ERC-4 Interface & My HyGain Ham-IV Rotator Controller – Part 4

Calibration

Now it is time to calibrate your ERC.

Start by checking the calibration of your HyGain Ham-IV controller.

[ ] Press and hold the Brake lever on your controller.

[ ] Press and hold the CCW lever to move the rotator to the stop at the end of the left scale.

[ ] Release the Brake and CCW levers.

[ ] Check that the meter reads exactly 180 on the left hand side.

Full CCW
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ERC-4 Interface & My HyGain Ham-IV Rotator Controller – Part 3

Installation

My HyGain Ham-IV rotator was built in 2016. The control box has changed in its layout over the years. In the documentation from the CD, the picture of the Ham-IV shows that the meter board is installed vertically behind the meter. In my version, it is installed horizontally (parallel to the chassis surface) on the switch side of the cabinet.

Since this is where the ERC-4 was supposed to be installed, I had to find a new location. I chose to install it in the space under the transformer. There really didn’t seem to be many options, but this location worked out well. There is plenty of space between the transformer and the cover of the cabinet.

[ ] Choose a location to install the ERC-4 into the controller cabinet.

Mounting location for the ERC-4
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ERC-4 Interface & My HyGain Ham-IV Rotator Controller – Part 2

Checkout

[ ] Connect 11 – 15 vdc to the barrel power connector. The center contact is positive, the outside is negative.

[ ] Place the Jumper on JP1

[ ] Measure your input voltage (11 – 15vcc) at the +12V test point to ground

[ ] Measure +5vdc +/- 0.2v at the test point +5V to ground

[ ] If all is well, you may remove power from the board, and install IC1 & IC2 into their sockets. *** Pin 1 is top-left on both chips***

This usually requires the pins of the ICs to be straightened, as they tend to arrive bowed out too wide for the sockets. I just use a flat surface (my bench top) and lay one side of the IC against the surface at about a 45 degree angle, pressing gently to bend the legs in slightly. Then I repeat for the legs on the other side of the IC.

Be careful inserting the ICs, it is easy to miss a pin and bend it. That usually doesn’t end well.

5V & 12V Test Points, Jumper JP1 Installed
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ERC-4 Interface & My HyGain Ham-IV Rotator Controller

Having recently added a Flex Radio 6400 in my hamshack, I’m making progress on being able to operate the radio from my office in the house, while the radio is installed in my garage workshop. The radio makes remote operation very easy, with nearly all functions adjustable over the ethernet link.

The next step is to be able to turn my rotator from the computer in my office, while the rotator control box is located in the shop. In order to facilitate this operation, I purchased an ERC-4 rotator controller from Vibroplex. I have another one of these that I use with my balloon tracking station, and it has worked well with my Kenpro 5400 AZ/EL rotator.

ERC-4 Rotator Controller
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Building the W8NX Short Trap Dipole

For the past five years, I have been operating the lower bands (30, 40 and 80 meters) with a trap dipole that was modeled after a web article written by John DeGood NU3E. [1] While the antenna performed well, a monsoon storm last summer beat it up enough that the antenna wire broke at the center balun.

So I climbed the tower and lowered the remains of the antenna to the ground for repairs. On closer examination, I discovered that the relentless Arizona sun had taken its toll on the traps. The insulation on the exposed ends of the coax had rotted away. They were still working, but would need to be rebuilt and weatherized to insure good operation many years into the future.

Since I was going to have to rebuild the antenna, I started thinking about whether this antenna met my current needs and wishes. I had been wanting to get on 160 meters at this QTH for some time, but my small back yard would not accommodate an antenna of that size with conventional coaxial traps.

Some research led me to a QST article for a short 40, 80 and 160 meter trap dipole. [2][3] This design used double-wound traps made from only the inner conductor of RG-58 coax. The trap design was a little more complicated, but would almost fit into my back yard. I decided to pursue construction of this antenna, and bend the 160 meter end wire, if necessary to fit into the yard. A tradeoff of the loss of 30 meters for the addition of 160 meters fit my operating needs well.

In the construction of my prior trap dipole, I had used my MFJ-259B antenna analyzer to measure and adjust the traps and wire lengths. Since that time, I have acquired one of the new, cheap NanoVNA vector network analyzers[4][5]. It looked like the nanovna might make the job a little easier and present a clearer picture of the antenna characteristics. So I set off to construct my version of the W8NX short trapped dipole. Follow along for details and tips on how you might build this unique classic trap dipole for the lower bands.

W8NX Trap Dipole cut for Center Band
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