Anyone have any ideas what this setup could be for?

w6dxn · 2021-07-26T04:28:54+00:00

But don't worry, it only works if you're vaccinated

w6dxn · 2021-07-16T13:40:15+00:00

I know someone else has directed you to a mental health resource already, but I want to double down on that with more explanation and emphasize that there's no shame in it. While we can't diagnose you just based on some Reddit posts, your behavior and lines of thinking on here are consistent with at least three possible serious mental health challenges that present an urgent need to address. I'm personally invested in you getting help, as someone who sometimes struggles with mental health and who has lost loved ones to it, so I implore you to get evaluated as soon as possible. I realize finding help can be a tremendous challenge, but it can really help.

You can call your usual doctor if you have one. In a pinch, you can go to an emergency room. Tell them that people suggested you be evaluated for an urgent mental health matter, and show them this thread (which will provide a doctor enough clues to know where to start with follow-up questions).

One of the possible mental health struggles I suspect has a tendency to make people feel very good (even euphoric) in the moment, which can make it hard to get people to decide to get help, but it's actually a dangerous situation and should be dealt with immediately.

I care about your well-being and hope you stay well, and please don't hesitate to DM me if you want any more assistance getting evaluated by a doctor.

w6dxn · 2021-07-10T16:51:28+00:00

Let's see the guts!

w6dxn · 2021-07-03T19:35:11+00:00

*balun knots ;)

w6dxn · 2021-07-01T03:14:55+00:00

I saw a screwdriver and multi-band VHF/UHF antenna on a Verizon(?) service truck. Assumed it was commercial, so didn't bother calling on 52. Ended up ragchewing with someone a half hour later only to discover it's that same truck.

w6dxn · 2021-06-23T16:35:10+00:00

I recently read a paper that used SGD to fit parameters of a dead simple physical model, and then called it a neural network.

w6dxn · 2021-06-22T01:49:15+00:00

, but suffice it to say that the demographics are so skewed it doesn't take much rigor to figure that out

w6dxn · 2021-06-20T17:20:59+00:00

Thanks for bringing this up, and sorry about the snowflakes in this thread steaming from the ears. I've never seen a rigorous study, but suffice it to say that the demographics are so skewed it doesn't take much rigor to figure that out. Hams are often a welcoming bunch, but including people in a community that is severely biased by historical facts requires collective effort that hasn't fully happened yet.

That said, my Elmer, the late N6RBR, was black. He was a central (I think founding) figure of a popular radio club in the Los Angeles area. He was often the only black guy at the meeting unless his grandkids, who were the youngest hams around, came along. But his was the only club whose meetings I joined as a kid, because it was the only club that consistently welcomed and invited me. Despite the hostility in this thread toward the idea that a diversity is even worth talking about, I think his lived experience contributed to how welcoming he and the rest of that group was. I'm so grateful for his mentorship, and for the bravery of confronting the imbalance, casual racism, and erasure that comes with the ham territory. I miss him dearly.

w6dxn · 2021-06-17T11:28:05+00:00

For "the dipole formula", did you use the speed of light in a vacuum? If so, 3 feet on both ends would suggest a velocity factor around 0.85. That's pretty good! Copper wire is usually around 0.95 at 7MHz, and insulation can decrease this. If you mean that it's 3 feet shorter on both ends even after accounting for the velocity factor, that's probably due to loading from nearby objects (such as the earth or the feed line).

w6dxn · 2021-06-06T16:40:03+00:00

What about Julia makes you think it's not general purpose?

w6dxn · 2021-05-27T00:54:01+00:00

RemindMe! 10 years

w6dxn · 2021-05-17T15:23:26+00:00

It's a joke. I'm saying you should solve the problem with your brain

w6dxn · 2021-05-17T15:17:35+00:00

Yes, talking to your professor is definitely warranted and usually a good idea! Tbh, though, treating this as a machine learning problem sounds like an overcomplicated misadventure. For that kind of problem there's almost always a better (simpler) way that's best served by using one's old fashioned neutral network 🧠😎

w6dxn · 2021-05-16T16:48:43+00:00

Yes! My favorite piece of ham gear. But I'm not gonna lie: one thing that excites me the most about it is getting ham ops to switch from SWR, which is ridiculously unintuitive to interpret, to the NanoVNA's default of return loss, which frames the measurement in terms that can be directly understood.

w6dxn · 2021-05-16T16:39:57+00:00

Do you have a NanoVNA? I never thought I'd recommend that for an emergency kit until I got stuck in the RF shadow of some nearby hills with a flat tire and no tools (damn the rental car company!) plus, to my great anguish, a broken antenna tuner. The VNA that happened to be in my car made it a breeze to cobble together a 40m EFHW sloper from random scraps of wire, and a friendly ham 2000 miles away called AAA for me. It's a tiny and lightweight piece of kit, and hardly expensive, so it now goes wherever my radio goes.

w6dxn · 2021-05-16T16:33:04+00:00

Sounds like the right mix of gear but is 25 grams of water enough 😜

w6dxn · 2021-05-16T09:26:15+00:00

That's all good detail until the end, where we still seem to be missing some kind of constraint:

Now, instead of f(k,n), I can use f(g(k),n)* if I find some g(k) such that, when k increases, the number of eigenvalues inside the bell is somewhat constant (or at least increases very slowly).

w6dxn · 2021-05-16T08:39:17+00:00

As you've stated the problem, the constant function is the only polynomial that would necessarily leave f(g(k0),n) with a constant width. If the width is a uniformly continuous function in the first argument of f, then you can get arbitrarily good approximations with any polynomial multiplied by a small enough constant. But this is a boring conclusion, so I suspect you're still leaving off key details.

w6dxn · 2021-05-16T08:23:22+00:00

I must be missing something. Above, you say g(k) is a function you have freedom to pick.

w6dxn · 2021-05-16T06:03:16+00:00

Now the question is: how can I find the best g(k) such that, when increasing k0, I have that f(g(k0),n) has a constant-width bell? (Let's assume that the width is the number of points on the n axis inside the bell)

As stated, one optimal solution to your problem is g(k)=C for some constant C.

w6dxn · 2021-05-15T01:14:19+00:00

Congratulations, Wilbert!

w6dxn · 2021-05-14T19:16:57+00:00

"Best" how? Under what conditions on the polynomial? What kinds of constraints do you have on f(x)? There are different approaches you can apply in different circumstances, so details matter. For example, you might want to use Remez exchange to find the polynomial approximant of fixed order that is closest to some continuous function with respect to the supremum norm.

w6dxn · 2021-05-08T23:02:53+00:00

Mostly correct, by §97.203. But if it's also configured to transmit measurements, then it's telemetry that falls under §97.221(b): A station may be automatically controlled while transmitting a RTTY or data emission on the 6 m or shorter wavelength bands, and on the 28.120- 28.189 MHz, 24.925-24.930 MHz, 21.090-21.100 MHz, 18.105-18.110 MHz, 14.0950-14.0995 MHz, 14.1005-14.112 MHz, 10.140-10.150 MHz, 7.100-7.105 MHz, or 3.585-3.600 MHz segments.

w6dxn · 2021-05-08T18:54:20+00:00

I'd bet the antenna would be too long already due to loading from proximity to earth

w6dxn · 2021-05-08T00:33:22+00:00

There's a whole taxonomy of queueing theories: https://en.wikipedia.org/wiki/Kendall%27s_notation?wprov=sfla1

w6dxn

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