Magnetic California

It’s not going to win any beauty contests, but with my slapped-together Small Magnetic Loop Antenna (small MLA), I just worked two stations in the San Francisco Bay area with 20 Watts on FT8! (11pm CDT, 20-meters, antenna in living room.) By comparison, it takes me over 40 Watts to do the same on my 20m dipoles hanging outside. Huh.

Also, I heard a station in Hawaii and another further out in the Pacific, though they couldn’t hear me to log a contact. That’s a first for me.

Small Magnetic Loop Antenna, totally slapped together. Tripod, PVC pipe, non-conductive broom handle, pipe clamps, Velcro straps, and zip-ties. Primary (gamma match) loop: 1ft diameter, squished for SWR adjustment; RG57/U. Secondary (resonant) loop: 4ft diameter, RG8.
20~145pF air variable capacitor at top. Knob tunes the secondary loop for the target frequency (sweep knob until static on radio sharply increases in volume). Braid and center conductor of RG6 cable soldered together and clamped.
Primary loop (gamma match); RG-59/U, 1ft diameter. Braid and center conductor soldered together, then soldered across SO-239.
Close-up of bottom construction of gamma match.

The antenna matches with low-enough SWR on 20m (still have to use a tuner), and the capacitor isn’t high enough in value to get a good match on the low end of 40m (my band of interest), but it works better than expected. It’s a difficult, complex thing to fidget with, and is very fickle and easy to disturb because everything’s floppy. But…it works.

A nice feature of small MLAs (“small” meaning the outer loop is less than 1/10 wavelength of your intended frequency) is that they are selective and have strong nulls perpendicular to the loop plane. This allows you to rotate it to find and cancel nearby sources of radio noise. I’ve identified a few noises around the apartment complex, and want to take the rig outside (after some rework) to see if I can do better location of the noises.

I’m glad I put so little work into it; the cost of failure is lower this way. I was frustrated with it Sunday night when I built it, but tonight, even after sunset (with California in gray-zone), I managed to log a few contacts.

Research and more reworks are in the future. Potential improvements:

  • better construction with SO-239/PL259 connectors on weatherized capacitor box
  • use RG8/U (50ohm) for primary instead of RG6 (75ohm)
  • make primary closer to 1/5 size of secondary as recommended
  • use higher value capacitor (200pF?) with free 360° motion
  • design a remote tuning gearbox.

So let me say this: MLAs are interesting.

PERTURBATOR

The PERTURBATOR show on Thursday was everything I had hoped for.

Everything.

The music was phenomenal, and the light show was mind blowing. James Kent definitely takes after the Pink Floyd school of stagecraft: if what you do is mostly pretracked in the studio, then on stage you just have to dazzle ’em with a great light show.

Kudos to the lighting engineer for recognizing that there are more colors in the rainbow than red, green, and blue.

Sifting, Drifting

I think I’m naturally wired to quickly get bored.

The moment I learn a thing, do a thing, go somewhere, get settled in, I look up and around for the next nugget of interest, sifting through the chaos. My hobbies and lifestyle reflect this.

When it comes to supporting myself, I’m definitely a factory-worker kind of guy, pulling levers, getting a paycheck; a farmer, tilling the soil, sowing within the lines, reaping the grains when it’s time. But I have a hunter-gatherer heart, and I don’t trust in it to get me from season to season. I’ve never had faith in the future. And there’s the conflict.

I learn a thing, I know a thing, then I move on. I’m no expert at it, not by a long shot. But there I am, bored, looking for something new. It gets me into lots of interesting things and puts me in places of happenstance and serendipity, but I don’t feel like I profit from my finds. I end up sharing and telling people about the new thing I found, and they take it from there. That makes me a ranger, a rover, a muse.

To profit for myself, I need grit, tenacity, expediency, to finish before boredom takes over again.

A muse is someone who inspires others to achieve greatness without achieving any greatness of their own. Is that a bad thing? Is it a good thing?

Woke Nihilism

On the day of the burning of the Notre Dame cathedral, I was commiserating with a friend at the cafe about the disaster. A real moment.

Then another friend sat with us, tuned into our conversation, and brought up the fact that there are so many black churches that have been burned, and that the cathedral was probably built with slave labor because that was the style of the day, and that the Catholic Church has committed such atrocities and has enough money to fund the repairs on its own.

Look, dude, I get it, but you’re so woke you’re insufferable. Shut the fuck up. This isn’t about Flint, Michigan’s water supply problem. This isn’t about suppressed classes of people. This isn’t about everybody else’s suffering, as if that’s something that can be ranked and prioritized.

This is about a structure, a monument, a human work filled with history, heritage, and generations of longevity, falling to the forces of nature. Let us mourn, you bastards.

Rebalanced

Took out the drill and did repairs to my 1:1 and 4:1 baluns. Made the holes wide enough and at the 3/4″ centers necessary to accept the banana terminal blocks. Sealed the interface between the case and the block with a flattened piece of Coax-Seal(tm) for water protection.

Looks better, and now the terminals won’t twist and break the internal wires. The closer terminal spacing but extra case spacing changed the impedance a little; now it rolls off around 20MHz instead of 25-ish MHz previously. Not sure why.

4:1 balun with terminal block
4:1 with new banana terminal block. The banana plug fits perfectly, and now it’s permanently on my 300ohm feedline for ease of disconnection.
4:1 balun with completed banana terminal block.
Finished 4:1 balun, now on my 20m inverted-V dipole, matching better than the previous 1:1.

BTW, yes, those cores are wound with a pair of solid-core doorbell wire. Helluva lot cheaper than enameled magnet wire, and easily available at any hardware store.