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

Scouts on Long Island Contact the ISS via Amateur Radio

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Matinecock District Scout ISS Contact

Matinecock District Scout ISS Contact

I once again had the pleasure to help a group of young people make contact with an Astronaut on the International Space Station this past week.

NASA Astronaut Kjell Lindgren

NASA Astronaut Kjell Lindgren

Scouts from the Matinecock District made a contact with Astronaut Kjell Lindgren, KO5MOS on the International Space Station on Saturday, June 4th, 2022.  You can watch and listen to the contact on YouTube by clicking below.  The actual contact begins at about 40:35 into the video.

The Scouts’ contact lasted for approximately 10 minutes. The Scouts asked and Kjell answered 18 of their 20 questions and there was time at the end of the contact for “Thank Yous”.  Here are the questions that the Scouts asked:

1. What do you have to study after HS in order to have a career as an Astronaut?
2. Could the ISS ever be self-sustaining and not need care packages of food/water/oxygen from Earth?
3. Are ISS teams only picked based on skills or does NASA try to match personalities as well?
4. How does the ISS stay safe from all the “space junk” floating around the Earth?
5. Do you only do experiments in your field of expertise on the ISS or because of limited resources do you find yourself assisting others doing things you’re not as comfortable with?
6. Is automated piloting better than manual piloting in terms of flight controls and docking?
7. What one thing did you do as a young adult that you felt was your first significant step to becoming an astronaut?
8. I’ve heard being in space can change your taste buds. Have you created any interesting or creative recipes to make space food taste better?
9. How do they supply the ISS with constant oxygen?
10. We saw a video of a gorilla suit prank on the ISS a few months ago. Have there been any other funny pranks?
11. What jobs do you have to do on the ship?
12. Do the astronauts get to bring something from home with them to space?
13. I’ve heard astronauts from different countries will trade food. What country has the most popular dish on the ISS?
14. In your personal opinion, what is the best and least good thing about being on the ISS?
15. Can you swim in space when you’re floating?
16. Can you feel the effects being in space has on your body? If so, what’s it like?
17. Can you yo-yo upside down in space?
18. Does the ISS have technology installed that could capture Unidentified Aerial Phenomena (UAP)like the US Navy has recently? Have you seen anything up there that you can’t explain?
19. What does it feel like to go to space?
20. I read that there was once water on Mars. Where did all the water go?
AB1OC ARISS Ground Station Operations

AB1OC ARISS Ground Station Operations

This contact was made in a Telebridge format using my Ground Station here in New Hampshire, USA. The linkup with the Scouts on Long Island was via a Zoom conference call. You can learn more about our ground station here.
ARISS Ground Station

ARISS Ground Station

Helping young people make contact with astronauts on the ISS using Amateur Radio is great fun. My work with ARISS is near the top of my list in terms of the most rewarding work that I do with Amateur Radio.

Best and 73,

Fred, AB1OC

Scouts in Australia Contact the ISS via Amateur Radio

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Scout Making Contact with the ISS

Scouts in Victoria, Australia Making Contact with the ISS at VicJam

I once again had the pleasure to help a group of young people make contact with an Astronaut on the International Space Station this past week. The Scouts were participating in a Jamboree in Victoria, Australia. You can learn more about the event, called VicJam, here.

Astronaut Mark VandeHei, KG5GNP

Astronaut Mark VandeHei, KG5GNP

The Scouts made contact with Astronaut Mark VandeHei, KG5GNP this past Tuesday, January 4th, 2022. You can watch and listen to the contact on YouTube by clicking below. The actual contact begins at about 8:25 into the video.

The Scout’s contact lasted for approximately 10 minutes. The Scouts asked and Mark answered all of their questions and there was time at the end of the contact for “Thank You’s” and “Good Wishes”. Here are the questions that the Scouts asked:

  1. What 3 things do you miss from Earth? My Mum worked on a ship and missed; sleeping with the window open, the smell of cut grass, and the sound of rain on the roof.
  2. What do you have to do to become an astronaut?
  3. What would happen if someone were seriously ill on the ISS, and what would you do?
  4. How do you prepare and eat your meals while up in the space station?
  5. What is it like to float around in no gravity without friction?
  6. How does it feel going from zero gravity in space back to earth’s gravity? Does it hurt??
  7. What is the scariest thing to happen to you whilst you have been in space?
  8. How do you shower and go to the toilet in space?
  9. After being in the space station for so many months, how does it feel to experience planet Earth and nature again with all your senses, especially smell?
  10. How do the seasons affect the veggie production system on the ISS? How often do you get to eat fresh food?
  11. Did you always want to be an astronaut and how did you make it happen?
  12. Why do people go into space and how long is an average mission?
  13. How did you feel when you first learned of your selection to go to space and has this been a life-long ambition for you?
  14. Can you share some of the science that was worked on in space that we can now see on earth?
  15. Is there sound or much noise in space?
  16. Multiple nations have had space stations each bestowed with a specific name – Russia had Mir, NASA had Skylab, and China Tiangong-1. As a truly international effort and the largest man-made object in space, does the ISS have a Nickname, or is there a name that the astronauts use for the individual components?
  17. What energy supply do you use to power the station. If nuclear, what type of reactor do you use? If solar, how many solar panels do you use, and what is their power density?
ARISS Ground Station

ARISS Ground Station

This contact was made in a Telebridge format using my Ground Station here in New Hampshire, USA. The linkup with the Scouts in Australia was via a telephone connection using a phone patch in my shack. You can learn more about our ground station here.

AB1OC ARISS Ground Station Operations

AB1OC ARISS Ground Station Operations

Helping young people make contact with astronauts on the ISS using Amateur Radio is great fun. My work with ARISS is near the top of my list in terms of the most rewarding work that I do with Amateur Radio.

Best and 73,

Fred, AB1OC

Importance of Amateur Radio in Schools

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Amatuer Radio in Schools - Satellite Contact at Sussex County Charter School for Technology

Satellite Contact at Sussex County Charter School for Technology

It is vitally important that we make efforts to bring Amateur Radio to young people in schools and other venues. When we spend time bringing Amateur Radio to young people, we accomplish two important things. First, we have the potential to change a young person’s life for the better by involving them in Amateur Radio, a hobby and a service that inspires a lifetime of STEM learning and often leads to lifelong careers in Science or Engineering.

Secondly, our work in schools is one of the very best ways that we can make the general public aware of the positive benefits that Amateur Radio provides to their kids and to the general public…

Source: Importance of Amateur Radio in Schools

In my role as an ARISS Program Mentor, I recently had the pleasure of spending a week with Sussex County Charter School for Technology students and teachers to help teachers there to deliver their summer Radio Camp.

The summer Radio Camp was a STEM education program that the school developed in support of their upcoming contact with an astronaut on the International Space Station (ISS). Members of the local Sussex County Amateur Radio Club teamed with the teachers at the school to deliver a 5-day program grounded in STEM learning through Amateur Radio.

You can read more about the activities that we did at the week-long summer Radio Camp via the link above.

Fred, AB1OC

YOTA 2021 ISS Contact

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International Space Station (ISS)

International Space Station (ISS)

I had the pleasure of serving as the ARISS contact moderator for the Youth On The Air (YOTA) 2021 Camp’s contact with the International Space Station (ISS) using Amateur Radio today. Young Hams spent the week at the Voice of America Bethany Relay Station in West Chester, OH engaging in a variety of Amateur Radio Activities…

Source: YOTA 2021 ISS Contact

You can view the video of YOTA 2021 Camp’s contact with astronaut Aki Hoshide, KE5DNI via the link above.

Fred, AB1OC

Field Day as a Mentoring Opportunity

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ARRL Field Day is upon us and I wanted to share some thoughts about the mentoring and learning opportunities that Field Day can provide. Many Clubs and other groups here in New England are planning…

Source: Field Day as a Mentoring Opportunity

Field Day provides clubs and groups with a great opportunity to engage and mentor new and less experienced hams. I wanted to share some thoughts and ideas on how we can make mentoring a part of our Field Day activities. You can read more about some successful mentoring activities that have worked well as part of Field Day operations that we’ve been involved in via the link above.

I hope to work many of our readers during Field Day 2021!

Fred, AB1OC

Plans for Field Day 2021 – Nashua Area Radio Society

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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

Helping Amateur Radio Grow

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Fred, AB1OC Helping a School Make Contact with an Astronaut on the ISS

Helping a School Make Contact with an Astronaut on the ISS

As many of you know, I have been dedicating much of my time over the last 6 years to helping folks to get into Amateur Radio, to learn new skills through our hobby, and to experience the joy and sense of accomplishment that Amateur Radio brings. I hope to further this effort in the position of New England Director in the ARRL…

Source: Helping Amateur Radio Grow – Nashua Area Radio Society

Several friends and supporters have approached me about running for the position of New England Division Director in the ARRL. Directors serve on the Board of Directors of the ARRL for a Term of 3 years and are elected by the members of the ARRL in the Director’s Division. In our case, this encompasses ARRL members in Maine, New Hampshire, Vermont, Massachusetts, Connecticut, and Rhode Island.

After much consultation with friends, the NARS Executive Committee, my wife Anita, and others who have played major roles in the ARRL, I have decided to take on this challenge by running this fall. I am doing this, in part, to try to help Clubs and Hams here in New England and across the ARRL to grow participation in the Amateur Radio Service and to benefit from the many learning opportunities that it provides.

You can read more about what I am hoping to accomplish as New England Division Director of the ARRL via the link above.

Fred Kemmerer, AB1OC

A 6m DX Opening to Remember

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6m EU Opening - PSKReporter

6m DX Opening to Europe – PSKReporter Snapshot

Every now and then we get a really good opening 6m DX opening to Europe on from here in New England, USA. This past Friday, June 4 2021 presented us with just such an opening. This particular one may well be the best one that I have ever seen. The opening began early in the day on Friday and was still going strong late into the afternoon. As you can see from the PSKReporter snapshot above, the band was solidly open to most of Western Europe and evening into the Middle East.

6m EU Opening - WSJT-X Snapshot

WSJT-X Snapshot During 6m Opening

There were so many strong signals from DX stations in Europe, it was difficult to decide which station to call next! I was able to work the opening for most of the day on Friday and was rewarded with over 130 DX contacts into Europe. In addition, I was able to Work 3 new DXCCs and over 40 new Grids (over 30 of these Grids have confirmed on LoTW already)!

6m EU Opening - JTAlert Snapshot

JTAlert Snapshot Helps To Work New Grids

We use the JTAlert application along with WSJT-X and DXLab Suite. JTAlert helped to identify stations in new Grids that we had not Worked before in the flood of activity on the 6m Band during this opening. At times, there were 4 or 5 different stations in new Grids being decode at once!

AB1OC 6m Grids as of June 2021

AB1OC 6m Grids as of June 2021

The 6m Es season has been very good so far this year with great propagation and lots of activity. Let hope that this continues well into the end of the summer here in New England. We are especially hoping for good 6m openings during Field Day later this month.

Fred, AB1OC