Archive for the ‘radio’ category

More on the fundamentals: a story and confession

January 10th, 2008

Anyone (does anyone actually read it with regularity?) who reads this blog is familiar with my rant about the “decline of the fundamentals.” Here is a story about a recent antenna project and how trying to circumvent the fundamentals came back to bite me…

One of the perennial problems for hams on small city lots (and worse, rental property) is the installation of effective HF antenna systems. My current lot is about 170’x 100’…substantial for a city lot. But, it has a 1500-sq-ft duplex plus a two-car garage. There are streets on two sides and the (above-ground) power line comes in from the corner opposite the streets. There are four large trees ranging from about 40-70 feet tall, approximately forming a 70-ft square (yes, I know 80-meter 4-square).

I recently installed a 40-meter dipole between two of the trees and an inverted-L for 160 meters between another pair. These were decent antennas, all things considered. I worked EU on 160 and could actually hold a frequency on 40 in the CW SS. I’ve had two 80-meter antennas since we moved here. The first was a killer…a 40-ft top-loaded vertical with lots of radials where the garden is now. But, the landlady and Sarah asked me (nicely) to remove my radials from their garden. So, I hastily errected a zig-zag dipole about 20-25 ft up between three of the trees.

Needless to say, I’ve never been real happy with the dipole. Furthermore, I only got four radials down this Fall for the inverted-L and the extras I laid on the grass sorta looked like a rat’s nest. I got to thinking…I don’t operate 160 that much. I had a rope in the pine tree at almost 60 ft for the inverted-L and I’d successfully shot a line into the big tree in the back corner to install my 40-meter dipole. I shot another line into the tree from the roof of the house. Great! I can put an 80-meter dipole at 60 feet!

The neurons kept firing…if I feed it with open wire, I can short the feeder and run it as a top-loaded vertical on 160. Brilliant. I can put the matching unit on the roof and use elevated radials (I can’t believe I’m saying this…but, it’s the only option for this installation) on 160. Dad gave me a roll of #14 THHN for Christmas (raw materials make the best presents). I went to a big box hardware store and picked-up the remaining parts for $15. I started cutting PVC pipe for spreaders with a hacksaw in the basement…hard work! Then, I remembered that the CubeSat shop is in the lab next to my office. A minute and a half with the bandsaw did what I spent a half hour on the day before. And, they looked better to boot. I built the antenna and hauled it into the trees.

Of course, using open-wire line, I had to do some matching. I measured the input impedance after the 1:1 balun (built with type-31 ferrite using a K9YC recipe) with my Autek VA-1. It’s L-network time! I figured there’s got to be an L-network calculator on the Internet that will save me a few minutes’ work. Indeed there is. I punched in the numbers and hit [calculate]. The component values seemed reasonable; so, I built it. Finding a coil form was a bit of a challenge. I have some Miniductor stock; but, nothing big enough. I tried a lot of things that I’m too sheepish to mention here before one day as I was leaving the office…I saw my coil form…lots of them piled-up against the instrument cases and cardboard boxes: poster tubes from conference travel. For good luck, I selected the three-inch tube that got stuck in the baggage handling system at O’Hare on the way home from Spring AGU in Acapulco… Actually, it gave me great pleasure to carve that up with the bandsaw.

I built the coil, added some capacitance, and triumphantly returned the relay/matching unit to the roof. I hooked-up the VA-1…and it was awful. The impedance wasn’t even close (it’s like 20-j200) to 50 ohms. I started clipping capacitors in parallel and it got worse. Then, I cut some off (the original design had three in parallel) and it’s got worse again. I’m up a creek! I went inside and had lunch. After eating, I carefully checked every joint and wire…good. So, I calculated the expected transformation given the parts. Hmmm…it gave me what I measured. I looked at the online calculator more carefully…

The calculator took the parallel equivalent circuit for the load, not the series equivalent circuit! I was in disbelief…who uses the parallel equivalent circuit unless they’re doing a calculation?! Apparently, the author did. Of course, it makes sense in retrospect…if I was writing an L-network calculator, this is the logical way to do it. I computed the parallel equivalent circuit, recalculated, and rebuilt. It hit almost dead-on 50 ohms.

It’s easy to see the lesson here: pay attention to details. But, perhaps the more important lesson is that the existence of ready-made design software does not justify ignorance of the fundamentals. Had I calculated the L-network by hand, I would have made the series-to-parallel transformation myself (or even better, let the VA-1 do it for me…wait, isn’t that how I got here?) as a part of the process. To quote the country song (out of context, of course), this was “time well-wasted.” I have a story to tell my students some day!

Single-Op, Two-Radio

November 28th, 2007

Contesting, as I have said before, is an exercise in engineering.  They write the rules.  You design your station and strategy to maximize your score within those rules.  In such an arbitrary or contrived pursuit, it is often difficult to discern whether proposed rule changes are significant or important.  One of the latest targets is SO2R operation.  Let’s break down the reasons why the present categories exist:

  • Single Operator, power levels:  Power changes your strategy.  But, other things created equal, you’ll certainly make more contacts running higher power, regardless of strategy.  Power is a bolt-on advantage.
  • Single Operator, assisted:  Assistance makes use of information or skills (in the antiquated case of loggers) of additional operators who do not actually operate.  Clearly, one operator is not doing all of the operating.
  • Multi-Operator:  Clearly, adding additional transmitters increases your ability to attract QSOs by CQing.

Where does SO2R fit into this?  As expert K5ZD has observed, SO2R is something that you grow into being able to leverage.  This suggests that SO2R is predominantly a skill, at least on CW and Phone and perhaps to a lesser extent on RTTY (although, I will say that I think CW is more natural than RTTY).  Adding SO2R costs less than adding an amplifier.  So, it’s not a matter of haves and have-nots.  My scores sagged the first times I did SO2R—clearly not a bolt-on advantage here.

W4PA made an interesting observation about the M/S category recently:  Why is no one clamoring for MS1R, MS2R, MS3R, etc, categories?  Or in M/M for that matter?  Because these  guys are more interested in winning by pushing the state-of-the-art than by creating a new category for themselves.

Am I opposed to an SO2R category?  Not specifically.  If such a distinction were to be made, it should be included in a limited/unlimited distinction like the T/S category in WPX.  Fix all of the category “problems” in one motion.  But, until such a limited category is created, leave SO alone!

Contesting, Contesters, and Contests

November 26th, 2007

I cruised by eHam for the first time in a long time the other day.  As, I’ve mentioned here before, I left due to the low SNR and because the forums weren’t exactly, um, inspirational.  There was one of the perennial Contest-Anticontest threads raging in the Contesting forum.  The originator sarcastically “thanked” contesters for “trashing” the bands during the CQ WW CW contest last weekend.  I skimmed through the bashing from both sides until I got to a poster who said, “Thank you, contesters, for giving me some contacts.”

You’re quite welcome!  This guy knows what’s up.  He’s new to HF and had a terrible time making contacts outside of contests.  A lot of us started out in his shoes.  Honestly, when I first got on HF at 14, I didn’t feel like I had anything to say to older people on the radio—that’s why I left repeaterland.  Now that I’ve done some stuff, that’s different…but, I still like contesting.  Over the past five years, I’ve found friends that I’ve operated, built antennas, strategized, or just plain shook hands with.  Some of the most interesting people I know are contesters.  Tell me that ’59’ contacts are impersonal!

This is a great hobby.  Life is too short to bash any of your fellow hams!

Fall CW Sprint prelim

September 26th, 2007

N6TR has posted the draft Sprint results. Although I’m disappointed with my overall effort and score, I’m pleased that I missed the golden log by one busted QSO. I may not QSY fast, yet; but, at least I’m pretty accurate. The guys who do this contest well still amaze me.

When I put the teams together, KJ9C always says, “There’s a big party in Indy this weekend; I don’t know if I’ll be in any shape to contest.” Then, he swoops in and stomps me.  This is the second year he’s done that. K4LT always has a beer before a contest to keep the jitters down. Maybe there’s something to that. I don’t think it tastes good enough even if my scores did go up…

QSLing

September 14th, 2007

I started to work on my backlog of bureau (“buro”) QSLs last night.  Like many contesters, I find QSLing to be an enormous chore, especially via the bureaus.  But, as I am fond of saying, contesting is a marketing game; a nice QSL may be as important to operator you contacted as the QSO was to your score.

One of the fascinating things about the bureau cards is that they come in chunks by country.  I’ve received a lot of cards for my CE/K8GU operation in August 2006.  It seems as though Chile was highly sought-after in Europe, especially on CW.  I must have been pretty loud up there, too, with the antenna at the edge of the cliff.

Working through the QSLs did bring back memories of learning to work a pile-up and log on paper.  You see, I didn’t have a computer suitable for logging along on the trip.  So, I had to log on paper.  I entered the entire log into my computer on the flight home.  (At Sarah’s prodding, I had read Harry Potter on the way down.)  It’s a good thing I entered the entire log because I left the log in the back of the seat pocket in front of me.

Anyhow, I’m getting the itch to be DX again…

12 dB

September 7th, 2007

The Sprint, as I have written before, is a CW operator’s contest. Last night, the usual Thursday night gang, plus some, gathered for another happy half-hour of Sprint practice. But, the rules were different: high-power (1.5 kW) was permitted and no duplicate contacts (per band) were allowed. I felt puny, especially on 40 and 80 after the masses left 20 meters. Looking at 3830 this morning, I notice that almost everybody ran high power. 12 dB makes a difference…(not to mention that I have about the smallest antennas of anyone who participates.)

Upgrades at K8GU

July 30th, 2007

K9BF told me months ago that he had a pile of TA-33jr parts in his garage attic and that I would be welcome to dig through them. I finally had a chance to do just that a couple of weeks ago. He actually brought all of the parts over and dumped them in my garage (actually, our duplex neighbor, Ruth’s, half of the garage, since she was on vacation). It turns out that he had two essentially complete sets of elements and one boom. So, I sorted the best-looking antenna from the rest of the parts. It was time to do some refurbishing.

Mosley is somewhat (in)famous for charging an arm and a leg for replacement parts; so, I bought all of mine from McMaster.  That place has everything for the antenna-building ham!  I put the antenna up on two pieces of fence top-rail next to the garage.  As NO9Z says, “That bracket on the eves is doing all of the work.”  I have an old TR-2 “bell” rotor in the garage.  I think it might be a little too much antenna for it; but, when am I ever going to use this small of an antenna ever again?  It is fun to install an antenna by yourself, by hand.  Probably won’t be able to do that again, either.  Not like I’m complaining.

I played with the new antenna in the IARU…caught some Es on 10.  That was fun.  It’s about on-par with my groundplane on 20; although, F/B is better.  None of this is particularly surprising since it’s so low and surrounded by clutter.

After about two weeks, the landlady noticed the TA-33jr.  She seemed slightly annoyed that I hadn’t consulted her; but, didn’t seem to care that it was up there.  Note to renters:  this is a good example of shoot first and ask questions later.  Feel-out your landlord before you try this, though.

I’ve kinda had the itch to get on 160 since I got here.  I’ve been able to scratch the 160 itch once a year in the ARRL 160 with W9SZ, K9BF, and NO9Z, out at NO9Z’s.  The first year (W9SZ, 2005) that we did it, we did pretty well—it’s the first time I’ve ever had four straight 100+ hours—hard to complain about that!  Technical problems got the best of us last year (K8GU, 2006).  We’ll probably try again this year.

K9AN and I had a good discussion about wire antennas back in June that inspired me to buy a slingshot.  I was just playing around and easily launched a line over the spruce tree in our side yard.  When I realized that it was close to 60 feet up, I decided to put up an inverted-L for 160.  The DK9SQ mast was indispensible for maneuvering through tree branches.

I bought 1/4 mile of #16 aluminum for $17 at Farm and Fleet on Saturday.  I put four radials down (this is a lot of work when you’re trying to be somewhat stealthy) yesterday.  I’m going to wait until after the lawn guy comes again this week to see whether I’m doing a good job stapling it down.  Compared to the price of copper, I won’t feel too bad about leaving aluminum in the grass when we leave and it only has to last for one or two Topband “seasons.”  I figure I’ll just put a few radials in at a time until the feedpoint impedance stablizes or I get lazy, whichever happens first.

Inside, I re-routed some wiring and got rid of most of the crosstalk “hash” that I get between the TS-930’s.  NO9Z and I have most of the parts to build the KK1L antenna switches, thanks in no small part to the generosity of Ron in giving us the Gerber files for the board and K9BF for turning the Gerber files into a boards.  I still have parts for the N6BV SO2R box from ARRL Handbook sitting on my bench.  Sometime, K9SD is shipping me a dead ex-CB FT-757 to work on.  Plus, there’s some non-ham stuff there, too, like my iBook.

I also have a 160-meter SoftRock v6 kit to build.  I sold my 40/80 SoftRock v6 to KC9IKL—still not sure if that was a good idea or not. When I finally order the parts for the KK1L antenna switch from Mouser, I plan to buy some more FST3125’s to build a SoftRock interferometer (more on this at a future date).  I mentioned this idea some months back on the SMC reflector, to the great interest of at least one well-known Topbander.  It looks that VE3NEA has a version of Rocky that can do this now, too.  That man is amazing!

We acquired some “old” PC’s through surplus at work; they had SoundBlaster Live! cards in them, which, since work doesn’t require them, will form the A/D portion of the K8GU SoftRock interferometer.  The biggest problem with using these rather than an M-Audio card like the Delta-1010 is sample synchronization.  But, I’m a cheap ham…I’ll figure out how to calibrate them.

I think I’m destined to be an average contest operator with an above-average interest in the technology…

Selling Ourselves Short

July 23rd, 2007

Ham radio’s ability to set up ad hoc communications networks that are immune to natural disasters and jamming is legendary.  Rightly so, I add.  However, it disappoints me that so much ham radio recruiting has turned to this as a selling point…be a ham, carry an HT, be a HERO (a HERO…a HERO…a hero…a hero—if you don’t get this, it’s from a long-forgotten episode of the Simpsons.)  Of course, in this time of “war on terror” (“terror” is not a state and therefore does not deserve capitalization) and heroism and emergency preparedness are all the rage.  Why should ham radio be any different?

When I was in high school, I spent my summers working at a two-way radio shop. We installed and maintained the public service communications equipment for the surrounding towns and the county as a whole.  This was an enlightening experience on many levels…I learned some of my most important troubleshooting skills at that job.  But, another thing that I recall is the sheer enormity and robustness of the systems, especially for 911 and dispatching.  I’m sorry; but, ham radio has nothing on these guys.  It’s organized and has better back-up power , redundancy, and lightning protection than 95% of hams.  And, I’m talking about a rural county with a population less than 40000.
So, what about disasters that destroy or disable this sort of sophisticated system?  I’m glad you asked.  The efficacy of ham radio as a communication resource is heavily rooted in its ability to self-organize and self-deploy…flexibility and technical competence.  Have you been to your local radio club meeting lately…or listened to your local repeater lately?  Flexibility isn’t exactly the first word that comes to mind.

The technical competence of the average ham has been declining since commercial equipment was first available, probably in the 1920’s.  When I see and hear about some “go-kits” and “emergency comm centers” that have been built, I shake my head.  An FT-817 to a screwdriver antenna does not an emergency communication system make.  Sure, they look pretty and professional.  But, trust me; when the poop jumps off, I’ll be the guy with the communications-grade transceiver using full-sized antennas.

And then there’s the paramilitary types.  The genesis of this blog entry was the following ad on QRZ.com.  Advertising, even on the Internet, costs money.  Somebody thought that hams were an important part of this market.  Note that the other ads on the site are almost exclusively about ham radio.  It’s like the old Sesame Street game, “Which one does not belong?”

Self-organize, self-deploy, and self-defend?  Right.  If you want to serve your country in this way, you should be in the National Guard or the military.  If they don’t want you, there’s probably a good reason for that.

Anyhow, the point of all of this is not to point fingers at those who are interested in emergency communications.  Rather, step back and evaluate what you’re doing.  Playing the emergency communications card repeatedly is not sustainable.  Do we really want a ham population that’s gung ho on emergency communications but has no other skills or interests in the hobby?  My primary interest is contesting; and I’ll be the first to say that I’m glad not every ham is a contester!  Think about that one.

“You should have a reason for everything you do.” –K3ZO

June 15th, 2007

I happened to stumble across this K3ZO message mentioned on Don, K8BB’s, web site:

http://lists.contesting.com/archives//html/CQ-Contest/1999-09/msg00125.html 

It’s perhaps one of the most insightful things posted to CQ-Contest during its 15-year life.  Preparation and planning is important to success in most aspects of life.  Why should contesting be any different?

Peanuts and Cracker Jacks…

June 14th, 2007

I swear, they must be giving out ham radio licenses in boxes of Cracker Jacks these days…this gem is from eHam…

Can 2 radios in the same house different antenna’s a 2 meter and a 10 meter, transmit at the same time without disturbing the radio waves or will it change the patern of them and if so how well will we get out?

I think I’m going to put a sign in my shack that says, “Don’t disturb the radio waves.”