Operation Rolling Pork

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In 2011, I got together with Ben (NN9S) and Tymme (K9TYM), and we participated in the Indiana QSO Party from Tymme’s house, just outside Bloomington, Indiana. None of us were experienced contest operators, but we managed to set up a multi-multi station in short order and kept it on the air for the duration of the event, giving out QSOs for Monroe County.

We couldn’t pull the team together last year because of jobs and travel schedules, but we entered this year as a Rover team. My 2009 Hyundai Sonata is outfitted with a Kenwood B2000, similar to the TS-2000, but without  a front panel. The main radio unit is housed in the trunk, with a remote head mounted on the dash.

Over the last year, I’ve gradually modified the car for this operation, with power connectors running down the left electrical channel to the trunk, and audio, keying, RS-232 and antenna control cables running along the right electrical channel. One of the radio’s antenna ports is dedicated to a 2m/70cm antenna, while the other is used for HF: either a screw driver antenna or MFJ hamsticks.

IMG_20130502_192123I took a few days off of work for the event and camped on the way out and back to Indiana from Virginia. Before leaving, I lightened up the car a bit by removing the passenger side seat. The seat is held down by four bolts, easily removable with a socket wrench, plus some electrical cables that had to be disconnected.  In place of the seat, I screwed in a RAM Mount for my panasonic toughbook laptop, with power from the car’s accessory power port and rig control via RS-232. This allowed the computer to be operated from either the driver position or the rear seat. Similarly, the microphone reached to the rear seat.

Either passenger in the back could operate the microphone, and the passenger behind the driver typically also fulfilled the role of navigator. The other passenger in the rear seat operated the computer, and the driver either drove, or while parked, operated CW using paddles mounted on the center console behind the shift lever. An autokeyer with rate adjustment was installed into the front dash.

We followed a counter-clockwise loop, starting near Tymme’s house in Monroe county. Our plan was to aim for county borders that were along an efficient route. In the weeks before the event, we roughed out a plan using Google Maps and Street View to try to find places that would be safe to pull over and operate and ideally far from sources of electrical interference. We also tried to find locations with some elevation and good prospects for pitching an antenna into a tree or setting up a support pole.

Our signboard reminds us that we are parked at the Monroe/Lawrence county border.
Our signboard reminds us that we are parked at the Monroe/Lawrence county border.

We got off to a wobbly start because we did not make good time from Chicago to Bloomington, and we got a little turned around in Bloomington. Consequently, when the contest started, we were still on the way to Tymme’s house. This wasn’t a major set back, as we just started operating mobile on voice until we got there. As soon as we pulled it, storm clouds were gathering, and the decision was made to shoot the 80m antenna for the evening’s operations before the sky let loose. While Ben and Tymme disappeared into the woods to shoot strings into trees, I operated CW from Tymme’s driveway.

Before long, we were underway, first way point: the Monroe/Lawrence border. Our circuit continued with operations in Orange, Dubois, Martin, Washington, Scott, and Jackson counties.  We had surprisingly few contacts in Martin country, which I thought would be a highly sought location, and I’m not sure why — we had a remote, high location; maybe propagation was just off at that point in the day.

As the first person to operate phone when we got to the Orange/Dubois border, I learned that “Dubois” isn’t pronounced the way I thought I was. In Indiana, it rhymes with “noise” rather than “quoi”.

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Ben and Jack pose with the Porkmobile and the trunk-mounted screw driver antenna in front of a genre-appropriate restaurant

We continued operating the entire duration of the contest, driving through pouring rain for the last few hours. The rate began to drop off in the evening, a reflection of the poor efficiency of mobile antennas on the lower bands. Looking at the clock and the map, we reckoned that we would need to get back to Monroe country quickly if we wanted to have a chance to use the 80m full-length dipole that we had spent some time setting up earlier in the day.  We nicked Brown county on the way back to Tymme’s, but unfortunately didn’t land any QSOs.  In retrospect, I think we should have written off getting back and tried to get a couple contacts in Brown country, but we were also constrained by our over all travel plans — we had to be back in Chicago by 6 am the next morning, so we were keen to get back to Tymme’s by midnight and catch a few hours of sleep.

Tymme took the wheel for the last hour or two of the contest, flying through Indiana back roads like Luke Skywalker in the trenches of the version 1.0 deathstar. I’m pretty sure Tymme turned off the targeting computer and just followed his instincts home. Surprisingly (to me), when we got to Tymme’s house, he didn’t stop driving, even though the driveway had run out. Tymme continued to sail over lawn and into the forest behind his house, with the car slicing through waist-high grass. He stopped when he got to the tree supporting the 80m dipole and we hooked up the feed line to the radio in the car’s trunk.

Tymme operating phone from the back seat
Tymme operating phone from the back seat

Aside from some boozy yokels on 75m, we didn’t hear much activity, but once we started calling CQ, we had a pile up of responses. When we had wrung out sideband, we switched down to CW and a similar hot run. In the last half hour of the contest, I was pleased to work many calls that I recognized as QRP stations.

During the 12 hour event, we reckon that we worked 30 states/provinces and 48 sections. This is actually fewer states than we had worked in 2011. I believe that this could be improved in future efforts if we used higher antennas and paid more attention to the 7Q contest. Here is the breakdown by band and mode:

band  mode   qsos   pts  mults
3.5   cw     33     66   8
3.5   lsb    24     24   6
7     cw     135    270  47
7     lsb    127    127  44
14    cw     12     24   5
14    usb    13     13   8
21    cw     2      4    0
total        346    528  118
score: 62,304

Doing some quick calculations after the contest, it appears that Ben has now achieved the first rank of “worked all Indiana” between Operations Sizzling Pork and Rolling Pork.

On the way home, I attached the 10m MFJ hamstick to the trunk mount and worked CW. Conditions were great, with solar flux up around 150. I logged QSOs to the following countries: Honduras, Nicaragua, Argentina, Cuba, Guadeloupe, Brazil, Canary Islands, Mexico, Paraguay, Puerto Rico, the Balearic Islands, and South Africa.

This year, we had some nice mini-pileups, which made it an exciting event. After getting back to Virginia, I called up records from dxsummit to see if and when we were spotted (thanks, by the way, to everyone who did spot us). I would have guessed that we had been spotted at some additional times, so maybe this records isn’t all-inclusive of spots, or perhaps people are just good at finding fresh stations to work:

N9IO  3530.0 NN9S inqp      0347 05 May   United States
K3CT  7225.0 NN9S QSO Party 0012 05 May   United States
KB9NW 7244.9 NN9S           2244 04 May   United States

I hope we are able to build on our effort in INQP 2014. The first item on the plan for INQP 2014 will be operation from Brown County.

SCAF audio filter build

Completed FilterI have a few CW rigs that have lousy filtering. Rockmites and other low part count direct conversion rigs naturally don’t have much in the way of selectivity, but this is also (unfortunately) true of my unmodified Yaesu FT-817nd.  I should probably invest in the an IF filter for the 817, but for other rigs, it makes sense to have an external audio filter that I can use across projects. A natural choice would be the New England QRP Club’s NESCAF filter.

The NESCAF filter is designed around a family of versatile switched capacitor filter chips. The grand-daddy of the family is the MF10, but more modern versions exist (e.g., the pin-compatible LMF100 or the LTC1060) and have better performance. Each of these chips has two 2nd order filter stages, which can be configured as low pass, high pass, all pass , notch, or band pass depending on how it is wired up and what external components are used. One stage can serve as input to the other to create 4th order filters.

IMG_20130525_232918In the case of the NESCAF, the chip is configured as a Butterworth filter — maybe not the sharpest band edges, but minimal ripple in the pass band. Referring to the MF10 datasheet, it looks like the NESCAF implements this through two sequential mode 1 filters with a Q of 10. The filter bandwidth is controlled by two ganged 50k ohm potentiometers, with a section devoted to each filter stage. The center frequency is driven by dividing a time base by 100. A 555 timer outputing 70 kHz will result in a 700Hz center frequency. The 555 rate is controlled by a panel-mounted potentiometer. The center point of that potentiometer is set an onboard trimmer potentiometer. Output from the filter is amplified by an LM386. Some builders make this an onboard trimmer set to yield a gain of 1 relative to the input signal, but I made it panel mount to allow adjustment of volume.

Power input is nominal 12V and the LM386 uses this level directly, with only a couple of capacitors for smoothing. The rest of the circuit operates at 9V regulated by an 78L09. The MF10 chip is used in single-supply mode via a resistive voltage divider.

IMG_20130526_221504This design is sold as a kit through the New England QRP club, but schematics are openly available.  To try it out,  I decided to build my version on vector board, which was great in terms of character building, but next time I would certainly save a boat load of time and get their PC board.

The dual-ganged bandwidth pot takes up a lot of room in a case, so ideally the project would be housed in a deep enclosure. I had a bud box on hand, so I used that. The project schematics call for a 4.7k resistor on the power indicator LED, but that value results in such a dim LED that it would only be useful in a dark room. I knocked the value down to 1k in one build and 1.5k in another, and both worked fine. The marginal power cost is insignificant to me — I’d rather have a reasonably bright LED to let me know that the unit is powered.

scafback04I had no difficulty machining the cast aluminum case with titanium coated bits, but a stepped drill bit made it a pleasure to bore out the holes for pots and switches, leaving a burr-free hole with minimal effort. The rectangular hole for the power pole connector is still something of a pain. I drill a few holes, enlarge them, and then refine it with some tedious file work. It amazes me that there is no elegant way to panel  a single power pole pair. There are snap-fit panel mounts for 2×2 and larger arrays, but I would think the most common requirement would be a simple pair. The only solution I have found so far is to order very overpriced metal retention brackets that clamp on both sides of the socket. With a single screw in each bracket, they have a tendency to tilt, which gives the project an unprofessional look.

For once, I remembered to drill first and paint later. In this case, two layers of white spray paint. I made the lettering by printing text on water gilde decal paper using my laser printer. I filled the sheet with words, numbers, abbreviations, etc., that I thought I might need in future projects, since the paper is somewhat costly. After applying the decals and letting the cure for half a day, I went over everything with two coats of clear matte acrylic spray and then assembled the project.

WaterfallAs a functional test, I played back a recorded session of PSK31 signals and output to a computer running MixW. I made a video of this session and also took the photo at left. In that photo, events at the bottom of the waterfall are the oldest. So, proceeding upward, I had the filter off with audio bypassing it entirely. When the filter was turned on, signal was lost until I turned the AF gain up to the point where the level was similar to the source volume. The filter was already set to narrow bandwidth and the curvy line resulted from me dialing down the center frequency. Towards the top of the waterfall, I had opened up the bandwidth and then dialed up the AF gain to greater than unity, oversaturating the waterfall.