My experience with the six meter band has been, appropriately enough, sporadic, but I’m planning to make it more of a centerpiece over the next few years.Continue reading “Magic Band”
Last night on 30m
Last week, I put up a new HF antenna and this week, I set the station up to operate in FT8 mode. Below, I describe a minimalist implementation using an Elecraft K3, a computer and two audio patch cords. I am focusing only on items specific to the radio and not found in the WSJT-X documentation.Continue reading “Operating FT8 on the Elecraft K3”
After Fairview Mountain and Emmaville Mountain North, we continued roughly along Interstate 70 towards Pigeon Hills North. This area is a mixture of private houses and farms, and from various postings, I got the sense that the folks here value their privacy and aren’t all that warm when it comes to visitors. Continue reading “SOTA W3/SV-041: Pigeon Hills North”
I have a few days of meetings in Paris before returning to Madagascar and before arriving, I mapped out a couple SOTA peaks near Paris. I was not sure when I would work them in since my only free time will probably be in the evenings, but I have already operated from one: FL/NO-120.
I had some confusion about the name and designation. There area references on the sotawatch website that list F/NO-120 as “Buttes de Parisis”, and Google points to older versions of the sota.uk website that also referenced that peak. The French SOTA website indicates that as of February 1, 2017, there was a reorganization of France into the FL and F associations, so these websites just need to catch up. I had planned the trip back in January 2017, hence my use of the older term. For logging purposes, since the Nord-Ouest summits now fall under FL rather than F, I used the FL/NO-120 designation. Oddly, the name seems to have changed to “Fort de Cormeilles”, which is a historical building in the area. In any event, the GPS coordinates are the same.
This past weekend was the CQ WW SSB contest — one of the big ones. I usually have a vague idea about the approach of a contest and decide whether to take part on Friday of the contest weekend, but I had marked this one on the calendar ahead of time and was prepared. Aside from setting up everything and working a bit of SSB earlier in the week, I spent some time looking at propagation and figuring out where to point the antenna at different times of day to hit both areas with high densities of hams (NA, EU, Japan), but also beam heading that would cover the most DXCC entities, the multiplier for this contest.
While on vacation on the beach in Montauk, New York, I took part in this year’s Flight of the Bumblebees, a QRP event in which portable stations receive a bumblebee number in advance of the event, and work home stations and each other during a four hour period. I wasn’t sure that I’d have time to play radio this weekend, as this was a family outing, but by the Sunday of the event, the family had enough sun and sand, and I was able to drive to Camp Hero to set up my station.
This is about the best location that I could ask for: the very tip of Long Island: surrounded on three sides by salt water, no neighbors or noisy interference (except occasional low-flying planes and helicopters), and a flat plane in all directions. Camp Hero is a former US Air Force Base, but is now a New York State Park. It is a little less traveled than the rest of Montauk as there is a small cover fee to enter the park, and there is no beach. The park is surrounded by cliffs with warnings that the edges may be undermined and that people should keep back from them.
When I got to the parking lot on the Atlantic side of the park, I took it as a good sign that a giant (now inactive) radar dish was keeping watch over my site. I struck on foot to the NE along a path that parallels the cliffs. It was tempting to set up on what must have been a missile placement, but I kept going, past various bushes until I came to an area that had a conveniently placed wood fence. In the distance, the Montauk lighthouse alternately faded and resolidified in the mist.
I managed to carry in everything in one trip: a push up mast, antenna, radios, chair, operating table, batteries, water, etc. Earlier this year, when W7SUA moved to Arizona, I had purchased a push-up mast from him, and that mast was used to support the center of the “untangleable folded dipole” that I had made earlier this year for the W5O operation at the QRPTTF event. I attached the mast about six feed down because the top gets pretty thin and I wasn’t keen to guy the pole. In fact, I got away with duct taping the pole to the fence at two points and called it a day. I tied down the two ends of the folded dipole to form an inverted V. The antenna had given me about 1:1 swr when flat topped at QRPTTF, and it did likewise in this configuration — which is good, since I didn’t bring a tuner.
I set up the FT817nd using a 2Ah battery as a support and a 7Ah battery as a back-stop. As usual, the palm paddle key mounted magnetically on the 817. Since the 817 is wide as a barn, with no roof filter, I ran the speaker output through my recently built switched capacitor audio filter based on the New England QRP Club’s NESCAF design. I cranked the filter over to “narrow” and peaked it on my side tone. After that, the filter made all the difference in the world in pulling out close-in signals. Thankfully, there were no other major contests that weekend except the NJQP, which was inside the skip zone, so front-end overload was not an issue.
I slathered myself in sun block, downed a liter of water and settled in about half an hour before the event. I had a test QSO with with Mark, K4NC, who said that he was also getting ready to try QRP in the FOBB. I wished him luck and was glad to work him again a few hours later during the contest proper.
In four hours, I logged 69 contacts, although three were duplicates. It may be that those stations didn’t copy all my info on the first pass or that like me they were logging by hand in a notebook, so I happily worked them a second time. Of the 66 stations worked, 40 were fellow bumblebees. I noted that a couple stations were on the event listing as bumblebees, but gave their power in the exchange, so I assume that they were folks that had planned to get into the field, but had to work as a home station on the day of the event, likely due to weather. Contacts included 27 US States, including all three continental west coast states. In Canada, I had two contacts to Ontario, and my best DX was with France grâce à F6BZG. Most of the non-bumblebee stations sent 5W, and the lowest power in my log was 2W K4MU and 3W AA7EQ.
20 meters yielded a fairly steady rate, and having carried in 9Ah worth of battery, I was not adverse to calling CQ all afternoon. I had a couple lulls, but was happy enough with 20 meters that I didn’t feel compelled to dig into my bag for the 15 meter end-fed that I had also brought along. Twenty seemed to be in good shape all afternoon.
I worked W7CNL‘s 4W station from Idaho just under the wire at the conclusion of the contest – this was a 339/339 exchange, and we were both struggling as the clock counted down. Thanks, W7CNL for hanging in there! FOBB was a FB event.
[We interrupt this stream of usually relevant material, for a gripe about a local service. Please bear with me, after this vent, back to the usual topics]
A few weeks ago, plastic-wrapped issues of the Washington Times started arriving sporadically on or near our door. For those not familiar with the paper, it’s a far second in the DC market to the respectable Washington Post, and the editorial slant of the paper is strongly to the right. Add in that it was founded by the Unification Church cult.
For the first couple weeks, I’d just throw them away if they ended up near my door — then a bill came, asking me to pay for my subscription. What? There’s no way I’d ever subscribe to this rag. From past experience, I know that I don’t have time to read even a good newspaper, so from an environmental perspective, I would not want one delivered (much less piling up on my door step, my neighbor’s lawn, and in the storm sewer in their plastic wrap).
I phoned the Times, had a bit of a wait, and talked with a representative who suggested that college kids may have gone around selling subscriptions. I don’t recall any students selling anything, and certainly not the Times. This seems like a very lame excuse for what appears to be a marketing scam. After shoving newspapers at people, how many feel obligated to pay when they receive a bill? This seems like a particularly scummy business practice, so I’m sharing it here in the hope that other people in the region will read it and be forewarned, and also that similar stories can be aggregated.
According to the representative in the call center, the subscription is cancelled (how can you cancel something I never had… oh, never mind) and the account is zeroed out. If bills continue to arrive or this shows up on my credit report, I will be showing up physically in their offices, not in a good mood.
Last weekend, a bunch of us from the Vienna Wireless Society set up a table for a Sally Ride Science Festival held at George Mason University. This is annual event, which promotes science, math, and engineering for girls in grades 5 to 8. Part of the fair takes place outdoors in the morning and early afternoon, with seminars held indoors in the afternoon.
Since it was drizzly, we set up on three plastic folding tables under tarps. We brought a smattering of equipment for show-and-tell including a portable satellite station, an HF station, an electronics demonstration, and some of the equipment from our most recent high altitude balloon launch.
My instructions on the event were to bring stuff that would be attractive to kids, so I asked with my kids about what kind of presentation would catch their interest. They suggested demos that would either make noise or “be shiny”. They also suggested candy.
To cover the noise angle, I brought a few morse code keys and paddles hooked to a code practice oscillator. I made a little cheat sheet for sending morse code and handed them out. For the demo, I printed a few sheets of five letter words, chopped them up, and put them in a tupperware bowl. I put another bowl right behind it full of candy and a sign: “send code. get candy. 5 letters = 5 Calories”. I ended up handing out 75 pieces of candy, and some of the kids had good fists. A couple used the paddles in addition to the key.
While I was shopping for the candy at the store “Five Below”, which caters to girls of just this age bracket, I noticed that they were selling laser pointers for $2 each. I figured the little batteries were probably worth that much alone, so I bought four lasers to play with. It occurred to me that I could cover the “shiny” criterion with some sort of laser project.
I had seen on the net a description of simple circuits for amplitude modulation of a laser by an audio signal, so that’s what I put together. Line level output enters through 1000:8 ohm transformer and directly modulates the supply voltage to the laser. A couple diodes are thrown in to protect the laser diode from spikes, but that’s about it. A couple months back, the Dollar store had been selling overruns of Disney Princess puzzles in nice tins, a dollar each, so I had bought a bunch of them for projects that didn’t quite fit the Altoids form factor.
The day before the event, I recorded the audio from my radio tuned to 14.070 USB, to capture USB conversations. I had the 2.4 kHz filter on, so there were quite a few PSK31 conversations in the audio band pass. I saved the sound as a *.wav and transferred it to my ipod. The ipod then plugged into the Pink Princess Laser Modulator.
On the receiving end, the circuit was even simpler, all that stood between a 1.5v battery and the audio output jack was a photoresistor. I knew that I had one kicking around, but couldn’t put my finger on it for most of the day, until I remembered that a CdS photoresistor is included with the Arduino experimenter kit as an optical sensor. The receiver went in an Altoids box, and the output ran into an audio breakout box that allowed me to split the signal to a speaker and to a computer. I duct taped the speaker to the awning of the demonstration booth and let visitors click on individual psk31 streams to decode them.
I seem to be doing well enough running the Kenwood B2000 at 5W or the TenTec 1320 at around 4 watts, but I haven’t made many contacts with my Rockmite, which on a good day puts out around 250+ mW, but less when the battery runs down a bit. A while back, I had ordered the Texas Topper (a.k.a. Tuna Topper) amplifier (nominally 5W out) from www.QRPme.com. For $25 it’s a good deal. The design lends itself to flexibility and experimentation, allowing the user to choose whether to use onboard/offboard options, a tuna-shaped round or altoids-shaped rectangular form factor, a range of input powers (using fixed or variable attenuator, if necessary), fast/slow switching, and transceiver or xmtr/rcvr configuration.
I put the kit together last week, made an enclosure, stuck it in, connected everything up, and … nothing. Well, not quite nothing. My WM-2 wattmeter read about 50mW output. Not good — the amplifier was doing something, but not in the direction that I had hoped.
The amplifier is well-documented on Chuck Carpenter’s website, which provides a parts list, pictures of the board, schematics and helpful advice. From the circuit diagram, it’s apparent that there are two halves to the pc board — one that controls switching through a relay, and the business end of the amplifier that centers on a MOSFET followed by a filter network. As far as I could tell, nothing was shorted. In the “receive” state, signals fed straight through from input to output connectors. When I keyed down the rockmite, I could hear the relay click in, and I was able to verify that the input signal was being appropriately routed over to a 4:1 transformer to feed to the MOSFET.
I checked DC voltages with a DVM, and verified that the bias voltage (determined by the forward voltage drop across an LED that conveniently also serves to let you know power is applied) was 2.05V. The voltage on the MOSFET’s metal tab (the drain) was about the same as battery voltage, as it should be. Unfortunately, I didn’t have an RF probe on hand for tracing of RF voltages — the probe was lost in the last move. It would be easy enough to build one (see nice plans on W5ESE‘s site), but I didn’t have a suitable diode on hand and apparently Radio Shack no longer carries the 1N34 in stock. No problem — I have something better, although not quite as portable: an oscilloscope.
The incoming signal was about 8Vpp, and 4Vpp after the 4:1 input transformer. I expected to detect something on the drain of the MOSFET, but all I got was hum (maybe just background). Probing beyond the MOSFET, I didn’t get much. I was stumped at this point, and starting wondering if I had done something wrong during construction.
It seemed to me that there were two likely places that I could have screwed up — in winding the two bifilar transformers (which, I recall I did while watching an episode of “No Ordinary Family”, so maybe I was distracted), or maybe in installing the MOSFET. I had placed a mouser order at the same time as the kit order, so I had a couple extra MOSFETs to play with. Using static-free everything (mat, wrist band, soldering tip, etc) and low heat, I replaced the MOSFET. No change. The kit comes with 22 and 26 gauge red magnet wire for winding toroids. To be extra careful, when I rewound the two bifilar transformers, I used on strand of red, and a strand of another color. Radio Shack does carry a magnet wire set, which conveniently includes 22, 26 and 30 Ga lacquered wire, and the 22 is gold and the 26 is green. The transformers look much better when wound with two color wire, and it’s easy to verify at a glance that the correct wires are tied together and that they all end up where they should. Again, though, no change.
I tried replacing the MOSFET one more time, as I thought that perhaps I had not had the right load on the amplifier when I tested it the first time, but again, no change.
After I looked at the data sheet for the FET and noted that the gate threshold voltage is listed as a minimum of 2v and max of 4v. The transfer function graph showed the drain current picking up sharply above 4v. My rockmite has lower output than most, and it occurred to me that I might be at the lower end of this amplifier’s design — not enough umph to drive the FET’s gate. To up the bias voltage, I stuck a 1N4148 diode between the stock LED and ground. This bumped the bias from about 2V up to 2.75V. Result: 1.5W output. On the oscilloscope, the waveform was a bit distorted on the FET’s drain, but smoothed out in the filter and was well formed at output. Going from 250 mW to 1.5W is somewhere around 7dB gain — not quite the 10 dB gain typical for this amp, but a huge improvement over my rockmite’s usual output.
So, now I am playing around a little to see what happens when I run this system with a fully charged battery and play a bit with the bias voltage. Hopefully, I’ll have a chance to try out the rockmite-on-steroids this weekend.
Continuing my over-analysis of TWIFcomp, which is now several times longer than all of the code in the competition combined, I thought I’d take a look back on the rules and see how they panned out. I thought that a comp about short works should have a short list of rules, that they should be posted quickly, and that they should not drift during the competition. I did get the rules up in 24 hours, and for the most part they didn’t change over the course of the competition, except by additions where clarifications were necessary. Obviously, I didn’t plug every loop hole.
Rule 1: Dates
For such a small comp, I didn’t require any declaraction of entry. It wouldn’t have really helped me anyhow. If no one entered, I was up a roll of duct tape and a package of noodles. Conversely, if it was wildly popular, I have a closet full of duct tape and noodles, so no big loss (actually, they are kept in separate closets, but still). Times: GMT confused some people, but in the same way that you don’t deserve to rule the world if you can’t stick the megabucks stickers on the poker chips, a little technical darwinism never hurt anyone. The announcement of results excluseively by tweet was a gimmick specific to the TWIFcomp, but for future comps, it couldn’t hurt to push out the results by various feeds. Actually, this is probably something that would happen anyhow, with or without the involvement of the organizer.
Rule 2: Games
Any programming language, any human language, white space doesn’t count, has to be interactive. I had anticipated that the definition of interactivity would have been debated, but it was the white space rule that got the most discussion. I really appreciate that some of the participants were purists and held to an absolute 140 byte limit. However, with different encoding schemes, operating systems, etc., length is a slippery concept. Also, you can’t tweet a tab or carriage return. I believe that the most tweetable entry, as submitted, would be Doug Orlean’s Manifest Destiny, written in PLT Scheme. Even with spaces, it fit the length limit, and it had no white space other than single spaces. So, bravo, Doug.
Now, regarding the white space. Here, I realized that I was giving authors a loophole, but it was a non-trivial one. I figured that if someone really could make clever use of white space, that in itself would be a worthy goal. I’m only one vote, though, so if other people didn’t agree, that would have been reflected in the voting. It is obvious from the results of the competition, that people appreciated Adam Thornton’s ingenuity in turning a game of less than 140 characters into a half-gigabyte monstrosity (and I say that affectionately). In the first comment on TWIFcomp, someone had joked about writing a game in white space, and I countered with a dare to write a z-machine. Adam went one step further, squishing the entire inform development system into the invisible world between printable characters.
Conclusion: Some rules are made to be cleverly interpreted.
Rule 3: Submission
Nothing special here. Everyone sent their game in, and I didn’t get a lot of requests to update games during the comp (which is good, since the submission by email system was a little unwieldy). I guess not many people felt much urge to update a 140 character game (although I notice that Alexandre Muniz came out with a revised “Make All Sad” that manages to shave off enough characters to allow addition of new features.
Rule 4: Behavior during the comp.
The rules explicitly allowed discussion of anything during the competition, and I didn’t even care if people posted the games on their own sites as long as they pointed people towards the version on the TWIFcomp site as the canonical version for judging. I did not have time to set up an Author’s Club, as had been done for the last two years for IFcomp — it seemed like overkill for such a short competition. Even so, some author-to-author discussion took place in blog space.
I was happy to find that during the entire comp, I didn’t see any flame wars, insulting posts, etc., on any forum. It was downright civil.
Rule 5: Voting.
I had hoped for a stronger showing in terms of votes, mostly because I was afraid that some games would not get enough votes to make the average reliable, and that one outlier could strongly skew the results. The game with the least number of votes received five, and the game with the most received 15. The votes were relatively consistent, particularly for the top-placing games. Everyone recused themselves appropriately, and I did not detect any kind of cheating or favoritism in the voting. So, quantitatively poor, but qualitatively good. I had considered setting a threshold number of votes below which a game would not be evaluated, but given the low numbers and consistency of voting, I went with a simple average.
Rule 6: Prizes.
From duct tape to pokemon. I was very pleased to see enthusiasm for a comp that did not offer cash prizes. I’m sure part of this is that the games were so short, and so little time was invested in writing. On the other hand, in the bigger comps, the amount of the cash prize cannot possibly compensate people for the time they sink into those projects. It is clear from TWIFcomp that peer recognition can be a substantial motivator for online competitions.
Rule 7: Intellectual property.
This was mainly a “I don’t want to get sued rule.” The more the comp went along and people asked if me if their code could be considered as infringing on someone else’s IP, the more I realized that it would be very hard to do so in 140 characters. Even if someone lifted text verbatim out of some other work, it would be a very short quote and probably fair use. Most instances also would have been considered a parody of the original work. Since there was no way of making any kind of profit in TWIFcomp, I would assume that the waters are not sufficiently chummed to attract lawyers.
The mega-supplemental rule about libraries. This arose as a FAQ, and was tweaked a couple times. This rules was a distant second to the whitespace rule in terms of abuse. The prime offender (and most entertaining example) was Adventiture which took the entire original adventure game as a library. The library had been published before the comp, was online, and freely available, so I have to say that this was entirely within the rules. I am a little surprised that this was not abused by more authors, actually. If I were to run something like TWIFcomp again, I would probably not allow external libraries in the same way, but restrict the entry to “core” tools for each language (either defining them explicitly or requiring that entrants run their proposed tools by me for approval).
OK, I will now stop obsessing about TWIFcomp. No, really.