Posts Tagged ‘portable’

April 2016 trip to American Sa’moa

May 17th, 2016

I had originally planned to make a maintenance and upgrade visit to my instrumentation in American Samoa in February 2016.  There are lots of advantages to February:  It’s cold here in W3, the ARRL DX CW contest is in February, and the phenomenon I’m studying is most active during the equinoxes.  I scheduled a 7-day trip that ended with the weekend of ARRL DX so I had the opportunity work through the weekend or play some radio if work went better than expected.

My flight had been booked out of Washington National (DCA) airport at 5:15 am Monday morning, which is the best possible time of day at the worst possible airport.  A snowstorm of unknown magnitude was bearing down on the mid-Atlantic.  And, around 4:00 pm on Sunday afternoon, I fell asleep on the couch.  When I awoke 90 minutes later, it rapidly became clear that I had a nasty stomach flu.  As my condition deteriorated further, I finally decided I didn’t want to be fighting that for the next 24 hours on 767s on my way to a foreign place where I wasn’t sure what kind of medical facilities I could access.  I cancelled the trip and spent the next 24 hours in bed instead.

The trip was rescheduled for three weeks later in March and I managed to get this itinerary out of BWI, which is much more convenient.  I loaded up my gear and went to the airport at 4:00 am.  My upgrade had cleared so I didn’t pay excess on my overweight and extra Pelican cases.  Hurray for small victories!  We sat at the end of the runway on the tarmac doing the preflight checks and the cabin lights started flickering intermittently.  And we sat, and we sat. And, we returned to the gate and sat some more.  I nervously refreshed the ETA on my phone finally watching the arrival in PHX slip past the departure to HNL.  I deplaned.

The agents tried to convince me that I could “just take the flight to Honolulu tomorrow.”  With some effort, I communicated to them that the HNL-PPG (Sa’moa) leg of my journey only goes on Mondays and Fridays and that I would rather be stuck at home for a week rather than a week in Honolulu.  So, I cancelled the trip for a second time.  My bags went to PHX and were delivered to my house the next day.  I rescheduled the trip for late April with a night in Honolulu on the outbound leg to avoid this bit of bad luck happening twice.

Two days before I left, my local contact called me on the phone to tell me that Tropical Cyclone Amos was bearing down on the island.  Fortunately, the hurricane dumped some rain and brought some winds but passed to the north of island.  The April trip went off without a hitch, although it was scheduled for four days (Monday night – Friday night) instead of the original seven.  So, I was hustling to get my work done and find time for radio.

I was vaguely aware that KC0W is also in KH8, but given my historical bad luck with this particular visit, I didn’t reach out to him.  In fact, he’s the one that contacted me once I arrived.  We met for breakfast at the McDonald’s in Tafuna one morning and had a nice long ragchew about radio and travel.  Typical hams.  I decided to focus on bands (especially 160) that Tom wasn’t on given my limited time on the island.

Fortunately, I had access to this mobile phone tower, which I use for my wireless networking for instruments as well.  So, I climbed up to check on the network equipment and put a pulley on the tower so I could raise and lower ham antennas safely after-hours when no one was around.


The tower is on the top of Cape Matatula, which sticks out of the northeast corner of Tutuila island.  It’s the bit of land jutting out in the middle of the photo below.  If you open the full-size photo, you can see the tower just at the edge of a rather precipitous drop-off toward the rocky shore about 1/3 of the way from the right-hand side of the frame.  Needless to say, it’s a great QTH with 270 degrees of saltwater view as I’ve mentioned before.  At sunrise and sunset, the middle and higher bands are open to EU, JA, and NA/SA all at once.  The pileups are thrilling but very challenging.


Here’s the radio setup from this trip:  K2/100, KPA500, WKUSB, and TRLinux running under VirtualBox on my Mac.  This worked OK, but the WKUSB would drop out every few QSOs and needed to be completely rebooted which meant that I had to unplug the USB cable and restart TRLinux.  Obviously, this worked when I tested it at home but I was not stressing it like I was in the field.  I’m not sure whether it was an RF issue or software/hardware.  In any case, I will probably be installing another Windows VM like I’ve used previously.


I only ended up making about 400 QSOs on this trip, which is way down from the approximately 3000 QSOs I made over the past two trips.  The combination of aggressive work schedule, glitchy keying, and poor 160-meter conditions (too late in the season, but I made a few guys happy), made it hard to get excited about operating a lot.  Furthermore, my operating position was located in a room with an air compressor nearby that would kick on every few minutes.  Even with the excellent Etymotic MC5 earbuds, it was still loud.  Enough complaining!  There will be at least one more trip out there under my present project and if KC0W hasn’t worked everybody, I’ll be there to give you all new counters again.  I just uploaded the log to LoTW before I posted this blog entry.  I have not responded to any direct QSL cards yet.

Making the Palm Mini Paddle Stay Put

March 1st, 2016


In my on-going quest to produce a lightweight yet good-performing kit of portable equipment to carry along on my exotic work travels, I set my sights once again upon the Morse keying paddles.  When I was a student, I carried what I had: a black-base Bencher BY-1.  This caught the attention of nearly every airport security screener and was obviously quite heavy, but it stayed put on the table (for the most part) when I aggressively worked a pileup.  A few years back, my wonderful, loving, and patient wife, solicited suggestions for Christmas gifts and I suggested a Palm Radio Mini Paddle.  (She’s grateful when I provide a link to a web site with a shopping cart in these situations.)

The Palm is really a joy to use and is extraordinarily lightweight, which is perfect for travel.  However, I’ve always struggled with how to keep it steady on a table.  I have the magnetic base, but that presupposes a ferromagnetic surface to which it will mount.  Since both the Elecraft K3 and K2 have aluminum panels, I can’t count on the radio.  I tried a variety of additional things, up to and including, trying to design a 3D-printed carrier that is akin to the Begali Traveler.  So, I shelved the project, only using the Palm key for casual portable operating when mass trumped long-term operating comfort and efficiency.  Good fortune happened upon me and I built this.

When I decided to add an amplifier (more on this in the future) to my portable setup, again pressure set in on the mass of everything.  So, I revisited the Palm Mini project.  I had purchased a number of mounting clips for the key (hedging my bets against the ephemeral nature of ham radio businesses); so, I set out to attach one to the K2.  I’d seen the photo of the base attached to the right-hand side panel of the K2 by the power switch.  But, I really didn’t want to drill holes in the panel, plus that puts the paddles too high when the tilt bail is raised (which is necessary to see the display).

So, I fabricated two strips of 3/16-inch aluminum plate (leftover from the hexagonal beam I built a few years ago) with a hole bored down between them to clamp on the tilt bail of the K2 or the K3.  There’s nothing particularly critical about the construction of it, although I used a Bridgeport mill to do all the cutting; you might be able to do it in a drill press.  I think I ended up with a #14 drill for the clamp hole.  I used 6-32 hardware because I had it on-hand and I like the bigger stuff.  I had to enlarge the adjustment slot in the Palm base to handle the bigger diameter.

Pictures from KH8/K8GU

October 8th, 2014

I don’t really have time to do a full write-up, but I made a “quick” trip to American Samoa over the weekend to plan a future scientific instrument installation and managed to get on the air for a few hours.  Here are some snapshots from my phone.


June 1st, 2014


An annually-recurring professional meeting has started to put me in interesting DX locales.  This year was no different: the meeting was held at UNIS (University Centre in Svalbard) in Longyearbyen, Svalbard.  My friend and colleague, Nathaniel, W2NAF, did a semester of his graduate studies at UNIS and was excited to return for the meeting.  He suggested that the JW5E clubstation “hut” (depicted below) might be both an attractive lodging option for cost, location, and of course, radio.  The hut is a bit rustic with no running water but we did manage to maintain a nearly professional level of appearance and personal hygene due to Nathaniel’s insider knowledge.


As is typical for the kind of travel I do, there was no straightforward way to get from A to B.  Nathaniel and my flight schedules put us into Longyearbyen (via London, Oslo, and Tromso, in my case) on Friday and Saturday, respectively, giving us a shot at the CQ WPX CW contest.  We elected to operate this under our own callsigns, which proved to be a bit of a limitation since for much of the contest 20 meters was the only band that produced rates.  So, we had to share 20m.  Nathaniel operated high power using the JW5E FT-1000MP mkV and Icom IC-2KL amplifier connected to the JW5E antenna system.  I operated low power with my K2/100 and the JW5E antennas.  He came out a little bit ahead on QSOs and pretty far ahead on points, mostly due to the day of head start and effectively exploiting 20m.  I also worked a lot of empty-calorie EU stations while he focused on 3-pt DX stations.  Despite our initial optimism, neither of us were particularly dedicated to a full effort in the contest.  We both had a bit of trouble adapting to polar day and slept through prime openings on Sunday.

40 meters and lower frequency bands were useless, as were 10 and 12 meters. Nathaniel and I did work each other on 160 with the power turned all the way down.  And, of course we worked each other in the contest for an easy prefix multiplier.  The 12m situation was a little disappointing since I know a lot of people needed JW there.  Had we been there in March, it probably would have been open.  I worked two CTs and that’s it.

During the week of the meetings, I only managed 1-2 of hours operating each day, and Nathaniel maybe a little more.  We developed a protocol of uploading to LoTW first thing in the morning when we got to the meeting (where we had free network access, versus roaming 3G on my phone at JW5E).  Since I don’t use ClubLog, this is a good way for DXers to see if they’re in the log and get a quick confirmation.  As I told a DXer who thanked me profusely for doing it, my employment covers the largest costs of my DX travel and my operating is secondary to my work.  Therefore, I feel no need to extract or solicit donations from DXers. I am ordering cards today and they will be ready to mail in a week or two.

On the last night, I put in a solid 6 hours of operating, making about 600 QSOs in one sitting.  30m was always a struggle with most signals right near the noise level.  The other bands (15/17/20) produced big signals and were pretty easy to work.  I’m always a bit slow to operate split because I don’t want to use more bandwidth than necessary.  With an amp, I could probably have operated simplex most of the time.  Usually once people stop coming back to my 599s or they start duping me mercilessly, I know it’s time to split the pile.

The pileups were generally very responsive to my instructions with only one station really raising my blood pressure to the point that I QRT’ed to cool off.  Based on his profile and how loud he was compared to all the stations he was obliterating, he was running as much as 4 kW on 30m.  Good show.

I heard that someone on a DX club e-mail list suggested that I go next to Jan Mayen (JX).  Please negotiate that with my wife and we can work something out. Don’t forget to include that Jan Mayen has one flight per month.  My Norwegian colleagues were amused by this and asked also about Bouvet (3Y).  Only scientists and hams know about Bouvet and Jan Mayen.  Seriously, if I didn’t have a young family, I would consider doing that sort of thing, but I miss them too much when I travel.  The next DX trip will be someplace warmer with regular commercial air service.


I’m still sort of converging on the best equipment for portable DX operating. While I like the K3 a lot, the K2 is a bit smaller.  In its flight case, it fits under all airliner seats and not just some of them like the K3.  Although it is a stupendous performer, the K2 has some idiosyncrasies occasionally cause me to notice that it’s not as well integrated as the K3 and modern JA radios.  The diminutive size and negligible RF emissions from the MRF-4125 switching power supply are big pros, but I noticed the fan making a particularly awful noise on this trip.  Need to look into that.  The K1EL WKUSB continues to be a star performer for computer and hand keying.  While I love the action of the Palm Mini paddle, the lack of a solid base can be frustrating.  I brought the recently-mounted Schurr Einbau and it sang. Although, it produces the best reactions from security screeners: “What is it?  Is it an antique?”  And, my favorite from a screener in Longyearbyen: “Is that the new iPhone?”

The real stars of this operation were the Etymotic Research MC5 in-ear monitor earphones.  Wow.  I’ve been using them for a couple of months now at the recommendation of someone on the Elecraft reflector and they are my new favorite headphones for travel.  They do excellent with noise isolation on long-haul flights and in noisy QTHs; they reproduce music flawlessly; you don’t have to turn the volume up to 11 to hear with them; and they fit in a tiny little pouch that’s smaller than a deck of playing cards.  And the best part?  They only cost 60 USD.

The GU Special came along on this trip but was not needed since I had access to an OptiBeam for 20/17/15 meters, dipoles for 30/40/80, and a Cushcraft R7 vertical for 40-10 meters.  I was tempted to take my gear on the 8-hr boat trip we took up another fjord.  However, I decided against it for a variety of reasons including the desire to do some birdwatching and look for polar bears—we saw some seals and an artic fox but no bears.  The seals and the fox amounted to no more than a couple of pixels in the photos I tried to shoot of them, even with a modest 200mm telephoto lens.  OK, that’s a short lens by wildlife photo standards.  Please accept this puffin photo in place of a bear photo.


And the Tempelfjorden glacier and sea ice shot from my phone…


This photo is looking back up Adventfjorden toward Longyearbyen and shows the JW5E tower right near the water in the center.  (The heftier one on the right.) Also in the background are the dishes for the EISCAT Svalbard incoherent scatter radar.

And a photo from our visit to EISCAT in tracked vehicles.  It was practically June and there was a lot of snow on the ground.


Finally, here are two YouTube videos related to our operation.  The first was shot by W2NAF and has a tour of the JW5E station.  The second was shot by KB9UWU during the WPX contest and shows pretty much what 15m was like for me: the band was obviously open but I didn’t have many callers.


Thanks to everybody who stopped by to say hi.  I worked lots of friends on the air from all over the world and received SWL reports from a few more.

More paddle work

May 16th, 2014

Over the past couple of weeks, I’ve managed to steal away to the machine shop and continue to work on mounting the Schurr Einbau mechanism. I found a piece of polycarbonate in my scrap bin to make the interface between the Einbau and the base. It turned out that the mounting holes are tapped M3-0.5 so I had to make trip to Ace. While I was there, I picked up some brass screws also. Total cost of the project is 52.99 USD. I bored the holes in the base today with the milling machine and tapped them when I got home. Couldn’t resist putting it all together even though I haven’t finished polishing the base or the polycarbonate plate…

MiQP from Ohio

April 22nd, 2014

Sarah, Evan, and I had the opportunity to go to her parents’ place for the Easter holiday weekend. Since the trip coincided with the Michigan QSO Party, I decided this might be a good test of the portability of the K2. Unfortunately, I was unable to operate much longer than a half hour but I had some fun on 40 meters and tried out N3WG’s (Pignology) HamLog for logging. Neat stuff.

The Birthplace of the Wind

September 4th, 2012

I recently had the good fortune (Sarah and some Alaskan friends might question the use of the adjective “good”) to spend about 10 days on the Aleutian island of Adak for work.  In the midst of preparing for the trip, I learned that my fellow travelers Kevin, KJ4OAP, and Nathaniel, W2NAF, were planning to bring ham gear.  Of course, I was as well, so we ended up with quite the merry bunch of hams on Adak.  I don’t collect IOTAs, but I know it’s popular.  So, I checked out Adak Island in the IOTA directory—NA-039, Andreanof Group.  Fewer than 20% had claimed it, so it’s not super-rare, but not super-common, either.  I was assured by at least one friend that we would be very popular, especially in Europe.

One of the first things you notice about Adak when you get off the plane is the wind.  In fact, the locals call Adak “the Birthplace of the Wind.”  It’s actually quite poetic considering that the winds are so strong that you don’t leave furniture outside and that the houses shudder with typical gusts.  I experienced 75-mph gusts and 60-mph sustained winds during my short visit alone.

Adak is probably best known as the forward base from which the U.S. conducted its counteroffensive against the Japanese invasion of Attu and Siska during World War II.  It also played an important role during the Cold War and although the military left some 10 years ago, it retains much of the infrastructure including heavy machinery, a port, and a large airport.  The population shrank rapidly from a peak of just over 6000 in the 1990s to around 150 today.  Just before the military (principally Navy) pulled out, they were in the process of building new base housing.  The housing was completed nevertheless and so there are literally dozens if not a hundred homes that have never been occupied!  Some of the others have been converted into a small hotel (this is where we stayed).

The economy is heavily dependent on fishing and fish canning right now.  However, the locals are excited about the possibility of becoming a logistics hub for oil and gas work in the Bering Sea.  In fact, the aircraft I came out on (An Alaska Airlines 737-400) had an unprecedented 60+ passengers on it because executives from an oil company were coming to check the place out.
Alaska Airlines operates “regular” flights twice per week.

Due to a fiction of time zones, Adak is only one hour behind Anchorage, despite being some 27 degrees west.  So, sunrise and sunset are both very late in local time.  It is also very far south, about the same latitude as Vancouver.  Although I arrived at 6:30 pm, it was still light out for almost another four hours.  So, I quickly put up the vertical on 20 meters just before sunset.

While we were putting up the vertical, Nathaniel met Jeff, KL2HD, who happened to have flown in on the same flight as us and who also happened to have his office and station across the street from my apartment.  Neat.  He works for U.S. Fish and Wildlife Service and they have field sites throughout the Aleutians.  They use HF to communicate with their camps.  So, he just plugs into a well-installed folded dipole to do his hamming.  Have you ever seen a folded dipole installed between two (yes, two) Rohn 45 towers?  Intense.  Wind.

Due to our work schedule (8-10 hours per day plus meals), I often did not manage to get on until 0500 UT at the earliest, and sometimes even later.  But, when I did, I was greeted with a roaring pileup of the “deserving.”  This elicited a little bit of mail from my East Coast friends about getting on the air earlier.  It turns out, however, that for most of the trip, 20 and 17 meters were open to the entire U.S. until 0630 UT.  Both the skimmers and the QSOs bear this out.

Why yes, I did get a new radio to replace the FT-840.  More on this in the future.

It was pretty apparent that I had a lot of callers who couldn’t (for a variety of reasons) copy me.  European friends reported a total lidfest on their end the first night I was on the air, although I learned a lot about pileup control on this trip.  I have great respect for the “real” DXpeditioners who do this from the rarest locations.  This was tremendous fun, though, and I enjoyed working each and every one.  Thank you for calling!

There was one night on 17 meters that I CQed dead air for almost a half hour, making just two QSOs with stateside stations.  And like a switch, the Europeans came in over the pole.  It was incredible: I made 300 QSOs in 2.5 hours that night…mostly Europeans and Japanese.

Oh, one more photo…this is one of our rental vehicles on Adak.  No, your ARES group cannot buy it.  The siren and lights don’t work anyway.

So, I got home on Monday and Sarah is amused by the amount of fan mail (QSL cards) the trip generated.  Speaking of QSLing, the log has been uploaded to LoTW and has already generated about a 25% return rate.  If you worked KL7/K8GU, you can get a nice photo card by sending an SASE or SAE+green stamp to my callbook address.  I also use the bureau.  To this point, Kevin and Nathaniel and I have been planning to share a card.  They are still there for another week (so, if you missed me, you still have a chance for NA-039) and then we will figure out a card and order them.  So, it will be a few weeks until cards can go out.

K8GU/5 Field Day 1B1Op Battery

July 1st, 2012

I found myself in Santa Fe, NM, for Field Day this year to attend a conference. As I have shared before, I have mixed feelings about Field Day, but this was a genuinely good time.  I first checked ARRL’s Field Day finder map and the local club’s web site for activity.  Zilch. So, I remembered staying at the Fort Marcy Hotel Suites on several previous visits to Santa Fe.  These condos are up on a hill overlooking town.  Across the street is Hillside Park, with a couple of scraggly trees that might be suitable for antennas.

Instead of bringing the “usual” portable station, I brought a Small Wonder Labs SW-40, a K1EL K12 memory keyer (assembled especially for this trip), Palm Mini paddles, a 40-meter dipole, and a AA battery pack.  The whole station took up less space in my luggage than my notebook computer and set up in 15 minutes.  I got the dipole center about 4-5 meters off the ground and the ends sloped down to about 2-3 meters high…just enough to allow cars and small trucks to pass under them in the parking lot.  Apologies for the photographs…they were taken with my cell phone (which is a regular old “dumb” phone).

The SW-40 did not appear to be transmitting correctly when I first hooked everything up.  So, I pulled the cover off (packing a Leatherman tool is another good reason to check a bag) and wiggled some wires around until it fired up.  Not an auspicious sign.

But, I did manage to operate for about an hour and make 12 or 15 QSOs.  They’re logged in a notebook, but I haven’t looked at it since making the contacts.  Virtually every QSO was a struggle.  Low power (1.5 watts), wrong band (20 meters would have been better), a low antenna, and the fact that I hadn’t used the SW-40 for any QSOs in over 10 years, conspired to make thing difficult.  Most operators pulled me right out once I was in the clear and zero beat (which I think was a serious challenge with the slightly drifty and definitely touchy SW-40).

My final QSO was with my old radio club from my college days, W8FT.  The operator was my good friend Bill, AD8P, who worked hard to pull me out once he got my call right.  After I packed up, I noticed that I had a missed call on my phone…sure enough it was from Bill.  So, I gave him a call and we talked for a couple of minutes.  “When he answered the phone, he said, `New Mexico?!?!  I told Kelsey (N8ET) that’s what I had copied.'”  We had a nice chat as I hiked back down the hillside into town and he pulled into his driveway after his FD shift.

I don’t think I’ve ever been so delighted with a Field Day effort of so few QSOs (except maybe my first Field Day, which was much more work for about twice the number of QSOs).  Including the walk from my hotel to the park, setup, tear-down, and operating, I think the whole exercise took about 3 hours, and was tremendously FUN.


April 3rd, 2012

Loyal readers know that from time to time, I am fortunate to travel to interesting and exotic locales for work—they usually come in pairs, so Greenland and Peru are it for a while.  Although the motivation is usually field work, occasionally a conference pops up.  The International Symposium on Equatorial Aeronomy occurs every three to four years and can be counted on for an exotic locale.  Sarah had such a good time when we attended the 12th ISEA in Crete in 2008 that she insisted on attending the 13th in Peru with me this year.  Of course, Evan complicated that a bit, and so we evaluated the pros and cons of leaving him with grandparents or bringing grandparents along, eventually finding a willing pair of grandparents to come along.  If you’re interested in a general travelogue (and following posts) and some photographs, you might check out my father’s blogs.  This short post is mostly focused on radio aspects of the adventure.

In retrospect, it may not have been such a good idea to bring ham gear to this meeting.  Between being the most seasoned traveler in my family and the only one with a functional command of the Spanish language, plus Evan, plus hours of meetings and collaborations each day, there was little time/energy to actually operate.  Getting to Peru was uneventful—we took an American Airlines codeshare flight on LAN Airlines via Miama to Lima and got there early in the morning.  Unlike their neighbors to the south, Peruvian Customs is by far the most curious I’ve encountered while carrying radio gear—just a minor headache but Sarah was a bit concerned when they took me away for additional questioning.  I carry modest gear—a Yaesu FT-840, Astron SS-30 (this should be replaced with something smaller, but it’s what I have), WKUSB, Palm Mini-Paddle, the K8GU portable antenna system, and various cables to connect it all up.  After clearing Customs, we boarded a bus to Paracas, where the meeting would be held…

Paracas, which is about four hours’ drive south of Lima, was the site of a major earthquake several years prior and is still in recovery.  The hotel that hosted the conference and a few nearby hotels had all been rebuilt from the ground up since the earthquake.  The city is on a small bay that is protected from the Pacific.  It’s very beautiful—desert sands that go right down to the bay.  After a few days at the meeting, I managed to get the antenna set up.

One of the things that surprised me was an excellent JA opening on 20 meters just after sunrise before I went to breakfast and then the meeting.  I am pretty sure it was a direct-path opening because the signals did not sound like long path and the long path crosses the southern auroral oval, whereas the direct path does not.  (Auroral absorption, by the way, is one reason that the long path can be more effective than the short path.)  Any time I called CQ as OA5/K8GU, I was greeted with a roaring pileup.  Not bad for an antenna propped up on my veranda.  Verticals on the beach rule, and this one wasn’t even really on the beach.

At the request of a friend, I made a special effort to operate on 12-meter CW in the afternoon.  The portable antenna would not tune up on 12 meters with the wire radials I had laid out.  In a moment of desperation, I assembled some extra pieces of my portable antenna to produce a tuned radial that I clip-leaded to the ground lug as depicted in the photo above.  It worked right away and I was quite popular there as well.

A comment about computers—my standard work-issued computer is a MacBook Pro, which although perfect for my work, is essentially useless for amateur radio.  I know this will generate a torrent of discussion, but if you are accustomed to real contest/DXpedition logging software available for DOS and Windows, you know that the stuff for the Mac doesn’t cut the mustard.  I have logged DX operations on paper (CE/K8GU), or in the case of the OX/K8GU operation, brought along a second computer.  However, in a long-delayed flash of insight, I bought and installed VMware Fusion on the Mac in February.  It runs Windows XP and TR4W with the WKUSB just brilliantly and with no special configuration.  Aside from having to press Fn+F1 to CQ, this was an epic win.  KB9UWU tells me that there’s an option in VMware to eliminate this nuisance as well.

After the meeting in Paracas, we returned to Lima, where we celebrated the 50th anniversary of the Jicamarca Radio Observatory.  The cornerstone of the Jicamarca facility is a 49.92-MHz radar that feeds an 18,720-element phased array, pictured above.  Jicamarca is one of the most powerful radio transmitters in the world, capable of 4.5 MW output, and is used for a variety of atmospheric, ionospheric, and space science experiments.  Like Arecibo, it was originally designed to perform incoherent scatter measurements of the ionospheric electron density profile.

Lots of fire in that wire!  Have you ever seen a coaxial cable that’s rated for over a megawatt at 50 MHz?  This is the feedpoint of the phased array.  There are a few tuned stubs in there, too.

Here’s one of the four 1.5-MW transmitter cavities.  A maximum of three are used together.  When configured for three transmitters, the driver stage puts out 7 kW!  Needless to say, everything is custom made on site.  The transmitting tetrodes (8973s, if I recall correctly) are refurbished by the manufacturer as needed.

After Jicamarca, we went to Cusco, which is south and east of Paracas, and much more lush than the deserts around Lima and Paracas.

We spent a lot of time being tourists in Cusco and vicinity and I had some difficulty with my computer so I only made a handful of OA7/K8GU QSOs from Cusco on 17 meters.  It is quite remarkable how much better the bands were from the coast.  As someone who has operated from W3, W8, W9 and W0, I can attest to that difference as well.  I missed my morning JA run…

A final thought—we drove through a lot of towns and communities in OA4, OA5, and OA7, on this trip.  Nearly every town, no matter how small, had at least one building with an HF fan dipole on the roof.  HF is alive and well in a mountainous country like Peru!

QSL information:  If you worked OA5/K8GU or OA7/K8GU, the best way to get a confirmation is through ARRL’s Logbook of the World.  I have been responding to direct cards (to my FCC address) with a one-day turn-around lately.

A Portable Vertical Antenna

March 23rd, 2012

With the loss of my preferred frequent flyer status, airlines tightening their checked luggage allowances, and the addition of another traveler to the family, I’ve been contemplating a new portable antenna that is easier to pack than my usual DK9SQ mast and dipoles.  I don’t do high-priced reduced-size antennas if at all possible since portable installations usually have other efficiency-reducing problems.  Multi-element antennas take up additional space and have feeding and installation complications that are unnecessary for the casual DX operator.  So, that leaves us to choose between a vertical and a dipole.

A few words about efficiency:  Dipoles have a distinct efficiency advantage over verticals in almost every practical installation for 40 meters and up, except when the vertical is physically placed in or over salt water.  Radiation efficiency tends to be dominated by near-field conditions, pattern is dominated by stuff that’s farther away.  This is why vertical dipoles work so well for long-haul DX when placed within a few wavelengths of salt water.  They don’t need the near-field efficiency enhancement as much as base-fed verticals, but they still leverage salt water for developing their far-field radiation pattern, especially at low angles required for long-haul communication.

I’m a casual DX operator, not a DXpeditioner, so I never operate on 160 or 80 meters.   That is, considering the discussion above, why I have been using dipoles with the DK9SQ.  But, verticals have a distinct advantage over dipoles in the sense that they are self-supporting.  I decided to build a vertical because: 1) my next DX trip would include time near a beach and 2) I wanted to be able to bring my own support as I had with the DK9SQ.

My remaining requirements were now simple:

  1. A vertical antenna that requires no additional supports.  Guying is OK.
  2. The antenna must be full-size (quarter wavelength) on 40 meters and above.
  3. Experience has shown that multi-band operation is desirable, but instant band switching is not necessary.
  4. The longest piece must fit inside my suitcase (20 in / 50.8 cm maximum length).
  5. Field assembly and repair with only a Leatherman tool.
  6. Minimum cost, minimum weight, minimum volume, minimum installation time.

And this is what I came up with:

There are 21 aluminum sections, most with a “swaged” (actually, a poor-man’s swage to be described in a moment) end and a slit end.  They are shown here bundled perfectly inside a section of cardboard shipping tube.  An 18 x 2.5 x 0.125-inch aluminum plate serves as the base.  I used DX Engineering resin support blocks to insulate vertical from the base.  A point could be fashioned on the bottom of the base and a foot plate attached to push into soft soil, but that has not been done.

Most sections fit together using overlapping joiner pieces that I previously referred to as “poor-man’s swaging.”  I’m not sure that it’s actually a savings over paying a local shop to swage the ends for you when time is considered in addition to material, but I cut telescoping pieces six inches long and fastened them three inches deep in one end of a 17-inch section of tubing with two offset and orthogonally-placed aluminum pop rivets for a total length of 20 inches.  This geometry not only fits in my suitcase, but results in a very small amount of wasted material as well.

The other end of each piece is slit about 2 inches and they mate with an all-stainless steel hose clamp.  The first 10 feet of the antenna are 0.75-inch 6063-T832 tubing followed by telescoping sizes down to 0.375-inch at the very top.  The transition pieces are a full 20 inches long and are slit on both ends.  The full-size antenna will stand in a light breeze, but guying is a good idea.  Guy rings are fashioned out of flat washers drilled in three places.

Tune-up is easy…the more radials you use, the less critical their length.  After about 8 or 10, you’re in the clear here.  I never attached enough to prevent them from affecting the tuning.  If you only plan to have a couple of radials, go ahead and cut them to 1/4 wavelength (even though ground proximity will detune them).  Then, set the length of the antenna using the required number of 17-inch sections (the 234/f formula is surprisingly close) with the last section being a variable length for fine tuning.

I’ve intentionally left out most of the details of the antenna itself because I don’t expect anyone duplicate it exactly.  But, here are a few notes for anyone considering building one themselves:

  1. There are lots of parts vendors out there.  McMaster-Carr and DX Engineering will get you there in one order from each.  There is a surprising amount of overlap in their inventories.  Get the hose clamps from McMaster…even if you get stainless-stainless (stainless band, stainless screw), they are about 1/3 of the DXE price.  On the other hand, the resin support blocks are cheaper from DXE.
  2. I carry a compact antenna analyzer (Autek Research VA-1) with me.  Field tune-up is a snap and it runs on a single transistor battery.  It’s about 1/4 the size and weight of an MFJ-259 and good enough for amateur work.  Oh, and I bought mine used for a fraction of the MFJ.
  3. A tubing cutter is fine if you only have a half-dozen or so cuts.  But, if you have a chop saw or need an excuse to buy a chop saw, it will make cutting the tubing far easier.  My hands were raw for a few days after cutting the tubing by hand.  I’m sure the antenna performs better on account of it, though.
  4. Find a friend with a metal-cutting bandsaw to slit the ends of your tubes.  I went through a half pack (McMaster mega-size pack) of cut-off wheels for my rotary tool doing my slits.
  5. McMaster only sells the aluminum plate in 36-inch pieces.  If you don’t have the aforementioned chop saw, an angle grinder with a cut-off disk does a surprisingly good job.
  6. I pack a combination-screwdriver that has hex drivers that fit the hose clamps and #6 nuts.  Even though the antenna can be erected with only a Leatherman tool doesn’t mean it has to be.
  7. The small parts box shown in the top picture holds all of the parts for the antenna—it was 2 USD at Home Depot.
  8. The final and most critical component is a clip-lead that can be used to attach various nearby metal structures to your ground plane.  I have used it to make a temporary radial out of excess tubing sections on 12 meters as well.

That’s it.  The antenna goes up in a few minutes, especially if not used at full length.  I used it successfully last week as OA5/K8GU, which will be detailed in a future post.