Balcony Into the Sky

Getting more brazen with my antenna projects at my apartment.

Used a reshaped coat hanger with a pulley and a lead weight to hook over a tree limb over my balcony. Now I have an anchor point to hang my 10m vertical dipole (or any other antenna that’ll fit). The anchor is below the peak of my apartment roof, so it’s deaf to the East for groundwave, but at least I can get out to anybody locally with decent towers at their QTH. Can’t wait for sunspots to kick up again for 10m to open up for DX, but that might be a while yet.

I also built this crazy, screwy-looking antenna.

Slinky Dipole, mounted and ready. Just add feedline. Radio not included.

It’s a Slinky Dipole, made from a pair of Slinky™ metal spring toys attached to a custom PVC center insulator and suspended with clothesline rope. I have it slung under the eve of my balcony for protection from rain since it’s not galvanized.

I used the length = 2πr * turns formula to calculate the actual uncoiled length and determined that it would resonate somewhere around 12.8MHz if completely straight. What I got was somewhere around 9.5MHz due to the induction of the coils lowering the resonance, as well as its proximity to the metal rain gutter and balcony railing. It’s electrically too short to resonate on 40m, so I tuned the antenna to 20m by clamping turns of the spring together with twist-ties to short them out. That got me close enough. I could probably dangle some wires from the ends or add another pair of springs to lower the resonance, but that’s another battle for another day.

Slinky Dipole, from the end, showing rope and mounts

Anyway, it’s a crappy antenna. It’s kinda deaf to real signals and picks up a ton of nearby noise, but it’s better than not having an antenna at all. I was kinda let down by how badly it performs, considering all the work I put into it, but heck, I did it and now I know.

The Slinky Dipole after completed construction.

I do have some improvement ideas, though. Maybe if I built a swing-arm assembly to move it out over the yard and away from the building. I could also try using a 1:1 balun to kill some of the common-mode interference, or just connect a 300Ω twinlead or 450Ω window line with a 4:1 balun to make it more broadband so that it almost always resonates with lower feedline losses. Speaking of, with my antenna tuner, I can get a resonant match on 40m, 20m, 30m, 10m, and sometimes 15m with 1.5:1 SWR or better. I’m surprised, even. However, 17m is 2.5:1 SWR, 80m is unmatchable, and 160m is almost dead silent.

Slinky Dipole, close-up feature of center insulator, bracket, and feedline attachment.

I’m going through the ARRL Antenna Book for inspiration. I wonder if I should make an inverted V and hang it from the tree hook, or if I should attempt something more grandiose like a triangle loop antenna from the hook or some kind of antenna-and-pulley system to ascend the arch of my roof. Who knows? I certainly don’t.

And I certainly don’t want to hear my landlord complain about it, that’s for sure. I haven’t paid an antenna deposit yet. Don’t want to hear it from my neighbors, either. But so far in the past week of operations, I haven’t heard a single knock on my door, but that’s not to say the neighbors aren’t getting interference. I have a desk lamp that gets brighter when it’s touched; when I key down and speak while pushing more than 40W, every voice peak causes the lamp to change state. So it’s a reminder to be kind.

BTW, I almost had a successful QSO with a station in Cuba on 40m the other night, running at 50W with FT-8 mode while using my Slinky dipole. Would’ve worked if my timing on FT-8 was right. Amazing, considering my balcony faces East and Cuba is due West-Southwest. Radio is funny sometimes.

Here’s hoping I can figure it all out, or at least enjoy the bumbling.

Heterodyne

I just had some first-hand experience with some very wideband heterodyne mixing in my radio shack. (For those not in the know, a heterodyne is where you mix a signal at one frequency with a signal at another frequency to derive a new pair of frequencies that are mathematically related.)

My 2-meter radio was tuned to 146.940MHz, a local repeater W5KA, squelched down to silence. I was assembling a 10-meter dipole inside my apartment and working on trimming the ends for resonance. As I swept my MFJ-259 antenna analyzer around 28.718MHz, the squelch on my 2-meter radio briefly popped open with some random noise. As I scanned around and centered on that frequency, what I heard was piano music, classical piano music. Huh!

My apartment is line-of-sight with the range of broadcast towers over the river in Westlake, so it’s highly likely that what I was hearing was bleed-over from one of those stations. Sure enough, the local classical music station, KMFA, broadcasts at 89.5MHz on the commercial FM dial. So I was getting some heterodyning.

146.940 – (28.718 * 2) = 89.504

Wowza!

So why that station? Why not the others, which broadcast at higher power? Might be that my 10m dipole had hit a resonant spot and pumped enough of the signal from the analyzer into the nearby J-pole antenna connected to the 2m radio, raising the noise floor enough to open the squelch.

Also, why does the mixing frequency 28.718MHz have to be doubled? Is there a harmonic coming out of the antenna analyzer? Is it a triangle wave instead of a sine? Is KMFA itself sending a harmonic at 118.218MHz? (That’s in the restricted Air Band!) Is it because the 2m J-Pole was perpendicular to the center point of one leg of the 10m dipole? Is that where the doubling comes into play?

Radio is perplexing, and I love these mysteries.

Really, heterodyne mixing is used all the time in almost every radio device. It’s an important tool used to convert one frequency into another; you simply generate a constant modulated signal at one frequency (the “intermediate frequency”, or IF), and then use a variable mixing frequency to generate a heterodyne signal at your desired transmission frequency before sending it to the amplifier for transmission.

It’s all magic. Magic!

Transit

Ultimately, all technological systems are mediums for human systems. As much as I love computers, networking, radio, etc., I still have to wrestle with the human factor. People are why those things exist. I can study and focus and fixate on the tech, but the tech is completely, irrevocably, in service of human communications. I have to answer to other people.

At the lowest level, closest to the silicon, we all need to be a little bit of Bryce, but even Bryce knows that he has to make deals with the people who ask a lot of him. My job, my hobbies, my relationships ask lots of things of me, and I have to arbitrate expectations and deliverables. I have to be a human.

Please excuse me if I don’t look you in the eye; I’m working through some things and hope to return to humanity soon. Hope you understand.

Dit-Dah

I’ve decided that I need to take my radio hobby to a new direction. I have difficulty getting out of the region with my radio and antennas with only voice communications. I haven’t gotten into the digital modes because, honestly, I don’t have a decent laptop to do it. Everything I have is kind of a hack.

If I want to log any sort of long distance (DX) contacts, I’m gonna have to use something that’s not voice. I’m jealous of the stations that talk about logging contacts from South America, Europe, Africa, places all over the world, on 10 Watts or less. I’m over here going “how the hell did they do that? I’m using 100 Watts!” The answer is Morse Code. Once you learn it, it’s fairly easy to make contacts that are readable — the code key turns the radio transmitter on when you key down, so either the radio signal is there, or it isn’t. It’s the most efficient use to radio energy ever.

In that light, what I’m proposing to do is dedicate the month of April 2018 to learning Morse Code. All 26 letters, all 10 numbers, all important punctuation. I want to be able to hear and key the code proficiently by month’s end.

I have a few apps, among them is one called Morse Machine. It’s pretty decent, and it allows me to learn code using the Koch method, which is recommended (it plays symbols at their normal speed with extra space between so I have time to recognize the sound and type the symbol). Once I can demonstrate a high enough proficiency with a few symbols, it unlocks the next group.

My plan is to do this for at least 15 minutes a day, every day. I already got far enough along, but since it’s been a few months since I last tried practicing, I’ve forgotten it all. So this time around, I’m going to clear my training scores and start from scratch. It’s really the only way.

I hope I can get up to at least 10 WPM by month’s end, at least for being able to hear code. I have a practice code key at home with an oscillator so I can pound it out without going over the air. But really, the best practice is to just Get On The Air. But first I need to learn the language.

Wish me luck.

Fourty-Six and Two

Started my birthday on a conference call, waiting to unplug a rack of servers and move them to another corner of town. Four hours later, the project was a success. Wrapped up the event by driving a pair of customers to their hotel, dropping off a coworker at the office, and heading home to consume the last inch of my bottle of vodka.

Four hours later, I woke up again. Circadian rhythm can’t be beat. Made breakfast, cleared the cobwebs, put on some Tool, Sepultura, King’s X, whatever. Far cry from the electronica of late. Shaved, showered, found clean clothes. Went out.

10-meter Net went up at 3; band was noisy due to contesting. Station in central America was sitting on the net’s usual frequency, so there was a lot of interference. Still managed to log 10 stations in the Austin area, which is usual. Not bad.

Spent some time up on the parking garage to try out the 2-meter flexible J-Pole antenna I built Friday night. The damn thing works well. With my handie-talkie I was able to reach a repeater in Georgetown (30 miles north) on 7 Watts. Scratchy, but readable. That’s a massive success. Punched in my new amplifier and was Full Quieting. This makes me happy.

Reached a repeater in Marble Falls / Dripping Springs to the southwest with the amp and J-pole. Either nobody was on frequency or I was too noisy to read, so no signal report. Anyway, the repeater itself responded with its station ID and squelch tail, so I know I got in.

Bummed around, took myself out to Ramen Tatsu-Ya for a solo meal. Terrible line and noisy joint with zero personal space. Food was good, but everything around it was not what I needed that day. My birthdays are usually spent alone; space and solitude are the best gift. I blame the over-the-top birthday parties of my childhood. Now I’d rather just be left alone. For once, Austin denies solitude when I actually want it.

However, my buddy Doug did take me up the street to Workhorse for a beer, gratis. We had a decent time hanging with other Epochians on the back patio. I spied a lady sitting along the wall alone with a book, something from Vonnegut. I thought I was the only one who read in bars; glad to know there’s still others.

Got home tired and bleary-eyed. Lack of sleep keeps me mute sometimes (today especially so). Otherwise, it was an OK day. 46 is going to be more fresh Hell. Here’s hoping it’s not that terrible.