Tag Archives: Station Design

6m Antenna Upgrade Part 3 – microHam Antenna Control System

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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 chose 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 and 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. We 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 that 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

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6m High-Power Preamp Housing

6m High-Power Preamp System 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 have added a 1N4007 1000V 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

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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 from InnoVAntennas. 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
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 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 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

Reducing RFI From Our QTH

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Reducing RFI - Fiber Optic Network Wall Outlet

Fiber Wall Outlet

Many Hams (including this one) have problems with RF Interference (RFI) at their stations. Many RFI sources typically come from inside our own homes. Symptoms include birdies at single frequencies, interference that moves around across the Amateur Radio Bands, and high noise floors. We have had all of these problems here.

We recently built an improved EME station for the 2m Band. We noticed a higher-than-ideal noise floor when operating 2m EME during the initial testing of the new station. We decided to do some additional testing to see if we could isolate the source of the noise levels. One test we did was to shut down much of the ethernet network and associated devices here at our QTH. To our surprise, this lowered our noise floor on 2m by some 6 dB, and eliminated many birdies in the EME section of the 2m Band!

Our network mostly uses wired Ethernet running throughout our home on Cat 5e and Cat 6 unshielded ethernet cables. Many of the devices in our home use Power Over Ethernet (PoE) connections to power them through the ethernet cables.

NAS Drives with 10 GbE Optical Interfaces

NAS Drives for Video Storage and Backups

We also do quite a bit of video editing work and often transfer large files from our computers to several large Network Attached Storage (NAS) drives for file storage and backup. We also use an extensive IP Camera System to monitor our towers and for general security purposes.

reducing RFI - Core Fiber Optic Network Rack Enclosure

Core Network Rack Enclosure

We decided to solve our noise problems via a pretty major upgrade to our home network. The upgrade included:

  • Installing OM4 multimode fiber optic cables to replace all of the non-PoE wired Ethernet connections to the rooms in our home. The fiber cables were chosen to support 1 GbE and 10 GbE connections now and to be upgradable to 100 GbE connections in the future.
  • Installing a shielded rack enclosure to house the switches and management devices for our upgraded Network
  • Installing new Cat 6A Shielded Ethernet cables to PoE devices that we wanted to remotely shut down when we are operating using weak-signal modes on 6m and above
  • Upgrading portions of our network to 10 Gbs Ethernet speeds to improve the efficiency of Video Editing and Backups

The project began with the installation of a Shielded Rack Enclosure in our basement. The Rack is wall-mounted and fully shielded and grounded. It also includes cooling fans that move air vertically through the Rack to keep the gear inside cool.

Fiber Optic network - Core Network in Rack - Reducing RFI

Core Network in Rack

Next, we mounted all of the gear for our upgraded core network in the Rack. The main components include (from bottom to top):

PDU Web Interface for Network Control and Management

PDU Web Interface for Network Control and Management

We are going to power down most of our IP Cameras and the WiFi AP devices around our home when we are operating on 6m and above. We implemented this capability using an IP-Controlled Power Distribution Unit (PDU) that allows us to remotely turn network devices in our network on and off via a web browser from anywhere in our home.

IP Camera PoE Switches

IP Camera PoE Switches

The PDU controls a pair of Netgear PoE Edge Switches that power most of the IP Cameras in our home via PoE connections. Shutting down these switches via the PDU removes power from the associated IP Cameras which eliminates a great deal of noise and other RFI.

WiFi AP Control via PoE Edge Switch

WiFi Acess Point Control via PoE Edge Switch

We also installed a VLAN-capable Netgear PoE Edge Switch and connected it to the PDU. This switch enables us to shut down other devices on our network such as WiFi Access Points which are also significant sources of RFI. This switch uses a pair of optical interfaces that connect it to our core network

OM4 Fiber Cable with LC Connectors Installed

OM4 Fiber Cable with LC Connectors Installed

A large part of the work associated with our network upgrade project involved running OM4 Multi-mode Fiber Optic cables to all of the rooms in our home. We ran 12-fiber cables to locations that would likely benefit from upgrades to 100 GbE in the future (ex. our shack, home offices, media-equipped rooms, and servers/NAS devices) and 6-fiber cables were used elsewhere. All of our fiber cables use LC connectors with two fibers for each Ethernet connection (one for Tx and one for Rx). We used a mix of pre-terminated cable assemblies and unterminated cables to complete the room installations.

Fiber Prep using Fiber Cleaver

Fiber Prep using a Fiber Cleaver

Field terminating fiber optic cables is not difficult but it does require some special tools and careful attention to detail. The ends of each fiber must be prepared to precise specifications and be very clean before the LC connectors can be installed. The image above shows a Fiber Cleaver which is used to “cleave” the end of each fiber to form a square, low-reflection/low-loss connection to a field-installable LC connector. Proper use of a high-quality Fiber Cleaver is important if you are to achieve low-loss, low-dispersion field terminations.

Fiber Optic Network - Verifying an LC Connector Installation using Visual Fault Locator

Verifying an LC Connector Installation using a Visual Fault Locator

A Visual Fault Locator (VFL) with an LC Connector Adapter is used to confirm the proper installation of each LC connector. The tool shines a bright red laser light through the LC connector and fiber cable. The field installable LC connectors include a window that indicates laser dispersion at the fiber/connector junction. Too much light in the window due to dispersion indicates a poor connection. The VFL tool is also very useful for checking end-to-end optical transmission and continuity of the completed fiber cable installations.

Fiber Wall Outlet

Fiber Wall Outlet and Patch Cables

The fibers were terminated in wall outlets in the rooms of our home. The outlet plates accept standard keystone jacks. We used LC Keystone Couplers with our wall jack plates. This approach ensures that the ends of fragile fiber optic cables running to the rooms will not be damaged or broken when connecting the fibers to ethernet switches and other devices.

Fiber Interconnect Tray

Fiber LC Interconnect Enclosure

The other end of each fiber cable is terminated in a Fiber LC Patch Enclosure Tray in our Rack. The enclosures provide a test point and LC patch cable interconnect point for the fiber cables. The advantage of using enclosures such as these is that they protect the ends of the fiber cables running to the rooms from damage. A total of three trays terminate a total of 72 OM4 fiber pairs that we installed in our home.

Optical Fiber Connector Cleaner

Optical Fiber Connector Cleaner

It is very important to keep all of the fiber connections clean. Standard practice should be to ALWAYS clean the ends of each LC connector with an Optical Fiber Connector Cleaner each time before an LC connector is installed in a jack. It is also important to keep the supplied caps that come with LC connectors installed when they are not connected to a jack or optical SFP.

10GBase-SR SFP+ Transceiver

10GBase-SR SFP+ Transceiver

The fibers in the core rack and in the rooms are connected to switches, computers, and NAS devices via SFP or SFP+ Transceivers. An example of an SFP+ Transceiver is shown above. These devices convert the laser signals carried on the multimode OM4 fibers to a standard electrical format that can be handled by the core and edge switches in our network.

Core Network Components

Core Network Components

The connections between the Fiber Termination and Patch Enclosures and the SFPs and SFP+s in the Core Switches in our rack are made using OM4 LC Patch Cables (the aqua cables shown in the image above).

Fiber Wall Outlet

Fiber Wall Outlet and Patch Cables

Similar patch cables are run from the Wall Jacks to the Ethernet Edge switches in each room to complete the connections to the core network. Most of our Edge Switches in the rooms in our home use two pairs of fibers in a LAG configuration. This increases the bandwidth capacity of the connections and also increases reliability. Should one of the fiber pairs experience a failure, the other pair continues to carry the traffic until the problem can be repaired.

Reducting RFI - Shielded CAT6A Ethernet Terminations

Shielded CAT6A Ethernet Terminations

Some devices in our network such as the PoE IP Cameras on our Towers and a portion of our WiFi Access Points cannot be shut down without significantly compromising the operation and functionality of our Network. We controlled the noise and RFI contribution from these devices by installing new, Cat 6A Shield Ethernet cabling to connect them. The Cat 6A cables must be terminated using a grounded, fully shielded ethernet panel. This device is 10 Gbps Ethernet capable and properly terminates the shielded Cat 6A cables in our Rack.

Cat 6A Shielded Keystone Jack

Cat 6A Shielded Keystone Jack

Shielded Cat 6A Keystone Jacks and Shielded Ethernet Patch Cables are used in the rooms to connect to the edge devices.

10 GbE Connected Computer

10 Gbps Ethernet Connected Computer

So how did all of this workout? We are seeing a 6 – 7 dB improvement in the noise floor on 2m. This is a huge improvement for our EME station! We are also seeing about 1 dB in noise floor improvement on 6m. We are also seeing a significant reduction in birdies on all the bands. Finally, many of our computers and most of our NAS drives have been upgraded to 10 Gbps Ethernet which enables us to move large files around our network much more quickly. We are also seeing some improvement in the actual measured throughput of our 1 Gbs/400 Mbps Fiber Internet connection.

I hope that our readers find our Fiber Optic and 10 Gbps Networking project interesting.

Fred, AB1OC

Tech Night – EME II: Station Construction and Operation

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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.

A key part of optimizing our EME Station was to reduce RFI from the network in our home. You can read about the installation of Fiber Optic Networking to reduce RFI and improve our EME station’s performance here.

Fred, AB1OC

EME Station 2.0 Part 12 – Station Software

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EME Operating Position

EME Operating Position

Software is a big part of most current EME stations. The JT65 Protocol, which was created by Joe Taylor, K1JT, has revolutionized EME operations. It has made it possible for modest single and two yagi stations to have lots of fun with EME.

Phase 1 of our 2m EME station software and hardware uses manual switching/selection of receive polarity. This Phase is about integrating all of the station components together and sorting out operational issues. After some experimentation, we have settled on a dual-decoder architecture for the First Phase of our 2m EME Station.

You can learn more about the Phase 1 EME hardware setup at our station here.

EME Software Environment

EME Station Block Diagram - Phase 1

EME Station Block Diagram – Phase 1

The diagram above shows the current configuration of our 2m EME station. As explained in a previous article in this series, we are using a FUNCube Pro+ Dongle with the MAP65 application as our primary JT65b decoder and we are using our IC-9700 Transceiver along with WSJT-X as a secondary, averaging decoder. Using multiple decoders has proven to be a significant advantage. It is quite common for one of the two applications to decode a weak signal that the other does not.

We use two custom applications (WSJTBridge and Flex-Bridge) to capture the Moon Azimuth and Elevation data generated by the MAP65 application and use it to control the rotators for our EME Antenna Array.

We have been experimenting with Linrad as a front-end to MAP65 and WSJT-X. At present, we are using the NB/NR functions in MAP65 and in our IC-9700 as an alternative to Linrad. We expect the add Linrad into our setup when we add Adaptive Polarity capabilities in Phase 2.

EME Software Operating Environment

EME Software Operating Environment (click for a larger view)

We use the DXLab Suite for logging and QSL’ing our contacts along with several web apps to find potential EME contacts and to determine the level of EME Degradation on any given day.

The screenshot above shows most of these apps running during a 2m EME operating session.

MAP65 Application – Primary Decoder and Operating Application

MAP65 Software

MAP65 Software

We are using MAP65 as our primary decoder. It also controls our IC-9700 Transceiver when transmitting JT65b messages. MAP65 used the I/Q data from our FUNCube Pro+ Dongle to detect and decode all of the signals in the 2m EME sub-band. A waterfall window displays all of the signals on the band as well as a zoomed-in view of the spectrum around the current QSO frequency. MAP65 also generates heading data for our rotators as well as estimates for the doppler shift between stations. The MAP65 application also provides windows that list all of the stations on the band as well as the messages that they are sending.

EME QSOs via MAP65

EME QSOs via MAP65

The screenshot above shows the main MAP65 window during a QSO with HB9Q. Round trip delay (DT) and signal strength information (dB) is shown for each message that is decoded. The MAP65 application along with a manual that explains how to set up and use the program for 2m EME can be downloaded here.

Moon Tracking and Rotator Control

Custom Rotator Control Apps

Custom Rotator Control Apps (WSJT-Bridge and FlexBridge)

We developed an application we call FlexBridge some time back as part of our ongoing project to remote our Satellite Ground Station using our Flex-6700 based SDR Remote Operating Gateway. This application includes functionality to operate Az/El rotator controllers based upon UDP messages which contain tracking data. We wrote a second application that we call WSJT-Bridge which reads the Moon heading data that either MAP65 or WSJT-X and generates and sends UDP messages that enable FlexBridge to track the moon. The combination enables MAP65 to control tracking the moon in our setup.

Both of these applications are at an alpha stage and we will probably separate the rotator control functionality from FlexBridge and make it into a dedicated application.

Antennas On The Moon

Antennas On The Moon

One of the first steps in the integration process was to carefully calibrate our rotators to point precisely at the moon. We got the azimuth calibration close using the K1FO Beacon in CT. With this done, we made final adjustments visually until our antennas were centered on the moon on a clear night.

EME Tower Camera at Night

EME Tower Camera at Night

We recently installed an additional IP camera which gives us a view of our EME tower. This is a useful capability as it enables us to confirm the operation of our rotator from our shack.

WSJT-X – Secondary Decoder

WSJT-X Software

WSJT-X Software

We also run WSJT-X as a second decoder using the receive audio stream from our IC-9700 Transceiver. WSJT-X has some more advanced decoding functions and can average several sequences of JT65b 50-second transmissions to improve decoding sensitivity. It only works on one specific frequency at a time so we use it to complement the broadband decoding capability that MAP65 provides.

We can also transmit using WSJT-X which enables us to use its Echo Test functionality to confirm that we can receive our own signals off the moon.

The WSJT-X application along with a manual that explains how to set up and use the program for EME can be downloaded here.

Finding Contacts and Logging

Finding QSOs and Logging

Finding Contacts and Logging

We use the DXLab Suite for logging and QSL’ing our contacts. DXLab’s Commander application provides the interface between WSJT-X and our IC-9700 Transceiver. This enables the DXLab Suite to determine the current QSO frequency and mode for logging purposes.

MAP65 Software

MAP65 Software and DXKeeper’s Capture Window

We keep DXKeeper’s Capture Window open on the screen where we run MAP65 so we can easily transfer QSO information to our log as we make contacts.

We also use several web apps to find potential EME contacts and to get an estimate of the level of EME Degradation on any given day:

We are working on interfacing our instance of MAP65 to LiveCQ so that we can contribute spots when we are operating. More on this to come in a future article in this series.

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.

We are planning some enhancements to our H-Frame to enable better alignment of our antennas along with improved reliability and stability when rotator our antennas. We will cover these enhancements 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.

A key part of optimizing our EME Station was to reduce RFI from the network in our home. You can read about the installation of Fiber Optic Networking to reduce RFI and improve our EME station’s performance here.

Fred, AB1OC

EME Station 2.0 Part 11 – Station Hardware In Shack

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EME Station Hardware Components

EME and Satellite Ground Station Hardware Components

Now that our 2m EME Antenna Array is fully installed, we have turned our attention to the setup of the equipment in our Shack. Our plan is to do a mix of JT65 Digital and CW operation with our 2m EME Station.

The image above shows the equipment that is dedicated to EME and Satellite operations in our station. We built some shelves to make room for all of the equipment as well as to create some space to move our Satellite Ground Station 4.0 to this same area. The components in our 2m EME station include (left to right):

We’ll explain each of these components as well as the supporting shack infrastructure that we are using for EME below.

Phase 1 EME Station Architecture

EME Station Block Diagram - Phase 1

EME Station Block Diagram – Phase 1 (Manual Rx Polarity Selection)

Unfortunately, the LinkRF Receiver and Sound Card to enable a full MAP65 Adaptive Polarity installation are not currently available. As a result, we’ve created a Phase I Architecture that uses an SDR Dongle and manual selection of Receive Polarity via a switch. We also added a receive splitter and a Transmit/Receive relay in front of an Icom IC-9700 Transceiver which is dedicated to our EME setup to enable both the MAP65 and one of either the WSJT10 or WSJT-X Software Decoders to operate simultaneously.

This approach has some significant advantages when conditions are poor as one of either MAP65 or WSJT10/WSJT-X will often decode a marginal signal when the other will not. More on this in the next article in this series which will explain the software we are using more.

Transceiver, SDR Receiver, and Sequencing

IC-9700 Transceiver and Sequencer

IC-9700 Transceiver and Sequencer

A combination of an Icom IC-9700 Transceiver and M2 Antennas S2 Sequencer handle the Transmit side of our EME Station including the associated sequencing of the preamplifiers and Transmit/Receive Switching which is part of our Antenna System. The IC-9700’s receiver is also used with the WSJT10 Decoder in our setup.

IC-9700 Frequency Drift and Stability

Controlling IC-9700 frequency drift - GDSO Injection Board Installed in IC-9700

Controlling IC-9700 Frequency Drift – Reference Injection Board Installed in IC-9700 (Leo Bodnar Website)

To ensure good frequency stability and limit IC-9700 frequency drift in our setup, we installed a Reference Injection Board from Leo Bodnar in our IC-9700.  The Reference Injection Board uses Leo Bodnar’s Mini Precision GPS Reference Clock (the small device on top of our IC-9700 in the photo above) to lock the IC-9700 to a highly accurate GPS-sourced clock. The installation and configuration of the Reference Injection Board in our IC-9700 were simple and Leo Bodnar’s website covers the installation and setup procedure for these components. FUNcube Dongle Pro+

FUNcube Dongle Pro+

We used a FUNcube Dongle Pro+ as a second Software Defined Radio (SDR) Receiver in our setup and as an I/Q source to drive the MAP65 Software. Good information on configuring the MAP65 software to work with this dongle can be found here.

EME Station RF Paths and Sequencing

EME Station RF Paths and Sequencing

The diagram above shows the RF Paths and associated sequencing in our Version 1 EME Station. A Manual Antenna Switch is used to select either Horizontal or Vertical polarity when in receive mode. The S2 Sequencer handles polarity selection during transmit. A splitter divides the Rx signal between the FUNcube Pro+ Dongle for MAP65 and a Transmit/Receive Switching Circuit in front of our IC-9700 Transceiver. The relay enables the IC-9700 to provide Transmit signals for both the MAP65 and WSJT10/WSJT-X Software applications. The IC-9700 drives a 1.2 Kw Amplifier during Transmit and the final Tx output is metered using a WaveNode WN-2 Wattmeter.

Completed T/R Relay Assembly

Completed T/R Relay Assembly

To enable both the receivers in our IC-9700 and the FUNcube Dongle to function simultaneously, we built a circuit using a CX800N DPDT RF Relay and a Mini-Circuits 2-Way RF Splitter. We also built a simple driver circuit for the relay using a Darlington Power Transistor and some protection diodes. The circuit enabled our S2 Sequencer to control the relay along with the rest of the sequencing required when changing our EME Station from Receive to Transmit and back.

Finally, we configured a 30mS transmit delay in our IC-9700 to ensure that the S2 Sequencer had some time to do its job as the station changed from Receive to Transmit. This delay coupled with the Transmit delays built into the MAP65 and WSJT10 software ensures that we will not hot switch the MAP65 Preamp System on our tower. One must be very careful to ensure that RF power is not applied before the sequencer can complete its transition to the Transmit state or damage to the Preamplifiers and/or relays at the tower will occur.

Amplifier and Rotator Controls

EME Station Hardware Components

EME and Satellite Ground Station Hardware Components

The Elevation Rotator from our Antenna System was added to the Green Heron RT-21 Az/El Rotator Controller previously installed in our shack and both the Azimuth and Elevation Rotators were roughly calibrated. Our EME station requires quite a few USB connections to our Windows 10 Computer so we added a powered USB hub to our setup. Chokes were added to the USB cables which run to our IC-9700 Transceiver and our FUNcube Dongle to minimize digital noise from getting into our receivers.

Our 2M-1K2 Amplifier can produce about 1KW of power on 2m when operating in JT65 mode and this should be enough power for our planned EME wor. Our S2 Sequencer also controls the keying of our Amplifier as part of the T/R changeover sequence in our EME station.

WaveNode WN-2 Wattmeter

WaveNode WN-2 Wattmeter

We added a 2m high power sensor to the output of our Amplifier and connected it to a free port on one of the WaveNode WN-2 Wattmeters in our station to provide output and SWR monitoring of the Transmit output of our EME station.

Supporting EME Station Infrastructure

VHF+ Antenna Switching Console

VHF+ Antenna Switching Console

We had some work to do to configure the antenna, grounding, and DC power infrastructure in our station. We redid the manual switching in our VHF/UHF Antenna Switching consoles to accommodate our new EME Antenna System as well as to prepare for our Satellite Station to be moved into our shack in the near future. The console on the right provides Grounding of the Transmit and Receive sides of our EME Antenna System as well as the selection of the Antenna’s Horizontal or Vertical polarity for decoding.

We also expanded our station grounding system to provide a ground point directly behind all of our EME equipment. Our DC power system was also expanded to accommodate our EME equipment.

GPS NTP Server

GPS NTP Server

Our station already has a GPS Controlled NTP Time Server installed and we’ll use it to ensure that the clock on the PC which will run the MAP65 and WSJT10 software will have very accurate clocks for JT65 decoding.

EME Tower CAM

EME Tower CAM

We already have cameras that cover our Main and Satellite Towers. We’ve added a third camera to allow us to view our EME Tower’s operation from our shack. This ensures that we can visually confirm the operation of our antennas and detect any problems should they occur.

Next Steps

All of the new EME equipment has to be integrated and tested with the software components which provide digital operation, tracking of the moon, logging, and other functions in our station. The software setup as well as our initial experience with operating our new 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.

A key part of optimizing our EME Station was to reduce RFI from the network in our home. You can read about the installation of Fiber Optic Networking to reduce RFI and improve our EME station’s performance here.

Fred, AB1OC

EME Station 2.0 Part 10 – Antennas On The Tower

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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

EME Station 2.0 Part 8 – Elevation Rotator Assembly and Sub-System Test

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Elevation Rotator and MAP65 EME Preamp System Test

The next major component in our new EME station is the assembly of the Elevation Rotator. This step also involves pre-assembly and testing of the MAP65 Pre-amp Housing, Antenna Power Dividers, Transmit/Receive Sequencer, and the Rotator Controller. Here are the components involved in this part of our project:

We choose the MT-3000A Elevation Rotator for its heavy-duty construction. This will be important to handle the weight of our EME antenna array as well as the winter conditions that we encounter here in New England.

Elevation Rotator Assembly

MT-3000A Elevation Rotator Parts

MT-3000A Elevation Rotator Parts

The first step was to inventory all of the parts for the MT-3000A Elevation Rotator and carefully read the MT-3000A manual from M2 Antennas.

Assembled MT-3000A Elevation Rotator

Assembled MT-3000A Elevation Rotator

Assembly of the MT-3000A is pretty straight forward. It uses a chain-drive system to produce a very strong, high-torque elevation rotator system. It’s important to fill the gear-box with the supplied gear oil and to lube the chain with the proper lubricant prior to testing and installing the rotator. Spray style chain lubricants for motorcycle chains work well in this application.

Rotator Controller Integration and Testing

Green Heron RT-21 Az-El Rotator Controller

Green Heron RT-21 Az-El Rotator Controller

The next step was to make up a rotator and connect the MT-3000A to our Green Heron RT-21 Az/El Rotator Controller for a test. The RT-21 Az/El is a very flexible controller that is capable of controlling almost any popular antenna rotator. We’ve already tested this unit with the M2 Antennas OR2800G2 Azimuth Rotator that is installed on our EME tower.

RT-21 Configuration of the MT-3000A Elevation Rotator

RT-21 Configuration of the MT-3000A Elevation Rotator

The MT-3000A is a pulse-counter style rotator with 0.1-degree positioning resolution. It required a custom setup in the Green Heron RT-21 Az/El which was easily accomplished with Green Heron Engineering’s setup utility. One must determine the correct Divide Ratio setting by experimentation. When the correct value is found, a rotation of 90 degrees on the controller will result in exactly 90 degrees of actual movement by the MT-3000A. This calibration was much easier to do with the MT-3000A in our shop than it would have been once the unit was installed on our tower. We also set up the RT-21 Az/El Controller to allow for 5 degrees of rotation beyond the 0 and 90-degree points.

After some testing, I decided to use the 42Vdc tap setting in the RT-21 Elevation Controller with our MT-3000A. The specifications for the MT-3000A allow for up to 42 Vdc to be used to run its motor. To be safe, we set the Max Speed setting in the RT-21 Az/El to “8” which resulted in a maximum of 40 Vdc measured with a voltmeter at the output of the controller.

Assembly and Integration of MAP65 Housing and Cross Boom

Elevation Rotator and MAP65 Preamp Housing Assembly

Elevation Rotator and MAP65 Preamp Housing Assembly

The next step was to install the H-frame Main Boom center section and Truss Support Tubes in the MT-3000A. The MAP65 EME Preamp Housing is mounted on the horizontal Truss Support Tube as shown above.

MAP65 EME Preamp System Housing

MAP65 EME Preamp System Housing

A control cable for the MAP65 EME Preamp Housing was made up and connected to the terminal strip on the housing.

EME Sequencer Testing

S2 Sequencer

S2 Sequencer

The S2 EME Sequencer from M2 Antennas is designed to control the MAP65 Housing but its internal jumpers must be properly set to do this. We spent some time with the manual for the S2 Sequencer and for the MAP65 Housing carefully setting the S2 Sequencer’s jumpers and verifying proper voltages at both the output of the S2 Sequencer and the terminal strip in the MAP65 housing with a voltmeter. The manuals for the S2 EME Sequencer and the MAP65 EME Preamp Housing were clear on these steps.

Mounting Power Dividers

Power Divider Mounting Bracket

Power Divider Mounting Bracket

The next step in this part of our project was to mount the M2 Antennas 4-Port Power Dividers that are used to connect the MAP65 Pre-Amp housing to the four 2MXP28 Antennas. Two power dividers are required as each antenna has a separate feed point connection for their horizontal and vertical polarities. We made up some custom mounting brackets for the power dividers from 1-1/4″ aluminum angle material.

MAP65 EME Preamp Housing Connections

MAP65 EME Preamp Housing Connections

The MAP65 Preamp Housing connects to the outputs of the two Power Dividers that feed the H-polarity and V-polarity of the antenna array. The outputs from the MAP65 EME Housing connect to the H-polarity and V-polarity receive coax cables and the Transmit Hardline Coax Cable that runs from the tower to our shack.

Coax Interconnect Cables

Power Divider and Feedline Jumper Coax Cables

Power Divider and Feedline Jumper Coax Cables

The final step was to make up LMR-400 coax cables to connect the MAP65 Preamp Housing to the Power Dividers. We used right-angle male N connectors to make the connections to the 4-Port power drivers to avoid sharp bends in the cables.

We also made up three additional LMR-400uF coax cables to connect the MAP65 Preamp Housing to the coax Tx and Rx feedlines that are installed on our tower. It’s important to keep the H-Pol and V-Pol cables as close to identical in length as possible to minimize and phase differences between the associated receive feedline systems.

Next Steps

The next step in our project will be the final assembly and preparation of the H-frame which will be used to mount our four 2MXP28 Antennas. 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 Teach Night on this topic. You can find the EME Tech Night here.

Fred – AB1OC

Tech Night – VHF+ Weak Signal Stations Part 1 (Intro and 6 Meters)

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Tech Night - VHF+ Weak Signal Stations Part 1 - Overview and 6 Meters

Tech Night – VHF+ Weak Signal Stations Part 1 – Overview and 6 Meters

We recently did a Tech Night on building and operating VHF+ stations as part of the Nashua Area Radio Society’s educational 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 get started and build their own VHF+ Weak Signal Station.

There is a lot to this topic so we’re going to cover it with two Tech Night presentations. The first one in the series is included here and it provides an Introduction to the VHF+ topic along with details on building and operating a station for the 6 Meter Band.

July 2020 Tech Night Video – VHF+ Weak Signal Stations Part 1 – Introduction and 6 Meters

You can view this Tech Night session via 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.

We have built a number of stations and antennas for the VHF+ Bands (6 Meters and above). Here are some links to articles about those projects and our operations on the VHF+ Bands here on our Blog:

Fred, AB1OC