Dayton 2013 Recap

May 20th, 2013 by k8gu No comments »

dayton_big_dish

Some good planning on Sarah’s part yielded a bridal shower for her sister scheduled on the same weekend as the Hamvention.  Huge win.

  1. Speaking of huge wins, there was no sewer back up this year.
  2. Like the last time I attended in 2011, I’m pleased to see more younger (than me) hams in attendance.  A high-ranking ARRL official noted to me the “energy and enthusiasm” present in this generation of young hams that was not present 15 years ago (this year marks my 20th year as a ham, but I didn’t mention that).  Attendance was still thin compared to my first visit in the mid 1990s.
  3. Deals.  I stimulated the economy by purchasing a small CDE rotor for my VHF activities, an HP server power supply for a future solid state amplifier project (>55 amps at 50 volts), a couple of 900-MHz antennas, and some miscellaneous small parts.  I sold some junk to partially cover that expense.
  4. People.  Ran into a lot of old friends and made some new ones.  This is really why I go to Dayton, well, that and the junk.  K8MFO tells me there are Bureau cards coming.  W8AV has 930s for me to work on.  W2NAF had people for me to meet.  AD8P was able to win himself a pizza from an unnamed W5 in the “SB-200 challenge” of correctly differentiating an SB-200 from an SB-220 at a distance of 20 feet—a tribute to the W5’s failure to distinguish the two until after the sale last year.
  5. W2NAF has written an article about our trip to Adak (NA-039) that was published in the June 2013 issue of CQ.  It has a lot more background detail than what I wrote on the blog.  Check it out.  I picked up a copy of that and the May 2013 issue which has the 2012 CQ WW CW results in it.
  6. Products.  I just don’t care that much about new products.  The Ten-Tec Rebel that several people have already discussed is a cool idea.  I know that Ten-Tec took some flak for not opening up the Orion SDR core when they produced it.  But, let’s be realistic, people.  Hams would have bricked those suckers in a heartbeat.  A sandbox “open source” radio is a step in the right direction, but I question what a ham can really customize that matters without screwing it up.  Maybe I’m just not visionary enough.  Almost 10 years ago now, I interned in the R&D lab at a large consumer appliance manufacturer as an undergraduate my supervisor was always saying, “How can we make this attractive to the [hardware] hackers?”
  7. Guns.  The Hamvention web site was very specific that the Trotwood Police Department would be actively enforcing Hara Arena as a non-gun zone.  Seriously?  It’s a ham radio convention.  Bill Goodman is there at least once a month the rest of the year.  Do hams bring their go-kits to gun shows?  They must.  Inquiring minds want to know…
  8. Suites.  I did not do the contester suite thing.  Was thinking of going on Friday night but fell asleep in my in-laws’ living room.  This is a recurring problem when I visit so no one bothered to awaken me.

Was the trip worthwhile?  I think so.

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W3APL/B 903-MHz beacon

May 7th, 2013 by k8gu No comments »

Late last Summer, it came to my attention that the 903-MHz W3APL beacon had gone off-line.  The failure was intermittent and seemed to resolve itself after power was reset.  Several efforts to troubleshoot it were undertaken by myself and others, including running it at high duty into a dummy load over a period of days.  I was unable to get the problem to manifest itself on my bench.

A synthesized source (Analog Devices demo board) was offered by a friend of the Club, however it did not produce the desired output (or any output at all).  It’s not clear whether this was the fault of the synthesizer or the user (me).  The notional plan was to replace the beacon, which consists of a 75-MHz crystal oscillator followed by 12x of multiplication and a small RF power module, with the synthesizer and a new RF power module.  The project languished, as they often do in my hands.  But, two weeks ago I picked up the task again and made some real headway.

Really, the failure had to be one of a couple of things:  1.  Intermittent connection exacerbated by thermal cycling.  2. Oscillator “unlock” due to component aging and thermal cycling. I reasoned that as long as we could eliminate #1, the multiplier chain and amplifier should be fine.  The behavior seemed to point toward #2 or perhaps a combination of #1 and #2.  I came across a forlorn Programmed Test Sources PTS-040 that I had rescued from another group’s surplus heap to put in my lab.  I hadn’t used it in the two years that it was in my possession, so it seemed logical to provide it to the Club on a long-term loan.  The problem was that it didn’t go up to 75-MHz.  So, I cooked up a little multiplier chain.  My “good” HP spectrum analyzer is on-loan to a paying program so I had to make do with the FFT function on the fastest Tektronix portable scope I had in the lab.

My initial effort at the multiplier chain was to build a 2N3904 amplifier that swung way into saturation producing a signal rich in harmonics.  I went straight away for the 903-MHz signal but I couldn’t get a good enough lumped-element filter to eliminate the adjacent harmonics.  So, I tried for the 75-MHz injection.  This demanded a buffer amplifier so I lazily reached for the MMIC drawer in and retrieved one of the plentiful MAR-8s.  Plenty of gain…and, as I would find out in a moment…conditionally stable!  To exercise the eloquent euphemism of Ben, N3UM, the MMIC “burst into song” at about 63 MHz.

Back to the drawing board.  I knew that I had something that would work, so I redesigned the deadbug layout on an SMD protoboard (the kind with all the pads in a grid).  I replaced the discrete 2N3904 and MAR-8 MMIC amps with SGA-4586Z MMICs (which are a little too nice for this service, but I have a ton of them).  Viola!

w3apl_b_903

It’s the little board on the far wall of the diecast box with the SMA connector on the left and two toroids.  37-MHz RF comes in from the PTS-040 through the BNC jack in the wall.  It’s multiplied up to 75 MHz on the new board and piped down to the remaining 12x multiplication and amplification stages before going to the little brick PA in the lower left (not visible).

So far, it sounds good.  I was able to monitor it with my W1GHZ transverter strapped to the IC-290A in my car and using a WA5VJB cheap Yagi tossed in the back seat.  I lost the signal about 5 miles away with that setup, which is really pretty decent all things considered at that frequency, etc, etc.  Nominally, the frequency should be 903.054 MHz.  I found it at about 903.048 MHz on the lash-up.  Brian, ND3F (aka N3IQ/R) reported that he found it at 903.046 MHz with KA3EJJ’s setup.  If you’re in the vicinity of FM19ne and are setup on 902/903, we’d appreciate a report.  The big thing is the long-term stability.  So, we’ll continue to monitor it.

Now…to get back to that 930 on my bench…

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More Hexbeam

February 25th, 2013 by k8gu No comments »

hex-gym

“What have you done to my play set?”  This gym made a convenient place to string wires, etc.  Two poles in the photo form part of the EWE RX antenna here at K8GU that was hastily erected before the NA Sprint CW.  One of the poles is ty-wrapped to the play set.  Doing my best to keep it klassy and impress the neighbors.

hex-up

And, we’re up in the air!  The M2 9M2SSB is a little bit out of alignment due to the hex getting tangled in one of the antennas that it was due to replace.  I have already realigned that.  So far, the antenna seems to have useful front-to-back.  Gain is hard to tell since I took down all of the antennas it was to replace.  But, it does seem to work.  I’m suffering from high SWR (above 3) on both 21 and 50 MHz.  G3TXQ warns of interaction between 18 MHz and 50 MHz.  Do not yet know the cause, but I’m looking into it.

Although the antenna is relatively easy to handle, I don’t plan to make a habit of taking it down for work.  Speaking of taking down, the 40m dipole whose center insulator is just visible behind the reflector of the 2-meter beam will be replaced by an as-of-yet-secret antenna.

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Hexbeam Photos

February 12th, 2013 by k8gu No comments »

  

Construction project:  G3TXQ hex beam built from scratch.  K4KIO directions with K8GU modifications (and reverse-engineered square coaxial center post).  Details to follow once I determine it works to my satisfaction.

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The Elecraft Effect

February 9th, 2013 by k8gu No comments »

Heard this on the radio the other day on my way to work.  Does it explain, at least in part, the popularity of Elecraft products?

In other news, the blog has been silent for a while, but that doesn’t mean things haven’t been happening.  I have a couple of challenging projects that have been taking up the usual blogging time.  Stay tuned!

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New Radio Thoughts

November 19th, 2012 by k8gu No comments »

As I mentioned in a previous post about my trip to the Aleutians, I am the owner of a new radio.  The reasons for the purchase were manifold, but driven by a fundamental shift in the way I view my operating (and living) philosophy.  I had long (at least 10 years) been collecting gear for a two- (or three-) tower contest station.  In this philosophy, the emphasis was on collecting antennas and towers as they became available on attractive terms.  It also meant keeping the inexpensive but well-performing pair of TS-930S HF transceivers for my SO2R setup and the FT-840 for my portable operations.  You can imagine from those past few sentences of description alone that this consumed a non-trivial amount of space and time.

Sarah began subtly hinting that “wouldn’t it be nice if we could clean up that pile of tower on the patio so we could have people over?”  My parents have been slowly migrating my junkbox from their place to ours.  It became increasingly clear to me that as long as we lived in this area it would be unlikely that I would put up the towers.  I started contemplating how to remedy this situation.  I identified a large collection of gear (including the Rohn 45 on the patio) that 1) could be replaced by a new radio, 2) I was not using, or 3) for which I simply did not have a plan.  So, I set out with the following theme to find a new rig:

Excellence in portable operation and competence at home.

I considered four radios:  Ten-Tec Eagle, Kenwood TS-590S, Elecraft K2/100, Elecraft K3/100.

I was strongly considering the K2/100 initially.  Its size and price seemed attractive.  However, when I did the math on what configuration I wanted, it basically ended up a draw with the Kenwood and the Ten-Tec with only a small bump more to the K3/100.  Plus, I’ve built enough kits to know that many of life’s most rewarding tasks tend to look better in the past than they do in the future.  Personal preference, of course!

The Kenwood TS-590S is acclaimed by a number of contesters as “the poor man’s K3.”  It has very similar features and performance numbers at a very attractive price.  I have always enjoyed Kenwoods as well.  But, the one thing that ultimately killed the TS-590S and the Ten-Tec Eagle was their lack of BCD band-data outputs.  The K3 also offered the 2-meter option, IF output (for panadapters), and very easy transverter interfacing.  It was really a no-brainer for me at that point since I had sold off enough gear to cover the cost entirely.

I bought the K3 kit and assembled it.  Anomalies notwithstanding, it amuses me greatly when people announce to the Elecraft e-mail list that “K3 #7777 is on the air”…it’s hard to keep from responding, “Congratulations on assembling your first LEGO kit.”  Unlike the K2, these “modular-kit” radios are very easy to assemble if you have a few hand tools and can follow basic directions.

My friend Oli, DJ9AO, informally asked me to compare the K3 to the TS-930S.  I’ve tested (subjectively) the K3 in a couple of demanding environments and I’m pleased to say that the K3 performed well, even with essentially “factory default” settings.

The K3 wins hands-down the strong-signal handling contest, even with the Inrad roofing filter in the TS-930S.  40 meters in ARRL Sweepstakes CW is a good test for this.  The FT-840 used to have severe mixing products (“beeps and bloops”).  These are not common with the TS-930S, but severe AGC pumping from nearby signals often covered up weaker signals.  Neither of these are problems with the K3.  In fact, the K3 is so good that you can tell just exactly who has key clicks because it’s possible to find two signals of otherwise identical strength on the S-meter and one will be inaudible within a few hundred Hz and the other will continue to bleed through and pump the AGC.  Well-done, Elecraft.

One thing that surprised me about the K3 was its apparently poor performance on the pileups from NA-039.  With the BW cranked down to 400 Hz, the filters rang like a bell in a pileup.  I have the 400-Hz 8-pole and 2.7-kHz 5-pole filters.  Widening the DSP bandwidth out to 700 Hz or so (which switches to the 2.7-kHz roofing filter) alleviated the problem with occasional AGC pumping from louder signals in the pileup.  In a post to the PVRC e-mail list recently, Frank, W3LPL, also confirmed that he prefers the 1-kHz 8-pole filter for CW operation.  Because I had the opportunity, I recently sprung for the special-order 700-Hz roofing filter.  It should arrive in March 2013.  I suspect there is considerable tailoring that could be done to the AGC system but I’m not there yet.  Once I realized that the bandwidth of 700 Hz was a sweet spot, the radio worked great in the pileups.  I have a feeling that I’ll also end up with the 1-kHz filter eventually.  But, I rarely open up beyond 700 Hz on CW so it will be interesting to see what is best.

A few other bright spots:

  1. CW-to-Digital:  This is just plain cool.  Send with the built-in keyer and the radio modulates PSK31 or RTTY for you.  Decode it right on the screen.
  2. Multifunction knobs:  The entire industrial design of the K3 is really unmatched in my opinion.  It has just the right number of knobs and menus.
  3. Options:  They are plentiful and easy to install.  Keeps the initial cost low(er).

I’m extremely delighted with the K3 so far and my shack is getting more compact.  It’s also nice to have a radio with a built-in keyer for once…

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The Birthplace of the Wind

September 4th, 2012 by k8gu 2 comments »

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.

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Aurora 15 July 2012

July 16th, 2012 by k8gu No comments »

I was enjoying a leisurely sweltering summer Sunday afternoon in the back yard with Evan, Sarah, two Adirondack chairs, a kiddie pool, and the schematics for an IC-290A I have on the bench.  I came in to get a glass of water and while I was inside, I checked my e-mail (since I have some equipment for sale).  No prospective buyers, but I did have a message from Sean, KX9X, that he was working aurora on 6 and 2 meters.  I quickly plugged in the 2-meter rig and swung the beam around to the north.  Sure enough, there were raspy aurora signals all over two meters.  I quickly put N9GX (EN60) in the log for my first ever aurora QSO.  This was at least as cool as working K5QE on 2-meter Es with 10 watts.

So, I fumbled around a drawer and pulled out a cable to connect the TS-700S to the computer and fired up Audacity.  I made this interesting recording of KA1ZE/3.  I started out with the beam to the NE (45 degrees azimuth) with a strong auroral buzz on Stan’s signal.  Then I swung the beam around to the NNW direct path (345 degrees azimuth).  I’m in FM19la and he’s in FN01xt, which is exactly 200 miles (322 km) direct path.  On the direct (forward tropo scatter) path, there is still a hint of aurora, but the tone is a bit purer.  When I turn the rotor there is pretty bad hum from a (not unexpected) ground loop.

In order to better visualize a few things, I ran a short-time Fourier transform (this is the actual technical term for a “waterfall”) on the audio file.  I need to code-up a polyphase implementation of the FFT like that used in Rocky, but there are only so many hours in a day.  Click on the image for full-size.

There are lots of interesting details here.  First, you can see that the auroral scatter is both Doppler-shifted (lower in frequency) and Doppler-broadened (spread out from the central frequency) compared with the direct tropo scatter signal.  Second, you can see the ground-loop-induced hum at the low-frequency end.  Auroral backscatter comes from field-aligned plasma density irregularities embedded in the auroral convection flow.  Because most readers will be allergic to the vector math, we make the (somewhat gross) approximation that KA1ZE and I are transmitting and receiving from the same location.  Now, we can take a stab at estimating the flow velocity from the following equation:

Where delta-f is the Doppler shifted frequency (about 300-Hz from these data), c0 is the speed of light (300,000,000 m/s), f is the carrier frequency (144 MHz), and vflow is the flow velocity.  While we’re making approximations, if we round f up to 150 MHz, the twos cancel and we get the Doppler shift of 300 Hz corresponding to a flow velocity of 300 m/s (670 mi/hr).  Fast!  Because it is lower in frequency than the direct signal, we can also infer that the flow was directed away from us.

There you have it!  Science fair projects with your ham radio.

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K8GU/5 Field Day 1B1Op Battery

July 1st, 2012 by k8gu 1 comment »

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.

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2012 WPX CW contest

May 27th, 2012 by k8gu 2 comments »

I don’t normally operate the WPX contests, but several friends (e.g., KB9UWU and SM2WMV/SJ2W) were planning efforts and I thought it would be worthwhile to spend some time working them.  The high bands have been in good shape lately.  And, WPX CW was the first CW contest I ever operated (in 1997…my call was AA8UP then if you want to look up my stellar performance).  Why not have a little fun?!

The 30-meter open-wire fed dipole at 40 feet worked great as two half-waves in-phase on 15 meters into Europe (and the Pacific).  Now, I can move the lackluster 15-meter dipole high into the back tree for N/S operation.  In fact, it might actually be smart to just put a second 30-meter open-wire fed dipole there.  Interesting thought.  Probably have the parts to build another tuner in the junkbox(es).

I paid basically no attention to strategy and just did whatever I pleased working interesting stuff and running a little bit later on.  I didn’t spend much time on 40 and I didn’t work the 2nd radio very hard until the last 1.5 hours between 2114 and 2249 on Sunday when I made 124 QSOs…not big rates, but a nice pace for using the second radio to fill in dead space.  Here is the damage:

Call: K8GU
Operator(s): K8GU
Station: K8GU

Class: SOAB LP
QTH: MD
Operating Time (hrs): 6
Radios: SO2R

Summary:
 Band  QSOs
------------
  160:    0
   80:    0
   40:   52
   20:  206
   15:   97
   10:   12
------------
Total:  367  Prefixes = 256  Total Score = 266,496

Club: Potomac Valley Radio Club

 

“Sleep when the baby sleeps,” new parents are told.  All six hours of operating were with Evan asleep and about four were with Sarah asleep.  So, guess who’s behind now!

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