6m Antenna Upgrade Part 3 – microHam Antenna Control System

6m Antennas choices on the Station Master Deluxe

6m Antenna choices on the Station Master Deluxe

The next step in our project is to configure our microHam station management system to support the new antennas and other components in our 6m antenna project. Each radio in our station (we have five that are 6m capable) has a microHam Station Master Deluxe antenna controller that is used to select and control all of our antennas. These units use the band selection and frequency data from their associated Transceivers to present a set of antenna choices and associated rotator, LNA, amplifier, and other controls to the user.

We are adding the following components to our 6m antenna farm that will need to be controlled by our microHam system:

Any of these antennas and their associated Preamp Housings can be used by any of the six Transceivers in our station. There are also two Elecraft KPA-1500 1500w amplifiers (one is shared) that operate on 6m and can be used by three of the five Transceivers in our setup. In this article, I will cover the configuration of our microHam system to support all of the new elements.

Remote Antenna Switching

microHam TEN SWITCH

microHam TEN SWITCH

I choose a microHam TEN SWITCH to handle switching between the new 7-Element LFA and the 6m Antenna Stacks that we will be installing. This switch is can be mounted outdoors on our tower and has good SWR, power handling, and loss performance at 50 MHz. I also choose the option to have N-connectors installed on our TEN SWITCH.

Control Interface Installation

microHam Control Boxes - Relay 10 (Remote Ant. Switch) & Relay 6 (Preamp Housings)

microHam Control Boxes – Relay 10 (Ant. Switch) & Relay 6 (Preamp Housings)

The first step in this part of our project was to install two new microHam Control Boxes to control the new remote antenna switch and the two 6m Preamp Housings. These control boxes are connected to a control bus which allows the Station Master Deluxe antenna controllers associated with our transceivers to control all of our equipment and antennas. The microHam TEN SWITCH that we are using requires ten 12 Vdc control lines to select one of its ten antenna inputs. Each of the two 6m Preamp Housings requires a combination of two 28 Vdc control lines to manage its relays and a 13.8 Vdc line to power its LNA. The microHam Relay 10 Control Box is a good choice for controlling the antenna switch and a single microHam Relay 6 Control Box can be configured to control the two Preamp Housings. I installed the two new control boxes as well as a DIN Rail Terminal Block for ground fan out on an existing section of DIN rail in our shack. Finally, I extended the microHam control bus to the new units and connected the control boxes to the 13.8 Vdc and 28 Vdc power systems in our shack, and set the addresses of the two new control boxes.

Relay 10 (Ant. Switch) and Relay 6 (Preamp Housing) Control Box Configuration

Relay 10 (Ant. Switch) and Relay 6 (Preamp Housing) Control Box Configuration

Next, we updated the firmware in the new Control Boxes and configured their relays into groups for interfacing to the remote microHam TEN SWITCH and the components in the 6m Preamp Housings.

New Antenna and Remote Switch Configuration

microHam Ten Switch on Tower

microHam Ten Switch on Tower

The next step was to define “RF Boxes” in the microHam program for the 7-Element LFA, three fixed-direction 3-Element LFA Antenna Stacks, and the two 6m Preamp Housings that we are going to be installing on our towers.

With this done, we created an additional RF box for the microHam TEN SWITCH which will be located on our main tower. The image above shows how the switch is configured in the microHAM system. We also needed to associate the Relay 10 control box with the switch to enable the microHam system to control it.

6m Preamp Housing Configuration

6m Shared Preamp Housing.jpg

6m Shared Preamp Housing.jpg

The next step was to configure our 6m Preamp Housings. The image above shows the configuration of the shared housing installed on our main tower behind the microHAM TEN SWITCH.

Antenna Switching Matrix

Station Antenna Switching Matrix

The shared Preamp housing will be connected to one of the inputs on our antenna switching matrix shown above.

This arrangement allows us to use the 6m LNA in the housing with any of the 3-Element LFA antenna stacks or the 7-Element LFA antenna we are installing on this tower. One of the features of the microHam system is that it can understand and correctly sequence shared devices like LNAs, amplifiers, and other active RF components.

LNA Controls

Preamp Housing LNA Control

Preamp Housing LNA Control

The image above shows the configuration for the LNA control button that will appear on our SMDs. The configuration above creates a button and display to turn the LNA on or off when an associated button on one SMDs is pressed. This control will appear on the SMDs for any radio using one of the associated 6m antennas.

LNA and PTT Sequencing

Preamp Housing Sequencer

Preamp Housing Sequencer

We also need to configure a sequencing element for each of our 6m Preamp Housings. This ensures that the Push To Talk (PTT) lines and transceiver inhibit lines are properly sequenced for the transceivers, amplifiers, and relays in the Preamp Housing that is part of a path to a selected antenna. The microHam system automatically applies the appropriate timing and sequencing rules to all of the RF elements in the path based on the sequencer settings shown above. Configuring the sequencer also involved associating the appropriate relay control units on the newly installed Relay 6 Control Box with the elements in the sequencer timing diagram above. One item to note here is the 20 – 30 ms tail on the sequencing of the Preamp Housing relays when going from Transmit to Receive. This is done to allow extra time for any stored RF energy in the feedlines during high-power Tx to dissipate before bringing the LNA back into the feedline system.

We also added our second 6m Preamp Housing to the RF path for our existing 7-Element M2 Antenna on our VHF Tower and configured it similarly.

Virtual Rotator for Fixed Antenna Stacks

6m Antenna Stacks - microHam Virtual Rotator

6m Antenna Stacks – microHam Virtual Rotator

The microHam system has a Virtual Rotator feature which is a great way to control selecting between fixed stacks of antennas of the type we are installing. The image above shows the Virtual Rotator we configured for our 3-Element LFA stacks. The Virtual Rotator becomes an additional antenna choice that accepts a direction in the same way that a conventional rotator does. The microHam system figures out which of the available stacks would best match any heading selected and automatically switches the antenna path to the stack that best matches the chosen heading. This capability will be a great tool in VHF contests when we are working multiplier grids on 6m.

microHam Control App - 7-Element LFA, shared LNA, and Rotator Controls

microHam Control App – 7-Element LFA, shared LNA, and Rotator Controls

Final Testing

With all the configuration work done, I downloaded the final microHam program to all of our Control Boxes and SMDs and did some more testing. I connected one of our 6m Preamp Housings to the newly installed Relay 6 Control Box and tested the operation with our Transceivers. Everything worked as expected.

I also used the microHam Control App (shown above) to test the various combinations of 6m antenna selections and configured options. The image above shows the selection of the new 7-Element LFA we are adding. Note the availability of controls for the LNA in the shared Preamp Housing and the controls for pointing the antenna via the associated rotator.

Virtual Rotator for 6m Stacks

Virtual Rotator for 6m Stacks

The image above shows the selections and controls for the 6m Antenna Stacks. The Virtual Rotator choice (STK-VR) is selected in this example. Each SMD has a control knob that can be turned to any heading. When the heading for the STK-VR antenna choice is changed, the system automatically chooses the stack that most closely matches the chosen direction. Choices are also available to choose any of the three stacks directly (ex. EU-STK for the LFA stack facing Europe).

microHam Control App - 6m Split Tx and Rx Antennas

microHam Control App – 6m Split Tx and Rx Antennas

Another nice feature of the microHam system is its ability to use different antennas for Transmit and Receive. The example above shows a setup that uses two different antennas for Tx and Tx.

As you can probably tell, the microHam Station Master Deluxe (SMD) system provides many features for controlling complex antenna arrangements and shared equipment. You can learn more about the microHam SMD system and what it can do here. You can learn more about the programming and operation of the SMD components via the SMD manual.

Next Steps

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 6m Antenna Upgrade Project:

Our new LFA antennas and supporting equipment have arrived. The next step in our project will be assembling them and creating an adjustable mounting system for the 3-Element LFA antennas in our stacks.

Fred, AB1OC

6m Antenna Upgrade Part 2 – High-Power Preamp System

6m High-Power Preamp Housing

6m High-Power Preamp Housing

The next step in our 6m Antenna upgrade project is to build two high-power preamp housings using high-performance, Low-Noise Amplifiers (LNAs). I plan to use one of the housings with our existing 7-element Yagi on our house-bracketed tower and the other housing as a shared preamp system for the new 3-element stacks and the new 7-element Yagi on our 100 ft tower. The housings handle legal limit power (1500w) in all modes, including digital modes.

Preamp System Design

6m Preamp System Design

6m Preamp System Design

The diagram above shows the design of the 6m preamp systems we are building. The main RF path is switched via a pair of high-power vacuum relays. The low-noise LNA we choose includes an RF bypass feature so that the un-amplified receive path can be maintained when the LNA is turned off. I added a relay to the system to provide additional isolation and protection for the LNA when the system is in Tx mode. The protection relay also provides terminations for the LNA when the system is in Tx mode. This provides an extra degree of protection and ensures that the LNA is operational and stable as soon as the system switches to Rx mode. I will add a 1N4002 100V diode across each relay coil to avoid voltage spikes on the control lines when the relays are de-energized.

System Components

6m Preamp Housing Component Details

6m Preamp Housing Component Details

All of the components in the preamp system are mounted in a 12″ x 10″ x 5″ NEMA housing from Cooper B-line (PN 12105-12CHC). I purchased two of these from a local electrical supply store. In addition to the relays and LNA, I used the following components to complete the 6m Preamp Housings:

Sections of 1/4″ aluminum bar stock are bolted to the mounting tabs on the enclosure to provide a means to anchor the enclosure to our towers via Saddle Clamps. Female N connector bulkheads provide the RF connections to the antenna and Amplifier/Feedline sides of the preamp system. The relays and LNA are mounted to the plate that came with the enclosure. A piece of aluminum bar stock material and some aluminum tubing were used to make a stand-off mount for a screw connector terminal block for the control connections to the preamp system.

Main Feedline Path

M2 HPR-1 High Power Coaxial Relay

M2 Antenna Systems HPR-1 High Power Coaxial Relay

I choose the HPR-1 Vacumn relays from M2 Antenna Systems to implement the main Tx/Rx path in the preamp system. These relays handle the power levels required and provide an extra degree of protection should an accidental hot-switch event occur. They provide 32 dB of isolation at 50 MHz which is not quite enough to fully protect the LNA at legal limit power. These relays are 24 Vdc powered and are switched together.

LNA and Protection Relay

6m Antenna Project

Advanced Receiver Research RF Switched LNA

I choose a GaAsFET LNA from Advanced Receiver Research (PN SP50VDG) for the preamp system. This LNA provides 24 dB of gain, has a low noise factor of 0.55 dB, and has a relatively high dynamic range and immunity to overload. The LNA is 12 Vdc powered. I choose at RF switched version of this LNA as it includes an RF relay that bypasses the LNA circuitry when the unit is powered off. This will allow me to turn off the LNA remotely and use my antennas without the additional amplification provided by the LNA. This also allows SWR measurements to be made through the preamp system without having to force the preamp system into Tx mode.

M2 HPR-1 High Power Coaxial Relay

M2 HPR-1 High Power Coaxial Relay

I added a DPDT relay from Tohtsu (PN CX-800N) to provide additional isolation to protect the LNA during Tx. This relay provides an additional 50 dB of isolation and is 24 Vdc powered. The protection relay is used to switch a combination of a short circuit (on the LNA input) and a 50-ohm termination (on the LNA output) during Tx. The combination of the relays provides over 80 dB of isolation during Tx. The isolation relay, the terminations, and the high overload capability of the LNA should ensure safe and trouble-free operation at legal limit power.

Power, Control, and Sequencing

microHAM Control Boxes And Hub

microHAM Control Boxes

I will use our microHam system to provide the switching and sequencing capabilities required to operate the preamp housings. The microHam system enables devices like LNAs to be placed in feedline paths where they can be shared among multiple antennas, amplifiers, and transceivers. The microHam system includes shared control boxes (ex. Relay 6 shown above) that provide relays that we will use to control the LNA powering and relays in our preamp housing. I will share more on this part of the project in the following article in this series. Our station includes bulk DC power supplies that provide 28 Vdc and 13.8 Vdc power to drive the relays and power the LNA in the preamp housings.

Next Steps

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 6m Antenna Upgrade Project:

The next step in this project will be to configure our microHam system to support the Preamp Housings and the remote antenna switching elements that are part of our project.

Fred, AB1OC

6m Antenna Upgrade Part 1 – Plans for Antenna Enhancements

6m LFA Yagi for Field Day and Mountain Topping

6m LFA Yagi for Field Day and Mountain Topping

I’ve been very active on 6m over the past several years. I am closing in on DXCC and Worked All States on the magic band. I operate on 6m daily during Es season. We are also very active in VHF contesting on the 6m band and have worked just under 700 grids on 6m.  This post is about our plans to develop an enhanced 6m antenna system for contesting and DX’ing.

6m LFA Antenna for Field Day

6m LFA Portable Antenna System

We developed an updated 6m antenna system for Field Day and portable use a few years back. The portable setup is based upon a 3-element Loop Fed Array (LFA) antenna. I was impressed with the improvement in the ability to hear weak stations above the noise floor compared to our previous 3-element conventional yagi antenna. Subsequent conversations with Joel Harrison, W5ZN suggested that fixed direction stacks of 3-element antennas would make a very good setup for 6m contesting and grid chasing. This led to our plans for some significant 6m antenna upgrades at our station.

6m Antenna Plans

Our planned 6m antenna upgrade consists of the following elements:

All of these antennas will use 7/8″ hardline coax cables for the main segments of their feedline system.

6m Antenna Project

Advanced Receiver Research RF Switched LNA

I am in the process of building two high-power capable LNA systems for our 6m antennas. These systems will be based upon low noise factor (0.55 dB) GaAsFET RF switched preamps from Advanced Receiver Research. These LNAs should improve the overall noise-factor performance of the 6m receivers in our station by a noticeable amount. We choose the RF switched version of these preamps so that we could disable the preamps and maintain a direct receive path through the LNAs to our antennas. This is desirable for SWR testing and for situations where very strong signals may cause overloading. It also ensures that we can continue to use our antenna should we experience an LNA failure.

I plan to use the shared LNA sequencing capability of our microHam system to control the two LNA systems. All of the antennas for this project will come from InnoVAntennas. The 3-element LFA antennas will be custom-made for fixed direction rear mounting on our tower.

Why LFA Antennas?

The use of a loop-driven element has several advantages, which include:

  • Better suppression of side lobes in the antenna pattern which results in an antenna that hears better (lower noise temperature)
  • The potential for an efficient direct feed design that does not require driven element matching
  • Wider useful bandwidth
  • Slightly high gain
InnoVAntennas 7 Element WOS LFA

InnoVAntennas 7 Element WOS LFA

The 7-element LFA Yagi that I chose takes this one step further by employing a bent reflector to further improve the ability to suppress side and rear lobes in the antenna’s pattern and further improve the antenna’s noise temperature.

6m Antenna Stack Designs

I performed several High-Frequency Terrain Analysis (HFTA) runs to determine the heights and directions for our 4-Stack Antenna Arrays.

6m Antenna Project

4-Stack Facing the EU – Gain vs. Arrival Angles

The example above shows the projected performance of the 4-stack facing Europe. The 3-element LFA Yagi that we are using has a 3 dB azimuthal beamwidth of about 60 degrees. This gives each stack an effect range of azimuth angles approximately the same as the 3 dB beamwidth. The headings that I choose for the stacks are as follows:

  • Europe facing 4-stack – 50 degrees
  • Central/South America and the Caribbean facing 4-stack – 180 degrees
  • The United States facing 3-stack – 260 degrees

I looked at both a 3 Yagi and a 4 Yagi configuration for the U.S. facing stack on the top half of our tower. It turned out that the 3 Yagi design did a better overall job of covering the range of arrival angles that we can expect. This situation is due to a combination of the high elevation of the stack above ground and the wide range of potential arrival angles encountered when working stations across the U.S.

The combination of the new and existing 7-element 6m rotatable Yagis that I am planning or already have installed should cover the remaining directions nicely.

6m Antenna Project

Gain vs. Arrival Angles Towards Oceania – 7-Element Yagi and 3-Stack

The HFTA analysis illustrates the performance of the combination of the west-facing 3-stack and the new 7-element LFA Yagi towards Oceania (ex., Australia and New Zealand). The minimum gain achieved by switching between these two antenna systems is never less than 10 dBi. This part of the analysis also suggests good performance towards Hawaii.

6m Antenna Project

7-Element LFA Yagi Gain vs. Arrival Angles for Japan and Asia

Finally, I looked at the projected performance of the 7-element LFA Yagi towards Japan and Asia. The height above ground for this antenna results in both good performance at low arrival angles and a good bit of gain variation across arrival angles. The low noise performance of this antenna combined with our planned use of high-performance LNAs in the receive path should provide some opportunities to work stations in Japan and Asia.

I also built a combined EZNEC model to look at possible interactions between these and other antennas on our tower. This analysis indicated that we should be fine if we remove the 6m passives from our SteppIR DB36 antennas. The combination of the stacks and the new 7-element LFA Yagi we are planning will replace the 6m capabilities that our SteppIR antennas have been providing.

Next Steps

The antennas will arrive in the next few weeks, and work is underway to build the high-power LFA housings. I will be posting additional articles about this project as we go. Here are some links to other articles about our 6m Antenna Upgrade Project:

Fred, AB1OC

 

Plans for Field Day 2021 – Nashua Area Radio Society

We are holding an in-person Field Day operation at Keyes Memorial Park in Milford, NH. Here’s some more on our plans for Field Day 2021. We’d like to invite you to join us…

Source: Plans for Field Day 2021 – Nashua Area Radio Society

I’d like to invite our friends here on our Blog to visit us during Field Day on Saturday, June 26th, and Sunday, June 27th. We will be at Keyes Memorial Park in Milford, NH.

Testing Our Field Day Satellite Station

Testing Our Field Day Satellite Station

We will have a Tower up with a Triband Yagi and we’ll have our computer-controlled portable satellite station at Field Day.

6m LFA Antenna for Field Day

6m LFA Antenna for Field Day

We’ll also have a new LFA Yagi for the 6m Band. We will be a 4A station with a total of 5 Transmitters on the air. Our stations will be equipped for SSB Phone, CW, and FT8/FT4 Digital modes.

We’ll also be doing training sessions on Satellite Operations, FT8 Digital on 6m, and Fox Hunting at 12:30 pm on Saturday, June 26th. If you have an HT, bring it and you can use it to hunt our foxes. We’ll also have HTs available for folks to use for Fox Hunting.

You can read more about what we are planning and find directions to get to our Field Day site here. I hope that we’ll see some of our followers at Field Day!

Fred, AB1OC

Field Day Satellite Station for 2021 – Setup and Test in Hollis

The Nashua Area Radio Society will be using our portable Satellite Station this year at Summer Field Day. A number of members got together recently to assemble and test our Computer-Controlled Portable Satellite Station for Field Day. Here are some pictures of our Field Day Satellite Station Test…

Source: Field Day Satellite Station for 2021 – Setup and Test in Hollis

Several members of the Nashua Area Radio Society got together to set up and test our Portable Satellite Station for Field Day 2021. Our station is a computer-controlled one and enables us to work FM and Linear Satellites using phone mode and CW.

The setup uses an M2 Antenna Systems LEO Pack Antenna System on a Glen Martin Aluminum Tower that is set up to be portable. Feedlines use 100 ft lengths for LMR-400uF and LMR-600uF coax cable for the 2m and 70cm bands. The rotator is an Alfa-SPID Az/El unit. The antenna system also uses coax-powered preamplifiers from Advanced Receiver Research. The station uses an IC-9700 Transceiver, a Green Heron RT-21 Az/El Rotator Controller, and a MacBook Air Laptop running MacDoppler and MacLogger DX.

This setup is an updated version of the portable satellite station that we built for an ISS Crew Contact that a local school did with us some time ago.

You can see how the portable station goes together in the article above. You can learn more about the design and construction of our Portable Sation from the series of articles that begins here. We hope to work some of our readers on the birds during Field Day this year!

Fred, AB1OC

6m LFA Yagi for Field Day and Mountain Topping

6m LFA Yagi for Field Day and Mountain Topping

6m LFA Yagi for Field Day and Mountain Topping

Our 6m Field Day station will be a portable setup and features a new antenna – a 3-Element Loop Fed Array (LFA) Yagi from InnoVAntennas…

Source: 6m Field Day Station – Nashua Area Radio Society

We’ve been wanting to try a Loop Fed Array (LFA) Yagi on the 6m Band. The Nashua Area Radio Society’s 2021 Field Day operation presented us with a good opportunity to do this. We choose a lightweight 3-Element LFA Yagi from InnoVAntennas and used a fiberglass mast to get it up 25 ft (about 8 meters).

The LFA Yagi performed very well! You can read more about this antenna’s performance and our upgraded portable station via the link above.

Fred, AB1OC

Tech Night – EME II: Station Construction and Operation

EME II - Station Construction and Operation

EME II Tech Night – Station Construction and Operation

We recently did a second Tech Night Program on EME as part of the Nashua Area Radio Society’s Tech Night program. I wanted to share the presentation and video from this Tech Night so that our readers might learn a little more about how to build and operate an EME station for the 2m band.

January 2021 Tech Night – EME II: Station Construction and Operation

You can view the Tech Night presentation by clicking on the video above. Here’s a link to the presentation that goes with the video. You can learn more about the Nashua Area Radio Society’s Tech Night program here. There is a demonstration of an actual live EME contact on the 2m band at 57:57 in the video.

The first Tech Night in the EME Series was about Getting Started in EME Communications. You can view that Tech Night here.

We are in the process of upgrading our EME station to include adaptive polarity. you can read more about that project here.

Fred, AB1OC

Satellite Station 4.0 Part 12 – Antenna Upgrades

Satellite Antennas On the Tower - Parked

Upgraded Satellite Antennas On the Tower

We’ve been making good use of our Satellite Ground Station. Our existing 2MCP14 and 436CP30 antennas have enabled us to make over 2,000 satellite contacts; working 49 of the 50 U.S. States, 290+ Grid Squares, and 31 DXCCs. Our station is also an ARISS Ground Station which enables us to help Schools around the world talk to astronauts on the ISS.

As you can tell, we are pretty active on Satellites so we decided to take our station up a level by upgrading our antennas. We choose the 2MCP22 and 436CP42UG antennas from M2 Antenna Systems with optional remote polarity switches. These are larger yagis with booms over 18+ ft in length. The upgrade required us to improve the mechanical aspects of our Satellite Antenna System as well.

Antenna Assembly

2MCP22 Parts Inventory

2MCP22 Parts Inventory

The first step in the project was to unpack and carefully inventory all of the parts for each antenna. This included carefully presorting and marking each element as we did during the assembly of our EME antennas.

2MCP22 Completed Antenna

2MCP22 Completed Antenna

The new antennas are quite large and they took most of the available space in our workshop during assembly. Getting good results from any antenna is all about attention to the details. Small things like turning the boom sections to get a good alignment of the elements, using NOALOX on the boom sections and hardware to prevent corrosion and galling, carefully measuring and centering the elements, etc. are all good things to do.

2MCP22 Feedpoint Assembly

2MCP22 Feedpoint Assembly including Polarity Switch Upgrade

The feedpoint system on these circular polarized antennas requires careful attention during assembly. It’s important to install drive element blocks, shorting bars, polarity switches, feedpoint splitters, and all phasing lines EXACTLY as shown in the antenna assembly manual. Failure to do these steps will likely results in SWR problems down the road.

436CP42UG Feedpoint Assembly

436CP42UG Feedpoint Assembly

The images above show the feedpoint assemblies for both of our new antennas.

New Satellite Yagis

New Satellite Yagis Ready For Installation

A rough SWR measurement with the antennas on the ground was performed to check for assembly errors. It’s a good idea to use a 12V battery to test the antenna SWR’s in both RHCP and LHCP. These tests checked out fine and we are ready to begin installing the antennas on our Tower.

Old Antenna Takedown and Work Stand

Old Antenna Assembly Takedown Using Boom Lift

Old Antenna Assembly Takedown Using Boom Lift

The next step in the installation was to take down our existing antennas. We rented a 50 ft Boom Lift for the project. The lift makes the work much easier and safer.

Old Antennas on Test Stand

Old Antennas on Test Stand

We have a ground tower that we use for portable satellite operations. It was fitted with a longer mast to create clearance for our larger antennas. We lowered the existing antenna system onto the ground tower for disassembly, installation, and testing of our new antennas.

It’s important to fully test a complex antenna system like this on the ground prior to installation on a Tower. We have routinely found and corrected problems this way. This approach also enabled us to properly adjust our cross boom and antenna support trusses and balance the final assembly properly. All of the required adjustments are MUCH easier with the antennas on the ground.

We also run our rotators under computer control for at least one full day before installing the completed assembly on our Tower. We have consistently found and corrected problems with cabling and balance this way.

Antenna Mounting and Trussing

2MCP22 Boom Truss

2MCP22 Boom Truss

The new antennas have very long booms (approximately 18 ft) and they have a tendency to sag. Add the ice and snow load that we experience here in New England and you end up with quite a bit of stress on the booms over time. Robert at M2 Antenna Systems came up with a custom truss assembly for our installation to address this problem. It’s important to minimize any metal in a setup like this to avoid distortion of the antenna patterns. The trusses use a solid fiberglass rod and small turnbuckles to support the ends of each antenna boom. There is much more weight on the rear of the booms due to the weight of the attached coax cables and polarity switches. For this reason, we located the truss anchor point for the rear of the boom such that it creates a sharper angle for the truss ropes at that end of the truss. This reduces the compression load on the rear of the boom and enables the truss to better carry the weight at the back of the antenna.

436CP42UG Boom Truss

436CP42UG Boom Truss

Installing a truss on the 70cm yagi is much trickier due to the tight pattern of this antenna. We minimized the added metal components by drilling the antenna boom to mount the truss plate directly to the boom via bolts.

We relocated the boom support plates on both antennas as far to the rear of the largest boom sections as possible to improve overall antenna balance. The clamps were also adjusted to change the orientation of the elements from vertical/horizontal to a 45-degree X arrangement. This maximizes the separation between the element tips and other metal components like the cross boom and truss plates.

Tubing Drill Guide

Tubing Drill Guide

All of this required drilling some new holes in our antenna booms. We used a Tubing Drill Guide and C-clamps to perform the required drilling operations accurately.

Satellite Antenna Boom Assembly

Satellite Antenna Boom Assembly

The photo above shows the new antennas mounted on our cross boom. The modifications worked out great resulting in well supported and aligned antennas on the cross boom.

Balancing The Array

Cross Boom Counterweight and Trusses

Cross Boom Counterweight and Trusses

It’s very important to properly balance any antenna assembly that is used with an elevation rotator. Failure to do this will usually result in the failure of your elevation rotator in a short period of time. We initially had some pretty major balance problems with our new antennas. This is due, in part, to the weight of coax cables that run from the antenna feed points along the L-Brace Assemblies. The added weight of the Polarity Switches near the rear of the booms was also a significant contributor to this problem.

We created a counterweight by replacing one of our cross boom truss tubes with a metal section of pipe about 4 ft long. The pipe acts as a counterweight to the weight of the coaxes, etc.

Wheel Weights Used for Balancing

Wheel Weights Used for Balancing

Next, we added 4 1/2 pounds of weights to the front on the metal pipe. We used several layers of Wheel Weights built up in multiple layers to get the necessary counterweight. A heavy layer of electrical tape and some large cable ties were used to ensure that the weights say in place.

This got us close to a good balance but the boom of the 2MCP22 was still significantly out of balance. Matt at XX-Towers came up with a good solution to this problem. We added a few strips of wheel weights inside the very front of the boom of the 2MCP22 to finally get the antennas balanced. A combination of the adhesive tape on the weights and two small machine screws through the boom ensures that the weights remain in place and do not short the elements to the boom.

Finally, we adjusted our Green Heron RT-21 Az/El Rotator Controller to slow down the ramps for the rotator. Final testing indicated the smooth operation of the rotator at slow speeds.

SWR Testing and Baseline

2MCP22 Installed SWR

2MCP22 Installed SWR

A final check and baseline of all of our antennas were made on the ground. Both RCHP and LHCP modes were checked and recorded for future reference.

432CP42UG Installed SWR

432CP42UG Installed SWR

We found that some fine-tuning of the locations and routing of the phasing lines on our 436CP42UG improved the SWR curves. This is a common situation and it’s well worth the time to make small adjustments while carefully observing how they impact your SWR readings. The phasing cables are firmly secured to the antenna boom after the fine-tuning is complete.

New Antenna Installation and Integration on Tower

Upgraded Antennas Going On Tower

Upgraded Antennas Going On Tower

The next step in our project was to install the updated antenna assembly back on our Tower. We had to push the lower rotator and mast up about 4 ft to accommodate the larger antennas. We removed our 6M7JHVHD Yagi and temporarily fastened it to the side of our tower to make these steps easier. We also took the opportunity to work on our 6M7JHVHD Antenna to adjust the length of the Driven Element  for better SWR performance in the FT8 and MSK144 section of the 6m band.

Satellite Tower Infrastructure and Accessories

Satellite Tower Infrastructure and Accessories

There is quite a bit of feed line and control cabling involved in a complex antenna system such as ours. The next step in the project was to reconnect all of the cables and coax feedlines.

Control Cable Junction Box Internals

Control Cable Junction Box at the Base of VHF Tower

We use small junction boxes on our tower and a larger one at our tower base to make it easy to remove and reinstall all of the required control cables. Our approach was to hook up and test the rotators first to ensure that we did not have any new mechanical or balance problems. This step checked out fine. The stiffer chrome molly mast and its added length actually resulted in smoother operation of rotators than we saw during ground testing.

The final step was to work through the other control cables and feed line connections; testing each connection as we went. The Boom Lift makes this work much easier to do.

We took advantage of the availability of the Boom Lift and added some additional enhancements to our VHF Tower. Previously. changing the battery in our Weather Station involved climbing our main tower to 50 ft. We moved the weather station to the 30 ft level on our VHF tower to make this maintenance step easier.

We also added an ADS-B antenna and feedline for the Raspberry Pi FlightAware tracker in our Shack. The parts that we used for the ADS-B antenna include:

You can view the statistics from our FlightAware Tracking station here. More on the FlightAware project to come in a future post.

Upgraded Antenna Performance

Satellite Antennas On the Tower - Tracking

Satellite Antennas On the Tower – Tracking

Initial testing of our new antennas is showing some major improvements. The uplink power required to work LEO satellites has been reduced significantly. As an example, I have worked stations using the RS-44 Linear Satellite with just 0.4 watts of uplink power out of our Satellite IC-9700. The signal reports we’ve received have been excellent as well.

More About Our Ground Station

Here are links to some additional posts about our Satellite Ground Stations:

Fred, AB1OC

EME Station 2.0 Part 13 – H-Frame Enhancements

Completed 2m EME Antenna System

Completed 2m EME Antenna System

Our new 2m EME Antenna System has been performing very well. One area that we noticed that could use improvement was the alignment of our antennas as we move them in the Elevation plane. The problem is caused by the weight of the coax feedlines running from the antenna feed points to the power dividers on our H-Frame assembly. Our H-Frame assembly includes T-Braces to support the coax feedlines but the T-Braces tended to bend and distort the alignment of our antennas as the Elevation Rotator is moved.

Custom EME H-Frame Truss System

Custom H-Frame Truss System

Matt at XX-Towers and Robert at M2 Antenna Systems helped us to come up with a very nice custom solution to solve these alignment problems. The solution consists of two additional truss cables on each of the H-Frame’s T-Brace assemblies. The truss cables are made from Phillystran Cable which is non-conductive and is adjusted via Turnbuckles that are anchored at the center of the H-Frame’s Vertical Risers. This approach minimizes any metal in locations that would affect the pattern of our antennas.

Cross Boom Extension

Cross Boom Extension

The first truss is mounted on a short custom extension on each end of our H-Frame’s Cross Boom and is run to an eye bolt in the center of each T-Brace Vertical Rod.

T-Brace Main Truss

T-Brace Main Truss

These risers stabilize the tendency for the T-Brace Vertical Assembly to flex and move towards the center of the H-Frame when the full weight of the coax cables are bearing on them at various elevation angles. Careful adjustment of the combination of these new Truss Cables and the existing 45-degree T-Brace Horizontal Support Assemblies results in the rear of each antenna boom staying perfectly aligned as we rotate our antennas in elevation.

T-Brace Rear Truss

T-Brace Rear Truss

The other problem that our custom Truss Solution addresses is the tendency for the weight of the coax cables to bend the rear of the antenna booms down when the antennas are at 0-degrees in elevation. The bending is due to the weight of the coax cables on the T-brace being unsupported and bearing down on the rear of the antenna booms. This problem is solved by a second Phillystran truss cable that runs from the metal section of each Vertical Riser assembly to the junction between the rear of the bottom antenna booms and the associated junction of the Vertical T-Brace Assemblies.

We fastened the Phillystan cables directly to the junction point without the use of any metal hardware to ensure that the pattern of our antennas was not affected. These secondary Trusses now carry all of the weight of the coax cables on the T-brace as the antennas approach at 0-degrees in elevation and have eliminated the bending at the rear of our antenna booms.

With these modifications, our antennas remain perfectly aligned at any elevation angle. There is also noticeably less stress on the fiberglass sections of the Vertical Riser Assemblies since they are no longer carrying the load of the coax cables.

Next Steps

We have a dual-channel coherent SDR receiver from Afedri in hand which will allow us to do Adaptive Polarity using MAP65. We will be upgrading our station hardware and software to support Adaptive Polarity in the near future.

Our initial experience with operating our new 2m EME station will be covered in the next article in this series.

You can read more about our EME station project via the links that follow:

If you’d like to learn more about How To Get Started in EME, check out the Nashua Area Radio Society Tech Night on this topic. You can find the EME Tech Night here.

Fred, AB1OC

EME Station 2.0 Part 10 – Antennas On The Tower

Completed 2m EME Antenna System

After a year’s worth of planning and 10 months of construction, we have our new 2m EME Antenna System installed on our EME Tower and working! This stage of our project took about a week and included a lot of help from Matt and Andrew at XX Towers.

Final Preparations

Antenna Ground Test

The first step was to arrange the four 2MXP28 Yagis that we built on saw horses near our EME Tower and check each antenna’s vertical and horizontal SWR. Performing SWR measurements with the antennas close to the ground like this does not produce very accurate measurements. Doing this does allow one to spot potential problems if some of the measured SWR fail to show a resonance or are wildly different than the other antennas in the group. All of our antennas checked out as expected.

50 Ft Boom Lift, H-Frame Cross Boom Assembly On The Ground

We also rented a 50-ft Boom Lift and set it up near our EME Tower. A tool like this is almost essential to safely assemble and adjust a large, complex antenna system involving an H-Frame. It also speeds up the assembly and adjustment process considerably.

Elevation Rotator and H-Frame

Elevation Rotator Installation on Mast

Elevation Rotator Installation on Mast

The first step was to install the MT-3000A Elevation Rotator on the mast. We pre-installed the control cable for the elevation rotator before installing it on the tower. This enabled us to get it temporarily hooked up to the Rotator Controller in our shack so that we could adjust the elevation of the H-Frame and Antennas as we installed them.

H-Frame Assembly on Tower

H-Frame Assembly on Tower

Next, Matt and Andrew installed the H-Frame Crossboom and Truss assembly on the Elevation Rotator. The assembled Vertical Risers went on next to complete the H-frame. The time spent pre-assembling these components and marking centers to enable accurate final assembly saved a great deal of time.

Antenna Installation

Upper Antenna Installation

Upper Antenna Installation

With the H-Frame in place, we installed the upper 2MXP28 Yagi Antennas next. The image above shows the rigging of the boom trusses which was done on the Tower.

Lower Antenna Installation and Adjustments

Lower Antenna Installation and Adjustments

Next came the lower 2MXP28 Yagis. We spent considerable time leveling and aligning all of the Antennas and H-Frame components at this stage.

Feedlines, Electronics, and Balancing

T-Braces and Feedlines

T-Braces and Feedlines

The T-Brace assemblies and Antenna Phasing Lines were installed next. Each Antenna requires two LMR-400 Phasing Lines and these coax cables add considerable weight to the backs of the Antennas. The T-Braces support these cables and help to align the Antennas on the H-Frame.

We replaced the Vertical H-Frame Boom Truss Pipe with a heavy section of Mast Pipe to act as a counter-weight and balance the final H-Frame and Antenna assembly. This step is critical to ensuring a long life for the Elevation Rotator’s drive system and chain.

Phasing Lines, Power Dividers, and Feedline Connections on Crossboom

Phasing Lines, Power Dividers, and Feedline Connections on Crossboom

The photo above shows the final installation of the Power Dividers, Antenna Phasing Lines (there are 8 in total), the MAP65 Preamp Housing, and the Feed and Control Cables that run down the Tower. We took the time to carefully make SWR measurements on each Antenna and check all of the connections to the MAP65 Housing at this stage.

Antenna Integration Details

Rotator Loop

Rotator Loop

The Rotator Loop contains the following cables and Coax Feedline connections from the H-Frame/Antenna assembly:

  • Vertical and Horizontal Rx Feedlines
  • Tx Feedline
  • Elevation Rotator Control Cable
  • MAP65 Housing Control Cable

All of these cables are bundled and securely fastened to the H-Frame Cross Boom and to the Tower. Andrew is a master at this sort of rigging!

Control Cable Connections at Tower Base

Control Cable Connections at Tower Base

I took some time to finalize the Control Cable connections at the base of our tower. Time was spent with a voltmeter doing checks to ensure that everything was connected correctly and working. This effort resulted in the discovery and correction of some wiring errors and a faulty relay in the MAP65 housing. Had I not done these steps, we would have surely destroyed the Preamps in the MAP65 Housing when we transmitted for the first time.

Testing Our New Antenna System

Vertical Polarity Tx SWR at Shack

Vertical Polarity Tx SWR at Shack

A series of SWR measurements were taken before sealing the coax cable connections on the tower. SWR measurements were checked and recorded for future reference at the following points in the feedline system:

  • At the ends of the phasing lines associated with each antenna
  • At the output of the two Power Dividers on the tower
  • At the shack entry ground block

Measurements were taken separately for both the Vertical and Horizontal elements of the final Antenna System. The image above shows a typical SWR measurement for our final Antenna System.

I did many final checks and adjustments while the Boom Lift was still here. These steps included:

  • Checking the oil level in the elevation rotator
  • Re-lubing the elevation rotator chain
  • Adjusting the limit switch stops on the Elevation Rotator to allow enough over-travel for future adjustments and maintenance
  • Checking all hardware for tightness
  • Sealing all coax cable connectors with Coax Wrap and Electrical Tape
  • Making some final adjustments to align the four 2MXP28 Antennas with each other and the H-Frame

Next Steps

The next step in our project will be the integration of our new 2m EME Antenna System into our shack. This step will include the final setup, configuration, and testing of the Rotator Controller, Interim SDR Receiver, Transmitter, Amplifier, and the MAP65 and Moon Tracking Software.

You can read more about our EME station project via the links that follow:

If you’d like to learn more about How To Get Started in EME, check out the Nashua Area Radio Society Tech Night on this topic. You can find the EME Tech Night here.

Fred, AB1OC