Building And Operating A Mobile HF Station

May 10, 2015 by AB1OC

Presentation On Building And Operating A Mobile HF Station

We recently had the chance to do a presentation on building and operating a mobile HF station for the Nashua Area Radio Club here in New Hampshire, USA. I thought it would be interesting for our readers to see this presentation as it contains some new information we have not previously covered on our Blog.

Mobile HF Antennas

Safety in mounting mobile antennas and anything else on the exterior of your vehicle is a primary concern. This was discussed in some detail during the presentation. The best source to understand safety considerations and proper installation and mounting of Mobile HF antennas is Alan Applegate’s excellent website, K0BG.com.

The most important part of any Amateur Radio Station is the antenna system. This is especially true in a Mobile HF Station because antennas in these applications are almost always short-loaded verticals. To create an effective antenna system for a Mobile HF application, one must pay extra attention to the “3 R’s” – Radiation Resistance, Loading Coil Loss, and Ground Loss. Radiation Resistance (a measure of the antenna’s ability to transfer transmitter power to radiated waves) is the “good R,” and the other two R’s dissipate power from our transmitter in the form of heat.

Mobile Antenna System Typical Parameters

There is some good information on the typical efficiency in the ARRL Antenna Book. As you can see from the table above, the Radiation Resistance of a mobile antenna becomes quite small on the lower bands (40m, 80m, and 160m). Also, as the antenna becomes increasingly shorter to RF on these bands, more loading coil inductance is needed to compensate for the short radiator length on these bands. Coil Loss and Ground Loss can easily dissipate most of our transmit power in a very inefficient antenna system on these bands. The net of all this is that one must carefully control the Ground and Coil losses while trying to make the Radiation Resistance of the antenna as high as possible. One good way to improve the Radiation Resistance of a mobile antenna is to make the whip longer. For more on mobile HF antenna efficiency, please consult K0BG.com.

Scorpion SA-680 Screwdriver Antenna With Rod And Cap Hat

Here in New England, we have many low tree branches that limit a mobile whip’s practical length. A good technique, if the installation permits it, is to use top loading in the form of a Capacitance Hat. The Cap Hat makes the antenna appear longer and thus increases the Radiation Resistance of the Rod below it. The increase in apparent electric length at Radio Frequencies also means less loading coil inductance will be required, which in turn also lowers the Coil Loss. This is a win-win. The only problem is that this setup significantly increases the wind load on the antenna when driving, so a mechanically strong antenna and mounting system are required for a safe installation. Ground Losses can be minimized by making the vehicle on which the antenna is installed a good RF surface to couple to the ground. This is best accomplished by properly bonding the metal surfaces on the vehicle to each other and the vehicle’s frame if there is one.

Mobile HF Equipment

The next part of the presentation covered the equipment selection for a Mobile HF Station. Safety and good usability are the paramount concerns here. I believe that a Transceiver should have the following attributes to be a good choice in Mobile HF applications:

It should have at least 100W output on the HF bands
It must have an effective Noise Blank and a good Noise Reduction system
It should have a removable control head to allow you to mount the radio’s controls and display where they can be easily seen without taking one’s eyes off the road.

It is extremely important to consider safety in all things mobile HF. Safe, non-distracting mounting of controls is a top concern. One also needs to consider what could happen in a crash. Loosely mounted parts or anything that can get between a deploying airbag and the vehicle’s passengers is among the important safety concerns. One should also consider accessories that facilitate safe mobile operation. Automated antenna controllers and a voice recorder to capture contact details for later transcription in logs are some good items to consider.

Bonding And Choking

I believe the bonding and the associated effect on noise levels and ground losses is perhaps the most important factor in determining the performance of a mobile HF station. “If you can’t hear them, you can’t work them.” Proper bonding of the exhaust system, body parts, and the engine’s ground are key items in this area. You can read more about how we did this here. To give some idea of how important this area is, I took the initial S9+ noise levels (with the radio’s preamp off) of my F-150 pickup truck before properly bonding to an S3-4 level with the radio’s preamp on. This is a huge improvement and is a primary reason for the DX performance of our mobile HF station. Bonding also lowers the Ground Losses of the installation, which improves the efficiency of the antenna system when transmitting as well – again, a win-win. Proper bonding is not expensive, but it does take some work. One must also be careful when drilling holes to install ground straps so that you do not accidentally drill into wiring harnesses, gas tanks, electronic boxes, and other vehicle systems. Again, consult K0BG.com for more information on properly bonding your vehicle. If you use a screwdriver antenna, you must also properly choke your control leads to keep RF out of your vehicle and its electronics. Here’s some good information explaining how to do this.

Stage 1 Mobile HF Station

I am a proponent of building a Mobile HF Station in stages, from a simple one using to perhaps a more involved project later on. This allows the operator to have a lot of fun on the air with a reasonable initial amount of work and expense. The approach also provides the opportunity to see how the various steps outlined in the presentation contribute to improved performance. Our stage one installation consisted of a 100W transceiver and Hamstick antennas. You can read more about our Stage 1 installation here. The focus at this step includes proper bonding/noise control, safe installation of a suitable transceiver and simple Hamstick antennas. This stage gives you an inexpensive and effective, one band at a time, station on the 20m and higher HF bands. This type of installation is not difficult to do as is possible on most vehicles.

Stage 2 Mobile HF Station

A Stage 2 installation would probably involve a multi-band remotely controlled antenna – typically a screwdriver antenna. You can read more about our Stage 2 installation here. It’s important to choose an efficient screwdriver antenna. You can read more about the choices and what to look for here. We used a Scorpion SA-680 Screwdriver Antenna and are very happy with it. This is a big antenna; you must carefully focus on a strong, secure mounting system to use it safely. Our Stage 2 station was QRV on all HF bands from 80m – 10m and utilized a screwdriver controller to automate the adjustment of the antenna when changing frequencies and bands. We also use a 4′ rod and a Cap Hat to improve the antenna system’s efficiency. This important safety feature should be strongly considered in any screwdriver antenna installation.

Stage 3 Mobile HF Station

A Stage 3 Station is probably not for most folks due to the added complexity and cost, but it does create a “work the world” Mobile HF Station and can open the door to effective operation on 160m from a Mobile Station. This step involves the installation of an Amplifier and may also include an extension of the antenna system to operate on 160m. I would have to say that the upgrade to Stage 3 was as much work in our station as Stages 1 and 2 combined. It also brings a new set of important safety considerations due to the high current DC powering required by a mobile amplifier. You can read more about this Stage of our installation here.

Mobile HF In A Car

Installing a Mobile HF station in a car is also quite feasible. The slide above shows Dave, N1RF’s installation of a Stage 2 setup in his Honda Accord. The antenna mount is a custom-made unit done by a local fabricator. Also, note the equipment mounting on the fold-down rear seat of the vehicle. This installation uses an Icom IC-7100 and has produced some great DX contacts, including one to the Philippines from New England on 20m using 100w.

Operating Mobile HF

Our presentation included some tips for operating a Mobile HF station. See the graphic above for details. I believe that even a well-executed Stage 1 station coupled with good operating technique and some patience can yield a DXCC in many parts of the US and Europe. I was able to make many contacts in Europe and some in Australia, New Zealand, Hawaii, and Alaska using our Stage One setup. If you progress through Stages 2 and 3, this gets easier. We have worked over 110 DXCCs from our Mobile HF Station and confirmed 100 in about 9 months with our Stage 3 setup. The Stage 3 setup has produced some of our most memorable QSOs to date, including my very first 75m phone contact ever to Japan and a contact with Ulleung Island, South Korea, on the 40m band using SSB phone (these contacts were made from the East Coast of the USA).

Fun With Mobile HF – US Counties Tour

There are lots of fun things that you can do with a well-built mobile HF station. I have worked many DX contacts from the mobile, for example, and some have netted as many as 75+ DXCCs in a weekend. County Hunting and Tours to activate rarer US Counties are another popular activity for Mobile HF operators. You can read about one such County Hunting tour here on our Blog.

We have found building and operating a Mobile HF station to be a lot of fun! It’s almost like beginning our Amateur Radio experience all over again.

– Fred, AB1OC/M

Mobile HF Installation – Part 4/4 (500W Amplifier, 160M and Accesories)

November 19, 2014 by AB1OC

Scorpion SA-680 Screwdriver Antenna Setup for 80m – 15m

This article will cover the completion of our Mobile HF project. Our installation is fairly complex, so we’ve broken the project into several phases:

Phase 1 – Install the Icom IC-7000 running barefoot with a simple MFJ HAMStick Antenna (to be replaced with the Scorpion Screwdriver Antenna in Phase 3)
Phase 2 – Properly bond all elements of my truck and deal with any noise issues
Phase 3 – Install the Scorpion Screwdriver Antenna and Controller
Phase 4 – Install a 500w Amplifier, 160m capability, and operating accessories (this article)

The first step in this part of our project was to add upgrades to our Scorpion SA-680 Screwdriver Antenna to enable it to be used on 160m.

Screwdriver Antenna Configured For 160m

Ron at Scorpion Antennas makes an add-on coil unit to enable his 80m – 10m antennas to work on 160m. The picture above shows the add-on coil installed along with a 3 ft rod and Cap Hat. The coil adds additional base loading inductance to enable the antenna to work on 160m.

Antenna Base With Shunt Coil Switching Unit

A different shunt coil is required to properly tune up the 160m configuration. Ron makes a very nice shunt coil switching unit (the grey box attached to the base of the antenna in the picture above) to allow multiple shunt coils to be used.

Antenna Shut Coil Switching Unit

The unit contains two shunt coils (one for 160m and one for 80m/40m) and a 12V relay. The relay switches in the appropriate shunt coil are under the control of a switch that I’ve added to our truck’s console. After properly adjusting both shunt coils, I was able to get a good match (SWR < 1.4:1) across the 160m, 80m, and 40m bands.

The next step in this phase of our project was the installation of a mobile HF amplifier and some accessories to make the operation of our mobile HF station easier. Alan Applegate (K0BG), author of the excellent K0BG.com website on mobile HF, points out that installing an amplifier in a mobile application is not a trivial project. One must pay a great deal of attention to the following areas:

Beefing up the vehicle’s electrical system to be able to supply adequate 13.8V power (a 500W mobile amplifier will require 60A – 80A of sustained current when transmitting at full output and may draw close to 100A on peaks).
Proper physical mounting and adequate cooling to dissipate the heat generated (a 500W amplifier will generate approximately 500W of heat when operating at full output)
Proper choking of antenna control leads to ensue that conducted RF does not get into your vehicle or electronics (this area was covered during the installation of our Screwdriver Antenna)
Drive/output power and SWR monitoring to ensure that the amplifier is not over-driven and is working into a properly tuned and matched load

I am going to cover each of these points as they were handled in our installation.

Secondary Battery And Fuses

It’s important that your vehicle’s alternator is capable of supplying enough current to operate the amplifier and the rest of your vehicle’s electrical system with overloading or major drops in voltage. Fortunately, our F-150 Truck came with a 150A alternator from the factory. The next problem to solve is to provide 100A+ of peak current during transmit without excessive voltage drop (you want to have no more than 0.5V of drop between your primary battery and the power terminals of your amplifier). The easiest way to achieve this in our application was to install a secondary battery in the bed of our truck. We choose an Optima Red-Top series battery for the secondary battery and as a replacement for our truck’s primary battery. The Red-Top series provides very high current for short periods of time (ex., engine cranking). This profile is ideal of supplying a mobile amplifier. Both batteries are connected in parallel with custom-made 2 ga cables for both +13.8V and ground. The batteries must be identical when connected this way to ensure that differences in operating voltage do not result in uneven charging. For safety reasons, It is also critical to properly fuse the connections between the batteries at both ends and in both the +13.8V and ground leads! We used high-current fuses (the insulated holders to the right of the battery in the picture above on both ends of the battery cabling. If either cable becomes shorted to the other or to ground, the fuses by the batteries will blow and prevent a fire. It’s also important to securely mount the batteries and associated cabling and properly protect the cables. We used insulated cable clamps and convoluted tubing to accomplish this.

Ameritron ALS-500M Amplifier And Radio Interface

The next step was to select a location for the amplifier that enabled good airflow around the unit and securely mount it to the truck’s floor. The spot we chose was under the flip-up rear seat of our truck. We used The mounting location at the corner of the seat, ensuring good airflow around the unit. We also made an aluminum plate that sits between the amplifier and the carpet in the truck to ensure that cool air can circulate under the amplifier without being blocked by the carpet. The Ameritron ALS-500M Amplifier we used comes with mounting brackets that allow it to be securely screwed to the floor of the truck so that it does not become a safety hazard during a quick stop, etc. We also installed an Ameritron ARI-500 Radio Interface Unit, which provides automatic amplifier band switching and a keying interface for our Icom IC-7000 Transceiver.

Amplifer And Accessories Under Rear Seat

Amplifier And Accessories Under The Rear Seat

The picture above shows the location of the amplifier under the rear seat. Note the clear path that the vents in the case have to the air which circulates within the vehicle. There are air conditioner vents behind the front seats in the center console, which can direct cool air on the amplifier during warm conditions.

Power Distribution, Antenna Controller And Wattmeter Sensors

The picture above shows the layout of our installation’s power and accessory electronics. Note the two high-current fuses protecting the power connections between the amplifier and the secondary battery. We also installed a RIGRunner 4005 Power Distribution Block to supply 13.8V fused power to all our accessories. Again, we used black convoluted tubing to protect all of the cabling and dress up the installation.

Wattmeter Sensors And Screwdriver Antenna Controller

The picture above shows the remote sensors (left) for the Elecraft W2 Wattmeter that we are using in our installation. A separate sensor is used on the input (200W range) and the output (2Kw range) side of the amplifier so that we can accurately set our drive power as well as monitor the amplifier’s output power and the SWR, which is being presented by our antenna.

The TuneMatic unit is an Automatic Screwdriver Antenna Controller. This unit senses the frequency of our radio and automatically adjusts our screwdriver antenna to provide a good match. It also has auto-tune capabilities and includes an amplifier key line interrupter relay to ensure that we do not transmit high power into the antenna while it is being tuned.

Control Layout On F-150 Console

All of the controls for the Amplifier, Screwdriver Antenna Controller, and Elecraft Wattmeter are mounted next to the driver on the F-150’s shifter console. We used heavy-duty Velcro strips to mount everything. The device in the right foreground is a Remote Control Unit for the Amplifier. The device in the left foreground is the control head for the TuneMatic Screwdriver Antenna Controller. Just behind the Screwdriver controller unit is a lighted 13.8V switch which we installed in the console to switch the shunt coil relay between the 160m and 80m/40m shunt coils. Finally, the unit in the background is the Elecraft W2 Wattmeter.

Antenna Controller, 160m Shunt Coil Switch, And Amplifier Remote Unit

The TuneMatic Antenna Controller will automatically adjust our screwdriver antenna with a simple touch to the Tune (TU) button when the radio frequency is changed. This unit can also be used to manually move the antenna up or down to fine-tune the match. There is also an auto-tune function which works well. An antenna controller such as the TuneMatic makes changing bands and frequencies much safer and easier to do and ensures one keeps an eye on the road.

The Ameritron ALS-500RC unit provides a switch to enable or reset the amplifier if it should trip and a remote current meter, which shows how much current the amplifier is drawing.

Elecraft W2 Wattmeter

The Elecraft W2 Wattmeter worked out well in our mobile HF application. One can easily select the input or output sensors, and its auto-ranging features provide accurate power and SWR readouts. It also has an LED brightness adjustment which is nice when operating at night.

Voltage Monitor

It’s important to be able to monitor your vehicle’s voltage when using an amplifier. The heavy current demands of an amplifier at full power output can cause significant voltage drops, especially if the vehicle is idling and other power accessories like de-icers or seat heaters are in use. I found a simple and inexpensive solution for voltage monitoring – a unit that plugs into the cigarette lighter jack in the vehicle. The unit has an easy-to-read display and does not draw much current, so it can be left plugged in when our truck is parked.

It took a little time to set up the TuneMatic Antenna Controller to quickly adjust the Scorpion Screwdriver antenna on all the bands from 160m – 10m. The instructions which come with the unit explain this process, and it is not difficult to do. The TuneMatic must be configured to work with your particular screwdriver antenna when it is first installed. This involves setting some option switches and adjusting a pot inside the TuneMatic unit. Again, the instructions cover the setup steps well.

Icom HM-151 Microphone

The Icom IC-7000 Transceiver is an excellent radio for mobile HF applications. Unfortunately, the quality of the transmitted audio with the “stock” Icom HM-151 microphone, which comes with the radio, is less than ideal. To solve this problem, I sent my HM-151 microphone to Bob Nagy (AB5N) for some upgrades. Bob performed several upgrades, including replacing the element with a higher quality unit, installing a heavy-duty PTT switch, weighting and vibration deadening the housing, and other mods. After adjusting the equalization in the IC-7000 to match the new element, we are getting some very nice reports on our audio quality from the stations that we are working while mobile.

You can click on the above video to hear what our mobile HF station sounded like in Europe during initial testing with the new amplifier and upgraded microphone. We were still adjusting the audio settings when the recording was made, but it will give you an idea of what the setup sounds like on the air.

There was a lot of integration and working with the folks at all the companies who supplied the components for our mobile HF project. Ron Douglas at Scorpion Antennas, Mike at Ameritron, Jim at TuneMatic, Bob Nagy (AB5N Microphone Upgrades), and the folks at DX Engineering were all very helpful in answering our questions and getting everything to work together.

Scorpion Whip Quick Disconnect

We are operating across a wide range of bands (160m – 10m), and I’ve found that it is best to use a range of “whips” on our screwdriver antenna to cover all the bands. The Scorpion Quick Disconnects make changing “whips” a snap. Our “go-to” configurations are as follows:

160m – We use the add-on 160m coil plus a 3 ft rod with a Cap Hat. The Cap Hat makes the rod appear electrically longer, improving overall efficiency on the Top Band. This combination allows the antenna to be tuned for all but the top 50 kHz (above 1.950 MHz) of the 160m band.
80m – 15m, including 30m and 17m – We use a 4 ft rod with a Cap Hat. This combination is very efficient, and our results on 80m have been particularly good. I am able to work DX from New England, USA, into Europe on 80m with 100W (amplifier off) using this combination. The 4 ft rod/Cap Hat combo is electrically too long to tune above the 15m band. The 3 ft rod/Cap Hat will tune up on the 12m band but not on the 10m band.
12m and 10m – We use a 6 ft whip for these bands.

We really like the combinations which utilize a Cap Hat. These setups are definitely more efficient than the 6 ft whip, and the overall height of the combination is low enough to stay out of the low tree branches here in New England, USA. The Cap Hat combinations allow less of the screwdriver antenna’s coil to be used. The coil is one of the largest sources of loss in a properly installed screwdriver antenna setup, which is why the Cap Hat/short rod combinations work so well.

It’s nice to have the extra power when operating from our truck, and I find that I can call CQ and sometimes generate a pileup while operating mobile! I’ve also been working quite a bit of DX from our mobile HF station (95 DXCCs worked so far), and the improved antenna and the added power have also helped in this area.

We hope you have enjoyed our series of articles on our Mobile HF project. We have learned a great deal doing the project, and we’ve made over 600 contacts from our truck along the way, with many more to come.

– Fred (AB1OC)

ARRL Centennial Convention This Week – Come Join Us In Hartford!

July 16, 2014 by AB1OC

ARRL Centennial

Anita (AB1QB) and I will be attending the ARRL Centennial Convention in Hartford Connecticut, USA this coming weekend. We are looking forward to seeing the vendor exhibits, Contest University and the many fine forum presentations which are scheduled.

Station Design Presentation

I will be doing a presentation on the design, construction and operation of our station at the ARRL Centennial event. My presentation is scheduled for Saturday, July 19th at 11 am in Room 27 at the Connecticut Convention Center. I will be presenting the complete story of our station from planning and design, through construction and finally how the station operates and performs. The presentation will include lots of high-resolution pictures and video including material on our shack, tower and antennas.

Updated Station Tour

The presentation will include lots of new material covering all of our recent projects as well as an updated virtual station tour.

Latest Antenna Projects

Some new topics will include our latest antenna projects and some information on our recently completed LEO Satellite System.

Station Automation Overview

The presentation will also include information on our recently installed Station Automation System from microHAM.

Current Station Performance

We plan to talk about how our station is performing against our original design goals and we’ll have some updated video too!

For those who are attending the ARRL Centennial Convention in Hartford Connecticut, I hope you stop by and say hello to Anita and me. We’re anxious to meet as many of our readers as we can at the event. For those who cannot make the trip, we will be taking lots of pictures and we plan to post a summary of what we saw here after the event.

– Fred (AB1OC)

Station Building Presentation At YCCC

April 7, 2014 by AB1OC

Yankee Clipper Contest Club Logo

Anita (AB1QB) and I are members of the Yankee Clipper Contest Club (YCCC) and we had the opportunity to give a presentation Station Design and Building at the YCCC Meeting this past weekend. The meeting also included two other excellent presentations:

“How to be a better single operator” by Randy Thompson, K5ZD
“Field Day from a Sailboat” by Chet Slabinski, N8RA

Our presentation was well received and the YCCC is a great group of contesters who are quite technically advanced in our hobby. We’ve updated our Station Building Series to include some of the latest information on these topics as well as the latest version of our presentation which may be found here.

– Fred (AB1OC)

Station Automation Part 2 – Second Operating Position And Antenna Switching

March 18, 2014 by AB1OC

microHAM Gear At Second Operating Position

microHAM Gear At Anita’s (AB1QB) Operating Position

We have continued our work on automating our station’s operation using microHAM equipment. I have integrated the second operating position into our station into the system via the installation of a second microHAM MK2R+ SO2R interface and two more Station Master Deluxe (SMD) antenna controllers. This position has a Yaesu FTdx5000 Transceiver and an Icom IC-7600 Transceiver. The integration of the FTdx5000 was straightforward and involved a cable hookup to the transceiver. I will add the Icom IC-7600 once the interface cable arrives here.

Current Antenna Control Stack

We’ve also begun to integrate the control of our antenna equipment into the microHAM system. I’ve moved our three SteppIR SDA100 controllers for our two SteppIR DB36 Yagis and our BigIR Vertical, as well as the two Green Heron RT-21 rotator controllers to a set of microHAM DATA control boxes (all of these devices have RS-232 interfaces). With these steps complete, any of our four radios can control the Rotators or provide frequency data to automatically tune our SteppIR antennas.

Antenna Switching Matrix

The biggest part of this project is the construction of a 4 x 10 antenna switching matrix. This element of the system allows any of our 4 radios to connect to any of up to 10 antennas. We built the Antenna Switching Matrix on a 4′ x 8′ board mounted on the wall outside our shack. As you can see from the picture above, this step required quite a few control cable connections as well as the construction of 40 coax interconnect cables (LMR400 Coax and crimp-on connectors were used here).

microHAM Ten Switch

Our Antenna Switching Matrix uses a set of microHAM Ten and 4+4 antenna switches along with multiple RELAY10 control boxes for control.

Antenna Switch Matrix SWR Test

It’s important to test an element like this as it is constructed to catch any errors and to ensure that the final system performance is as expected. I did a combination of continuity, voltage, and end-to-end SWR measurements on the Antenna Switching Matrix as it was built. The microHAM control boxes have a nice manual mode that is available via their front panel buttons which allowed me to configure each antenna switch manually to fully test all of the coax and control cabling in the system.

Receive Antenna Splitter And LNAs

Our antenna farm includes a steerable 8 Circle Vertical Receive Array for the low-bands, and we decided to create two separate appearances of this antenna on our switching matrix. This approach allows two different transceivers to use the receive antenna at the same time. This involves splitting the incoming signal from the receive antenna using a 2-port Splitter from DX Engineering. We also decided to include a pair of Low-Noise Amplifiers (LNAs) to boost the signals from the splitter before feeding the received signals to our antenna switching matrix. The Splitter and LNAs are 75-ohm devices. The signals are passed through a pair of 75-ohm to 50-ohm transformers from Wilson to match their 75-ohm impedance to our 50-ohm antenna switching system and feed lines. The SMD(s) control the LNAs, which have the associated receive antenna connection selected at any given time. This way, an operator can turn off the LNA at their SMD if they don’t need the extra amplification.

Antenna Matrix And Receive Antenna Control

All of this antenna switching requires quite a number of microHAM control boxes. We are also planning to terminate our 8 Circle Receive Antenna’s control lines at this point in our system. The receive antenna requires control leads to steer its direction and a sequencer capability to ensure it is not damaged by strong signals from other nearby transmit antennas. The microHAM system handles these functions easily via a combination of RELAY10 and RELAY6 control boxes, the units in the upper row in the picture above. These boxes also control the two receive LNAs.

With these steps done, we must complete the hookups of our Switchable Band Pass Filters and amplifiers to their associated SMDs. With that done, we can begin moving the feed lines for our antennas and radios over to the system. This will be the topic of our next article. For more information on our automation project, you might want to look at these articles:

– Fred, AB1OC

Station Automation Part 1 – microHAM SO2R And System Design

March 12, 2014 by AB1OC

One Of Two SO2R Operating Positions In Our Shack (AB1OC)

As some of our readers probably know, it has been part of our plan from the beginning to setup our station for multi-SO2R operation . We took the first step in this direction some time back with the installation of a microHAM MK2R+ SO2R Controller (the box one top of the left radio in the picture above) at one of our two operating positions. The MK2R+ is a full-featured and powerful SO2R controller. It provides many capabilities across the two radios at its operating position. Some of its capabilities include:

Sharing a single microphone, set of CW paddles, speakers and headset between two radios
A built-in sound card interface for both radios
Integrated voice and CW keyer capability
Dual-foot pedal control for keying each radio in the SO2R setup
Sharing of SteppIR antenna control between two radios

MK2R+ Audio Routing

One of the most powerful capabilities of the MK2R+ is its sophisticated audio routing capabilities which are configurable via microHAM’s USB Device Router. The picture above shows the audio routing configuration options for the MK2R+. The operator can do things like listen to a mix of 4 VFOs from two radios at the same time. Hear one radio’s audio in one ear and the other radio’s audio in the other ear. The routing of audio can be automatically changed based upon which radio is selected for transmit, foot pedal presses, etc. These capabilities are very useful when operating in an SO2R configuration during contests.

MK2R+ Control Ports

The microHAM USB Router software runs on the PC controlling the associated SO2R operating position/MK2R+ and provides a unified set of interfaces to both radios in the SO2R setup via a set of virtual COM ports. The picture above shows how this is configured for my operating position. In addition to a full set of ports to control each radio, there are common interfaces for the integrated WinKey CW Keyer and for controlling the MK2R+ itself. Loggers like N1MM know the microHAM control protocol and can automatically switch audio, sound cards, the radio which has focus for Tx, etc. based upon what the operator does inside N1MM. Again, this is very useful when operating SO2R or SO2V in a contest.

Current Antenna Control Stack

The MK2R+ alone works great for a shack with a single SO2R position but it leaves the operator to manually control antenna switching, rotators, and other antenna-related functions. Up to now, we have managed our antennas via the stack of antenna and rotator control boxes shown above. Manual operation of this type is fine for DX’ing or for one person operating alone in a contest.

Current Manual Antenna Switching System

The problem of switching and controlling antennas becomes more complex in a multi-operator station like ours (we have two separate SO2R positions in our shack with a total of 4 radios). We currently use the custom-built manual antenna switching system shown above to assign our available transmit antennas to one of our 4 radios and to select which antenna a given radio is connected to. We must manually handle control of antenna rotators as well as manually setting the operating frequency of our three SteppIR antennas when they are not connected to the first of our two SO2R operating positions. This sort of manual operation works OK for DX’ing and casual operating with one person in the shack at a time. It is highly error prone with two operators working at once so we decided to expand our microHAM system to fully automate the control of our antennas and associated equipment.

microHAM Station Master Deluxe Antenna Controller

We are using microHAM’s Station Master Deluxe (SMD) antenna controllers to automate the control of our antenna systems. We are installing an SMD with each of our 4 radios in the shack. The SMD provides a number of antenna control automation capabilities including:

Band and frequency specific selection and configuration of available antennas
Routing of frequency and other control data to our two SteppIR DB36 Yagis and our SteppIR BigIR Vertical based upon which radio has selected these antennas
Control and routing of our two rotators on our tower based upon the radio which has an associated antenna selected. For example, if one position selects our upper DB36 Yagi and another selects the lower DB36 Yagi on our tower, each SMD will independently control the rotator associated with its selected antenna. If one radio has both antennas selected as a stack, then that radio’s SMD will control both rotators together.
Sharing and control of our 8-Circle Directional Receive Array including creating a “virtual rotator” for it which allows its direction to be set via the SMD’s rotary encoder or via a COM port by an external rotator control program or logger. We have also created a “scan” feature for this antenna which switches its direction clockwise by 45 degrees every few seconds. This is useful when one hears a weak station and needs to determine where to point the receive array for best reception.
Automatic transmit/receive antenna switching for each of the four radios in the setup. For example, a radio can transmit on one antenna and receive on a different one. When the associated radio is keyed, the controlling SMD automatically switches the radio between the selected transmit and receive antennas.
Automatic control of the four Switchable Bandpass Filters associated with our radios. These are essential for operating multiple transmitters in the station on different bands at the same time.
Automatic control of our power amplifiers
Automatic same band lockout between the radios in our shack.
Enforcement and sequencing of antennas to avoid simultaneous Tx/Rx on closely spaced antennas from different radios.

SMD Rotator Control Ports

The Antenna Rotator management capabilities of the SMD are very useful for switching and sharing antennas on rotators. Each SMD has a pair of Virtual COM Ports which are automatically associated with the active rotator for the currently selected Transmit and Receive antennas. This allows loggers and other software running on the host PC to control the direction of the current selected antennas no matter which antennas are in use. The SMDs can also create a COM port for the “Virtual Rotator” from devices that are steered via switches such as transmit and receive vertical arrays. These devices behave just like they had a conventional rotator when they are selected and can be controlled by software running on the host PC via the Rotator COM Ports for the controlling SMD.

Our HF-6m Antennas

The first step in this upgrade was to layout a complete design for the RF and control elements of our station. The picture above shows the Antenna switching and control elements of our design. The tan boxes are switches and other RF elements such as Low-Noise pre-Amplifiers (LNAs) that are part of our antenna system. The grey boxes are microHAM control boxes which provide relay or serial data interfaces to shared equipment in our station.

microHAM Control Boxes And Hub

The microHAM control boxes are all part of a shared serial bus (microHAM’s uLink bus) that interconnects all of the control boxes to the four SMDs in our shack. The picture above shows the uLink Hub where the four SMDs connect to the uLink bus (lower right), the serial control boxes (uLink DATA – upper row) which control our SteppIR antennas and Green Heron Rotator Controllers, and several uLink Relay control boxes (uLink RELAY 10 & RELAY 6 – lower row on the left side) which provide relay closures to control antenna switches, stack controllers and other equipment.

SteppIR DB36 w/80m Dipole and Stack Switching Design

The microHAM SMD system is quite flexible and one can control just about any RF device or antenna system that you can dream up. We have two challenging configuration situations our station. The first is a SteppIR DB36 Yagi antenna with the 80m Rotatable Dipole Option installed parallel to the boom. The Rotatable Dipole uses the same SteppIR SDA100 Controller as the associated DB36 Yagi but must be pointed with a 90 degree offset when its selected. I was able to configure this easily using a virtual switch and antenna combination that made the Dipole appear as an independent antenna which shares the SDA100 controller with its associated DB36 Yagi.

The second configuration challenge was related to my custom Stack Switch and Phasing System. I built this element around the DX Engineering ProStack PS-2B Stack Switch and added a custom-built Feedline Breakout Switch to allow us to pull the lower SteppIR DB36 Yagi out of the stack so it can be used independently by a second radio. This allows one operator to use one of the two SteppIR Yagis on one band while the other operator uses the other one on a different band. Again, the flexibility of the microHAM SMD system allowed me to control the combination of the DXE Switch and the Custom Breakout Switch as a Single Two into Two Stack switch with Both Out of Phase (BOP) capability.

Automated Antenna Switching Matrix

The next stage of the antenna switching system is a 10 x 4 antenna RF switching matrix which allows any of 10 antennas to be connected to any of the four radios in our shack. This part of the design is being executed using microHAM’s Ten Switches and 4+4 Switches as shown above. The 4 SMDs in the system all have access to this antenna switching matrix via the uLink bus and the associated uLink RELAY 10 control boxes so they can connect antennas to their radios. This matrix also provides switching between independent transmit and receive antennas for the 4 radios in our shack.

Operating Position Design (AB1OC)

The final element of the design is the two SO2R operating positions. The picture above shows my operating position. As you can see, the MK2R+ provides the interface to the two radios and exchanges radio frequency, PTT, inhibit and other information with the two SMDs associated with each to the radios at this position. The SMDs provide direct control of the Band-Pass Filters (BPFs) and amplifiers for their associated radios. They both interface to the uLink bus via the uLink Hub so that they can control all of the antennas and switches which are shared across the station as well as coordinate the utilization of shared resources between the four radios in the setup.

The microHAM system has tremendous flexibility and my early work with it has gone well. There is a learning curve involved but microHAM’s documentation is excellent and Jozef, OM7ZZ and Joe, W4TV at microHAM have been great about answering my questions and helping me to configure my system. There is also a microHAM Yahoo! group which has been quite helpful. Many stations will not have the complexity to warrant the installation of a full microHAM system such as ours. For simpler stations, the microHAM Keyers, USB Interfaces or an MK2R or MK2R+ can provide simplified sharing and control of equipment across two radios.

As you can probably tell, the construction of the antenna automation portion of our station is a significant project. I will cover the rest of the project and more about the configuration of the system in a series of future posts. Right now I have our uLink bus built and all of the control boxes installed and configured. Two of our four SMDs are installed and operating. The planned next steps include adding a second MK2R+ and a second pair of SMDs to integrate Anita’s operating position into the system, building the antenna switching matrix and beginning to cut over some of our antennas to the new system. You can read the other articles our series on station automation here:

– Fred (AB1OC)

AB1OC & AB1QB Interview on HAM Nation

March 11, 2014 by AB1OC

Anita and I were recently contacted by Bob Heil, K9EID about an interview on the HAM Nation webcast series on our station. We have been fortunate to be able to spend some time with Bob and get to know him.

Bob Heil, K9EID

Bob has a very interesting background in Amateur Radio and Musical Performance. Bob is probably best known by the Amateur Radio community for his excellent line of microphones, headsets and other audio equipment. We used Bob’s HAM Radio Handbook as a resource in the design and construction of our station. Less known is Bob’s association with top name Rock and Roll performers like Joe Walsh, Peter Frampton and others. Bob is also an accomplished musician. Bob is a super guy and he spent a great deal of time with Anita and I getting to know us and helping us to prepare for our interview on HAM Nation.

Our interview is scheduled to be broadcast live on twit.tv this Wednesday evening March 12th at 9 pm Eastern, 8 pm Central, 6 pm Pacific time(this is 01:00 UTC on Thursday, March 13th). You can view the webcast live via the this link. The show will also be available for download here and on iTunes in the near future.

We really appreciate the opportunity to get to know Bob Heil and to be part of HAM Nation. We hope that our readers will check out the excellent HAM Nation podcast series.

– Fred (AB1OC) and Anita (AB1QB)

Amateur Radio For Young People At Sci-Tech

July 14, 2013 by AB1OC

Sci-Tech In Frisco, Texas USA

I recently learned of the Sci-Tech Discovery Center in Frisco, Texas USA. This fine facility is dedicated to helping young people to learn about Science and Technology and to hopefully encourage them to pursue Science and Technology learning and vocations. A group of local HAMs in Texas has teamed up with Sci-Tech to install and operate a very nice Amateur Radio Station at Sci-Tech. I recently met with Barry Goldblatt, WA5KXX to tour the station at Sci-Tech and to learn more about what Barry and his team are doing with the Boy Scouts and other youth groups to promote Amateur Radio among young people in the Dallas, Texas area. The following is Barry’s description of his work and progress at Sci-Tech. I think that you will find his article interesting and enjoyable. The Sci-Tech HAM team is currently working to raise funds to create a more private area for young operators to discover Amateur Radio at Sci-Tech and to further expand the station’s capabilities. A link to a website where you can make a donation to help with this expansion is included at the end of the article (I suggest that you note in the comments that the donation is being made to benefit the Amateur Radio Station if that is your desire). I believe that the work at Sci-Tech truly represents the Amateur Radio community at its best.

– Fred (AB1OC)

* * * * *

The McKinney Amateur Radio Club (MARC) and the Plano Amateur Radio Klub (PARK) teamed up over the past six months to install an HF-UHF station at the Sci-Tech Discovery Center in Frisco, TX. Sci-Tech is a science, technology, engineering, and mathematics (STEM) learning center for elementary and middle-school age students. The facility has hosted over 100,000 visitors in the past 12 months and provided outreach experiences for additional 165,000 students in Collin County schools. The teams completed the project on September 15, just in time for the station to be in operation for the Boy Scout Jamboree-on-the-Air (JOTA) on October 20-21.

The project began with a donation by David and Diana Brandenburg of the Brandenburg Life Foundation in February 2012. David, K5RA, has provided funding for amateur radio stations in schools and museums throughout the country including the Heard Museum in McKinney, Haggard Middle School in Plano and the Saint Paul School in Richardson. Additional funding for a WeatherBug commercial-grade weather station was provided by the Goldblatt Family Trust. The installation at Sci-Tech provides up-to-the-minute reporting of weather conditions on the Internet and is used by WFAA Channel 8, an ABC affiliate, as well as other news organizations that monitor weather in the north Texas area.

Tower Mount At Sci-Tech

The clubs went to work immediately on the antenna installation and station design. That was not an easy task. The Sci-Tech Discovery Center is located in a commercial tilt-wall structure with 50-foot walls. PARK President, Kip Moravec, AE5IB, designed an antenna mount that would clamp to the perimeter wall and allow the Rohn tower section to pivot down for easy servicing of the antennas, the rotor, and the weather station components. The mount was constructed using quarter-inch steel angle stock and weighed over 400 pounds. It took one full day to cut the steel and drill the necessary holes so the structure could be assembled and then powder-coated to protect it from rust and match the color of the building.

Once the antenna mount was complete, MARC President Walter Lemons, AE5IT SK, President of the McKinney club, along with Rusty Delaney, K5FEA, and other members of the team loaded it onto a flatbed trailer for transport. The team hauled the mount to the roof of the building and began the installation. It took two sessions the use of a 50 foot lift to position and secure the mount in place. The team then installed the Rohn tower sections and added a Force 12 C3SS 10, 15, 20-meter beam, a VHF-UHF vertical and the weather station components.

During these two sessions, other members of the team began drilling a three-inch hole in the building wall for the cable entry. Again, this was not an easy task, since the walls are eight-inch-thick concrete. The cabling run from the tower to the station measured 175 feet. Cabling included coax runs of LMR 400 for the HF-6 frequencies and LMR 600 for the VHF-UHF frequencies plus wire for the Yaesu antenna rotator, WeatherBug weather station and two runs of CAT-5 Ethernet cable. The CAT-5 cables are reserved for a future installation of HSMM equipment.

HAM Station At Sci-Tech

A second team that included Tony Campbell, W5ADC, completed the cabling and connected the radios for their first QSO on September 15. Rusty Delany, K5FEA, made the first VHF contact. Dan Howard, KE5CIR, and Michael Porter, KF5LDJ, from the Lake Area Amateur Radio Klub (LAARK) made the first HF contact with N1LS in Colorado on September 29 in preparation for the upcoming JOTA event.

This installation was extremely complicated and arduous because of the building structure and the fact that the teams were working during a hot Texas summer. The Brandenburg Life Foundation, the Goldblatt Family Trust and the Sci-Tech Discovery Center are extremely grateful to club presidents, Walter Lemons, AE5IT SK, and Kip Moravec, AE5IB, and the members of the McKinney and Plano radio clubs for their expertise and hard work. This installation would not have been possible without their help.

Sci-Tech Antenna System

In July 2013 Sci-Tech was provided with a much-needed expansion by the City of Frisco Community Development Commission (CDC) at their June 2013 meeting. The 3,800 square foot expansion will provide for more classroom and exhibit space. The expansion provides enough room so that the amateur radio station equipment can be moved to a permanent location. The new 60 square foot “shack” will feature sound-proofed walls and a glass door and viewing window. The enclosed space will allow Sci-Tech to expand its amateur radio programs and sets the stage for a special event station day later in 2013 or early 2014. There are plans to add more functionality to the installation including HSMM capability.

Sci-Tech currently opens the station to the public one day per month. Planning is underway to develop a radio exploration camp for young visitors during the summer of 2014. Ideas for other events include an all-night DX party and a Boy Scout One-Night Radio Merit Badge

More information is available about Sci-Tech by clicking here. Sci-Tech is a 501(c)(3) non-profit organization located in Frisco, TX that delivers innovative educational experiences for all ages in science, technology, engineering and math (STEM).

* * * * *

Author: Barry A. Goldblatt, WA5KXX

Amateur Radio Station Design And Construction

March 19, 2013 by AB1OC

Station Design And Construction

A little ways back, John (W1MBG) discovered our Blog and approached us about doing a presentation for the Nashua Area Radio Club (NARC) on the design, construction, and operation of our recently completed station. The NARC group invited us to their March meeting where we shared our presentation with the nice group of folks in the Club. I wanted to post an overview of what we shared as well as a link to the full presentation so that our readers can have a look at the material and hopefully benefit from the information that we have assembled. I have also used this post as an opportunity to create an index to all of the articles on this Blog related to the design, construction, and performance of our station.

Topics Covered

Our new station project involved both the construction of a dedicated room for a new shack and a tower-based antenna system. It took us about 1 1/2 years to build our station including the associated antenna system and we covered quite a number of areas during the project. Our presentation focused on some things that we did to plan and build our station that should be useful to many Hams building or upgrading anything from a simple station to an all-out effort to create a state of the art multi-op station.

Station Goals

I think that it’s important to begin a new or upgrade station project by thinking through and writing down the goals that you have for your new station prior to purchasing equipment or beginning construction. This step is important because it helps you to think through what you want to accomplish and serves as a high-level blueprint for making the design, equipment selection and construction decisions as you build your station.

Radio Shack Layout

We put considerable time and thought into the design of the room and operating area for our new shack including many rounds of drawings and some “human engineering” to arrive at the final room layout. While not every Ham will build a dedicated room for their shack, some careful thought put into the layout of the operating and storage areas for your shack and the associated support systems is an important design step.

Antenna System Planning

The other major element in the design of our station was a new tower-based antenna system. We had some pretty expansive goals for the band capabilities and associated performance of our new antenna system and the presentation explains how we went about developing and executing a plan to meet our goals.

Additional Antenna Construction

Since the initial installation of our tower antenna system, we added an 8-Circle Vertical Receive Array for the Low Bands and we’ve reinstalled our SteppIR BigIR Vertical Antenna. These new antenna systems provide important additional performance on the low bands and during contests. We’ve also added an Antenna System and Electronics for LEO Satellites.

Station Automation

We’ve also installed an SO2R and Station Automation System from microHAM. The microHAM system enables much smoother and less error-prone operation of our station and enables SO2R and Multi-two operation during contests.

Virtual Station Tour

Our presentation includes several slides that cover the construction of our new shack and tower as well as the feedline, antenna, power, and other supporting systems. The end result of all of this work is shown via a few slides that provide a “Virtual Tour” of our station.

Virtual Station Tour – Operational Videos

The “Virtual Station Tour” slides contain several videos. You can play these videos below.

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Other posts in this Blog contain more detailed information and many additional pictures and videos about our station. See the index of links at the end of this post to view more detail about the areas that interest you.

Station Performance

Our new station has been complete for several months now and we wanted to take some time to look at how it is performing against our original design goals. As you can see from the above slide, we are on a good track to meet or exceed all of the original goals that we set during the planning stage of our project.

What We Learned

Finally, we shared some additional information about what we learned during the project and a set of links to various sources of equipment and information that we used to complete our new station (see the full presentation). This Blog contains many more details (and pictures) about the design and construction of our station for those who are interested. Some good places to begin are categorized in the index of links below:

A Tour Of Our Shack

Shack Design and Construction:

Antenna and Tower Design:

Tower Construction:

Antenna Construction:

Tower Integration:

Station Integration:

Station Operation and Performance:

I hope that you can apply some of the ideas and information shared here to building or improving your station. We’d also like to extend a special thanks to John, W1MBG and the NARS Group for encouraging us to create and share this presentation. We are available to provide this presentation to other clubs or Ham gatherings. If your club or event is interested, please contact us at ab1oc@arrl.org.

Fred, AB1OC

Site of the Day – K9CT Contest Station

November 29, 2012 by AB1OC

One of our readers Craig, K9CT has built a very nice Contest Station. The above video is an overview of his station’s antenna farm – well worth watching! Craig also makes use of Stacked SteppIR antennas in his setup and his station features an 80m yagi as well as a 160m vertical array. I think many of our readers might enjoy taking a look at the K9CT contest station website. Check it out via K9CT Contest Station.

– Fred, AB1OC

Our HAM Station

Notes on the construction and operation of a multi-op Amateur Radio Station

Category Archives: Station Design

Building And Operating A Mobile HF Station

Mobile HF Installation – Part 4/4 (500W Amplifier, 160M and Accesories)

ARRL Centennial Convention This Week – Come Join Us In Hartford!

Station Building Presentation At YCCC

Station Automation Part 2 – Second Operating Position And Antenna Switching

Station Automation Part 1 – microHAM SO2R And System Design

AB1OC & AB1QB Interview on HAM Nation

Amateur Radio For Young People At Sci-Tech

Amateur Radio Station Design And Construction

Site of the Day – K9CT Contest Station

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