AB1QB Operating Position

The final article in our microHAM installation series will be about our station’s cut-over, configuration, and integration testing. The first step was to bring the second radio in Anita’s (AB1QB) position into the microHAM system. We also added a PR 781 microphone and boom from Heil Sound to her setup at the same time.

AB1QB Position Design

Anita’s second radio is an Icom IC-7610, and its integration into the system went very smoothly. We also integrated the control of our Power Amplifiers (a combination of Icom PW-1s and an Elecraft KPA500) into the microHAM system. As you can see from the diagram above, the amplifiers are dedicated to specific radios and can be controlled directly by each radio’s Station Master Deluxe (SMD). We used microHAM-supplied amplifier control cables for the PW-1, and I built a custom control cable for the Elecraft KPA500 (this was not difficult – both microHAM and Elecraft provide good documentation for the interfaces involved).

Bandpass Filter Control

I also built custom cables to allow our SMDs to control and automate the switching of our Bandpass Filter Units from Array Solutions.

Bandpass Filter Configuration

With the cabling done, I configured the SMDs to correctly set the control leads to switch the Amplifier and Bandpass filter bands based on the Transmit (Tx) frequency of the associated transceiver. The picture above shows the configuration for the bandpass filters. The configuration for the amplifiers is similar.

Control Box Configuration

The next step in the process was to add some microHAM Control Boxes to the uLink bus and configure their addresses. The picture above shows the control interfaces in our system, including the four SMDs. The addressing convention we use in our station has 40-series control boxes that control our 4×10 antenna switching matrix, 50-series control boxes that control our Tx antennas, and 60-series control boxes that control our Receive (Rx) antennas and associated equipment. The picture above also illustrates some of the Units we’ve defined on our Control Boxes to create interfaces to amplifiers, filters, antenna switching, and other controls.

Palstar Dummy Load

The first step in the cutover of our antennas was to connect the antennas and devices, which did not require complex control. This included our OCF Dipole and our Palstar High-Power Dummy Load. As each antenna was connected, the associated path was configured in the system and tested to ensure everything worked as expected.

Dummy Load Modification

I modified the Dummy Load to allow its lamp to be switched on when one of the radios in the shack selects it. This involved adding a couple of binding posts to the device and running the lamp bulb circuit through the binding posts. The posts are connected to a RELAY6 control box, and the microHAM system is configured to close the associated relay whenever a radio selects the Dummy Load. This makes it easy to see that the Dummy Load is selected and extends the life of the bulb.

Transmit Antenna Controls

The next step in the cutover process was to move all of our transmit antennas and rotators to the system one at a time and test them. This required constructing and testing some RS-232 serial cables to connect our three SteppIR Antennas and our Green Heron RT-21D Rotator Controllers to their associated DATA Control Boxes (top row in the picture above).

SteppIR DB36 Control

The picture above shows the configuration for one of our SteppIR Antennas – The Upper DB36 Yagi. This particular configuration step involved assigning the antenna to a DATA Control Box as well as telling the system the type of control protocol to use to control the antenna. The microHAM system “knows” about a wide array of serial and other controllable devices and implements the necessary protocols.

Receive Array Control And Sequencer

The integration of our 8-Circle Low-Band Receive Array involved some special steps at both the Hardware and Configuration levels. The connections on the RELAY10 control box above are used to “steer” the Rx array and enable or disable the shared Low-Noise pre-Amplifiers (LNAs). To protect this antenna from damage from nearby transmit antennas, power to the array must be removed a few milliseconds before transmission begins. This is normally done by a sequencer in a single radio station. Our station can have up to four radios transmitting on any of several different antennas on the low bands. To solve this problem, I used a RELAY6 control box to create a multi-radio sequencer. Each antenna that can transmit on the 160m – 60m bands has one of the relays on the RELAY6 shown above associated with it.

80m Delta Loop Sequencer

These relays are controlled via an optional SEQ control unit configured for each of the associated antennas. These relays are wired in series with the power lead for the 8-Circle Receive Array. Whenever any radio transmits on any band from 160m – 60m on one of the low-band Tx antennas, the associated relay is first opened (with appropriate delay) before Tx is enabled. This approach implements a multi-radio low-band sequencer across the four radios in our station. The control logic also powers down the array when it is not in use by any radio.

Virtual Rotator For 8-Circle Receive Array

The other “special” step involved in the integration of our 8-Circle Receive Array was the implementation of a “virtual rotator” for it. This involves creating a table in the system configuration which maps all possible headings to one of the eight available direction settings for this antenna. Once this is configured, the antenna behaves as if it had a conventional rotator associated with it. When it’s selected, loggers like the DXLab Suite and N1MM can automatically steer the antenna to the best possible direction selection to work a given station. The front panel rotator controls on the SMDs can also be used to turn the antenna just as if it had a “real” rotator.

Available Antenna Paths

With all of the antennas and other RF devices properly configured and interconnected in the configuration, the microHAM router software generates a list of available antenna paths, as shown above. The software automatically determines the path and associated control resource to connect a given antenna to a radio. Note that some of our antennas have multiple paths by which they can be reached. The software detects this and allows the alternative paths to be selected or, if configured as is the case with our 8-Circle Receive Array, be used by multiple radios at the same time. This table represents all of the possible antenna selections in our system.

Antenna Selection Configuration

The final step in the configuration process is to determine which antennas may be used by which radios on each of the available bands. The microHAM router software initially populates this table with all possible choices based on the “available antennas.” I edited the automatically generated configuration to remove a few choices which were not needed and to reorder the lists for each band so that the displays on the SMD would be the most logical for us to use. With these steps done, our configuration was complete.

Yagi Stack Control

The system is quite easy to use and provides easy-to-read and useful displays. The picture above shows the selection of our Stack of two SteppIR DB36 yagis on one of the radios. That radio (an Icom IC-7800) is currently on the 20m band tuned to 14.267 MHz for both transmit and receive. The two white squares show that both yagis are currently included in the stack. Options exist to use either antenna independently and to use them either in or out of phase in the stack. Both SteppIR DB36 antennas are pointed to 45 degrees (we can turn them independently), as can be determined from the numbers next to the white blocks and the direction of the arrow next to them. The row of buttons numbers 1 – 7 shows the available antenna selections for this radio on the 20m band.

80m Split Tx/Rx Antenna Selection

The picture above shows the SMD display for the same radio tuned to 3.658 MHz on the 80m band. Note that the antenna selections have changed to those available in our station for the 80m band. In this example, I am using different antennas for Tx (our 80m Delta Loop) and Rx (our 8-Circle Receive Array). The virtual rotator for the 8-Circle array is active, and you can see that this antenna is pointed toward 245 degrees (the virtual rotator input was 255 degrees, and the SMD picked the closed direction selection on the Rx antenna). Our 80m Delta Loop is vertically polarized and omnidirectional, which is indicated by the symbol next to it on the display.

Station Master Deluxe Keypad

In addition to the buttons and rotary controller on each of our SMDs, antennas can also be selected and steered via a keypad that is associated with each SMD. The keypads enable many functions, including direct entry of rotator headings, antenna selection, and setup for split Tx/Rx antenna operation.

MK2R+ Virtual COM Port Configuration

The microHAM platform (MK2R+ and SMDs) creates an interface to all our logging and control software on our PCs via a series of Virtual COM Ports. The ports for radio CAT interfaces, PTT and FSK (RTTY) keying, and control of the CW and Voice Keyers in the MK2R+ are created by the microHAM Router, as shown above. Each of the two radios at a given operating position has a unique set of ports for CAT and keying.

Station Master Deluxe Virtual COM Ports

In addition, the SMD associated with each radio creates additional virtual COM ports to allow software programs to control the rotator associated with the currently selected antenna(s) on that SMD. The control also includes any “virtual rotators” associated with antenna(s) that may be selected on a given SMD.

DXLab Radio Control

We use the DXLab Suite and the N1MM+ Logger at our station, which works well with the microHAM system. DXLab, including its Commander component (lower-right), is shown above, which provides the radio interface to the suite. If you look closely, you can see the Commander radio buttons, which select either of the two radios at this position. DXLab (and N1MM) know the microHAM control protocol and will automatically switch the associated MK2R+ to use the appropriate radio. This includes setting which radio is active to Tx, what audio is heard in the headphones/speakers, and what audio goes to the sound card for the associated MK2R+ and its radios. The appropriate routing of the shared microphone and CW paddles is also automatically configured.

DXLab and HRD Rotator Control

The picture above shows our rotator control software. We are using two programs here. In the upper left is DXLab’s DXView program, which will steer our antennas in the direction associated with the callsign currently entered into the logger. The other rotator controller is HRD Rotator (lower right) which displays a map of the world and a path. We can click on any location on HRD’s Rotator’s map, and the software will turn the currently selected antennas in that direction. The use of independent rotator control programs is made possible by the microHAM Router, which implements two separate Virtual COM Ports for the rotator(s) associated with each SMD’s selected antenna(s) for its associated radio.

As you can probably tell from the articles in this series, the microHAM system is very powerful and can handle most any station’s setup, including those which are much more complicated than ours. While the construction and configuration work described here may seem a little complex, it’s not that difficult to create a good plan for your system at the outset (see the first post in this series). The documentation for the microHAM system is very good, and Jozef (OM7ZZ) and Joe (W4TV) at microHAM were very good about answering my questions and steering me in the right direction as I built and configured my system. There is also a good Yahoo! group for the microHAM system. You may want to look at the other articles in this series for more information as well:

• Station Automation Part 1 – microHAM SO2R And System Design
• Station Automation Part 2 – Second Operating Position And Antenna Switching
• Station Automation Follow-On Project – Software-Defined Radio Integration

I had the opportunity to use our new microHAM System as part of the 2014 CQ WPX SSB Contest this weekend, which helped me improve my score. For more on this, check out the article on the contest on this Blog.

We are considering the addition of legal limit solid-state amplifiers and high-power bandpass filters to our station, which will be integrated into the microHAM system when installed. I am also experimenting with the addition of a software-defined radio to the setup. I plan to provide additional articles here as those projects proceed.

– Fred, AB1OC