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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.

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Marrying the TI-85 and the DJ-580T

April 13th, 2011

The May issue of QST arrived in the mail today and an article about building a “fox” for hidden-transmitter hunting was included.  That brought back memories of a teenage project of mine that I had once thought of writing up for QST, but now just makes a good story for the blog.

The first (and only) handheld radio I’ve owned is an Alinco DJ-580T.  Like most HTs of a certain age, it has provision for an external (“speaker”) microphone.  The microphone input is a sub-miniature (3/32-inch, “2.5 mm”) stereo phone plug.  As a high school student, one of my passions was tinkering with a graphing calculator—the venerable Texas Instruments TI-85—do kids these days even use this stuff or have they gone the way of slide rules and nomograms?  The TI-85 offered the provision to link to a computer or another calculator through a similar sub-miniature stereo phone plug.

Well, one afternoon in probably 1997, I was sitting with the DJ-580T in one hand and the TI-85 in the other…and it hit me…I wonder if I can use the the TI-85 to drive the DJ-580T microphone input?

A few preliminaries are now in order.  Thanks to a helpful (and still operational, albeit now with a CMS and the attendant spam) web site called ticalc.org, a few friends and I had learned to load our TI-85s with third-party binary machine code programs with considerably faster execution times than the built-in scripting language.  This allowed us to play relatively powerful video games surreptitiously on a school-sanctioned platform…a tactic that worked well until the English teacher wisened up to the fact that the five students with their calculators out were not typing essays on them.  Not satisfied to just play games—although I did set a very high score in Tetris during Spanish class—I sought to harness the power of the Z80 microprocessor in the TI-85 for myself.  Recall that this was before widely-available and inexpensive microcontroller development systems like the PIC, Arduino, and AVR.

I gathered the tools and eventually managed to write some fairly sophisticated (given my utter lack of formal training in computing) software in Z80 assembly language, including a crude clone of Space Invaders and a crude adventure game I called “Kashmir.”  Maybe some screenshots or stories about them will come later.

But, for the story at hand, I learned how to manipulate the link port.  Fortunately, the sleeve was ground on both the TI-85 and the DJ-580T.  So, it was just a matter of tip and ring—one was audio and the other was PTT on the radio, and both were settable on the TI-85 for some kind of two-wire communication link.  So, I reasoned that I could write up a bit of assembly code that would key the PTT by pulling it low, then toggle the audio line back and forth at 500 Hz or so to generate a rough audio tone.  It worked!

This was an expensive, although trivially so since I had the hardware, way to build a hidden transmitter.  So, I modified the software to send my callsign in Morse code (using a look-up table) and stuffed the whole thing in a cigar box.  It was good fun for a few of us teenage boys.

And, for the interested, I found the original source code, which is sadly not well commented or dated.  But, it does have my old callsign (AA8UP) listed by the lookup table.

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Recent tinkerings (9 Jan 2011 edition)

January 9th, 2011

Several people have commented over the years that I should “write more” on the blog.  I usually respond that I could spend my free time tinkering/hamming or blogging, but not both.  Here are a month’s worth of blog posts as freestyle poetry:

  • A section on my workshop has been added to k8gu.com under Engineering.
  • Discovered that although the SoftRock VHF Ensemble II won’t fit (barely) into the Bud CU-473 diecast box I bought for it, it will fit into an extruded enclosure that housed an ancient X-band radar detector I picked up at Dayton in 2002 in hopes of stripping the Gunn diode assembly and getting on 10 GHz.  Bonus points for thriftiness.  Photos will follow once I finish the project.
  • Did not observe Quadrantid meteor pings with the SoftRock VHF Ensemble II, but did notice something interesting about the W3APL beacon.  Need to investigate.
  • Have more CE/K8GU QSL cards again, finally.  Tonight, I might finish the bureau (and, ashamedly one direct) cards languishing.  Some K8GU (and AA8UP, no kidding) bureau cards are sitting here staring at me, too.  Not a big project, though.
  • Operated the NAQP CW on Saturday (8 January 2011) for four hours and twenty minutes and made 318 QSOs x 128 multipliers for 40,740 points before log-checking discounts.  This total is pleasing to me especially considering that it was almost all leap-frogging SO2R search-and-pounce, which can be very fatiguing.  It’s fun to see the rate meter stay over 100 when you’re S&Ping.  Good Sprint practice.
  • Still the best 30 minutes on the radio every week:  I operated the NS Ladder on Thursday (6 January) night and made my customary 30 QSOs x 24 multipliers for 720 points.  Hopefully, adding 160 will give me some momentum to increase this score back over 1000.
  • We had a spell of 50F (10C) weather on New Years’ Eve.  So, I put the 2-meter beam back up on the chimney.  It was formerly mounted on a steel mast that was ratchet-strapped to the chimney.  A strong wind (>50 mph gusts) before Christmas bent the mast (actually a fence top-rail) and I had removed it.  I cut the bent lower portion of the mast off and attached the remaining top portion with rotator to a “girder” constructed from two pieces of treated 2″ x 4″ x 10′ lumber joined with a half-dozen lag screws.  Again, I ratchet-strapped the entire assembly to the chimney.  The present configuration is much stronger and less prone to damage.  The 3-element 50-MHz Yagi is still on the ground until I actually get the transverter finished, which should be soon (as it has been for 12 months now).
  • Repaired a SoftRock v6.2 downconverter for WF1L and learned that you can solder leads back onto SOIC packages if you’re careful.
  • Have had delightful exchanges with KN6X and ZL1CDP about repairing the TS-930S.  Some of these discussions (and their fruits) may make it onto the site at some point.
  • Back in December, I started integrating the W1GHZ transverters using UT-141 semirigid jumpers with pre-installed SMA connectors obtained on attractive terms from Max-Gain Systems.  Mitsubishi RA18H1213G (1296 MHz) and RA30H0608M (50 MHz) modules arrived from RF Parts.  May have a lead on something less expensive with more gain for 903 MHz via HA1AG.  The big remaining tasks in all three transverter projects are the sequencer and IF interfacing.
  • Also in December, I had dinner with NS Ladder father Bill, N6ZFO, in San Francisco at the Hyde Street Seafood House & Raw Bar, which is a favorite of NA Sprint father, Rusty, W6OAT.  Yes, I did feel that I was in the presence of greatness.  (I had their excellent pork chops since I’m not into seafood, especially raw seafood.)  Like most contesters, Bill’s a super, fascinating guy apart from his radio contesting interests.

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“Electricity is NOT a toy”

January 2nd, 2011

The ARRL 10-meter (28-MHz) contest was a couple of weeks ago.  Given that I had bothered to install a 10-meter antenna at this QTH and that conditions seem to be improving, I thought it would be fun to play.

I fired up CQing on Saturday and after a few minutes, Sarah appeared at the shack doorway.  This usually means that something is broken or I’m causing RFI to something she wants to be using.  Since I’m not KT0R, who used to tell his neighbors that he was “busy and please come back on Monday,” I obliged her.  It was the CO detector again.  I unplugged it (it’s battery-backed, so it just means that contesting burns through 9-volt batteries) and returned to the game.  Peace reigned again in the Miller household.

Sneaking in a little bit of contesting before church on Sunday morning is a long-standing habit of mine, although it seems that the Sunday openings are usually better than the Saturday openings.  Today was no exception.  I was working hard to extract a few QSOs out of what appeared to be a mostly dead band and Sarah again showed up at the shack doorway—this time with wet hair and quite agitated.

“The outlet is popping when I plug the hair-dryer into it!”

I assured her that I would take care of it, adding that it was “probably just the radio getting into the GFI.  Let me send a few dits and see if it starts clicking.”

“No, you stay there, I’ll send the dits.  How do you do it?”

“Just press the left paddle.”

And so, Sarah made her first ham radio transmission on 10-meter CW this morning (after which I did identify, for the record).  I confirmed that the outlet made a little click.  She was not completely convinced, but I told her I would shut down while she dried her hair so I could monitor the situation.

The hairdryer (a prior unit), Sarah, and I have had run-ins before.  Several years ago, when we were poor graduate students, a loose screw was causing a nasty vibration in the old hairdryer.  So, I tightened it up and gave it back to her, not knowing that there was another screw floating around inside the case.  One morning, that screw found its way into the motor and sparked.  When Sarah called me on the phone, I thought she’d burnt the house down.  As much as it pains me, I no longer attempt to fix any appliances that cost less than $50 as a result of this episode.

Still worked up, Sarah took the opportunity to grill me about the compatibility of contesting with family life…”When have children, how will you hear them if they’re in trouble and you have your headphones on?  (In jest, I later proposed wiring a baby monitor into the SOnR audio chain.)  Can’t you listen with the speaker?  How will we keep them from eating your little parts, bits of wire, and globs of solder?  Electricity is not a toy!”

We laughed at the last one.  And she added, “I hope they’re all girls who want everything hot pink—so much hot pink that we want to barf.”

I suppose if someone makes a hot-pink Hello Kitty AK-47 (the photo actually looks like a painting of an AR-15) and the Sarah-cuda bow, we can find hot-pink solder irons, paddle finger pieces, headphones, and even radios (I seem to recall that there was a BabyPhat mod’ed hot-pink Motorola HT floating around the web a few years ago).

Anyhow, this post is for Sarah because she puts up with a lot of tinkering, RFI, and headphone time and gets very little blog recognition in return for it.

(The photo above is of Ft Rock, Oregon, taken by me when I was on assignment there.)

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An Evening of R/C

July 27th, 2010

It’s been over a year and a half since I flew the airplane, but interest from the young and impressionable prevailed.  We also piloted the newly-repaired boat, went swimming, listened to some 80s rock music, and had the best ice cream.  It was a good way to spend a Sunday evening.

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Odds and Ends

May 25th, 2010

Yesterday, I revisited this post listing on-going projects from December 2009.  Some things have changed, some remain the same.

The computer stuff has all been crossed-off the list, except that the home server is off-line with a dead power supply (or motherboard).  I’m somewhat loathe to spend any money on it, but I should be able to pick something up.

While it would probably have been cheaper to buy one of the HF/VHF/UHF combo radios, I’ve set off stupidly down the trail of building (and interfacing) transverters.  I am just three amplifier stages away from having 3-5 watts on 50 MHz!  …plus the interfacing.  I’ve decided that interfacing transverters to radios is more difficult than actually designing and building the transverters themselves.  I built the 903-MHz W1GHZ transverter during the Winter, but haven’t tried it on the air just yet.  W8ISS announced recently that he had some leftovers from the group buy of W1GHZ transverter parts, including boards for 2304 and 3456 as well as some G6Y relay kits.  I bought the lot.  I have enough MMICs and chip caps in the shop to build these and since I’ll need to order a couple of mixers for the other transverters, I can hit the Mini-Circuits minimum order.  Sometime.  Microwaves may all get pushed off to Fall and Winter.

Through a strange coincidence, my wife and I independently decided that it would be a good idea to move my ham shack.  The new location is closer to the center of activity in the house, which means I’ll operate more radio and be more accessible to her while I’m doing it.  But, the feedline and rotator cable no longer reach my 144-MHz Yagi.  Fortunately, I’ll be able to raid the K8GU coax stash shortly.  In the mean time, I’ve been missing what appear from the Hepburn maps to be epic tropo conditions.  Stuff happens.

QSLing, notably my favorite QSL topic—bureau cards.  All bureau requests for KP4/K8GU have been processed.  I ran out of CE/K8GU cards with 10 to go.  I will run some more of these from a photo printer in the next couple of days.  Piles of PJ2/K8GU, K8GU, and (go figure) AA8UP cards remain.  I will get the PJ2 cards done this weekend since I have a box of cards on-hand.  K8GU and AA8UP cards are awaiting a redesign.

Although it sounds like a lot, relatively little is getting done on any of these things thanks to an outdoor project at home.  More on this in the future.

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A License to …

May 13th, 2010

Jeff, KE9V, posted a note today about all of the bellyaching that goes on over the Hamvention venue at Hara Arena in Dayton, Ohio, also occasional home to Bill Goodman’s North American Gun and Knife Show (“Tell a buddy, bring a friend…Don’t you dare miss it!” the jingle goes).  In fact, according to the Hara calendar, it appears to host almost monthly gun and knife shows.  But, I digress.  I’m delighted that Hara is near my in-laws’ home should I ever wish to make a last-minute appearance—yes, it’s tempting to get in the car tonight.  And, I digress farther.  The point of this post is to explain the pervasive grumbling, finger-pointing, and misinformation, that spews forth from a vocal minority of the amateur community.

I was sitting in 8th grade math class adrift in daydreams as the teacher reviewed yet another topic from a prior grade.  Clearly, this was a widely-perceived problem, because one of my classmates persisted in talking to several others around her.  Finally, the teacher became so exasperated that he asked, “Young lady, do you have a license to talk?”  Of course she did not, but I chuckled noting that, as a newly-minted General class amateur radio operator, I had a license to talk.  I tucked that away for future use and went back to whatever it was I was daydreaming about.  And today, some 16 years later, the thought sprung into my mind as I read Jeff’s blog.

Another curious coincidence contributed to this confluence of cogitation.  As I was eating my lunch, I happened across an old KK7B paper from the Proceedings of Microwave Update ’94 entitled “Simply Getting on the Air from DC to Daylight.”  It’s not a particularly technical paper.  It is about the art of doing radio and it was fun to read.  In the first three paragraphs, he writes,

In the not-so-distant past, the primary emphasis in amateur radio was putting a station on the air…Sometime in the ’70s the ARRL stopped calling amateur radio a technical hobby and started referring to it as a communications hobby.

Brilliant.  I’d like to update that for the present,

In the not-so-distant past, the primary emphasis in amateur radio was communication via radio…Sometime in the ’00s, realizing that it had lost the communications game to telecom deregulation, mobile phones, and the Internet, the ARRL stopped calling amateur radio a communications hobby and started referring to it as an emergency service.

So, where does that leave us?  Well, we have a technical license exam structure impressed upon a group of people who are enthralled with communication but use the Internet because it’s easier.  No wonder anybody who reads about ham radio on the Internet thinks we’re up a creek!

I’m going to go make a CW contact or melt some solder to cheer myself up.  In the end, we have a license to communicate via radio.  Let’s use it.

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Knitting Electronics

April 29th, 2010

Sarah is a knitter.  She started when I was in graduate school.  It was a sort of support group for all of the other wives and girlfriends of grad students, postdocs, and faculty.  When we moved, several others also moved to various places and the group keeps in touch loosely via e-mail and (electronic) social networks.  The unofficial leader of their group moved to Switzerland while her husband was on sabatical there this year.  Knitting is to her what building and repairing electronics is to me—she always has multiple projects, buys more yarn than she needs for a project, etc, etc.

Sarah remarked yesterday that her friend in Switzerland had e-mailed an urgent plea for suggestions on some eight different projects.  “Gee, ” I thought, “this sounds like my problem.”  I was reminded also that one of my SuperDARN colleagues calls the portion of a radar build in which we construct the phasing cables and wire antennas “the knitting circle.”  Everyone sits around with a sharp knife, connectors, crimpers, or a solder iron, making up cables and chatting like a group of knitters.  Let’s extend this a little farther…

It occurred to me that it is socially acceptable to knit in coffee shops, during lectures, on mass transit, on airplanes (politically-incorrect jokes about knitting Afghans aside), and even during church services.  What are the barriers to knitting electronics in public?  A few thoughts came to mind…

  • Soldering is incompatible with the public sphere.
  • Knitting is inherently tidy by virtue of the yarn being continuous, unlike discrete components which are tiny and hard to contain.
  • Knitting is socially “understood” whereas building electronics in public might elicit the bomb squad.
  • Most of my projects (e.g., TS-930) are too heavy to schlep around.

Ok.  That settles it.  I guess I’ll have to settle for drawing block diagrams in my little black notebook.

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Trials and Tribulations of a Geriatric Electronics Specialist

February 6th, 2010

geriatrics

I have an old radio problem.  Make that three old radio problems…err…problem radios.

My first used radio was the TS-930S you see in this picture.  It’s been good to me, and I’ve tried to reciprocate, although I am a contester.  It hasn’t quite been the same since I put the third set of PA drivers in it and repaired the power supply.  Something deeper must be wrong.  I found out tonight that something deeper was indeed wrong, in the form of not one, but two, exploding electrolytic capacitors.  At least I had one of them in the junk box, but I figured I was pushing my luck and came up here to the shack to blog instead of blowing up another one.  The power supply pass transistors were assuredly toast since they were riding high at 40 volts—got that fixed.  But, it still pops caps.  Crap.  Something is amiss in the final PA bias circuit (MRF-422).  I don’t think that the ratings of the MRF-422’s have been exceeded.  So, it should be a matter of diagnosing the bias circuit and getting back on track.

The TS-700S at right is my most recent used find.  It’s in practically perfect cosmetic condition.  But, during the ARRL January VHF Sweepstakes, the output power started fluctuating before finally going to zero.  The T/R relay driver transistor failed, but there’s still something else going on—it looks like an ALC issue of some sort.  I did just finally find a service manual for this guy and that should help the diagnosis.  Although, the service manual is unusually vague about the purpose of some of the control signals that are passed between functional blocks.  This might take a while, too.

The other TS-930 actually works, except only on 40 CW.  On the other bands, the PLL unlocks.  KA5IPF suggested that I tweak the master oscillator to keep it off the ragged edge of unlock.  I’ve done that a few times and can’t quite hit the sweet spot.  My next plan is to pull the PLL unit out (a real pain) and reflow all the solder joints on the board since it comes from the early era of the TS-930, when cold solder joints were common.

I’ve pulled the FT-840 out to be the second radio for bands other than 40 CW.  And, I’m missing the Sprint tonight to spend time with my wife since I spent the better part of the afternoon tracing through the TS-700 and hooking up the FT-840.  Fortunately, I have the FT-840 configured as a drop-in replacement for a TS-930—this is in no small part due to the fact that the PIEXX boards use Yaesu-style BCD band-decoders—so, I can plug right in with the appropriate adapter.

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Projects, projects, projects

December 11th, 2009

There are lots of projects going on here at the ranch and I’m not sure where to start. So, I’ll make a dreaded bullet list. A lot of this stuff has been a long time coming and I haven’t even had to spend much money on it, just time.

QSLing:

  • Some PJ2/K8GU cards are still in the queue since USPS didn’t like the “gift” (a laser-engraved poker chip) I was including with them—need to get padded envelopes.
  • No KP4/K8GU cards have been replied to since I don’t have a card design yet. This will be a photo card.
  • Plan to have all direct QSLing caught-up by the New Year.

HF station:

  • QRV on 80/40/20 with full SO2R.
  • Right TS-930S still needs a new set of MRF-485 drivers (although it puts out a few watts).
  • Left TS-930S needs PLL/master-oscillator alignment so it will go to bands other than 40 meters.
  • Built IK4AUY 2N5109 push-pull preamp from QEX article—needs finished and tested.  Have enough parts to build two, but might go with the simpler W7IUV design for the other instead.
  • Plan reduced-size K9AY for 80/40, maybe 160.
  • Plan W3NQN RX filters to go on the K9AY ahead of the preamp.

VHF/UHF station:

  • Wired in Jones plug(s) for the rotator.
  • 50-MHz transverter project is stalled awaiting parts orders (SM caps and toroids).
  • Do a planning cost analysis of 50- and 432-MHz transverter costs vs buying a used FT-817.
  • Ordered W1GHZ 903- and 1296-MHz boards and kits with W8ISS.
  • Plan PAs for 903- and 1296-MHz transverters.

Computers:

  • Bought new keyboards and mice for sakhalin and formosa.
  • Thanks to the generosity of a friend, sakhalin now has two Seagate Cheatah Ultra320 10-krpm 36-gB disks.
  • Added the old 1.7-gB IDE disk from the “ham computer” to sakhalin so I can still run TR.
  • Added the extra RS-232 ports from the “ham computer” to sakhalin for rig control.
  • In the process of configuring sakhalin to triple-boot Windows 95 (aka MS-DOS 7 for contesting TR), Windows XP (so I have it), and Xubuntu.
  • Plan to migrate formosa user data (not much of it) to sakhalin.
  • Plan to convert formosa from Xubuntu to OpenBSD using 20-gB drive from sakhalin, plus 120-gB already inside.
  • Plan to migrate crete server contents to formosa.
  • Plan to convert crete back from Ubuntu Server to “ham portable computer” running Windows 95 (aka DOS 7).
  • May run a network drop to the basement to use crete in the shop.
  • The MacBook (vieques) still just works.
  • So does the OpenWRT box (home).

And that’s just the hobby stuff!  Well, most of it.

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