EME Station 2.0 Part 5 – Control Cables and Rotator Controller

Control Cable Junction Box on EME Tower

Control Cable Junction Box on EME Tower

Snow is coming to New England this weekend so we wanted to get the control cables run to our new EME Tower before the ground is covered with snow. The project involved installing a Utility Enclosure on our tower and running three control cables to our shack for the following devices:

Az-El Rotor and Preamp Switching Control Connections

Az-El Rotator and Preamp Switching Control Connections

We began by install some barrier strips and a copper ground strap in the Utility Enclosure. The copper strap provides a good ground connection to the tower and associated grounding system. The enclosure is clamped to the tower using two stainless steel clamps.

We ran three new control cables through the conduits that we installed between the tower and our shack and terminated them in the utility enclosure. We only needed 6 leads for control of the planned MAP65 Switching and Preamp System which will go on our tower later so we doubled up some of the higher current connections using two wires in the 8-conductor cable.

Green Heron RT-21 Az-El Rotator Controller

Green Heron RT-21 Az-El Rotator Controller

The final step was to hook up our rotator cables to a Green Heron RT-21 Az/El Rotator Controller in our shack.  We do not yet have our elevation rotator so we tested the M2 Orion 2800 Azimuth Rotator that is installed in our tower. The azimuth rotator is configured so that the rotator’s dead spot faces north. This is a good configuration of our planned EME operation.

With all of our control cabling in place, we are ready to begin preparing our Antennas, Elevation Rotator, H-Frame, and MAP65 components to go on our EME Tower. We’re hoping that the weather will cooperate and enable us to get these steps completed during this winter.

Here are some links to other articles in our series about our EME Station 2.0 project:

Fred, AB1OC

EME Station 2.0 Part 4 – New EME Tower Is Complete

Three Tower Antenna Farm

New EME Tower in Our Antenna Farm

Our goal for this phase of our EME Station Project is to get our new tower up, install the Azimuth Rotator and Mast, and run the hardline and coax cables for our antennas from the shack to our new tower. Our EME tower is constructed using Rohn 55G tower sections. It will be 26 ft tall and will have approximately 18″ of our 3″ mast protruding above the tower. The tower is a free-standing/guyed hybrid design with the first section being cemented into the ground.

EME Tower

FInished Tower Base

The base section and the three guy anchor blocks were completed a little while back. The holes were backfilled and we’ve given the cement a couple of weeks to cure.

First Tower Section Installed Using a Gin Pole

First Tower Section Installed Using a Gin Pole

Matt, KC1XX, and Andrew of XX Towers began by installing a winch and a gin pole on the base section of the tower. They used the Gin Pole to hoist the second tower section into place and secure it. They also attached the top plate to the third tower section in preparation for installing it along with our mast.

Mast and Top Tower Section Going Up

Mast and Top Tower Section Going Up

It is always a challenge to install a mast inside a new tower. The mast we are using is a heavy, 22 ft 4130 chrome molly steel mast that weighs over 250 lbs. Getting the mast inside the tower was quite a feat! Matt and Andrew rigged the top tower section and the mast together and pulled both up together on the Gin Pole. Next, one leg of the top tower section was attached and a second pully was used to pull the mast up through the top tower section until it could be placed inside the tower. The last step was to raise the top tower section a second time using the Gin Pole to seat it on top of the rest of the tower. Finally, the mast was lowered inside the tower to the base and the top tower section was bolted on to complete the tower.

Upper Guy Anchor Bracket on Tower

Upper Guy Anchor Bracket on Tower

The next step involved attaching the upper guy anchor bracket to the top section of the tower and rigging the guy anchor cables. We decided to use Phillystran Guy Cable to avoid interactions with our antennas.

Guy Anchor Cable

Guy Anchor Cable

The completed cables are tensioned using turnbuckles. We adjusted the cables to plumb the tower and then safety-wired the turnbuckles so they will not come loose.

Azimuth Rototor in Tower

Azimuth Rotator in Tower

The next step was to install an M2 Antenna Systems Orion 2800G2 Azimuth Rotator in our tower. The use of the 22 ft mast allowed us to place the rotator about 5 ft above the ground where we can easily service it in the future. The long mast also acts as a torque shock absorber when the rotator starts or stops moving suddenly. With the rotator in place, we attached the mast and clamped it at the rotator and thrust bearing at the top of the tower.

Tower Base, Coax Feedlines, and Guy Anchors

Tower Base, Coax Feedlines, and Guy Anchors

The last step in our project was to install our coax cables and hardlines on the tower and run them through a 4″ underground conduit to our shack. We pre-made the two LMR-600 coax cables for the receive side of our EME Antenna System previously. We cut a section of LDF5-50A 7/8″ Hardline to approximately the same length as the LMR-600 coax cables.

Pushing Coax Cables and Hardline Through the Condui

Pushing Coax Cables and Hardline Through the Conduit

We used a cutoff plastic bottle to protect the ends of the coax cables and hardline as we pushed them through approximately 50 ft of buried 4″ conduit. The conduits were constructed to create a gradual turn into and out of the ground and the cables went into the conduit smoothly.

Coax Cables Exiting the Conduit Near Our Shack

Coax Cables Exiting the Conduit Near Our Shack

With the cables in place, we installed N-female connectors on each end of the 7/8″ hardline. We used rubber reducers to make it easier to deter water from entering the conduits where the cables exit.

Coax Cable Ground Block Connections

Coax Cable Ground Block Connections

We expanded out main shack entry ground block using an 18 position tinned cover ground bar from Storm Copper to make room for additional static arrestors for our EME Antenna System. The LMR-600 receive-side coax cables and the 7/8″ hardline connection for the transmit-side of our EME antennas terminate on N-connector Static Arrestors from Alpha Delta.

Completed EME Tower

Completed EME Tower

Our new EME tower is complete and ready to accept the Elevation Rotator, H-Frame, and Antennas from M2 Antenna Systems when they arrive. We plan to complete the grounding system and get the Azimuth Rotator hooked up and tested with our Green Heron Engineering RT-21 Az/El Rotator Controller in the near future.

Here are some links to other articles in our series about our EME Station 2.0 project:

Fred, AB1OC

EME Station 2.0 Part 2 – Excavation, Footings, and Conduits for New Tower

EME Tower

FInished Tower Base and Cable Conduits

The first part of our EME project is to put up a new tower to support our antennas. Our plans call for a 26′ tower built using three Rohn 55G tower sections. Four feet of the first section of the tower is cemented in a concrete footing to anchor the tower’s base. The tower is also going to be guyed to ensure that it is very stable.

EME Tower

Digging Footings for our New Tower

We are working with Matt Strelow, KC1XX and Andrew Toth of XX Towers to put up our new tower. Matt brought out his tractor and dug the footings for our tower and for the associated conduits that will carry coax and control cables to our shack. The photo above shows the completed hole and form for the main tower base. Matt is working on the footings for one of the three guy anchors.

EME Tower

First Tower Section and Rebar Cage

Here’s a closer look at the tower base. The footing includes a rebar cage to reinforce the concrete footing. There is also 6″ of crushed stone in the bottom of the hole that the tower legs sit it. It is very important that the bottoms of the tower legs remain open and do not become plugged with cement so that water in the legs can drain. If the legs cannot drain properly, water will accumulate and freeze. This can split open the tower legs and ruin the tower.

EME Tower

Cable Conduits with Drains

We also installed two conduits (a 4″ and a 2″ run of schedule 80 conduits) from the base of our tower to our shack. These conduits will carry coax feed lines and control cables to our new tower. We used a pair of 22° elbows to create a smooth transition to bring the conduits out of the ground. This will ensure that our hardline and other coax cables can be placed in the conduits without creating excessive bends.

Conduits will fill with water even if they are sealed. This happens as a result of the condensation of water in the air. To prevent our conduits from filling with water, we created two drain pits at the bottom of the trench at the two lowest spots in the conduit runs and filled them with stone. We drilled a few holes in the bottom of the conduits above the drain pits to allow the water to drain so our cables will remain dry.

EME Tower

Cadweld’ed Ground Cable Bonded to a Ground Rod

We also created a bonding ground cable run from our new tower to the ground system at our shack entry. The bonding system was created by driving an 8′ ground rod every 10′ in the trench between our new tower and the perimeter ground around our house.

#2 stranded copper ground cable was Cadweld’ed to each ground rod to create a ground path to bond the tower to the perimeter grounding system around our house. Using a Cadweld system is simple and produces strong connections that will not deteriorate.

Here’s a video that shows our a Cadweld is made. We’ll cover completing the ground connections to the tower and the perimeter grounding system in a future article.

EME Tower

Completed Footings – Ready to Pour Cement

Finally, we used some sections of rebar to firmly support the guy anchor rods prior to pouring the cement. If you look closely, you can see a portion of the rebar material in one of the guy anchor footings in the photo above.

EME Tower

Cement Mixer

The next step in this part of our project was to pour the cement. A large cement mixer brought the proper cement mix to our QTH and Matt used his tractor to transport the cement from the mixer to the forms. We did a bit of finishing work on the cement base for our tower and let the cement dry for a few days.

EME Tower

FInished Tower Base and Cable Conduits

The last step was to remove the forms and backfill the footings. A little work with a cement finishing block was done on the cement base to round off the rough edges left by the forms. The cable conduits emerge from the ground next to the tower base. You can also see one end of the copper bonding cable next to the conduits as well.

EME Tower

Completed Guy Anchor

Here’s one of the completed guy anchor rods after backfilling. We are going to let the cement harden for a couple of weeks and then we’ll complete the construction of our new tower.

Here are some links to other articles in our series about our EME Station 2.0 project:

Fred, AB1OC

EME Station 2.0 Part 1 – Goals and Station Design

The Moon

The Moon

EME or Earth-Moon-Earth contacts involve bouncing signals off the moon to make contacts. EME provides a means to make DX contacts using the VHF and higher bands. There are also some EME Contests including the ARRL EME Contest that provides opportunities to make EME contacts.

We made some 2m EME contacts a while ago using the 2m antenna on our tower at about 112′. This experience created interest on my part in building a more capable EME station at some point in time. Well, the time has finally arrived.

EME Propagation

Understanding EME Propagation is a project in of itself. The following is a brief overview of some of the (mostly negative) effects involved.

The path loss for EME contacts varies by Band and is in excess of 250 dB on the 2m band. There are some significant “propagation” effects that further impair our ability to make EME contacts. These include:

  • Faraday Rotation – an effect which results in the polarity of signals being rotated by differing amounts as they pass through the ionosphere on their way to the moon and back
  • Libration Fading – fading caused by the adding of the multiple wave-fronts that are reflected by the uneven surface of the moon
  • Path loss variations as the earth to moon distance varies – the moon’s orbit around the earth is somewhat elliptical in shape resulting in a distance variation of approximately 50,000 km during the moon’s monthly orbital cycle. This equates to about a 2 dB variation in total path loss. An average figure for the path loss for 2m EME might be in the range of 252 dB.
  • Transit Delays – at the speed of light, it takes between 2.4 and 2.7 seconds for our signals to travel from earth to the moon and back.
  • Noise – the signals returning from the moon are extremely weak and must compete with natural (and man-made) noise sources. The sun and the noise from other stars in our galaxy are significant factors for EME communications on the 2m band.
  • Doppler shifts – as the earth rotates, the total length of the path to the moon and back is constantly changing and this results in some frequency shift due to doppler effects. Doppler shift changes fairly slowly compared to the time it takes to complete a 2m EME QSO so it is not a major factor for the 2m band.
  • Moon’s size vs. Antenna Aperture – the moon is a small target (about 0.5 degrees) compared to the radiation pattern of most 2m antenna systems. This means that most of our transmitted power passes by the moon and continues into space.

Taking the moon’s size, an average orbital distance, and an average Libration Fading level into account, one can expect only about 6.5 % of the power that is directed towards the moon to be reflected back towards earth.

EME “Good Guys”

One might look at the challenges associated with making EME contacts and say “why bother”? EME contacts present one of the most challenging and technical forms of Amateur Radio communications. It is this challenge the fascinates most EME’ers including this one. Fortunately, there are some “good-guy” effects that help to put EME communications within reach of most Amateur Radio stations. These include:

  • WSJT-X and the JT65 Digital Protocol – In the early days of EME communications, one had to rely on CW mode to make contacts. All of the impairments outlined above made these contacts very challenging and the antennas and power levels required put EME communications out of the reach of most Amateurs. Along came Joe Taylor’s digital JT65 protocol which changed all of this. It is now possible to make 2m EME contacts with a single (albeit large) 2m yagi and 200W or so of input power. As a result of these innovations, many more Amateurs have built EME stations and are active on the 2m (and other) bands. Many DXpeditions are now also including EME communications in their operations.
  • Ground Gain Effects – a horizontally polarized antenna system will experience approximately 6 dB of additional gain when the antenna(s) are pointed approximately parallel to the ground. Ground gain effects made it possible for us to use our single 2m antenna to make our first 2m EME contacts.
  • MAP65 Adaptive Polarization – Fading resulting from polarity changes due to Faraday Rotation can cause a received signal to fade to nothing over the period of time needed to complete a 2m EME contact. These polarity “lock-out” effects can make contacts take a significant amount of time to complete. Fortunately, a version of the software which implements the JT65 protocol called MAP65 has been created that will automatically detect and adapt to the actual polarity of signals returning from the moon. More on how this is achieved follows below. MAP65 is most useful for making “random” EME contacts during contests. In these situations, a variety of signals will be present in a given band with different polarities and the MAP65 software can adapt to each one’s polarity and decode as many simultaneous signals as possible.
  • Commercially Available Amplifiers for the VHF+ Bands – Modern, solid-state amplifiers have become much for available for the 2m band (and other VHF and higher bands). This has made single-antenna EME on 2m and above much more practical for smaller stations with a single antenna or a small antenna array.

Our 2m EME Goals and Station Design

We began this project by making a list of goals for our 2m EME Station 2.0. Here is that list:

  • Operation using JT65 and QRA64 digital protocols and possibly CW on the 2m EME band
  • 80th percentile or better station (i.e. we want to be able to work 80% of the JT65 capable 2m EME stations out there)
  • Operation in EME contests and EME DX’ing; earn a 2m EME DXCC

We have come up with the following station design parameters to meet these goals:

  • An array of four cross-polarized antennas with an aggregate gain of approximately 23 dBi
  • A new 26′ Rohn 55G tower to support the antennas
  • A computer-controlled Azimuth/Elevation rotator system to allow us to track the moon
  • Input power in the range of 900W
  • A MAP65 capable SDR-based receive system which can support adaptive polarity
  • Low-noise, high gain preamplifiers located at the antennas
  • A low-loss feedline system for both the transmit and receive sides of the system
  • Use of both the MAP65 and standard versions for WSJT-X for digital operations
  • Use of Linrad as a front-end to the receive side of our system
  • Our existing Icom IC-9100 Transceiver and M2 1K2 2m Power Amplifier for transmitting

Antennas

WA1NZP Antenna System (4 M2 XP32 X-Polarity Antenna Array)

WA1NPZ Antenna System (4 M2 Antennas XP32 X-Polarity Antenna Array)

It takes some fairly large antennas to create an 80th percentile EME station. We are planning a setup similar to Bob, WA1NPZ’s system shown above. We are going to put up a 26′ Rohn 55G tower for our EME antenna system. We will be using four M2 Antenna System XP28 Antennas mounted on an H-frame to create a 15′ x 15′ square array.

The combined gain of the system will be approximately 23 dBi with a 3 dB beamwidth of 12.5°. The XP28 antennas are designed for stacking and have good Gain/Temperature (G/T) characteristics. G/T is a measure of the gain and noise performance of an antenna system. See VE7BQH’s tables for some interesting data on G/T for many commercially available EME and VHF+ antennas.

The antenna system will have separate feeds for the antenna array’s Horizontal (H) and Vertical (V) planes. The Horizontal elements will be oriented parallel to the ground to maximize ground gain when the H plane is used for transmitting (and receive). A pair of 4-port power combiners will be used to combine the H and V polarities of the four antennas into a pair of H and V feedline connections.

Plans call for a combination of the M2 Orion 2800G2 and MT3000A rotators to be used along with a Green Heron RT-21 Az/El Rotator Controller to provide computer-controlled tracking of the moon. A 22′ section of 3″ Chrome Molly mast material will allow the azimuth rotator to be located near the base of the tower where it can be easily serviced.

Tower Mounted Preamps and Polarity Switching

MAP65 Switching and Preamp Housing

MAP65 Switching and Preamp Housing

M2 Antenna Systems will be supplying a MAP65 Switching and Preamp System that will mount on the tower near the antennas. The MAP65 Housing provides switching and separate receive preamplifiers and feedlines for the H and V polarities of the antennas. Separate H and V receive coax connections bring the Horizontal and Vertical elements of the antennas back to the shack. A third coax connection is provided for Transmit. The transmit feedline can be routed to either the H or the V antenna polarity to help minimize Faraday Rotation related fading at the other end of the contact.

S2 Sequencer

S2 Sequencer

An M2 Antennas S2 Sequencer will provide Tx/Rx sequencing and H/V transmit polarity selection via the MAP65 Switching and Preamp System on the tower. The sequencer is essential to provide safe changeovers between receive and transmit and to protect the preamplifiers and the power amplifier during high power operation.

Feedline plans call for a run of 7/8″ Hardline Coax for transmit and a pair of LMR-400uF Coax cables for the H and V receive polarities.

MAP65 Capable Receive Chain

LinRF IQ+ Block Diagram

LinRF IQ+ Block Diagram

The signals returning from the moon in an EME system are very, very weak. Because of this, Noise and Dynamic Range performance are critical factors in an EME receive system. In addition, we will need a pair of high-performance, phase-coherent receivers to enable Adaptive Polarization via MAP65.

LinkRF IQ+ Dual Polarity Receive System

LinkRF IQ+ Dual Polarity Receive System

We are planning to use a LinkRF IQ+ Dual Channel Receive Converter in our EME system. The Link RF IQ+ features excellent noise and dynamic range performance and its phase-coherent design will support adaptive polarity via MAP65. The IQ+ separately converts both the H and V polarities of the antennas into two separate pairs of I/Q streams.

UADC4 High-Performance A/D Converter

UADC4 High-Performance 4-Channel A/D Converter

The four channels (two I/Q streams) from the LinkRF IQ+ must be digitized and fed to a Windows PC for decoding. The conventional way to do this is with a 4-channel, 24-bit soundcard. The available computer soundcards add a good bit of noise and therefore limit the overall dynamic range of an EME system. Alex, HB9DRI at LinkRF has come up with the UADC4 – a high-performance 4-channel ADC that is specially designed for software-defined radio. The UADC4 design is based on CERO- IF conversion and is optimized for EME use. The UADC4 should add about 10 – 15 dB of dynamic range improvement over a typical 24-bit PC Soundcard. Alex is currently taking pre-orders for the next run for UADC4 devices. You can contact him at info@linkrf.ch for more information.

Software

JT65 Software Block Diagram

JT65B Software Block Diagram

Our plans for JT65 software and related components for our EME station are shown above. We are planning on running a combination of Linrad and WSJT software on the same Windows PC to handle JT65B QSOs. There are two configurations that are applicable to our plans:

We are also planning to develop a simple windows application that will read the Moon Tracking data that is generated by WSJT MAP65 and WSJT-X and use it to control the rotator system associated with our EME antennas. More on this to come in a future article.

Transmit System

2m Amplifier And Sequencers

2m Amplifier and Sequencers

A combination of our existing Icom IC-9100 Transceiver and our 2M-1K2 Amplifier will be used for the Transmit side of our system. The 2M-1K2 can generate about 900W when transmitting in JT65B mode.

Well, that about covers it as far as our 2m EME goals and station design go. The plan is to break ground for the new EME tower later this week. We’ll continue to post more articles in this series as our project proceeds.

Here are some links to other articles in our series about our EME Station 2.0 project:

Fred, AB1OC

New 70cm Yagi

M2 Antenna Systems 432-9WLA Specifications

M2 Antenna Systems 432-9WLA Specifications

We decided to replace our current 70cm yagi with a newer, higher performance one from M2 Antenna Systems. We choose the M2 432-9WLA. The new antenna has higher gain and a cleaner pattern than our current 70cm yagi. It also has a longer boom.

New Yagi Ready For Installation

New Yagi Ready For Installation

The first step in the project was to assemble the antenna and check its SWR on the ground. The elements on an antenna like this typically vary by small amounts and are usually not arranged from shortest to longest. It is important to carefully measure each element during installation to confirm that each element is installed at the correct location on the boom.

The folks at M2 Antenna Systems made up a custom boom support truss for us. This is important given the potential for ice and snow accumulation that we face here in New England. We also made up a section of LMR-600uF coax to connect the antenna to the feedline and preamp system on our tower.

Driven Element Details

Driven Element Details

The new antenna uses a Folded Dipole style feed point. This system is essentially a T-matching arrangement where the two sides of the driven element are fed 180 degrees out of phase. It is important to set the locations of the shorting blocks carefully to ensure proper operation of the driven element and a resulting low SWR.

Yagi Going Up The Tower

Yagi Going Up The Tower

Matt, KC1XX, and Andrew from XXTowers handled the installation of the new Yagi on our tower. The installation involved climbing our 100 ft tower and the 25 ft mast at the top to remove the old yagi and install the new one. Note the careful rigging of the new antenna and associated feedline. This allows the new antenna to be pulled up the tower without damaging it.

Climbing a mast is not for the faint at heart! An installation like this one is clearly a job for experienced professionals. Andrew makes this task look easy. Our tower camera captured some video (click on the image above to play) of Andrew’s handy work.

Completed Installation

Completed Installation

The new yagi (top antenna in the picture above) is installed on a 5 ft fiberglass mast extension. The extension is used to ensure that the antenna does not “see” a metal mast which would disrupt the antenna’s pattern. The final installed height of our new yagi is a little over 125 ft. Note Andrew’s good work in attaching the feedline to the mast.

432-9WLA Installed SDR - Shack End

432-9WLA Installed SDR – Shack End

With the new yagi installed and hooked up, we made a final check of the end-to-end SWR from the shack. The antenna’s SWR is very good and the 2:1 SWR bandwidth extends from the bottom of the 70cm band to almost 450 Mhz. The new antenna is optimized for weak signal work up through the ATV sub-band and its SWR is below 1.2:1 in this range.

Fred, AB1OC

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