VAQP 2013

VAQP 2013 didn’t go quite the way I’d imagined it would, but it was still fun. Getting N1MM set up the night before the event, I was surprised to see fields for an exchange number. I’m pretty sure this was a new feature, and I’m not sure how popular it will be with people who prefer more casual operation in state QSO parties.

The contest ran from 10 am to 10 pm on Saturday and 8 am to 8 pm on Sunday. I spent Saturday with the Vienna Wireless Society, operating from the Annandale Swim Club. We got to the club at 9 am and it was probably unrealistic to think that we’d have antennas up, rigs configured, and N1MM networked by 10 am.

fishing for an antenna lineWe had some technical difficulties — our spud gun line broke a few times, the reels jammed, and trees claimed a lot of line and a few spuds. At one point, while I was working on another antenna placement, I noticed the other antenna hanging team trying to get one of our fouled lines out of a tree using the tools at hand: a lifeguard chair and a pool net.

It took a couple hours to get the antennas deployed. With the contest starting at 10 am, we started operating from the parking lot. I popped the tarheel antenna on my car, tuned to 40 meters, and Kevin WB0POH began working stations. By the time we had the indoor stations set up and configured, he had worked fifty contacts, including the bonus station, K4NVA.  I think all his contacts were CW, so worth twice the points to boot.

I’m not sure why, but we were not able to get the two logging computers to talk to each other. We tied them both into the club’s router, which should have worked like a hub. Both computers received DHCP addresses, and as far as I could tell, could see each other on the network. Not wanting to waste any more time, I set up the voice station to start with an exchange number of 500, while the CW station continued to build on Kevin’s earlier contacts. I’m sure hearing our SSB exchanges in the 500 range early in the day put the fear of god into our more competitive neighboring clubs. Heh.

The CW station was set up in a different room from the SSB station, and we had a counter and some stools as operating space. After sitting for a while, I got rid of the stool and used the counter as a standing desk. It felt good to dance around while working CW, and I think I might try for this sort of set up in the future as it keeps the blood flowing. Ian, N0IMB, took some video of TS-450 I was using. Unfortunately, the video does not capture my dance moves.  You can’t  hear the dits and dahs on the video because I’m wearing headphones.

We broke down our field stations and took down the antennas on Saturday night. The next morning, I set the home station up again. I had brought a number of station items to the field, so I had a little rewiring to do before I could get on the air Sunday morning at around 11 am.  I worked intermittently until the end of the contest at 8pm that evening, but had a number of fairly large breaks to take care of family, do chores, etc. I entered as single-op, all bands, low power (100W), CW-only, non-assisted, one radio.

Propagation was so-so, and I kept hoping that after a break, it would improve. It wasn’t just my imagination: conditions were much better on Saturday. Looking at the space weather data, a CME thrown on Friday hit the ionosphere Sunday morning, just when I was starting operation. The K-index bumped up to five and stayed there the rest of the day. Conditions did seem to improve as the day went on, but this perception may also be a matter of more people joining the contest for the last few hours.

I spent almost all of my time on 40m, using the attic dipole rather than the outside 40m vertical that does better in DX contests. I had good coverage of New England earlier in the day, and worked westward into Wisconsin, Kentucky, and Arkansas. Operating NVIS, I had a reasonable chance of operating other VA stations, including VWS club member Kevin, WB0POH.

Twenty meters was not as helpful as I’d have liked — at one point, Europe opened somewhat, and I worked a succession of stations in Poland, Germany and  the Slovak Republic. Later in the day, I had a brief opening to the west coast: WA, OR, and CA. Otherwise, 20m was my direct line to Florida. I did reach two stations on ten meters, but probably ground wave.

In the last hour and a half, I did good business on 80m, where I mostly ran into stations that I had worked on other bands.

I was surprised in the contest how many times I was called by stations that I had already worked. As a matter of course, I worked them again.  Maybe conditions were marginal on some of those calls, and maybe they just wanted an insurance contact. I didn’t hear anyone else operating from Fairfax City (FXX) — at least not on CW — so maybe my exchange was in high demand.

My final tally was 166 contacts (some dupes), with a paltry 26 Virginia City/County, 23 State/Province, and 3 DX entities. If I calculated correctly, I may have nosed over 20,000 points. Not a great performance, but not too bad considering time and conditions.

As for the club log, I’ll have to more or less manually merge the databases from the two workstations that we used into one file for submission to the Sterling Club which runs the VAQP.

Significant Other: Firmware

It occurs to me that I’ll likely be writing about the Significant Other project for a while, so it now gets its own category on the blog. I’ll go back and fix the tagging on older posts to be consistent.

The main board and relay board prototypes are in a final enough state that I can begin to work on firmware. Rather than start from scratch, particularly as I don’t have a lot of experience with this type of project, I decided to look at similar projects with open source code for both ideas and potentially as a scaffold for this project’s firmware.

I have come across the K3NG cw keyer, which is as full-featured a keyer as you could ever want, and which is written in such a modular and generalizable way that it can be made to fit on a variety of chips, depending on their resources and which features are included in the build. The package also includes a serial interface, command-line mode, and debugging features that should make the development process as painless as it can be.

I hadn’t seen this project while I was planning the main board, but the hardware layout envisioned in the K3NG keyer was very similar to what I had come up with, so it took minimal work to get it running on my main board.

The K3NG code lives in a sourceforge repository, and one of my first concerns was how to manage the code base. Considering that the S.O. is a specific design (and perhaps one that only I will ever care about), it seemed reasonable to take the most recent version and start a separate repository — I guess this could be considered a fork. To keep things organized, I’ve deposited that code, some test programs for individual subsystems, and the schematic on GoogleCode.  As with other projects, I’ll update the repository whenever I’m working on any of these files.

I spent a few days reading and pondering the K3NG keyer code to get the gestalt. It is very well organized, and every feature can be enabled/disabled through compiler directives.  It may be poor programming practice, but I decided to thin out the code to make it easier to work with. I realize that having features commented out so that they are never compiled has the same effect in terms of final size of the compiled code that will be programmed onto the chip, but I felt that I needed to remove sections that are not part of the intended application for the S.O., particularly since I’ll be adding other features.

Consequently, with some reluctance, I performed some surgery, removing fun stuff like code practice, CW receive decoding, and the extensive winkey emulation functions. In developing this device, the code will become less general. For example,  instead of an expandable number of buttons, the S.O. front panel will have four. All feature selection will take place through these buttons and the LCD display, rather than via the paddles. This is consistent with the design goal of not being able to leave behind anything when heading into the field to operate — if you forget the paddles, you should still be able to have QSOs. To that end, the front panel buttons have been modified so it is possible to press two of them at a time — in a pinch, the front panel buttons themselves will be able to serve as a straight key or iambic paddles.

For all I took out, the core keyer functions still take a good deal of space. I’ll have to see what the trade offs are in implementing a menu-driven interface and then in adding the clock, frequency counter, and antenna tuner functionality. Fitting it all in will take some doing — I hope it is possible. I’m sure that during development,  I’ll have to turn off some features to test others if I want to make use of the serial interface and debugging features.

TEAPOT: The electronically actuated pneumatically operated transmitter

the electronically actuated pneumatically operated transmitterA couple days ago, before the NAQP-CW, Pete K6BFA mentioned that before the start of the contest, some Boy Scouts would come over to the club station to talk about learning morse code. This wasn’t about working towards a radio or electronics merit badge: they wanted to learn the code for team competitions in which they are required to send messages to each other in the field using whistles.

Before they came over, we thought about how people learn code, and figured that for their purposes, they could use traditional tools for learning morse code (like the LCWO site, MorseResource, and various programs for PC or smart phone), but they’d be best served by practicing with actual whistles.

This got the gears turning, and more out of curiosity than practicality, I decided to make an electronic whistle blower that could be driven by audio output from any of these practice tools. I had thought through a similar problem in developing the androidomatic keyer, although unlike the androidomatic keyer that was meant to operate without external power (other than the audio signal itself), for this project it was reasonable to use a nominally 12V power source since the contraption would require some kind of air compressor that would have similar power requirements.

The most exotic component in the keyer (aside from the whistle, which is also not typically found in my projects) is a normally closed 12V solenoid valve (Adafruit, #996). This is a brass valve, which is listed as a fluid-control valve, but seems to work just fine for air.  The valve has 1/2″ threads on each side, and I had no problem finding connectors for it at my local hardware store. Per a chart on the Adafruit website, the solenoid draws 3A at 12V. The website also recommends putting a 1N4001 snubber diode across the solenoid leads, so that’s just what I did.

The solenoid is driven by a vox circuit built around a 4558 (741c equivalent) op amp via a STP16NF06 N-channel power mosfet (incidentally, the same one that is used in the Texas Topper QRP amplifier). The top of the MOSFET sticks out of my box because I threw the whole thing together quickly the morning of the contest and didn’t want to bend the transistor down. Also, I wasn’t sure how much heat it would need to dissipate, so I gave it some breathing room.

Compressed air is provided by a 12V air mattress inflator — a glorified waffle fan. These are usually bundled with air mattresses or rafts, but I bought this one as a replacement at Walmart for about $12. The rest of the assembly is a matter of plumbing. I obtained some 1/2″ plastic connectors and modified one to fit onto the pump, and with some careful glue-gunning, embedded a whistle in the other. Originally, I inserted a T-joint and played around with improvised pressure relief valves and/or a balloon to serve as a capacitance vessel because I was worried that the abrupt shut off of flow would strain the compressor. I guess there is enough leakage in the pump itself that this is not a problem, though, because it works fine to simply connect the pump to the solenoid valve. The pump comes with instructions that it should not be used continuously for more than about 15 minutes without some cool-down period. That seemed fine for my application, which is deafening after a few minutes.

I had supposed that morse code sent by whistle would need to be slower than we’re used to hearing on the radio, but as you can see in the demo, the solenoid has no problem keying at a 20 words per minute. I assume that people could achieve a similar effect by tonguing the whistle like a recorder.

We had a good session with the scouts, and the TEAPOT was a hit, leading to a brief discussion of electronic projects, robotics and flame throwers. After our session on morse code, they  popped into the radio room, where the club had already started the NAQP contest, so they also got to see morse code being used to communicate.

Significant Other Update: Logic Board

For a few months, I’ve been playing working on a design for a QRP accessory as a way of becoming familiar with both the arduino platform and homebrewing technique. The basic idea was to put everything except a transceiver in one box, so I couldn’t leave anything behind when operating in the field. I wrote up a design overview when I started, and it is more or less up to date. The schematic isn’t necessarily finalized, but I’ve also posted the most recent version.

The first item I built was a relay board, with latching relays to route the signal through a bank of capacitors and inductors arranged in an L-network, configurable on the fly for low or high-Z. The prototype built on vector board  has nice blinky lights to help me visualize how the relays are switching. I’ve also built a power module and RF module (which senses SWR and reads frequency) on copper clad board.

Over the  New Year’s holiday break, I laid out the logic board, which contains the microprocessor (an ATmega368), a real time clock, LCD display, a piezo buzzer, some buttons, and connectors for paddle input and keyer output. The logic board also sports a USB interface to make my life simpler — I don’t think that will show up in the “final” version, which I envision being laid out as two PCBs: one for control, one for relays.  In the prototype, the two boards are joined by a ten-conductor ribbon cable (with RF connections through shielded cable, not added yet).

The two blank areas on the logic board are where the power module and RF module will be pasted in this prototype. For now, I’m leaving them off and concentrating on the programming aspect of the project. I’ve got some ideas about the global operation of the device and its menu structure, but before I really start any detailed coding, I’d like to look through a few similar projects. An obvious place to start is the full-featured CW keyer described by K3NG at http://radioartisan.wordpress.com/.  I can’t imagine putting all those features into this project, but I think I’ll learn a lot from reading through the code.

Significant Other Power Supply

Initially, I hadn’t given the power supply for the Significant Other project too much thought: I was more focused on the microcontroller, relays, and so on. After going for maximum efficiency with these components, though, it began to annoy me that it would be very wasteful to use an LM7805 regulator to bring lead acid battery voltage (13.8V) down to something that all the chips and relays could use (5V). The LM7805 tosses out the difference in heat, and while at the low currents that I need that doesn’t amount to much power — certainly, not enough to require heat sinks — it goes against the grain of QRP. If you have to haul a battery up a mountain, you’d like it to last as long as it can.

So, I started looking at more efficient (and lighter) means of powering the unit. The design I selected allows for two options. First, two AA batteries will fit inside the unit. Building them into the case assures that I can’t forget them. One of the goals of the SO project is to avoid unpleasant surprises while setting up the station in some remote location.  Since the unit draws so little current, I’d hope that a pair of AA batteries would last quite a while in field use.

Since radios are made to work from 13.8V sources, this is the other acceptable power input. The unit will be built with dual powerpole connectors, so that even if the battery has a single powerpole, it can be plugged into the unit, which effectively replicates the plug, so the radio can also be plugged into the unit. Even if the radio is greedy and pulls power from the battery causing the voltage to sag, the power regulator should cope with anything down to about 7.5V. If the lead acid battery gets that low, it’s probably toast anyhow.

Getting 5V from a 3V source requires a switching power supply, which could be a problem for a radio project since the switching happens at frequencies in the hundreds of kilohertz range. The LT1302-5 chip that I used in this project does not oscillate at a specific frequency, but is variable, and has the potential to produce RFI over a broad range of frequencies.

I followed the datasheet for the 1302 and built a “typical” supply using available parts. Layout is fairly critical, and I did my best to port their suggested PC board layout to manhattan construction. I didn’t have a 20k resistor, so I went with a 22k. I didn’t have any particularly low ESR electrolytics, so I used ones regular ones, etc. It seemed to work anyhow.

For testing purposes, I ran the power supply with a small load next to my FT-187nd, which was connected to a dummy load with cable that was unshielded for several centimeters. Within the ham bands, the only places I heard hash were on 160m and 80m, and even there, it only seemed to be around a couple frequencies. I had originally built the supply with a 10uH commercial inductor wound on a solid core. To limit EMI, I tried replacing this with an equivalent value hand-wound toroid (45 turns of 28Ga on a T50-2). This brought the noise level way down, and I couldn’t hear it when the antenna run was a couple cm away from the toroid. I suppose I could put the power supply in its own metal compartment, but it’s probably enough to just keep the RF path away from it in the layout.

Getting the right combination of bypass and charge-holding capacitors and discharge resistors is a bit empiric, and I’m not sure I did an optimal job, but I got out the voltage that I wanted. When connected to the oscilloscope, I noticed a periodic ~50mV spike that I thought could be a problem down the line for the microprocessor, so I borrowed a low pass filter from a similar project, the power supply in the Norcal 2030. I again had to substitute a bit — I think the filter inductors came out of an old TV. With that filter in place, the voltage is completely smooth as far as I can measure.

The two power supplies are connected by wire “OR”ing them together. The LT1302 senses 5V distal to a Schottky diode, but putting a diode after the higher power supply means that the voltage prior to its diode must be about 5.3 volts. To get that value, I used an LM317 and selected specific resistor values for its feedback network. The LM317 needs a small load to stabilize, so for the prototype, I threw in an indicator LED that lets me know when the high voltage supply is in use.

When the high power supply is active, it pulls up the LT1302 shutdown pin, which turns off the up-conversion. Without all that switching action, the voltage on the toroid side of the diode should be that of the AA batteries. This means that with the higher power supply active, the diode in the lower power supply is reverse biased and no current flows through it. This should mean that the unit can hot-switch between onboard and external power.

The prototype was a little smooshed because I had originally intended to only build the LT1302 circuit on that piece of copper clad board, and then I added the filter, and finally the 13.8V supply.

The real test of this supply will be whether it makes the other components happy.

Sky House: Arrival

view south towards the Pacific oceanThe Nerkspedition to Sky House is underway. We arrived in LA a couple days ago and drove up the 101 to around San Luis Obispo yesterday. The final road to Sky House is a long, winding dirt road that hairpins its way up a mountain to a fabulous house that overlooks neighboring mountains, Morro Bay, and the Pacific Ocean. Most of the first day was spent getting everyone unpacked and settled.

Earlier today, I set up the FT817 for local repeaters in San Luis Obispo and Los Osos. No problem hitting them with full quieting from the top of the mountain, but not a lot of activity on them.

Even though this is the IARU World Championship weekend, I didn’t bother setting up for HF today given the solar activity: strong wake from a CME and an intensely south vectoring magnetic field. By report, the bands were pretty dead earlier except for sporadic E on 6m later in the day.

I’m hoping tomorrow will be better, so I tossed the 40m half wave dipole antenna into the trees at the top of the mountain. The wire comes down near a comfy chair next to the pool, and if conditions are better on Monday or Tuesday, I’ll give HF a try.

slt plus board with a missing L1 toroidImmediately before leaving for California, I noticed that both my winkeyer and SLT+ antenna tuner had developed rattles. I have to assume that this happened during my last flight back, which had involved a bumpy segment on a regional jet from Reno to LAX. Either that, or the TSA got more curious than usual and looked inside them. The winkeyer was missing a screw and the rest of the screws were loose, but there was no internal damage. For the SLT+, however, L1 had fallen off the pc board. I rewound the toroid and soldered it in while I was packing my bags for this trip and as an extra measure tacked all the coils down with hot glue.

Field Day CW Totals

We’re still assembling the total number of contacts from FD 2012 because the SSB and CW stations were not networked, but here are the totals for the two CW stations. I’d say we hit our goals and then some.

 

The 80/20/10 station

Mhz Contacts
3.5 279
7 304
21 15
Total 599

The 40/15 station

Mhz Contacts
7 430
21 115
28 4
50 1
Total 550

So, our CW total for the event was 1159 contacts. The results from the SSB, VHF/satellite, and GOTA stations and all bonus points should be out soon.

RAC Canada Day 2012

While the emphasis is on working stations in Canada (10 points), other stations do count (2 points), and this year there was more of an “everyone works everyone” flavor to the event. I worked stations from BC to the maritimes, but also a few French, one Netherlands, and one Romanian station. I heard a Brazilian station calling, but he couldn’t hear me.

In addition to working this contest for fun, it was also a test that the outside vertical had survived the storm. Right after the storm, the antenna had more slack in it than usual because the counter weight was resting on the ground. Apparently, a few branches that the antenna had once draped over are no more. I tightened up the support rope and the vertical seems no worse for the wear.

Field Day 2012

Ray, K2HYD at the operating position of the 80/20/10 tent. Hap, K7HAP is at the second position on the laptop, and Byron, W4SSY, supervises

To make everyone’s life easier, we stuck mostly to the plan developed for last year’s event, although I made some effort to simplify the set up where possible. This year, the main rig was a TenTec Omni VII, a radio with clearly marked controls and big tuning knob. Most people could sit down at this rig and be on the air in a matter of minutes without reference to reading material, nifty or otherwise. Instead of three antennas, we went with two: a moxon for westward gain on 20 meters, and a G5RV for all band coverage. The Omni had no difficulty tuning the G5RV for any band that we tried (10, 15, 20, 40, 80).

One major difference from last year is that we did not shut down in the wee morning hours. Both of the CW stations pounded brass for the entire 24 hour period of the contest. We had more operators than the previous year and divided the shifts carefully to assure that at least one person would be at the key all the time. It also helped that several of us brought our own tents this year for quick cat naps. We were all a bit punchy by Sunday morning, but after several cups of coffee, we powered through the rest of the event.

The CW tent is near a busy intersection and more accessible to other parts of the park, so we had a number of visitors drop by the 80/20 tent.  Some of these visitors turned out to be hams eager to put their hands on the paddles, and a few of them racked up an impressive list of contacts and we made sure to invite them back for next year. The more operators we have, the more pleasant staffing becomes. We might even be able to put someone on VHF CW for part of field day next year.

The 20 meter moxon (left) and G5RV (right) supported by a 40 foot military push-up mast, guyed at 3 levels.

Our computer wasn’t fully networked in at the start of the contest, so I don’t know how all the stations did. I have fuzzy recollection that we had around three hundred contacts on 20m and another 300 or so on 80m. We also worked on 15m for a while on Saturday evening, when the 40/15 station had gone to 40m and our 20m operation had been interfering with the SSB 20m station. I’m eager to see the final numbers after all the logs are merged.

One item to consider for next year — is it time to bring an SDR radio to field day? Would a graphic view of the whole band give us an advantage? Would a Flex radio (or other similar radio) play well with the other radios? I like the feel of a big tuning knob and I am used to zipping up and down the band by ear, but that’s all a matter of habit, and if there is better technology, we should consider it. Maybe it would be worth a test drive at some other event before field day 2013.

June mW Sprint

The view west towards mount roseI was sent on fairly short notice to attend a meeting at Lake Tahoe, which is just south of Reno along the California/Nevada border. I had one free evening before the conference, and it just happened to fall on the date of an NAQCC Sprint. I gave serious thought to throwing a wire out the hotel window, but the surrounding mountains called to me. This was not the usual monthly sprint, but the milliwatt version, so I figured that I needed all the help I could get and wanted to take advantage of the elevation.

After some quality time with Google Maps, it looked like Mount Rose was the highest accessible peak in the area. There is a parking lot near the trails that lead to the top of the mountain, but I didn’t think a business suit and dress shoes would fair very well on the gravely slopes. Across the road from the park lot is a campground with picnic tables and tall trees: the ingredients for comfortable field operations. In principle, there is a trail that runs up from the campground to Mount Slide, which, like Mount Rose is a SOTA peak. Again, if I had the right clothing and gear I might have attempted it, but it just wasn’t going to happen this trip. I settled for the 9000+ foot elevation of the campsite.

The view North, down the slopeI tossed a water bottle with a string into a tree, fired up the FT817nd on internal batteries and tuned up with the Hendricks SLT tuner. Before the Sprint, I worked WW0SS in Minnesota on 2.5W. Everything went faster than I had planned, so I laid down on the picnic bench and basked for a while.

I started searching around just a bit before the sprint to get a sense of band conditions. When the sprint started, I alternated between searching and calling. A number of local signals masked the sprint stations for a while, particularly with the poor selectivity of the ft817 (without a filter). I heard quite a few, some of whom were operating at 5W, while others were true milliwatt (less than 1W) stations.

I kept the rig at 0.5W for the entire event, and although I had two small lead acid batteries in the radio bag, I never had to use them. The 817 was running on fumes by the end of the sprint, but I was glad to see that it could make it through two hours of minimal power operation that had included a lot of calling.

All in all, I had six qsos on 20 and 40m. I reported 5 on the NAQCC sprint page because I wasn’t sure the last qso was complete, but I heard afterwards by email from the other station and confirmed that he had, in fact, correctly copied by call at the end of the contest. I think we gave each others 339 for that contact, and I recall that we needed a lot of repeats due to a mixture of summer weather background sounds, QSB and neighboring signals.

I didn’t come close to winning the sprint or even my category, but I enjoyed the scenery and the chance to sign myself as AI4SV/7.