Amatuer Radio Video How-To – Putting Up A Tower

July 2019 Tech Night – Putting Up A Tower

We recently did a how-to presentation on Putting Up A Tower at a Nashua Area Radio Society Tech Night. The video from this presentation can be viewed above.

Putting Up A Tower Video – Topics Covered

We covered a variety of information related to planning, building and integrating Guyed and House-Bracketed towers. You can view the accompanying presentation materials here.

The Nashua Area Radio Society produces similar how-to training materials on almost a monthly basis and we make these materials available to our Members an Internet Subscribers (folks that live too far from our location to be regular members) for a small cost which supports our new Ham development programs and covers the production and storage costs associated with the video material. Here’s a list of the training topics that we’ve produced to date:

2019 Tech Nights

  • Fox Hunting: Radio Direction Finding for Beginners including a Tape Measure Yagi Build by Jamey Finchum, AC1DC
  • Surface Mount Technology by Hamilton Stewart, K1HMS
  • RF Design with Smith Charts, Building a First HF Station, and Begining with CW – Hamilton Stewart, K1HMS; Anthony Rizzolo, KC1DXL; and Jerry Doty, K1OKD
  • All About Field Day 2019 by our Field Day Planning Team
  • Putting up a Tower by Fred Kemmerer, AB1OC

2018 Tech Nights

  • Operating Your Station Remotely by Fred Kemmerer, AB1OC
  • Transceiver Frequency Measurement and Calibration by George Allison, K1IG.
  • DMR Radios and Programming by Bill Barber, NE1B
  • WSJT-X: FT8, WSPR, MSK144 and More by Fred Kemmerer, AB1OC
  • Getting Started with Raspberry Pi Computers by Anita Kemmerer, AB1QB, Jamey Finchum, AC1DC,  Brian McCaffrey, W1BP, Fred Kemmerer, AB1OC, and Craig Bailey, N1SFT
  • All About Field Day 2018 by our Field Day Planning Team
  • Portable Operating Gear – demonstrations by Nashua Area Radio Society Members
  • K1EL Kits by Steve Elliott, K1EL
  • Antenna Modeling I by Scott Andersen, NE1RD.
  • Building and Operating a Mobile HF Station by Fred Kemmerer, AB1OC

2017 Tech Nights

  • High-Altitude Balloons: Amateur Radio at the Edge of Space and was presented by our HAB Team.
  • Getting On The Air 2.0 by Fred Kemmerer, AB1OC, and B. Scott Andersen, NE1RD
  • All About n1fd.org – Getting the most from our Website by Fred Kemmerer, AB1OC.
  • Digital Modes: RTTY, PSK, and WSJT-X by Mike Struzik AB1YKAnita Kemmerer AB1QB, and Fred Kemmerer, AB1OC
  • Bonding and Grounding by Jeff Millar, WA1HCO and Fred Kemmerer, AB1OC.
  • All About Field Day 2017  by Dave Merchant, K1DLM, and our Field Day Planning Team.
  • Building and Operating a Satellite Ground Station by Burns Fisher, W2BFJ and Fred Kemmerer, AB1OC.
  • DXing and QSLing by Anita Kemmerer, AB1QB; Bill Barber, NE1B; Fred Kemmerer, AB1OC; and Dick Powell, WK1J.
  • Weak Signal VHF and UHF Stations by Jeff Millar, WA1HCO and Bill Barber, NE1B.
  • Getting the Most from your HF Transceiver and More by Fred Kemmerer, AB1OC and Dave Michaels, N1RF.

2016 Tech Nights

  • Popular Loggers – Ham Radio Deluxe and DXLab Suite by Dave Merchant, K1DLM and Fred Kemmerer, AB1OC.
  • Low-Band Antennas by Dennis Marandos, K1LGQ; Hamilton Stewart, K1HMS; Brian McCaffrey, W1BP; and Fred Kemmerer, AB1OC.
  • RF Simulation and Matching by Jeff Millar, WA1HCO
  • Directional Antennas by Fred Kemmerer, AB1OC; Dave Michaels, N1RF; Brian Smigielski, AB1ZO; and Greg Fuller, W1TEN
  • All About Field Day 2016  by our Field Day Planning Team.
  • Surface Mount Soldering and Desoldering, a Hands-On Presentation by Jeff Millar, WA1HCO
  • Building Your First Station and Getting On The Air by Fred Kemmerer, AB1OC, and Dave Michaels N1RF
  • Software Defined Radios by Fred Kemmerer, AB1OC and Skip Youngberg, K1NKR
  • Advanced Repeaters (DMR, EchoLink, DMR, and D-STAR) by Anita Kemmerer; AB1QB, Fred Kemmerer, AB1OC; and Bill Barber, NE1B
  • Antenna Modeling with EZNEC by Fred Kemmerer, AB1OC

You can gain on-going access to the full library of Amateur Radio Training and How-To materials by supporting our work to bring new people and young people into the Amateur Radio Service as a Nashua Area Radio Society Internet Subscriber. You can learn more about how to become an Internet Subscriber here.

Fred, AB1OC

Satellite Station 4.0 Part 6 – Tower Finishing Touches

New Shack Entry and Ground Block

We recently completed the finishing touches on our new VHF/Satellite Tower. The first step was to install a second set of entry conduits into our shack and a new ground block for our satellite antennas. This involved installing 4″ PVC conduits into our shack. The new entries are very close to the base of our tower and this will allow us to keep our feedlines as short as possible.

Hardline Coax Cables Up The Tower

We also replaced the section of our feedlines which run down the tower with 7/8″ hardline coax. We installed a total of four runs for 6m, 2m, 70cm, and 23cm. The use of hardline coax will help reduce our feedline losses – especially on 70cm and 23cm.

Hardlines at Base of Tower

The new hardlines are connected one of the two entries into our shack. The 6m hardline enters on the side closes to our antenna switching matrix and the 2m, 70cm, and 23 cm hardlines will enter the shack via the newly created entry which will be close to our satellite transceiver.

The next step in our project will be to upgrade our Flex-6700 SDR based Remote Gateway for operation on the satellite bands. You can find other articles about our Satellite Station 4.0 project here:

Fred, AB1OC

Satellite Station 4.0 Part 4 – Tower Camera and J Mode Desensitization Filter

IP Camera View of New Tower

IP Camera View of New Tower

It is winter here in New England and it is not the best time of year to work outdoors. I have been able to complete a few finishing touches on our new Satellite and 6m Tower.

Installed IP Camera

Installed IP Camera

The first enhancement is the addition of an SV3C IP Camera. The camera allows us to see what is going on with our antennas. The camera has IR illumination so we can see our antennas when operating at night as well. The camera will also be useful for demonstrations when we operate our satellite station remotely in the future. This camera can use Power Over Ethernet (PoE) for power and is compatible with most popular security and webcasting software.

The video above is from our IP Camera while our antennas are tracking AO-7 during a high-elevation pass.

The second enhancement relates to VU Mode (or J Mode) satellites such as SO-50 and FO-29 which use a 2 m uplink and a 70 cm downlink. Satellite ground stations are prone to problems with 70cm downlink receiver desensitization when transmitting on a 2m uplink. The symptom of this problem is difficulty in hearing your own transmissions in your downlink receiver while being able to here other operators in the downlink just fine. Our antennas are separated enough here that we have only minor problems with J Mode desensitization at our station. Fortunately, this is not a difficult problem to take care of.

Comet CF-4160N Duplexer

Comet CF-4160N Duplexer

Installation of a good quality duplexer in the 70 cm path between the antenna and electronics such as our 70 cm preamp provides about 60 dB of additional isolation when operating in J Mode. The Comet CF-4160 Duplexer is a good choice for this application.

J Mode FIlter Installed In Preamp Box

Duplexer J Mode FIlter Installed In Preamp Box

We added one to the preamp box on our tower to create a J Mode desensitization filter. The duplexer is mounted on the left side of the 70 cm preamplifier which is on the right side in the image above. The 70 cm output of the duplexer connects to the feedline from our 70 cm antenna and the common output goes to the input of our 70 cm preamp. We also added a connector cap to the unused 2 m port on the duplexer to protect it from moisture. You can read more about this approach to J Mode desensitization filtering here.

The next stage of our project will be to add hardlines to our new tower and install a second entry to our shack near our new tower to bring our feedlines and control cables permanently into our shack. These projects will have to wait until spring. For now, we are enjoying operating our new antennas from a temporary station set up in our house. We also have a new IC-9700 Transceiver on the way and we should have it installed sometime during the next couple of months.

You can find other articles about our Satellite Station 4.0 project here:

Fred, AB1OC

First Winter Field Day For The Nashua Area Radio Society

AB1OC Operating at Winter Field Day

AB1OC Operating at Winter Field Day

Source: Our First Winter Field Day – The Nashua Area Radio Society

The Nashua Area Radio Society participated in Winter Field Day for the first time this past weekend. We put up a 40 ft tower and we were QRV on all allowed bands from 160m through 2m and 70cm. Our station was a four transmitter one and we produced a great score during the 24-hour operating period. Winter Field Day presents some unique challenges that we did not encounter during Summer Field Day.

We put together a station for 160m for the first time as well as some other new things. You can read all about our approach to a station and operating for Winter Field Day via the link above.

Fred, AB1OC

Satellite Station 4.0 Part 3 – Antenna Integration and Testing

Satellite Antennas Off The Tower

Satellite Antennas Off The Tower

Sometimes we learn from problems and mistakes. We all go through this from time to time. It is part of the learning aspect of Amateur Radio. My most recent experience came while integrating our new tower-based satellite antenna system. After the antennas were up, initial testing revealed the following problems:

After an initial attempt to correct these problems with the antennas on the tower, we decided to take them down again to resolve the problems. The removal was enabled, in part, via rental of a 50 ft boom lift.

The lift made it relatively easy to remove the Satellite Antenna Assembly from the tower. We placed it on the Glen Martin Roof Tower stand that was built for the Portable Satellite Station 3.0. Once down, the Satellite Antenna System was completely disassembled and a replacement Alfa-Spid Az/El rotator was installed.

Cross Boom Truss System

Cross Boom Truss System

The photo above shows the reassembled cross boom and associated truss supports. Note the tilt in the truss tube on the left side. This allows the antennas to be flipped over 180 degrees without the truss contacting the mast.

Reinforcement Bushing

Reinforcement Bushing

As mentioned in the previous article, polycarbonate reinforcement bushings are installed in the fiberglass parts to prevent the clamps from crushing the tubes. The photo above shows one of the bushings installed at the end of one of the truss tubes.

Bushing Pin

Bushing Pin

The bushings are held in place with small machine screws. This ensures that they remain in the correct locations inside the fiberglass tubes.

Thorough Ground Test

Thorough Ground Test

With the Satellite Antenna Array back together and aligned, we took a few days to operate the system on the ground. This allowed me to adequately test everything to ensure that the system was working correctly.

Tower Integration Using Lift

Tower Integration Using A 50 ft Boom Lift

With the testing complete, the antennas went back up on the tower, and the integration and testing work resumed. Having the boom lift available made the remaining integration work much easier.

Control Cable Interconnect Boxes

Control Cable Interconnect Boxes On The Tower

There are quite a few control cables associated with the equipment on our new tower including:

A combination of junction boxes near the top of the tower and at the base make connecting and testing of the control circuits easier and more reliable. Tower mounted junction boxes were used to terminate the control cables near the rotators and antennas.

Control Cable Junction Box at Base of Tower

Control Cable Junction Box at Base of Tower

A combination of heavy-duty and standard 8 conductor control cable from DX Engineering was used for the cable runs from the top of the tower to a second junction box at the tower base.

Control Cable Junction Box Internals

Control Cable Junction Box Internals

The junction box at the base creates a single interconnect and testing point for all of the control cables. We’ve used this approach on both of our towers, and it makes things very easy when troubleshooting problems or making upgrades. Control cables for all of the tower systems were run to the temporary station set up in our house and terminated with connectors that are compatible with our Portable Satellite Station 3.0 system.

Satellite Preamp System

Satellite Preamp System

We built a tower mounted Preamplifier System for use with the egg beater satellite antennas on our 100 ft tower a while back. The Preamp System is being reused on our new tower. A set of Advanced Receiver Research 2m and 70cm preamplifiers are mounted in a NEMA enclosure to protect them from the weather and to make connecting the associated control cables easier.

Tower Mounted Preamp System

Tower Mounted Preamp System

The Preamp System was mounted near the top of the new tower and the feedlines from the 2m and 70 cm Satellite Antennas were connected to it. LMR-400uF coax is run from the Preamp System as well as from the Directive Systems DSE2324LYRM 23 cm Satellite Yagi and the M2 6M7JHVHD 6 m Yagi on our new tower to the station in our house to complete the feedlines. These LMR-400uF feedlines will be replaced with 7/8″ hardline coax to our shack in the spring when warmer weather makes working with the hardlines easier.

Temporary Station Setup

Temporary Station Setup

With all of the tower integration work done, we set up the station in our house for testing. This is the same station that is our Portable Satellite Station 3.0 with two additions:

Both of these additions will become part of the final Satellite Station 4.0 when it is moved to a permanent home in our shack.

Rotator Controls

Rotator Controls

The rotator setup on the new tower provides two separate azimuth rotators. The lower one above turns both the 6 m Yagi and the Satellite Antenna Array together. The upper box controls the Alfa-Spid Az/El rotator for the satellite antennas. Using two separate rotators and controllers will allow us to integrate the 6m Yagi into the microHam system in our station and will allow the MacDoopler Satellite Tracking Software running on the iMac to control the Satellite Antennas separately. When we are using the 6 m Yagi, the Satellite Antennas will be parked pointing up to minimize any coupling with the 6 m Yagi. When we are using the Satellite Antennas, the rotator that turns the mast will be set to 0 degrees to ensure accurate azimuth pointing of the Satellite Antennas by the Alfa-Spid Az/El rotator.

PSK Reporter View using New 6 m Yagi

PSK Reporter View using the M2 6M7JHVHD 6 m Yagi

So how does it all perform? With WSJT-X setup on our iMac, I was able to do some testing with the new 6 m Yagi using FT8. The IC-9100 Transceiver that we are using can produce 100W with WSJT-X. The 6m band is usually not very open here in New England in January so I was quite pleased with the results. As you can see from the PSKReporter snapshot above, the new antenna got out quite well on 6 m using 100W. I made several contacts during this opening including one with W5LDA in Oklahoma – a 1,400 mi contact. The 6M7JHVHD is a much quieter antenna on the receive side which helps to make more difficult contacts on 6 m.

MacDoppler Tracking AO-91

MacDoppler Tracking AO-91

We’ve made a little over 100 satellite contacts using the new system so far. With the satellite antennas at 45 feet, it’s much easier to make low-angle contacts and we can often continue QSOs down to elevation angles of 5 degrees or less. I have not had much of a chance to test 23 cm operation with AO-92 but I have heard my signal solidly in AO-92’s downlink using the L-band uplink on the new tower. This is a good sign as our IC-9100 has only 10W out on 23 cm and we are using almost 100 ft of LMR-400uF coax to feed our 23 cm antenna.

Satellite Grids Worked and Confirmed

Satellite Grids Worked and Confirmed

I’ve managed to work 10 new grid squares via satellites using the new antenna system including DX contacts with satellite operators in France, Germany, the United Kingdom, Italy, Spain, and Northern Ireland using AO-07 and FO-29. These were all low-angle passes.

So what did we learn from all of this? Due to concern over possible snow here in New England, I did not take the time to fully ground test the satellite antennas and new rotator before it went up on the tower the first time. My thinking was that the setup was the same as that used on Portable Satellite Station 3.0 for over a year. The problem was the replacement parts and new control cables were not tested previously and both of these created problems that were not discovered until the antennas were at 45 feet. While it would have made increased the risk that the antennas would not have gotten up before the first winter snow storm here, it would have been much better to run the antennas on the ground for a few days as I did the second time. Had I done this, both problems would have appeared and have been easily corrected.

The next step in our project will be to add transverters to our FlexRadio-6700 SDR and integrate the new antennas into our shack. You can find other articles about our Satellite Station 4.0 project here:

Fred, AB1OC

Satellite Station 4.0 Part 2 – Antennas

Portable Satellite Station 3.0 Antennas

Portable Satellite Station 3.0 Antennas

Our current Satellite 3.0 Antennas have worked well in their portable configuration. We’ve had them to License Classes, Field Day, Ham Fests, and ultimately to Hudson Memorial School for the ISS Crew Contact there. As you can see from the photo above, the weight of the antennas causes the Fiberglass Cross Boom that we are using to sag and this is not a good situation for a permanent installation.

Cross Boom Truss Support Mock Up

Cross Boom Truss Support Mock-Up

I decided to work with Spencer Webb, W2SW who owns AntennaSys, Inc. and M2 Antenna Systems to create a stronger Cross Boom solution. M2 Antenna Systems came up with a set of brackets, fiberglass truss tubes, and a Phillystran Truss System to support the ends of their Fiberglass Cross Boom.

Spencer, W2SW Machining Parts

Spencer Webb, W2SW Machining Parts

The remaining problem to be solved was to reinforce the fiberglass tubes in the Cross Boom and Truss System to prevent the clamps which hold the antennas and other parts in place from crushing the fiberglass tubes. Spencer did an amazing job of making a new center section and polycarbonate reinforcing plugs to provide the needed reinforcements.

Cross Boom Reinforcement Parts

Fiberglass Tube Reinforcement Parts

Polycarbonate material was used to avoid adding metal inside the Cross Booms and Truss Tubes near the antennas. Using metal for these parts runs the risk of distorting the antenna’s patterns and causing SWR problems. It was also necessary to keep Truss System parts like eye bolts, turnbuckles, and clamps away from the tips of the antennas for the same reason. As you can see from the photo above, Spencer did an amazing job making the needed parts!

Checking Cross Boom Center Section Runout

Checking Cross Boom Center Section Run-out

The first step in rebuilding the Satellite Array was to install the new center section in our Alfa-Spid Az/El Rotator. I used a dial indicator to properly center the center section in the rotator. While this level of precision is probably not necessary, I had the tools available and it was easy to do.

Assembled Cross Boom Truss Support

Assembled Cross Boom Truss Support

The photo above shows one of the two completed Truss Supports. The trusses support the Cross Boom when it’s either pointing straight up or is flat at 0 degrees on the horizon. It’s important to adjust the horizon truss tube orientation to be slightly tilted to allow the antennas to operate in a “flipped over” configuration where the elevation points 180 instead of 0 degrees. This mode occurs in one of about every 5 to 10 satellite passes to avoid tracking problems with an otherwise south-facing dead spot in the azimuth rotator. Also, note the safety wire on the turnbuckles to keep them from turning after final adjustment.

Fiberglass Tube Reinforcing Bushings

Fiberglass Tube Reinforcing Bushings

You can see one of the polycarbonate reinforcing bushings at the end of the horizontal truss tube in the photo above. These are held in place with a small stainless steel set screw at the proper location in the fiberglass tubes. It’s also important to drill small drainage holes in all of the fiberglass pieces so that condensation and water seepage can drain out of the tubes. Without the drainage, water will accumulate, freeze, and break the tubes. I arranged these holes so that the tubes will drain when the antennas are parked in the vertical position.

Satellite Antenna Array Ready to Tram

Satellite Antenna Array Ready to Tram

With everything secured with a combination of tape and large cable ties, Matt of XX Towers rigged a suspension system and tram line to hoist the Satellite Array onto our tower. You can see how well-balanced the antenna system was prior to tramming.

Tramming The Satellite Antennas

Tramming The Satellite Antennas

The photo above shows the Satellite Array headed up the tram line. The tram line is anchored to a Gin Pole at the top of our tower and to a vehicle on the ground.

Satellite Antennas On The Mast

Satellite Antennas On The Mast

We removed the rotator and dropped the mast down into the tower to make it easier to get the satellite antennas in place on the top of the mast. Also, note the orientation of the Satellite Antennas – the elements are at 45 degrees to the Cross Boom. This arrangement helps to keep the metal in the ends of the Truss System from getting close to the antenna element tips.

Satellite Antennas Installed On Top Of Mast

Satellite Antennas Installed On Top Of Mast

Here’s a final photo of the Satellite Antennas with the mast pushed up and the lower rotator back in the tower. You can also see the rigging of the rotator loops for the Satellite Antennas and both the vertical and horizontal Cross Boom Truss supports in place.

M2 6M7JHV HD 6 Meter Yagi

M2 6M7JHV HD 6 Meter Yagi

The last step in this part of our project was to place the assembled M2 6M7JHV HD 6 Meter Yagi onto the mast. The 6M7JHV features 7 elements on a 36′ – 8″ boom. The antenna has about 13 dBi of gain and is optimized with a clean pattern to suppress noise from unwanted directions. The antenna was trammed up the tower with a light rope.

Completed Antenna Stack On New Tower

Completed Antenna Stack

The picture above shows the completed antenna installation including a second rotator loop around the 6m antenna. The system has two azimuth rotators – one the turns just the Satellite Antennas at the top and a second that turns all of the antennas on the mast together. Our plan is to set the lower rotator to 0 degrees when operating with satellites and use the upper Alfa-Spid Rotator for Azimuth and Elevation positioning. The lower rotator will be used to turn the 6m yagi with the Satellite Antennas parked.

The next step of our project will be to install all of the control cables, satellite receive preamplifiers, and feed lines on the tower and test our new antenna system with the rest of our Satellite Station. You can read about other parts of our project via the links below.

Fred, AB1OC

 

Satellite Station 4.0 Part 1 – New Tower

New Satellite and 6m Tower

New Satellite and 6m Tower

Our plans for Satellite Station 4.0 are based, in part, on the idea that we can extend our current remote operating environment to include Satellite Operations. Now that our ISS Crew Contact is complete, the antennas from the current Satellite Station 3.0 can be permanently installed at our QTH.

Tower Footing

Tower Footing

The first step in the project is to put up a second, 35′ house bracketed tower. Our new tower will also feature a new 6m yagi along with a permanent installation of our Satellite 3.0 Antennas. The first step in the project was to secure a building permit and prepare the footing for our new tower. Using Rohn’s specifications for the 45G Tower that we are using calls for the first section of the tower to be placed 4′ below ground in a concrete form. It’s important to place a foot or so of stone at the base of the footing and to ensure that the legs of the tower remain open so water can train. Failure to do this part of the preparation properly will result in water freezing in the Tower Legs which will split them open and ruin the tower.

Also, note the rebar reinforcing material in the hole around the tower and the bracing to keep the first section of the tower level and plumb. The folks at Form King did an excellent job in preparing and pouring the footing for our new tower.

Tower Base

Tower Base

The picture above shows the completed tower base. We’ve also installed a lightning ground on each of the three legs of the tower and the ground are bonded to each other and to the rest of our station’s ground system.

Tower Section on Gin Pole

Tower Section on Gin Pole

With the base complete, Andrew and Matt from XX Towers helped me to put the tower up. Here Andrew is using a Gin Pole to hoist a section of the 45G Tower into place.

House Bracket

House Bracket

With a few sections of the tower in place, it was time to install the house bracket. The bracket needs to be reinforced with blocking material on both sides of the wall. The blocking and the bracket are held to together with 10″ galvanized bolts.

Rotator and Mast

Rotator and Mast

We chose a 2″ x 25′ Chrome Molly Mast for our tower. We wanted to have about 10′ of mast above the top of the tower. Rather than cut the mast, we choose to keep the mast full length by setting our M2 Orion Rotator down a section and a half from the top of the tower. This is a good thing to do for several reasons. First, it makes the rotator easier to access for service. Also, the mast can twist a bit to absorb the torque on the rotator when the antennas start and stop moving.

The combination of the 25′ tower and the 10′ of mast above top will place our Satellite Antennas at a height of about 45′. This will provide additional clearance above the trees in our backyard for low angle satellite contacts.

The next step in our project will be to rebuild and reinforce the Satellite 3.0 Antenna Cross Boom and rotator system, build our new 6m yagi, and install the antennas on our new tower. You can read about other parts of our project via the links below.

Fred, AB1OC

An 80m Broadband Matching System

Our Tower with 75m Loop

Our Tower with 75m Loop

We installed a 75m loop for SSB operation on our tower when we built it. The loop is full size and is diamond shaped so that our lower SteppIR DB36 yagi can rotate inside of it. The loop is fed at the bottom corner about 20 ft up from the ground. It works great for SSB operation on 75m but we have often wished we could use it across the entire 80m band. This goal led to a project to create a matching system for the antenna. The idea was to use a set of loading coils in series at the feed point create a good match in all segments of the 80m band.

EZ-NEC Model for 75m Loop

EZ-NEC Model for 75m Loop

The first step in the design of our 80m matching system was to build a model of our current loop using EZ-NEC. The model was then used to determine the correct values of a set of series loading inductors to match different segments of the 80m band.

Matching System Design Analysis

Matching System Design Analysis

We also considered how likely different segments of the 80m band were to be used by profiling historical spotting data from DXSummit. All of this analysis led to the creation of a final design which is captured in the spreadsheet shown above. The final design requires our current 75m loop to be shortened a bit to work well at the very top of the 80m band.

Modeled Loading Coil Inductance Values

Modeled Loading Coil Inductance Values

A set of 5 different inductor pairs can be used in series with the loop’s feed point to create a good match across the entire 80m band. The modeled values for the series matching inductors is shown above.

Matching System Modeled SWR

Matching System Modeled SWR

Our microHAM control system can easily implement the switching of the various inductance values based upon the frequency that a radio using the antenna is tuned to. Result modeled SWR for the final 80m loop and match combination is shown above. The design should achieve an SWR < 1.5:1 across the entire 80m band except for the very top where the SWR remains < 2:1. Also, the design optimizes the system’s SWR in the important CW DX, SSB DX, and Digital windows on the 80m band.

Layout of Components in Enclosure

Layout of Components in Enclosure

With the design completed, we choose an enclosure and all of the components. Here are the details of what we used:

The first step in the construction was to layout all of the components in the enclosure. Attention was paid to keeping the two series inductors at right angles to avoid coupling and to keep RF connections as short as possible. The relays were arranged to keep the leads connecting to the coils of roughly equal length. Finally, the control circuitry was kept as far removed from the RF leads as possible.

Enclosure Mounting Ears and Clamps

Enclosure Mounting Ears and Clamps

The matching system attaches to a tower leg via saddle clamps. We fabricated a set of mounting ears and spacer blocks to position the enclosure far enough away from the tower so that the antenna connections do not interact with the tower.

80m Matching System Construction

80m Matching System Construction

A summary of the completed matching system construction is shown above.The design uses a set of four double-pole double-throw relays to switch in different coil taps which selects the loading inductance provided by the matching system.

We did a set of calculations and found that our relays would be subjected to a worst case peak-peak voltage of about 2.1 KVp-p at the coil tap points.

The relays are arranged such that two sets of contacts have to be traversed to select any given coil tap. The relays we are using have a third pole which we are not using. We disassembled each relay and removed the internal contact wiring for the center pole which improves both the coil to contact voltage rating and the isolation values of the relays.

These steps combine to improve the voltage rating of the system. This is an important design element given that the match will operate at legal limit power.

Completed RF Deck

Completed RF Deck

The completed RF deck and control circuitry is shown above. The enclosure we choose came with a removable plastic plate that made mounting and wiring all of the components simple.

Loading Coil Mounting and Taps

Loading Coil Mounting and Taps

The loading inductors are mounted using nylon hardware with the ends connected to the two antenna terminals on the sides of the enclosure. The coils use movable tap clips to allow us to fine-tune the match once the system is installed with the antenna on our tower. The initial clip locations are set to create the inductance values modeled during the design phase.

Relay Control Circuit Connections

Relay Control Circuit Connections

The relay control leads use twisted pair wiring to minimize RF pickup. The control leads are routed away from the RF connections to minimize potential RF coupling.

Relay Control Circuit Details

Relay Control Circuit Details

The control circuits for each relay use a combination of a Diode, a Varistor (MOV) and a filter capacitor in parallel to avoid relay coil switching interference and to suppress control line noise.

1.5 to 1 Matching Balun

1.5 to 1 Matching Balun

The matching system is designed to operate at 75-ohms which is pretty close to the resonant impedance of our 75m loop. The current antenna uses a 1.5:1 Balun to match the loop to our 50-ohm coax feedline. We disassembled an identical matching balun (actually a 75-ohm balun plus a 1.5:1 unun) and used it without its enclosure to create a final 50-ohm match.

MicroHAM Setup to Control 80m Matching System

MicroHAM Setup to Control 80m Matching System

The final step in the construction of our matching system was to program our microHAM antenna switching system to properly configure the relays in our matching system. This was quite simple to do using microHAM’s frequency dependent antenna control capabilities. The microHAM system automatically operates the appropriate relays to create the best possible match as the radio which is using the matching system is tuned across the 80m band.

Unfortunately, we are in the middle of winter here in New England so I will have to wait for warmer weather to install our new matching system on the tower and make the final adjustments. I am planning another article here when the final integration steps are done to cover the performance of the completed project.

Fred, AB1OC

Giving Back To Amateur Radio

Nashua Area Radio Club - 2016 Year In Review

Nashua Area Radio Club – 2016 Highlights

Anita, AB1QB and I have spent a good deal of time this past year helping the Nashua Area Radio Club here in Nashua, NH USA as a way to give back to the Amateur Radio Service. Our work with the Nashua ARC has produced some of the most enjoyable and memorable times of our Amateur Radio experience.

Teaching Nashua Area Radio Club Hosted License Classes

Teaching Nashua Area Radio Club Hosted License Classes

In particular, our contributions to the work that our club is doing around helping people to earn licenses and introducing young people to the Amateur Radio Service has been most rewarding.

Abby, KC1FFX Operating a GOTA Station During Nashua ARC Youth Day

Abby, KC1FFX Operating our GOTA Station during Nashua ARC Youth Day

We recently produced a 2016 Highlights video about our Club’s activities and the club’s contributions to the Amateur Radio hobby. We thought that some of our readers here might enjoy the video. You can view it on our club’s home page here.

73,

Fred, AB1OC

 

Fall Antenna Projects – A New Low-Band Receive Antenna System

NCC-1 Receive Antenna System Control Unit and Filters

NCC-1 Receive Antenna System Control Unit and Filters

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 Antenna 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 coax 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.

Receive RF 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 Cable Conduit In Our Yard

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 (The NCC-1 Control Unit Is At The Bottom)

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.

microHAM 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.

microHam Antenna System Diagram

Updated microHam Antenna System Diagram

With all of the coax and control connections complete, I was able to update the microHam system design information for our station and add the new receive antenna system to our setup. You can find more about the programming of our microHam system here.

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 nulling 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 Null'ed 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.

NCC-1 Used For Noise Cancellation

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 (Bottom Two Gray Boxes)

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 One Of The Interconnect Enclosures

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