Add to that the fact that I am trying to get a DXCC in 80m and 160m., which are usually open when I am asleep. I created the DX Alarm Clock as a way to get notified that there is something new on the air when I am not down in the shack.  This article will talk about how I developed the software for the DX Alarm Clock.  Part 2 will talk about the building the Raspberry Pi based Hardware and loading the OS.

The DX Alarm Clock is a Python software program running on a Raspberry Pi that gathers data online about my log and what is on the spotting network and uses that data to alert me when there is a “new one” on the air.

DX Alarm Clock Architecture

The ClubLog website provides a light DX Cluster website called DXLite, which has an XML Interface. The DX Alarm Clock uses this interface to get the current spots. The software uses the Developer API from ClubLog to get a JSON matrix of all DXCC entities by band indicating whether I have worked, confirmed or verified each band-entity. The software loops through all of the spots returned by DXLite and looks each DXCC up in the JSON ClubLog matrix. I also use the QRZ.com XML Interface to get additional information for each callsign that is spotted, like the state.

DXCC Configuration Screen

The DX Alarm Clock uses tkinter/ttk for the GUI.  I used the Notebook widget to create a multi-tab GUI.  There is a tab for configuring filters for DX Entity. The user can choose all New DXCCs, as well as specific bands and nodes to provide alerts for.

WAS Configuration Screen

There is another tab for configuring filters for WAS. ClubLog has no log look up capability based on US State so the WAS filter lets you create a list of States and associated bands to provide alerts for.

Notification Configuration Screen

The Notification tab allows configuration of what notifications the user would like to receive. The user can specify a separate email address for New DXCCs, New Band Points, and New US States. This allows alerts to be sent to email accounts or as SMS texts. You can also configure the sounds the the DX Alarm Clock itself makes to “wake you up” when that ATNO or new Band Point is spotted.

The DXAlarm clock wakes up every 5 minutes and gets the latest spots from the DXLite Cluster. It checks each spot against the ClubLog log and if there is a match based on the configure filters, it sounds the alert, and then speaks the alarm, giving you the Callsign, DXCC Entity, Band and Mode.   A simple text to speech package called flite (festival-lite) was used to implement the speech on the Raspberry Pi.

Alert Screen

It also puts a message with these details and the Frequency, UTC Date/Time, Spotter and Comment on the display.

Text Notification to iPhone

Additionally it sends this information as an email to the configured email address, which results in a text or email.

 

Apple Watch Alert

I can even get the alert on my Apple Watch.

Filtered Spots Display

Once all spots are processed, it keeps a running list of all spots that resulted in alerts on the main screen. Spots are aged out if they do not recur over time.

DX Alarm Clock Hardware

The DX Alarm Clock just alerted me that ZC4SB is on 20m – that’s an ATNO!  Got to go down to the shack and work him!    Stay tuned for Part 2 of this post on the DXAlarm Clock Raspberry Pi based hardware and on setting up the Raspberry Pi OS.

Anita, AB1QB

Fall Antenna Projects at AB1OC/AB1QB

Anita and I like to take advantage of the mild fall weather to do antenna projects at our QTH. We have completed two such projects this fall – the installation of a Two-Element Phased Receive System and a rebuild of the control cable interconnect system at the base of our tower.

NCC-1 Receive Antenna System Components
NCC-1 Receive Antenna System Components

Our first project was the installation of a DXEngineering NCC-1 Receive Antenna System. This system uses two receive-only active vertical antennas to create a steerable receive antenna system. The combination can work on any band from 160m up to 10m. We set ours up for operation on the 80m and 160m bands.

NCC-1 Receive System Antenna Pattern
NCC-1 Receive System Antenna Pattern

The NCC-1 System can be used to peak or null a specific incoming signal. It can also be applied to a noise source to null it out. The direction that it peaks or nulls in is determined by changing the phase relationship between the two Active Antenna Elements via the NCC-1 Controller.

NCC-1 Filter Installation
NCC-1 Filter Installation

The first step in the project was to open the NCC-1 Control Unit to install a set of 80m and 160m bandpass filter boards. These filters prevent strong out-of-band signals (such as local AM radio stations) from overloading the NCC-1. The internal switches were also set to configure the NCC-1 to provide power from an external source to the receive antenna elements through the connecting coax cables.

Installed Active Receive Element
Installed Active Receive Antenna Element

The next step in the project was to select a suitable location for installing the Receive Antenna Elements. We choose a spot on a ridge which allowed the two Antenna Elements to be separated by 135 ft (for operation on 160m/80m) and which provided a favorable orientation toward both Europe and Japan. The antenna elements use active circuitry to provide uniform phase performance between each element’s 8 1/2 foot whip antenna and the rest of the system. The antenna elements should be separated by a 1/2 wavelength or more on the lowest band of operation from any towers or transmit antennas to enable the best possible noise rejection performance.

Received Antenna Element Closeup
Received Antenna Element Closeup

The two Antenna Elements were assembled and installed on 5 ft rods which were driven into the ground. To ensure a good ground for the elements and to improve their sensitivity, we opted to install 4 radials on each antenna (the black wires coming from the bottom of the unit in the picture above). The Antenna Elements are powered through 75 ohm flooded coax cables which connect them to the NCC-1 Control Unit in our shack. The coax cable connections in our setup are quite long –  the longer of the pair being approximately 500 ft. The use of flooded coax cable allows the cables to be run underground or buried. Should the outer jacket become nicked, the flooding glue inside the cable will seal the damage and keep water out of the cable.

RFC-1 Receive Line Choke
Receive RF Choke

It is also important to isolate the connecting coax cables from picking up strong signals from nearby AM Radio stations, etc. To help with this, we installed Receive RF Chokes in each of the two coax cables which connect the Antenna Elements to the NCC-1. These chokes need to be installed on ground rods near the Antenna Elements for best performance.

Underground Feedline Conduit
Underground Cable Conduit In Our Yard

We ran the coax cables underground inside cable conduits for a good portion of the run between the antenna elements and our shack. The conduits were installed in our yard when we built our tower a few years back so getting the coax cables to our shack was relatively easy.

Receive Antenna Coax Ground System
Receive Antenna Coax Ground System

The last step in the outdoor part of this project was to install a pair of 75 ohm coax surge protectors near the entry to our shack. An additional ground rod was driven for this purpose and was bonded to the rest of our station’s ground system. We routed both of the 75 ohm coax cables from the two Antenna Elements through surge protectors and into our shack. Alpha-Delta makes the copper ground rod bracket shown in the picture for mounting the surge protectors on the ground rod.

Antenna Equipment Shelf In Our Shack
Antenna Equipment Shelf In Our Shack (The NCC-1 Control Unit Is At The Bottom)

The installation work in our shack began with the construction of a larger shelf to hold all of our antenna control equipment and to make space for the NCC-1. The two incoming coax cables from the Antenna Elements were connected to the NCC-1.

uHAM Station Master Deluxe Antenna Controller
microHAM Station Master Deluxe Antenna Controller

Antenna switching and control in our station is handled by a microHAM System. Each radio has a dedicated microHAM Station Master Deluxe Antenna Controller which can be used to select separate transmit and receive antenna for the associated radio. The microHAM system allows our new Receive Antenna System to be shared between the 5 radios in our station.

Antenna Switching Matrix
Antenna Switching Matrix

The first step in integrating the Receive Antenna System was to connect the output of the NCC-1 to the Antenna Switching Matrix outside our shack. We added a low-noise pre-amp (shown in the upper left of the picture above) to increase the sensitivity of the Antenna System. The blue device in the picture is a 75 ohm to 50 ohm matching transformer which matches the NCC-1’s 75 ohm output to our 50 ohm radios. The other two pre-amps and transformers in the picture are part of our previously installed 8-Circle Receive Antenna System.

Multi-Radio Sequencer
Multi-Radio Sequencer

The Antenna Elements must be protected from overload and damage from strong nearly RF fields from our transmit antennas. In a single radio station, this can be handled via a simple sequencer unit associated with one’s radio. In a multi-op station such as ours, it is possible for a different radio than the one which is using the Receive Antenna System to be transmitting on a band which would damage the Receive Antenna System. To solve this problem, we built a multi-radio sequencer using one of the microHAM control boxes in our station. The 062 Relay Unit shown above has one relay associated with each of the five radios in our station. The power to the Receive Antenna System is routed through all 5 of these relays. When any radio transmits on a band that could damage the Antenna Elements, the associated relay is automatically opened 25 mS before the radio is allowed to key up which ensures that the system’s Antenna Elements are safely powered down and grounded.

NCC-1 Controls
NCC-1 Controls

So how well does the system work? To test it, we adjusted the NCC-1 to peak and then null a weak CW signal on 80m. This is done by first adjusting the Balance and Attenuator controls on the NCC-1 so that the incoming signal is heard at the same level by both Antenna Elements. Next, the B Phase switch is set to Rev to cause the system to operate in a signal null’ing configuration and the Phase control is adjusted to maximize the null’ing effect on the target signal. One can go back and forth a few times between the Balance and Phase controls to get the best possible null. Finally, the incoming signal is peaked by setting the B Phase switch to Norm.

Peaked And Nulled CW Signal
Peaked And Null’ed CW Signal

The picture above shows the display of the target CW signal on the radio using the NCC-1 Antenna System. If you look closely at the lower display in the figure (null’ed signal) you can still see the faint CW trace on the pan adapter. The difference between the peak and the null is about 3 S-units or 18 dB.

Peaked And Nulled SSB Signal With NCC-1 Used For Noise Cancelation
NCC-1 Used For Noise Cancellation

The NCC-1 can also be used to reduce (null out) background noise. The picture above shows the result of doing this for an incoming SSB signal on 75m. The system display at the top shows an S5 SSB signal in the presence of S4 – S5 noise (the lower display in the picture). Note how clean the noise floor for the received SSB signal becomes when the unit is set to null the noise source which comes from a different direction than the received SSB signal.

We are very pleased with the performance of our new Receive Antenna System. It should make a great tool for DX’ing on the low-bands. It is a good complement to our 8-circle steerable receive system which we use for contesting on 160m and 80m.

Tower Control Cable Interconnects
Tower Control Cable Interconnects (Bottom Two Gray Boxes)

Our other antenna project was a maintenance one. We have quite a number of control leads going to our tower. When we built our station, we placed surge protectors at the base of our tower and routed all of our control leads through exposed connections on these units. Over time, we found that surge protection was not necessary and we also became concerned about the effects that sunlight and weather were having on the exposed connections. To clean all of this up, we installed two DXEngineering Interconnect Enclosures on our tower and moved all the control cable connections inside them.

Inside View Of Interconnect Enclosures
Inside View Of Interconnect Enclosures

We began with a pair of enclosures from DXEngineering and we mounted screw terminal barrier strips on the aluminum mounting plates in each enclosure. The aluminum plates are grounded via copper strap material to our tower.

Closer Look At The Interconnects
Closer Look At One Of The Interconnect Enclosures

The picture above shows one of the interconnection boxes. This one is used to connect our two SteppIR DB36 Yagi Antennas and some of the supporting equipment. The barrier strips form a convenient set of test points for troubleshooting any problems with our equipment on the tower. There are almost 100 control leads passing through the two enclosures and this arrangement keeps everything organized and protected from the weather.

With all of our antenna projects complete, we are looking forward to a fun winter of contesting and low-band DX’ing.

73,

Fred, AB1OC