Field Day Antenna Plans

aerial photo of the field day site with antenna and ropes superimposed
80/20cw is at lower, righthand corner

Several of the people involved in planning for the VWS field day event came over to my house on Wednesday evening to brainstorm about antennas and setup for the 80/20cw station. By the end of the evening, we had run through quite a few possible configurations, some fancier than others, but in the end we decided to use two dipole antennas. I’ve updated the map showing the layout. Ian’s Buckmaster OCF dipole will run roughly East/West, between ropes suspended from the tree at the top of the hill next to the 80/20 SSB station, and to a tree across the road on the other end.  To help support the antenna, a 40′ double-guyed pole will be positioned near the 80/20cw tent. The same pole will also support one end of a multiband dipole oriented more or less North/South. Between the two antennas, we should have broad coverage (10-80m on the OCF, and 40/20/15/10 on the multiband).

At the station, we’ll have two radios, but only one will be used for transmit (according to the 2011 FD rules, class is determined by number of transmitters). Byron has made available his TenTec Argo VII transceiver, which I believe has been used in previous years as well. At the other position, we will have Jim Nagle’s ICOM 7000. If we have adequate staffing, the other radio can spot, populating the band map, while the other runs a frequency. After the bandmap is full, the second position can efficiently S&P the marked sites, while the other position marks another band.  Since all the band map information is shared on the LAN, we could also mark spots on 40/15, if desired.

I’m still looking for some CW operators for the 80/20cw station — if interested, sign up online or email me.

VWS Field Day 2011: 80/20 Station Planning

It’s about two weeks until Field Day. I’m captain of the 80/20 cw station, and I’m trying to pull together plans for the station. The club has done this event many times in the past, and there is plenty of experience to tap into, which is good, since this is my first time running anything at Field Day. Pete K6BFA is the top boss for the event, but there are a large number of people involved in logistics. A large chunk of the planning took place last month during a walk-through at the site, Burke Lake Park (see map of proposed station locations and antenna deployment). Due to work commitments, I was out of the area on that day, and on every weekend since then. Earlier today, I had a chance to scope out the site for myself. Tomorrow night, I’ve invited people who have signed up to work the station during the contest plus a few members of the planning committee over to my house to talk about antennas for the 80/20cw station, but I wanted to get the lay of the land before the meeting.

The present plan is relatively limited — to run a long wire antenna from a mast near the 80/20 station to a tall tree. It sounds like this would be reasonable for the 80m, although maybe not optimally high near the station end. I’m not sure it would work well for 20m. We have a number of other antennas available to us, plus a push-up 40-foot mast. Also, the station is near the spider beam, which is designated for the ssb station, but perhaps could be shared (?). In pow-wowing about antennas tomorrow night, my goals are:

  1. Put up a single and reliable antenna so we are ready to go when FD starts.
  2. Not interfere with the other stations.
  3. Lay out a strategy for best use of our resources at different times during FD.
  4. Incorporate any experimental suggestions that are not likely to interfere with #1-3.

I went to the site of the 80/20 station, and spun around, capturing the landscape around the site with my cell phone’s camera. The site is a bit lower then the surrounding area, and there is a slight grade upwards to the west. I am initially facing west. At 0:03 seconds, facing the non-40SSB. At 0:06, facing 40/15SSB support tree. At 0:09, facing the tall tree planned to support? the 80/20. Another potential support tree is masked in background at around 0:11 seconds.

I also took some still photos, thinking about trees that might make good antenna supports. Starting with the current plan, there is a really tall oak tree just across the road to the East, in the direction of the minigolf course. We could use a 40 foot mast towards the station end to give it some height. I counted 132 paces over to the tree, so something like 130 meters. A view towards the big oakAccording to the layout picture on google maps, the antenna is about 160 feet, and the support rope about 185 feet (but considerably longer in practice, since it has to go up to the top of the tree and the antenna wire will slope upwards, so not all of its run will contribute to the horizontal distance).

The advantage of this layout is that it should be dead simple to set up. An ICOM AH-4 antenna tuner would be at the tent, tied to a ground, and the single long wire would run up to the mast and then over to the tree.

A number of people have volunteers other antennas for the effort as well, including Ian N0IMB’s Buckmaster OCF dipole, my G5RV, or Byron W4SSY’s 80/20 fan dipole. Of these, the fan dipole may be the most attractive because it is resonant, and perhaps to least likely to interfere with other nearby stations. The difficulty with these antennas is getting the feed point near the 80/20 station.

 

There is another large tree to the South of the large oak, pictured above. On the aerial, the tree is just west of the run of three smaller trees near the road:Another large tree

 

 

A large tree at the top of a slight gradeThe other end of a dipole could be suspended from the large tree just up the hill from the station. According to the site layout, this tree would also support an antenna for the non-40 ssb station. The tree could be used to support a rope, so the two antennas would not be so near each other. Additionally, the two antennas would be near right angles to each other. This end of the antenna would also be near the spiderpole, though, so perhaps that would be a problem.

A view across the field towards the taller trees in the eastLooking eastward from the site of the non-40 ssb station, the “long wire” tree is to the left, and the tree proposed as the other end of the dipole is on the right in the background. Closer, the trees on the right are the site for the 80/20 cw station, so the dipole would run in a straight line past the station, requiring a 50-100 foot feedline if we played it right with the ropes on each end.

In addition to these antennas, Byron has volunteers the use of his 20-meter Moxon, which has been used several previous times at Field Day. John K4US has also made available a 40 foot push-up mast. We’ll have to figure out how to best use all of this equipment tomorrow night.

Guess I should get some soda and chips for tomorrow night…

QTH Cambridge

Two HR yagi antennas on teh roof at MIT
Yagis over Cambridge

I spent this weekend in Cambridge — not the one in the UK, the one in Massachusetts. I was there primarily for work, and spent many hours attending meetings in hotels, but I also had some fun. My hotel was right at the Kendall/MIT stop, and I had a good view of the campus from high up. I didn’t bring a radio  — there wouldn’t have been much point considering the state of the ionosphere after a solar flare towards the end of last week —  but I did spot a nice antenna from my hotel room window and trotted over to investigate. I assume this multiband HF Yagi belongs to the MIT Radio Society, which is one of (if not the) oldest college stations in the country.

On Friday, I had some time before meetings started, so I walked over to the MIT museum. I spent about three hours there, mostly entranced by the kinetic art exhibit — like Calder, but more gears and motors. I easily could have spent twice as long. I didn’t think the robotics exhibit would be so interesting, but with the actual prototypes on display, you could look under them, around them, see how they were put together, etc. They also had a huge exhibit on technology developed by alums from the Institute, including technological breakthroughs such as transistors, vacuum tube-switched magnetic core memory, even mechanical integration machines.

I had hoped to run into some of the IF crowd, but I was a day early for the monthly PR-IF meeting, and my flight times were too tight to make Sunday’s Grue Street meeting. Next time.

While I didn’t get any IF written on this trip, I did spend a lot of time in planes and airports, so I did finish the character sheets for RileyCon 15. I also worked on the rough draft of the main event. This is going to be a busy month for both me (talk at Cold Spring Harbor, running the 80/20 CW station for Field Day) and Mark (usual lab work plus five grants cooking on the barbie), so I feel a bit better having made some start on this material.

Chicago, Boxen, and Heil

A view out the window of the Marriott Courtyard downtown hotel. In the foreground: a tentec 1320, straight key, and Hendricks SLT+ longwire tuner
A view towards the lake

This week as the American Society of Clinical Oncology’s annual meeting in Chicago, and I spent five days just north of the river, at the Marriott on S. Ontario Street. When I arrived, I was quite excited to see that my 23rd floor window opened ever so slightly, meaning I could get an antenna out. For the next several days, though, I was busy around the clock, and only on the final day did I get a chance to try to operate from the hotel. As seems to be a trend with these hotel operations, it failed miserably.

The rig was the TenTec 1320, so I was looking at day time operation, but I had a slight problem – the side of the hotel was white and my antenna wire was black. I wasn’t so much worried about someone noticing my antenna from the street level, after all, 30 feet of black wire up about 200+ feet is pretty difficult to see, but I was worried about neighbors hearing something tapping at their window and then seeing the black, insulated wire dangling. One good pull, and various pieces of my station would be headed towards the pavement.

There is a Radio Shack on Michigan, just south of the river, and as Ben informed me, they are unusually competent. I walked in, asked for antenna wire, and they knew where it was!

When I got back to the room, I figured that since I was so high up, I might as well put up as long a wire as possible. I doubled the 31.5′ length recommended by the SLT+ tuner manual to make a full wave longwire. It would have been nice to have had a tape measure, but I was able to work it out in multiples of 8.5 and 11 inches, which was doable with what I had on hand. I weighted the far end down with a ring from a keychain. I ran the counterpoise wire along the floor of the hotel room, and yes, tripped over it several times.

I looked around for something to protect and insulate the wire as it passed through the window sash, and decided that one of the throw-away ASCO newspapers could be rolled into a tube, and would help get the wire a little bit away from the building.

Not far enough, though. Although I had two of the elements of the magical formula for antennas (lots of wire, high up), I think the wire’s proximity to the building killed it. I was able to tune the antenna to fully extinguish the LED on the SLT+ tuner, indicating a good match, but being near the metal structure of the building effectively shielded the antenna. I heard few cw conversations on 20m in the morning. Granted, it was a weekday, but even so, the signals were not loud. I tried calling CQ for a while, but no responses. Now that I’m back in Virginia, I’ll need to double check the radio to make sure it is transmitting correctly, but I’m pretty sure it was the antenna and not the radio.

two large cardboard boxes awaiting unpacking
Total weight: 50 kilos.

I got back late Tuesday night, and had two large boxes waiting for me when I walked in — the equipment that I had shipped out to Operation Sizzling Pork. Tymme had shipped it two days before. Score one for UPS Ground service (and Tymme’s professional-grade packing skillz).

Not really related to any of this travel, but still along the lines of amateur radio, on the way to work yesterday, I noticed that Bob Heil had produced three episodes of the “Ham Nation” podcast. I had enjoyed his interview with Leo Laporte on Triangulation a couple months ago, and I had heard in subsequent weeks that they would be working on a ham radio-specific show for the Twit network.

As much as I appreciate the effort, I can’t say that the first few shows have, pardon the expression, resonated with me. The show may need some time to find itself, but I think it needs more structure. I wonder if it wouldn’t work better to have two hosts, one of whom is not an expert and could ask the questions that might be occurring to the audience. The show also needs to figure out what audience it wants to address. The other shows on Twit presume a sophisticated audience with knowledge of the field (e.g., Security Now), but there is something of a proselytizing aspect to Ham Nation. There is a huge audience of people worldwide who are already hams, and these are the people who most likely have sought out the show (and, from a commercial aspect down the road, probably the best target audience for ham-related ads).