Finally . . . it’s time to sell my FT-847. Why? I’ve moved to an IC-9700 for a few convenience features. Now is the time to pick this up. The VHF contest is coming up this weekend and ARRL Field Day is just around the corner. This is a great radio for both of those events.
The price is $750.
Ok, what will you get in the package?
FT-847 in excellent condition
Original hand-held microphone
Original DC power cable
Original operators manual
I’ve owned this FT-847 for a long time. It has served as a lightly-used secondary radio for my office and for occasional VHF/UHF weak signal operations. A few years ago, i installed a satellite array and enjoyed many QSOs with this rig.
The rig is working FB. It looks great. I’d like to see it go to a new owner who will get as much enjoyment out of it as I have over the years.
The purpose of this survey is to establish a baseline on satisfaction with the overall ARRL membership experience. You are not asked to identify yourself, but several questions are included to help us better understand attitudes of various subgroups.
The purpose of this survey is to establish a baseline on satisfaction with the overall ARRL membership experience. You are not asked to identify yourself, but several questions are included to help us better understand attitudes of various subgroups.
Building a single vertical or an array? Do you have a plan for cleanly terminating the feedline at the base of the antenna? Is there a small circuit you’d like to protect from the weather at the base of the antenna? Here’s a solution I came up with over the past year as part of building three transmit 4-squares and an active receive array that’s currently in the works.
Requirements
Metal Box – I really wanted the box to be made of metal and to be able to use it as a ground interconnect for connectors and circuitry.
Weatherproof – It’s going to be out in the weather, so let’s find a box that’s up to the job.
Minimum Drilling – It would be great if I didn’t have to do much drilling or punching of large holes in the box to handle typical connectors for a simple feedpoint enclosure.
Insulation of the Hot Side to the Vertical Element – With a metal box, I needed to figure out a way to get the hot lead out through the side of the box to the antenna element. And, I wanted to do this without compromising the weather sealing for ht ebox too much.
Low Cost – Could we do this for less than $10 per feedpoint?
Hello Lowe’s
I went to the electrical department at the local Lowe’s see if they had anything that might work. And here’s what I found.
This box has three holes. They are drilled and threaded to connect electrical conduit. The holes are conveniently located for our connection requirements . . . don’t you think? The kit also comes with threaded metal plugs to seal up unused holes.
It turns out that the hole diameter is just right for a flange-mounted SO-239. I just lay the SO-239 in the hole and mark where I need to drill for #6 mounting screws. My approach is to drill and tap the wall of the box itself for the screw. You could also drill straight through and use nuts and lock washers,
SO-239 mounted in one of the conduit holes.
For the connections to ground and to the hot element, I use a hardware stack of screw, nut, washers and a wingnut mounted in one of the conduit holes with a plug. For ground, I use a metal plug. Insulating plugs are also available as an option. I picked up a handful of them and I simply drill a hole for a #8 or #10 screw and use the wingnut stack there for the hot connection. Works great.
Wingnut hardware stack mounted on an insulating plug for the hot connection to the antenna element.
Lowes also sells many flavors of covers for these boxes. For my application, a blank cover works fine.
Blank cover installed on box. Notice seal provided to keep moisture out.
Details of internal construction for a simple pass-through box. Note the convenient ground screw.
All the hardware combined comes in at about $9 including the SO-239 connector. Not bad!
Results
We built a 20m 4-square using these feedpoint boxes.
For about two years, K1IR has been home for a ham radio repeater. It’s part of the NEDECN DMR network. The repeater is on the 2 meter band and is accessible with these settings:
Callsign: K1IR
Frequency: 146.47000MHz
Offset: -1.5MHz
ColorCode: 0
The Challenge
The coverage area for the repeater has not been the best. That’s because we have been using a two-antenna system. The receive antenna is a Diamond vertical located at about 105 feet on top of the tower. That antenna works quite well. But, we’ve been using a second antenna only about 30 feet above ground level for transmitting. This antenna, another Diamond vertical, simply doesn’t perform very well at this low height. The result has been a very unbalanced coverage area for the repeater. Not very attractive to potential users. We needed to make a change.
The high repeater antenna at K1IR. We are looking in E-S-E direction.
Our first effort to improve the coverage was to put up a new vertical at about 70 feet on the tower. But, that project was never completed because getting a second low-loss feedline in place to feed that antenna proved quite difficult.
Adding a Duplexer – A Real Solution
Using a duplexer is another way to solve this problem. What is a duplexer? It’s a three-port device where the feedline to the antenna is connected to one port, a second is connected to the repeater receiver input, and the third is connected to the transmitter. The duplexer creates two low insertion-loss paths that have extremely high isolation from each other.
Antenna port to receiver port
Transmitter port to antenna port
Duplexer creates high-isolation paths to the antenna from both transmitter and receiver.
The duplexer that has some great advantages. It allows you to use the same coaxial feedline and antenna for both transmitting and receiving, with no compromise in performance.
Here we see the two paths through a typical duplexer. Each of the curves represents a path. At the lower frequency, one curve (path) has minimum insertion loss and the other has very high rejection. At the higher frequency, the profile is reversed.
To achieve these high-Q curves and deep isolation nulls, the long-proven approach is to build filters with resonant cavities. These cavities must be carefully tuned with specialized test equipment.
Duplexers are fairly expensive – and not in the K1IR repeater budget! But, they do become available on occasion as repeaters are upgraded or decommissioned. So, I put the word out to my network to be on the lookout for a surplus duplexer. That was at least a year ago.
A typical set of cavities setup as a duplexer. These are for the amateur 2 meter band. The exact frequency of each cavity is adjusted using the tuning rods on top.
About a month ago, long-time friend, Dom Mallozzi N1DM, told me he might just have a lead on a VHF duplexer coming out of service following a repeater upgrade in a public safety application. The frequencies for VHF public safety are close to the 2 meter band, so retuning would work just fine. That duplexer – a Sinclair Q201 – was made available as surplus just this week, so Dom got his hands on it as quickly as possible and we did the installation this morning.
Assembly and Tuning
Here’s Dom N1DM running preinstallation tests prior to installation.
Tuning is easy when you have the right gear. And, Dom came fully equipped. He pulled out his Rigol DA815-TG Spectrum Analyzer with built-in tracking generator. It didn’t take more than a few minutes to ensure that the tuning was within spec on the new frequencies.
This is the antenna-to-receiver path through the duplexer. Notice the low insertion loss at about 144.970 MHz and the deep notch at 146.47 where the repeater transmitter is set.
With the cavities pre-tuned, we built up a couple of cables and connected the duplexer in line with the repeater and antenna, and started our final testing.
Two-way radio master, N1DM, hard at work tweaking up cables and cavity tuning.
Initial tests showed low power output from the repeater. With a little micro-adjustment of one cavity on the transmitter side, power came up to exactly what it should be – and we were in business!
Coverage Testing – It’s a Big Win!
Final testing was a coverage area test. Dom packed up his stuff and headed south back towards his home QTH in Natick. I got my HT setup in the car, connected to a trunk lip mounted 5/8 wavelength whip. As we drove in opposite directions, it quickly became clear that coverage was greatly improved.
Great success! HT level coverage extended north into Littleton, MA (10.7 miles) and south to Framingham, MA (6.2 miles).
Again . . . huge thank you to Dom Mallozzi for finding and making the duplexer available and for his skills in getting it running on the Sudbury, MA 146.47 DMR machine.
This is an Array Solutions SixPak 2 x 6 antenna switch. Get ramped up for SO2R with this plug-and-play KW antenna switch. See Array Solutions for more information.
Original owner. Installed indoors in the switching closet . . . and never moved it. Unit was always reliably controlled by band decoders, so we never needed any manual controllers. Recently removed from service to make way for a new switching approach. Works fine; tested this week – all checks out ok. Contact K1IR to purchase or inquire.
Many thanks to Rusty Epps W6OAT and the senior leadership of the WWDXC for inviting me to present on the important topic of tower safety. I presented to the group via Zoom at it’s on-line August meeting on Tuesday, August 11, 2020.
Following the presentation, I received this note:
Tnx again for a magnificent presentation to WWDXC. Folks stayed on line for almost another hour, discussing and sharing horror stories. YOU WOKE US ALL UP!
Stay vigilant; learn what you need to know to be safe . . . and spread the word. Visit zerofalls.org for more information.
In the midst of a global pandemic, classroom learning continues. This is a story about a high school physics class continuing to operate and expand its horizons through exposure to the magic of amateur radio satellites – even while taking on the challenges of social distancing.
The Ask: Please Help Us Contact the ISS
About two weeks ago, one of my neighbors asked me if I could help some students contact the International Space Station (ISS) via ham radio as part of a Physics project for school. I thought, “Wow! What a great opportunity. It’s a big goal, but, if possible, I’d love to help them make this happen.”
Astronaut Sunita Williams, Expeditions 14 and 15 Flight Engineer, talks with students at the International School of Brussels in Belgium during an Amateur Radio on the International Space Station (ARISS) event – Courtesy NASA
I met with the three high school freshman immediately via Zoom to hear more about what they wanted to do. They had just completed a Physics unit on orbital mechanics and their final assignment was to find a practical way to experience what they had learned. But, when they told me that they needed to get the project done in about five days, I gently explained the issues of worldwide demand, limited availability of astronaut time and complexity in setting up a school contact with the ISS via amateur radio. They quickly understood that while possible, making one happen in just a few days would be impractical. They were slightly disappointed.
Disappointed, but not deterred!
How Else Might We Satisfy the Learning Objective?
There had to be a way to help the students experience the phenomenon of orbital motion. If we focused on the ISS, we could hope for a pass over our area and actually see the satellite as it crosses the night sky. But, would there be a good enough pass over the next few days? Would weather cooperate? How could we arrange this while still observing social distancing? Too many what-if’s. We needed a different approach.
ChubuSat – Courtesy JARL
So, I offered them the opportunity to learn about and experience communications using amateur radio satellites – an alternative that would allow them to achieve almost everything they wanted to accomplish. When they heard the idea, their enthusiasm rebounded immediately.
A Quick Ramp-Up and an Achievable Goal
So, we started to get ourselves educated on amateur radio satellites. I directed them to some helpful web resources:
A Diamond dual-band vertical – not optimal for satellite work . . . but good enough!
Meanwhile, my home satellite station hasn’t been running for a while. Two years ago, while I was setting up computer control of my Az-El rotor, the rotor failed – permanently. That, unfortunately, sidelined the project. So, I had to come up with something quickly to satisfy the needs of this new project. I dug out my trusty Yaesu FT-847 and connected it to SatPC32 pass prediction software running on a laptop and a dual-band vertical at 20 feet, just to see if I could hear any of the amateur satellites. Good news! They weren’t pinning the S-meter, but I was hearing several of the active satellites – SO-50, AO-73 (FUNcube-1) and the XW-2 satellites. Beacons and some QSOs were audible. Things seemed better on 2m downlink than 70cm.
I got back to the students and let them know that it would be possible to hear these satellites. Then we got to talking about their learning objectives. The goal was to get some hands-on experience with orbital motion. How could we accomplish that with an invisible amateur radio satellite?
First, we walked through the SATPC32 pass prediction software. We looked at the views of earth and the paths the satellites were taking as they orbited the globe. We discussed the concept of a visibility footprint. Then, an idea came to mind. I asked the girls if they had learned about the Doppler Effect in their Physics class. It turns out that they had been exposed to the concept earlier in the year – and the examples they studied were all in the audio realm. When I told them that the radio transmissions to and from a satellite would be affected by Doppler, they were interested. So, we set a goal to observe Doppler as we listened to transmissions from an amateur radio satellite.
Let’s listen in on an amateur radio satellite.
Getting it Done in this Time of Pandemic
Video conferencing has truly come of age in recent months. Previously used primarily by businesses and tech-savvy individuals, virtual meeting technology – driven by pandemic restrictions – has become the communication tool of choice for all of us – from the most to the least technically-oriented. And, the Zoom service has emerged as one of the most effective implementations for consumer use. The students were well-versed in the use of Zoom . . . and virtual conferencing and collaboration technology has been my business for 30 years . . . so it was easy to jump right into using Zoom meetings to keep our project on track.
I provided several references to help them get a basic understanding of Doppler in the context of satellite-based communication systems.
After reviewing the reference material and doing some research on their own, we got together on Zoom to discuss and observe the Doppler shift, in a real satellite communication system.
We listened to the XW-2A satellite as it went overhead. The beacon shifted frequency, as we predicted.
Understanding Doppler Shift and hearing it live.
Bonus . . . A Voice Contact Via the Satellite!
As the XW-2A satellite continued its journey across the sky, we noted that the beacon was quite strong. We wondered if we would be able to hear stations making contact through the satellite. As we scanned the satellite downlink frequency range, we found a station making a general call – looking for a contact. We replied to his call . . . and he responded!
A short voice contact with Don AK2S in New Jersey!
Our contact with Don, callsign AK2S, lasted only about 2 minutes, as the satellite was rapidly nearing the horizon. But, it was quite a success – more than we had expected to be able to accomplish with the limited time and antenna system available to us.
Lessons and Retrospective
Learning Objective: Accomplished . . . and More We were very pleased to have observed the Doppler Effect as the orbiting XW-2A satellite passed overhead. It gave the students a glimpse into the behavior of an object orbiting the earth at high speed. The students also had the opportunity to experience a two-way satellite contact.
Even a Global Pandemic Can’t Stop Us The restrictions imposed on the students by the Covid-19 pandemic were not enough to stop them. In fact, these unusual circumstances gave them the incentive they needed to go beyond the classroom and seek out an interesting new experience. The availability of easy-to-use. low-cost video conferencing made it possible to achieve the learning objectives while carefully observing the social distancing required in today’s world.
A Brief Introduction to Amateur Radio The students took the initiative to reach out in an effort to learn about ham radio and how it is connected to space and satellites. They came away with new knowledge about an avocation enjoyed by hundreds of thousands of individuals in the US and millions around the world.
Impact on Others After the satellite contact with Don AK2S, I reached out to him by email to tell him ‘the rest of the story’. We spoke for quite some time. I was pleasantly surprised to learn that Don spent his career designing commercial communication satellites, and now works with AMSAT on a variety of amateur satellite projects. Don is a big believer in STEM as an important element in the future of amateur radio. He was very pleased to be a part of this learning experience. As many hams do, Don passed along QSL cards for each of the students.
The US amateur radio community is on the move. Over the past ten years, we’ve seen new Technician licenses issued at a brisk pace. Our newly-licensed colleagues are excited about the opportunities for education, public service and enhanced personal safety that amateur radio affords.
This visualization gives you a glimpse into the ham radio population in the United States – with a particular emphasis on alignment with the organizational structure of the American Radio Relay League (ARRL).
Coronavirus is driving change across everything we do. With it’s April 2020 meeting The Northern Illinois DX Association (NIDXA) went to an online meeting format for the first time in its history. I did the keynote presentation from my home QTH in Massachusetts this past Friday evening April 10, 2020.
We used Zoom, the videoconferencing application that’s taken off in a big way as a result of mandatory social distancing and travel restrictions. As we kicked off the presentation, we took advantage of one of the in-built tools that Zoom offers – polling – to learn a little bit about the audience. Of the nearly 50 participants, we found that all but three – almost 95% – have some kind of regular interaction with amateur radio tower work. Clearly, this was an audience that should care about the topic.
The best indication of whether an online presentation has been successful may be the percent of participants who remain at the end of the talk . . . in this case, we had nearly 100% staying on to the end. It was also a pleasure to receive a few private emails after the meeting expressing appreciation for the information provided. We even got one email asking for an immediate purchase of one of the climbing kits.
A nationwide 5G cellular network is being built out now. The major network infrastructure owners and operators are taking this seriously. As they build up a force of expert tower installers and maintainers, they are committed to safety. Tower climbing can be risky – or it can be safe. The pros know how to make it safe – proper equipment and training are core requirements. Every ham who wants to work with antennas and towers should be paying attention.
During the short time we had to prepare for the show, we planned extensively in collaboration with the show’s producer. At one point, I asked if we could liven up the hour with some audio clips to allow listeners to really experience the sounds of amateur radio. “Sure!”, she said.
We assembled a set of clips that represent a broad range of amateur radio pursuits. But, just two hours before air time, our producer emailed me to say that Bradley didn’t want to use the clips. Ugh!
We were disheartened because we think we really captured sounds that effectively convey the wide range of on-the-air ham radio experiences.
Let’s not allow these clips go to waste!
WBZ and their listening audience did not get to hear these little gems. But, their loss need not be yours, too! Here are the clips we had all ready to go. They’re all pretty short. Enjoy. Don’t miss the last one – contact with the International Space Station.
History: Spark Transmission from Point JudithPublic Service: Boston Marathon CommunicationsEmergency Communications: Hurricane DorianCasual Radio: K1IR Contact with Ukraine on 20 meter bandRadiosport: Hope KM4IPF contacts Moroccoduring international competitionWhere does ham radio take place? Not just in the basement . . . everywhere!The new ham radio is digital. In this clip: ionospheric FT8, moon bounce JT65, meteor scatter MSK144Student-built satellite with Morse code beacon . . . and Doppler shift!Small, battery-powered handheld kit used to make many voice satellite contacts.International Space Station talks to school students in Hudson, NH.
Ham radio got a nationwide boost from Boston-based clear channel station WBZ. Tom Walsh, K1TW, our Eastern Massachusetts ARRL Section Manager contacted me to see if I could help satisfy a short-term request from Jay Talking a WBZ talk show hosted by veteran radio personality Bradley Jay. How could I refuse?
I partnered with Bruce Tinkler N9JBT to fill the hour with some great content. We wanted to convey a broad view of ham radio that captures both its historic roots and current advanced technology and relevance to modern-day STEM initiatives. Cameo appearance by Marty Sullaway NN1C!
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