Tag Archives: Homebrew

Raspberry Pi Satellite Rotator Interface

We’ve been using our Portable Satellite Station 2.0 for some time now and it works great. One area that can be improved is the interface between the MacDoppler Satellite Tracking program we use and the GHTracker application which controls the Green Heron Engineering RT-21 Az/El Rotator Controller in our setup…

Source: Raspberry Pi Satellite Rotator Interface | Our HAM Station

The Raspberry Pi is an inexpensive computer and control platform for many Ham Radio projects. We recently used a Raspberry Pi 3 to build an interface between the MacDoppler Satellite Tracking Software in our Portable Satellite Station and the Rotator Control System points the ground station antennas during satellite tracking. We put together an article about how we went about this project and some details of the hardware and software we used to put a Raspberry Pi 3 computer together for our project.

Fred, AB1OC

A Good ‘Day’ To Be A Ham? by Paul Mills, AC0HY

We have such a wonderful hobby with its myriad, almost limitless facets. No room for boredom here! Paul Mills, AC0HY, President of The Kaw Valley Amateur Radio Club [Kansas], wrote a very interesting article in their Newsletter, THE TRANSCEIVER September 2017. It’s republished here with his permission.Club Web Page: www.KVARC.org     Layne AE1N

A Good ‘Day’ To Be A Ham? by Paul Mills, AC0HY

I was thumbing through some magazines for inspiration, as I often do. Magazines for me are seldom read but frequently browsed. In some, I observe the advertisements more than I do the articles. I do read a few articles from beginning to end. But to a large extent, I look at titles, pictures, schematics, and captions. And frequently I scan the article for areas of interest. Today this caused me to think about how things have changed in my lifetime.

My earliest days in radio, tubes were still the norm. Transistors were out there, but the quality was not great, and most were used in portable or mobile electronics. Equipment was large and heavy. Transmitters and receivers were frequently separate. Power amplifiers were very large, and often two pieces – the amplifier, and the power supply.

Over the years, transistors changed, the move from germanium to silicone greatly improved reliability, though there still remains a place for a few germanium devices. And while early transistors were bipolar devices, there came to be many FET’s and a number of new materials and techniques used in their construction.

In many ways, this was a great time. It was easy to roll up your sleeves, and put together circuits, and observe how they worked. During these days, many parts houses sold electronics components. At one time, Topeka had 5 or 6 wholesale parts houses. Radio and television repair was a common business.   But even before this era was over, Integrated Circuits, and Large Scale Integration was upon us.

In many ways, this was a great time for the radio enthusiast. Parts were widely available, and building from scratch was therefore fairly easy. Likewise, repair was possible due to the wide availability of parts. Now Very Large Scale Integration and surface mount technology has totally changed electronics, and thus radio. This has done a lot of positive things for us.

Consider that your Smartphone is tiny compared to the radio-telephone of the 1970’s. And in addition, the Smartphone contains a room full of similar era computing power. On the down side of all of this, parts are harder to come by. If you need parts, you will probably have to order them, and wait. And in many cases, it is cheaper to replace a product than it is to repair.

What does this mean to us as ham radio operators? It means that to a degree, all of us have become appliance operators. Does that mean that we are doomed to a dumbed down hobby? NO! There are plenty of things we can do if we so desire.

Most obvious of these things we can still do is to build our own antennas. There are lots of antenna designs that we can experiment with. Many antenna projects can be done with a spool of #12 wire, and some homemade insulators. Let your imagination run wild.

Those who would like to play with electronics may find some satisfaction with parts houses such as Mouser, DigiKey, Newark, Arrow, MCM, Jameco.

Additionally, eBay can be a wonderful source for things to experiment with. And, if there is something you forgot, don’t forget the Radio Shack replacement –Amazon. You will be surprised at what you can find on Amazon – and if you have Amazon Prime, frequently have in 2 days with free shipping.

In many cases, instead of building from scratch, you will buy things like RaspberryPi, Arduino, or other small single board computers. These can be used to automate various tasks in the Shack. On eBay, there is a wealth of boards that can be found to do just about anything you want. Your imagination is the limit to what you can do here. There are SDR radio kits, various parts and pieces that can be cobbled together to create your own receiver, transmitter, transceiver, etc.

If this seems hard to believe, start searching the internet, you will find that there are lots of people already doing these things.I know these are not for everyone, but hopefully it will cause some of you to broaden your horizons. Even if you do not choose to do any of them, it can be interesting to find a read about what others are doing.

Until next time…73 de AC0HY

Ham Radio Hobby

How did I hang my dipole 50+ feet high in the trees?

Dipole Antenna Tree

I wanted to make an article that would explain to anyone who visits my home or QTH that would answer the question on “How did you get that rope so high in the trees and how did you get that rope over the perfect branch?

I started out with a fishing pole and a 4-inch long stick from the woods.  After a few attempts of getting the stick up and over the tree with the fishing line it finally made it over the tree and back to the ground.  I then reeled in all the fishing line while pulling a string over the tree.  After the string, I used it to pull over 3/8” poly rope.

I came up with the following idea to get a rope over the perfect branch.

Dipole Antenna Tree

The 3/8″ line holds an old branch from the woods in the center. The yellow rope to the left is the “control line” and the right side has a half rotten log as a weight secured with a slip knot as shown below.

Dipole Antenna Tree

In the diagram below the light blue line represents the yellow control line from the photo.  As you lift the whole unit you should consider that the weight of the control line may offset your balance as you go higher.    The magenta line shows the string with a slip knot.  When the half rotten log made it over the desired perfect branch by combinations of pulling the 3/8″ rope at either end (shown black) and/or the control line (shown light blue) I pulled out the slip knot and the half rotten log fell over the perfect branch along with the string (shown magenta).

Dipole Antenna Tree

I replaced the string with rope and then a wire rope loop (shown red). The wire rope will not fade and fall apart from the sun’s UV rays. The yellow circle represents a pulley for the poly rope that holds up the dipole. When the poly rope breaks down from UV, wear and tear it can easily be replaced by lowering the pulley.  I added weight to maintain proper tension on the dipole antenna as shown below.

Dipole Antenna Tree

In theory, the tension will remain the same even in wind storms when the trees swing back and forth. It turns out that an old cast iron rotor from my Toyota was the perfect weight for the application!

73,

Mike AB1YK

 

 

 

Go Kit for Field Day and EMCOM

We’ve been thinking about building a portable Go Kit for VHF/UHF Emergency Communications (EMCOM) and Field Day Applications for a while now. The following is a list of our requirements for a Go Kit –

  • 2m and 70cm operation with FM simplex and repeaters
  • APRS capability and tactical display for portable coordination
  • Digital messaging capability
  • Weather band monitoring capability
  • AC Power with flexible battery backup options

A plan to build our Go Kit came together during our trip to the Dayton Hamvention this year.

EMCOM Go Kit - Kenwood TM-D710GA At Dayton
Kenwood TM-D710GA At Dayton

The heart of any Go Kit is the Transceiver. We’ve been using Kenwood equipment for our APRS iGate for some time now and we have had good results with it. Kenwood’s latest 50W transceiver with APRS is the TM-D710GA. This unit provides full support for APRS tactical applications and now includes a built-in GPS receiver making it ideal for our Go Kit application.

EMCOM Go Kit - AvMap GeoSat 6 APRS Tactical Display
AvMap GeoSat 6 APRS Tactical Display

We have been using the Kenwood TM-D710 along with an AvMap GeoSat APRS display in our APRS iGate setup and the combination works very well. The AvMap display lets one see the location of portable and mobile APRS stations on a map display. This arrangement is perfect for coordinating activities in an EMCOM situation. The AvMap GeoSat 6 APRS display is no longer in production but I was able to locate a nearly new unit on eBay.

EMCOM Go Kit Packaging

 

EMCOM Go Kit - iPortable Enclosure
iPortable Enclosure

We had a chance to look at the iPortable enclosure at Dayton and decided that their Pro 2 4U deep unit would be a good choice for our Go Kit application. The iPortable enclosures are based on a portable rack mount case and include a DC power system, speaker and headphone hookups, a light, and provisions for a cooling fan.

EMCOM Go Kit Construction

 

EMCOM Go Kit - Radio Shelf
Radio Shelf

With all the components in hand, we began the construction of our Go Kit. Reliability is important in any portable system like this so we put some time into securely mounting all of the equipment and neatly arranging the cabling. First came the shelf which holds the Kenwood transceiver and a SignaLink USB sound card. A combination of drilling the shelf to secure gear with large cable ties and #8 stainless hardware was used here.

EMCOM Go Kit - Coax Connector Cables
Coax Connector Cables

Our iPortable case was equipped with both SO-239 and N-connectors on the front panel to allow for antennas and feed lines equipped for either connector type. To make the change over between the connector types easy, we installed separate PL-259 jumper cables for each connector. One simply connects the appropriate jumper to the radio.

EMCOM Go Kit - Display and Power Shelf
Display and Power Shelf

The power and AvMap display shelf were next. The AvMap display mount was dissembled and modified to accept a custom mounting bracket.

EMCOM Go Kit - PWRgate Battery Interface and Charger
PWRgate Battery Interface and Charger

The iPortable enclosure was drilled to mount a West Mountain Radio PWRgate to handle backup battery charging and management. The PWRgate supports instantaneous switching between an AC power supply and a backup battery and can accommodate a wide range of battery types and sizes.

EMCOM Go Kit Backup Battery
Backup Battery

The PWRgate was configured to properly charge our 18AH AGM backup battery. Note the use of a fuse in series with the battery for safety reasons. We used a Powerwerx SPS-30DM adjustable power supply set to 14.5Vdc to operate our Go Kit and to provide the proper charging voltage for our AGM battery.

EMCOM Go Kit Operation

 

EMCOM Go Kt - Diamond X-30 Antenna and Mast
Diamond X-30 Antenna and Mast

The last piece of the setup was the antenna. We wanted something that was portable, easy to set up and would provide good performance. We choose a Diamond X-30A 2m/70cm ground plane antenna and mounted it on a 12′ fiberglass push up mast. The feed line is made from 25′ of LMR-400UF coax. Several bungee cords are used to attach the mast to a fence post or other vertical structure.

EMCOM - Finished Go Kit In Use
Finished Go Kit In Use

The picture above shows the completed Go Kit in operation. We typically set one side of the Kenwood TM-D710GA to operate as an APRS transceiver and Digipeater and the other side to operate on a local repeater or simplex FM. The SignaLink sound card is used with a laptop computer running Fldigi and NBEMS for messaging applications. The iPortable case has a 13.8V lighter socket which connects to a power brick to power our laptop PC.

EMCOM Go Kit Packaged for Transport
Go Kit Packaged for Transport

The Go Kit is quite portable when closed. All of the equipment and cable connections are enclosed and protected by the case’s removable end caps. We’ve tested our Go Kit during our club’s weekly repeater net and it worked great. The first real use of our new Go Kit will be at Field Day this year. It will be located in our public information tent and will be used as a “talk-in” system.

Fred, AB1OC