Archive for the ‘hobbies’ category

Custom Backshells for Cinch-Jones Connectors

August 7th, 2014

What do you do to complete these hamfest bargains? 3D printing for the win!

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The best thing about it is that you can color-code the connectors, too! Finally, props to a CAD-ninja coworker for whipping up the beautiful SolidWorks model in a couple of minutes.

Latest Tinkering (or how Elecraft is taking all my money)

January 28th, 2014

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On Christmas Eve, I was sitting at my in-laws’ kitchen table with the Small Wonder Labs SW-40 I built as a high school kid in 1998 listening to beautiful music and I got the itch to come up with a radio smaller (and less expensive) than the K3 to drag around with me when I go places.  My mind wandered to the NorCal Sierra, which was a featured project in ARRL Handbook’s of my youth.  I was able to come up with a draft version of that Handbook article on the web—pause for a moment and think how revolutionary that is—my in-laws don’t have an ARRL Handbook, let alone the one that contained the Sierra article.  I looked at the bill of materials and realized that I had some 70% of the parts in my junkbox.  This seemed like a good idea until I went searching for a PCB.

Why PCB?  Well, I’ve done the dead-bug thing and it works great but it’s a pain to troubleshoot and unless you have decades of experience doing it, it looks like a Mexico City suburb, sprawling unpredictably in every direction with only the most tenuous connections to the core.  Since I was seeking a travel radio, I wanted it to be compact, easy-to-troubleshoot, and relatively rugged.  Due in no small part to the wishes of the Sierra’s designers (not coincidentally founders of Elecraft), boards are no longer available.  I looked into doing my own board, but if you don’t mix chemicals yourself, you’ve suddenly spent $150 on PCBs, plus the layout effort.  I toyed with making the board smaller (a win in several ways) by using surface-mount parts but even that was a non-starter since my junkbox parts are through-hole, requiring me to buy everything.

Astute readers can extrapolate what occurred next.  I went to the Elecraft web site to price the Sierra’s successor, the K1.  I had all but made up my mind to sell off some junkbox items and raise the capital to buy a K1 kit when something occurred to me:  fellow ham blogger Mike, VE3WDM, had recently moved to a smaller QTH and was offering a half-completed K2 kit for sale.  His asking price was only a little more than the K1 kit with some of the options I wanted and it was all-band.   The ad had been posted for some days by this point, so I fired off a sheepish e-mail to Mike asking if the radio was still available.  It was.  We sealed the deal and the radio made the somewhat tortuous ride (for us, not the radio—it sat in Chicago for two weeks) from his QTH to mine via the postal system.

I would not have bought a partially-finished kit from just anyone.  However, since this was Mike’s second K2 build and he was documenting it carefully in a blog, I figured it was a pretty safe bet.  So far, that is definitely true.

While I was eagerly awaiting the radio’s arrival, I redoubled my efforts to get a friend’s TS-930S off of my workbench, a task that involved replacing all 115 electrolytic capacitors on the cookie-sheet-sized “Signal Unit” board (similar to the K2 and K3 “RF unit”).  That radio still has low drive (it has ALC again and sounds like a million bucks), something I traced to a hard-to-find semiconductor that’s now on-order.  So, I gathered it up and started work on the K2 on Sunday afternoon.

Last night, I got it on 40 meters RX-only and peaked up the RX BPF.  Former K2 owner KL9A mentioned to me that it has some blow-by on strong signals but that he thinks it’s a pretty good radio.  I can confirm that based on my experience last night.  It sounds really really good on CW.

More on the build to come…including a look back at some troubleshooting of the BFO circuit.

Dayton 2013 Recap

May 20th, 2013

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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.

More Hexbeam

February 25th, 2013

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“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.

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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.

Hexbeam Photos

February 12th, 2013

  

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.

The Elecraft Effect

February 9th, 2013

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!

A Winter Trip to Greenland

February 3rd, 2012

Last year, I managed to scrape together some equipment funds at work to buy a small spectrograph system for studying atmospheric light emissions (airglow and aurora).  A co-worker secured the funds and contacts for us to install it at an observatory in Greenland.  Because we need to make the measurements at night, and because the instrument was delivered in early December, we made immediate plans to go to Greenland as soon as possible.  (Sarah is certainly laughing at this point because the plans were actually far from immediate and we bought our passage just over one week before departure.)

Greenland is only a short (4- to 6-hour) flight from the NE U.S., however the only route that operates in winter (and indeed the only commercial route) is on Air Greenland via Copenhagen, which operates four round-trip flights per week in winter.  This turned getting there into a two-day affair of perverse travel arrangements totaling over 12,000 air miles to go about 4200 miles round-trip on the great circle.  I met my co-worker, a United Airlines devotee (myself an American Airlines devotee), in Copenhagen and we flew to Kangerlussuaq (Sondrestrom) on Air Greenland.

One of the things that strikes you about Greenland as you approach Kangerlussuaq is how otherworldly and remote it is.  Kangerlussuaq is the site of the former U.S. Sondrestrom Air Force Base, and one of two runways (the other is at Thule) on the island large enough to accommodate aircraft capable of flying to Greenland from abroad (this is a mild, although amusing exaggeration).  Air Greenland has its hub there, shuttling passengers off to towns around Greenland on twin-engine turboprops like the Dash-8.  It is, as our host explained, “…not your typical Greenland town.  It is far inland at the end of the fjord and not on the coast.  The only reason it exists is because of the airport.”  Fuel and supplies are all brought in from outside.  Like most current and former U.S. military installations worldwide, it is reliant on diesel fuel for its on-going existence.  It’s sobering to be someplace that is totally unsustainable, although one might argue similarly of many U.S. cities, but I digress.

Kangerlussuaq is also near “the dog line,” north of which sled dogs are very common.  Here is one of the two road hazard signs we saw while driving around…dogsled crossing:

The instrument set up easily the first afternoon and we were able to collect some data with it that night.  As we were setting the instrument up, we heard reports of an Earth-directed CME from the Sun and hoped for aurora over the next few days. We were not disappointed…

The second night, I stood “aurora watch” in the cold while my warm-blooded co-worker processed the previous night’s data.  Soon, I saw some faint cloudy white sheets way down on the horizon and I ran back in to alert him and retrieve the camera tripod.  This photograph was taken facing toward the east southeast.

And, the 3.5-MW peak L-band incoherent scatter radar was running.  The dish is blurred because it is moving.

And, here is a shot of my fan dipole strung up on the DK9SQ mast.

Speaking of radio, I did manage to make a few QSOs as OX/K8GU on 17 meters, but not as many as I would have liked.  The combination of high absorption in the auroral oval (mostly to our south during our stay), little sunlight, a poor low-angle shot (required to avoid the auroral zone) to North America, short openings, and the fact that we were well-occupied with work for the four days we were there conspired to keep my contact count low.  QSOs will go into LoTW soon—the certificate was issued yesterday.  I have not yet designed a card, but there will be a special card.  Thanks to those who did contact me.

DXpedition QSLing

November 1st, 2011

This post might better be titled “supporting things that you value.”  A recent large-scale DXpedition to a “new one” just started sending out QSL cards in the past few weeks.  I have seen a bit of traffic leaking onto the regional contest club’s e-mail reflector about QSLing this operation and today someone complained that QSL requests that included donations were being processed rapidly and that he had not yet seen his. He was thoroughly chastised by a number of people on the reflector (including one of the DXpedition operators who went on at some length about the cost of the DXpedition) before the thread was (wisely) quashed by the moderator.

I composed a short reply very early in the melee, but decided (also wisely) not to contribute it because it really had little to do with contesting.  So, I’m writing here in hopes that someone finds it interesting.

When I was a new ham, I won a copy of the ARRL Operating Manual at a hamfest.  It sounds inane now, but I read the thing cover to cover.  In the chapter on DXpeditions, the author writes, “A donation should never be a condition for receiving a QSL card.”  That has stuck with me through the years.  The fundamental question is: why spend tens of thousands of dollars on the effort only to hold the operators who worked you hostage for a donation that might cover your QSLing costs if you’re lucky?

But, life is rarely black and white and most DXpeditions understand the futility of that question, so the situation outlined above rarely happens.  In the present scenario, the DXpedition stepped into the gray by prioritizing donors ahead of non-donors.  I have no problem with this.  In fact, as I began to write in my reply, it is a matter of supporting things that are important to you.  If having a card for the “new one” is important so you get on the Honor Roll for this year’s DXCC Yearbook, how much is that worth?

This falls into the same category as people who used to complain about the results of contests sponsored by CQ magazine being unavailable for free online.  Well, if you want the results, buy the magazine!

Enough ranting…did somebody mention that CW Sweepstakes is this weekend?  SWEEPSTAKES!

Fascinating signals: AA1TJ/QRPp

August 17th, 2011

Last night, as I have been doing lately in both the evenings and mornings, I was trawling the bands with a SoftRock (a dual-band v6.0 built for 40 and 80 meters—my first SoftRock) and Rocky.  Without fail, the waterfall enables me to see something interesting, which brings me to the point that I really need to integrate these receivers into my station.  But, I digress.  The really tantalizing, fascinating signals are the weak ones, especially when they are weak and unusual.

The subject weak and unusual signal is shown in the figure headlining this post.  Rocky’s cursor shows the approximate bandwidth of the CW filter (250 Hz, if I recall correctly) and the center frequency (7026.25 MHz).  I tuned it in and caught a CQ from “AA1T…”  Recalling that I head read about Mike, AA1TJ‘s, Das DereLicht transmitter built mostly from parts scavenged from a dead CFL, I suspected it was him.  After a moment the QSB came up and I caught the ‘J.’  Thanks to the fact that the SDR is not fully integrated into the station, I scrambled to plug my 15-year-old Small Wonder SW-40 in and get it online.  Mid-scramble, Sarah handed Evan off to me for a diaper change, but I did manage to snap the screenshot above.  By the time I returned to the shack awhile later to close things down, AA1TJ had disappeared.

Through the (ubiquitous) magic of the Internet, I sent Mike an apologetic e-mail QSL, which yielded a nice response.  It turns out that he was trying a 40-meter version of the first transistor transmitter described in the amateur literature.  The design for 146 MHz by K2AH appears in March 1953 QST.  If you are an ARRL member, pull up those old QSTs in the archives and read about it.  K2AH is on the cover of February 1953 QST with the same transmitter.  Mike figures he was making 20 mW, or 20650 miles/Watt on the path from his station to mine.  The more remarkable thing is that he was using a 1956-era point-contact transistor (the same type as in the K2AH article).  Fascinating stuff!  Hopefully, we’ll connect for a real over-the-air QSO sometime soon.

Thanks, Mike, for making my day by doing something interesting and sharing it on the air!

The Joy of Homebrew

May 18th, 2011

This is about building electronics, not making beer, at home; although, I am sure there are parallels.  Three things brought me to writing this:  1. an eHam forum thread I responded to a few weeks ago;  2. the June 2011 issue of IEEE Microwave magazine (has articles by K2UYH, N2UO, and KK7B, perhaps others? thanks to W3KL via the PVRC reflector for bringing it to my attention since I let my IEEE/MTT membership lapse); and 3. a few minutes spent last night resuming a partially-completed Softrock kit gifted to me by a friend who decided to buy a FLEX-3000 instead.

Every once in a while, a thread appears on an amateur radio forum that goes a little bit like this, “Hi, I’m a new ham and I don’t have a lot of money to spend so I want to build an HF SSB station from scratch” or something similar. Somehow, somewhere, somebody has given the impression that it is less expensive to build your own amateur radio equipment than to buy it.  That’s true in some circumstances, but certainly rarely for anything that is mature, mass-produced, and readily-available on the second-hand market.  After all, there is nothing novel about a 100-watt superheterodyne HF SSB transceiver these days. The principal uncounted cost is the “engineering cost” associated with getting your first few projects working and keeping them working.

One of the first construction projects I undertook as a new ham was to build a Ramsey Electronics HR-20 (NE602-based) 20-meter receiver—$20 at a hamfest.  It did actually work eventually—but this was a simple kit with maybe two dozen parts.  Next, I built a ONER transmitter kit from now defunct 624 Kits.  I think that was another $20.  I never made any QSOs with that combination because I was always afraid of blowing out the receiver with the transmitter.  The first thing that I built that I actually managed to make a QSO with was a Small Wonder Labs SW-40, which I still have.  That set me back $55 and it did not work immediately.  Suddenly, that’s over $100 by the time you include the money I spent on a soldering iron and solder.  That’s one-third to half-way to a “real” used HF transceiver and I had two bands at 1 watt on CW only.  Furthermore—these are all kits—they leverage economies of scale in purchasing parts from various vendors and they have instructions to help you along.  And, I’d like to think that I was a relatively representative example of a recently-minted ham who had more ambition than money or skills…

As I soldered down 1206-size (easy ones) SMT capacitors last night, I was thinking of times that I rushed through a homebrew or kit project just to get it on the air.  In those instances the process was often, as I have belabored above, about saving money, not about the act of creating something.  Last night was about creating, not saving, and that is the joy of homebrew.