A License to …

May 13th, 2010 by k8gu No comments »

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.

Platform Agnostic

May 6th, 2010 by k8gu No comments »

Are you?  Objectivity trumps hype.

Transverter Common-IF Box

May 1st, 2010 by k8gu No comments »

I weighed the pros and cons of tapping the low-level TX and RX lines inside of my FT-840 (the TS-930 brings these to the rear panel) versus installing an attenuator in the TX line.  I opted for the attenuator instead of doing surgery on the radio.

The circuit is not particularly remarkable:  the transceiver RF jack goes to a relay T/R switch.  The TX side of the relay goes through a hefty 20-dB attenuator to a BNC jack.  The attenuator is rated at 5 watts continuous duty and considerably more at lower duty cycles, perfect for this application.  The RX side goes straight through to a second BNC jack.  The TX circuit is normally closed (and RX normally open).  This minimizes the chance of accidentally dumping 5 watts into the RX side of the transverter.

50-MHz RX LNA (Day 2)

May 1st, 2010 by k8gu No comments »

Built a little low-noise amplifier for the RX converter today using one of the BF981s I received the other day.  The design is based on the dual-gate MOSFET VHF preamp in the 1993 ARRL Handbook.  My local noise level was too high to credibly optimize the match on the beacon alone.  But, it did improve my ability to hear it on the 10-meter dipole.

Knitting Electronics

April 29th, 2010 by k8gu No comments »

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.

Candy Deliveries

April 28th, 2010 by k8gu No comments »

I’m fond of telling visitors to our home that I stock more electronic parts than a RadioShack.  That used to mean something.  But, I digress.

I took delivery of a used Cushcraft A50-3S 6-meter Yagi antenna yesterday (tnx, W8RU).  And, today a package arrived from Dan’s Small Parts and Kits.  Dan’s is a good place to pick up some unusal semiconductors.  In fact, he probably has the largest stock of thru-hole dual-gate MOSFETs left in the world.  I ordered a lifetime supply of piston trimmers and BF981s, in addition to a few other odds and ends for my VHF+ adventure.  As I use some of this stuff, it will get written up here—reminds me, I owe a schematic for the 6-meter RX converter.

Tomorrow, I expect to receive the remaining components (mostly miscellaneous carbon composition resistors) to build the TX section of the 6-meter converter from Mouser, in addition to some TS-930 spare parts purchased to make the shipping worthwhile.  Enough shopping!  It’s time to build some stuff.

Common Loon in DC

April 27th, 2010 by k8gu No comments »

Friends from Champaign-Urbana, Matt and Robert (aka Common Loon), are on tour this spring and stopped by DC a little over a week ago.  Finally got the pictures out of the camera—erm, off the card—last night.  (Nikon D40 : ISO1600 : 50 mm : f/1.8 : 1/15)

Notes on the ham exams

April 26th, 2010 by k8gu No comments »

I really like reading KB6NU’s blog.  He is a good writer and he has a positive enthusiasm for amateur radio which balances some of the other outlets I peruse.  But, a recent post (largely sourced from a guest) left me scratching my head.

It’s more or less billed as the foolproof guide to passing the FCC’s Amateur Extra examination for the highest class of license.  I tend to look at the ham exams as having two components:  necessary information to bootstrap your ham operating career (to the next level) and trivia questions that for most purposes amount to hazing.  There is considerable overlap between the categories and once a question loses relevance to the point of being 100% hazing, it should be removed.  Although I was not happy about it at the time, this is why the Morse code requirement was dropped.  (I might add here that the Morse code exam should have been retained for the Extra, but I have my opinions.  Mode-specific examination should also include the “sound card modes” and SSB.  But, I digress.)

So, where is this going?  The point is that anyone who is an active ham should be able to pass the Extra with minimal study.  You need to know the rules and how to hook up your station.  Some of the math formulas are important to help diagnose problems or set up your station.  The rest are trivia and can be memorized.  It’s not rocket science (or brain surgery, as rocket scientists like to remind each other; don’t ask what the surgeons say).

Ok.  Done ranting.

50-MHz RX converter (Day 1)

April 26th, 2010 by k8gu No comments »

This is going to be short with a few pictures.  The schematics will follow once I get things into a final form.  As anyone who follows the blog knows, I have recently acquired a VHF habit.  I have endeavored to do this at reasonable cost.  Thus, the “transverters” series begins…

One of the first things Dad won at a hamfest after we got licensed was the 1993 ARRL Handbook.  Between us, we’ve read the thing cover-to-cover a few times.  OK, that was mostly me.  I ended up swiping it at some point a few years ago and I still read it now and then.  One of the objects of my interest since the very beginning has been the chapter full of VHF projects.  I was always frustrated as a new ham that the 6-meter transmitting converter article was not a complete transverter.  This is my story of building a 6-meter transverter based on the transmitting converter in the 1993 ARRL Handbook.

The Handbook calls for a 22-MHz LO, resulting in a 28-MHz  IF.  I elected a 24-MHz LO using an inexpensive (< $1) computer crystal instead of the $15-$25 custom crystal.  We’re talking most of the cost of the project going into the crystal.  The 24-MHz LO put the IF at 26 MHz.  For the non-engineer (or non-ham) readers who’ve made it this far, this is just arithmetic:  22+28=24+26=50.  26 MHz (28 MHz) is the frequency to which we are tuning our existing receiver, 50 MHz is where we wish to receive, and 24 MHz (22 MHz) is the oscillator frequency we need to mix with the 50 MHz signal make it show up at our receiver (26 or 28 MHz).  The designs are functionally equivalent except for some tighter filtering requirements when the IF and LO move closer together.  No big deal for this design, though.

After noting two important failures in the wiring (before the walls in the photo above were installed), the oscillator jumped to life and I tuned it for maximum smoke (peaked it).

As an aside, this picture reminds me that if I had a modern digital oscilloscope, I could have a soft copy saved to insert into this post.  Ah, analog!

While the LO chain was straight out of the ARRL Handbook, except for the 24-MHz crystal, the RX strip was completely of my design.  I don’t have the schematic in electronic (or paper, for that matter) form, yet.  But, it consists of a 2-resonator preselector filter (lifted from Experimental Methods in RF Design), a TUF-3 diode ring mixer, and a diplexer mixer IF-side termination (from the 144-/220-MHz transverter article in the same edition of the Handbook).  I had an SGA4586 MMIC amplifier board soldered-up from another project; so, I tacked that on the front end.  This final step was mostly because I was in a hurry to meet the weekly landline sked with my folks.

I hooked the whole mess up to my 10-meter dipole and FT-840 to have my first tune about 6 meters.  The preamp did not appear to work, so I shunted it.  (This was not surprising since I just found it on my bench in some unknown and unrecorded state.  Plan to build something better.)  Last night, thunderstorms were in the area, so I didn’t want to leave it connected for long.  I had cleverly shunted both the preamp and the preselector, so I was getting a fair bit of static crashes from the 2 MHz image, as well.  But, I heard the W3APL beacon on 50.064 (actually 26.0725…the LO is not exactly on 24.000 MHz).

This morning, I realized my error and put the preselector in line, shunting only the preamp.  I peaked the preselector on the beacon signal.  It is handy to have a local beacon.  If I ever live somewhere without them, I think I’d almost just install a set of them for the sole purpose of helping experimenters align their gear with minimal test equipment.  Although, the HP8640B is reasonably-priced, even with option 002.  Should probably pick one up at some point.

More on this adventure to follow…

Computer Projects

April 24th, 2010 by k8gu No comments »

Worked on a couple of computer projects this afternoon:  1. Finally requested a username/password from Verizon so I could do authenticated SMTP through their server and thus end my relationship with gmail.  I did not think this was working earlier, but now it is after fixing a couple of lines in the Postfix main.cf file.  2. Thinking about IPsec VPN for home to use the iPod Touch from the road.  Ideas solicited.  3.  Still fighting with the mod_rewrite error in Omeka.  Would like to get this working.  More later…