Caffeinated Thought for Today

 Eh, all I got for today.  Go build a j-pole.

Jurassic Duck Mk III & PRC-26

From that last post, you could probably tell that I've been up to something.  Following up on last month's Three Days In The Woods, it was painfully clear that we needed serious radio power in a backpack-able format.  Some discussion of updating the old AN/PRC-25/77 radio concept was batted around.  Starting with the Jurassic Duck Mk II as a prototype antenna and building up a backpack frame with a TYT-9000D 2m radio and a 20 AH LiFePO4 batt, we took the original DoD realization from 42 pounds and 2 watts for $5000 (inflation adjusted) to a much improved 14 pounds and 60 watts for $300.  Of course, that's 60 watts on 2m, which for the typical 40 MHz used with the PRC-25/77 series, has about the same punch as 5 watts at that frequency.  OK, so a third the weight and two and a half times the power for a sixteenth the cost.  Wrap it up, I'll take it.  Also, this being 2026, we dubbed it the "PRC-26."  Picture on the right.

Of course, any project such as this one will naturally bring in a few refinements and construction notes.  Here they are for this iteration:

• We used a cam-lock lever to allow the antenna pole to pivot over to half-size for storage and transport.  This has caused all kinds of havoc, and I don't recommend it.  First, it necessitated bringing the coax out through the side of the PVC pipe above the pivot, which makes slipping things in and out during adjustment a bear.  Also, it necessitates a longer lower segment, which makes the whole thing wobbly.
• Recommended for next iteration: Two glue-on male threaded adapters with a female threaded coupler to join them.  Note, the UHF plug connector can slip through all of these and come out through the bottom of the lower pipe.  Much simpler, more rugged, and easier to construct.
• Be damned sure to get thin-walled PVC!  Bring a section of 450 ohm window line to the hardware store with you and try slip-fitting it in.  It'll be snug, but make sure it fits fairly easily.
• Revised lengths for the j-pole internals: 
• main radiator = 38" with an inch or so of loop-over (cut it a little long and tune down 1/4" at a time)
• 450 ohm segment = 17" total length, remembering to leave enough to solder the bottom legs together and an extension on the hot side for the main radiator wire attachment
• tap 1.75" from the bottom of the window line

And that's it!  I'll be building up my own personal copy of this revised version in the near future.

Programming a TYT-9000D VHF Radio... by Hand

At FCEM we've been using TYT-9000D's for general-purpose 2m radios.  They're easy to work with, and at around $130, the price is right.  Also, up until now, they've all been really easy to program using chirp and the proper USB cable.  The data port's right there on the front, and there're no complicated "get this thing into programming mode" steps to follow.  It's more of "just plug it and do it."

Until lately.  The last couple of radios we've gotten in would. not. talk. to. the. computer. grrr. for anything.  Tried some of our other, older 90000D's, no problem.  Tried different computers; nope.  Got the latest copy of chirp, still no dice.  I just had a handful of repeaters and simplex channels to program in anyway, so how hard could it be?

As it turns out, it's not a lot of fun but not completely awful either.  Here's a useful video.  The guy over-explains a lot of stuff for somebody who just wants to get the job done, which stretches it out to 15 minutes.  However, all that over-explaining is way better than under-explaining, and some people might need it.  Anyway, if you just want to get down to business, here are the steps:

1. Set the bandwidth/frequency deviation as described near the bottom of this post first!  Fortunately, you'll only need to do this once, and can program in all the other channels without repeating this step.
2. Punch in the repeater's output frequency using the hand mic keypad.
3. Press P5 and use the big knob to set the PL tone.
• To cycle through T, TS, DCS & OFF options, use P5 repeatedly.
• Press P3 to return to VFO mode.
4. Press & hold P4 to get to the offset menu.
• Big knob changes offset (you'll want 0.6000 on any 2m repeaters)
• Press & hold P4 to cycle through +, –, and OFF.
• Press P3 to return to VFO mode.
5. To save into memory:
• Quick press F
• Use big knob to dial to the memory channel you want.
• Quick press P3 to save to that channel.

Done!  There now, that wasn't so easy, was it?  Oh, also, I have no flippin' idea of how to program in alphanumeric names by hand.  I think that it's theoretically possible, but you'd have to get Rainman to read the manual and show you how.  If it's just a half-dozen channels, make yourself a 3x5 card if you need to.

Also, here are a couple of handy items when in operating mode:

• P3 toggles between VFO and Memory modes.
• F P5 locks & unlocks the radio's controls (good when working in the brush).

While we're at it, here are three other useful setup items that took me a good long while to dig out of the manual.  I'll put them here, partly as a note to future self, and also as a help to other poor souls.

First, the digital noise reduction filter is way overkill, like dialed up to eleventy and sounding all underwaterey, and it's not needed for FM anyway.  Turn it off by:

1. Press the F key for about 3 seconds.
2. Use the P1 & P2 keys as up/down to get to Menu 31.
3. Turn the big knob to get it from "RENC-ON" to "RENC-OFF".
4. Press P4 to confirm setting & get back to operating mode.

Second, if you have managed to get your radio to work with chirp, you'll want it to display the alphanumeric name you put in, e.g., "CBELLE" rather than "145.230" for the case of the Carrabelle repeater.  Toggle that over by:

1. Press the F key for about 3 seconds.
2. Use the P1 & P2 keys as up/down to get to Menu 26.  (not 27 per the manual; it lies)
3. Turn the big knob to get it from "DSP-FR" to "DSP-CH" to "DSP-NM" – frequency, channel number, or alphanumeric name, whichever you want.  Probably the alpha name.
4. Press P5 to confirm setting & get back to operating mode.

Third, all the 9000D transceivers I've seen have three FM deviation settings.  For 2m ham, you want the widest setting.  (Yes, I know the manual only says two settings.  The manual lies.)  You can set these using chirp (if it works on your radio), or do it by hand.  Important: if you're programming channels by hand, do this first!  Here we go:

1. Press the F key for about 3 seconds.
2. Use the P1 & P2 keys as up/down to get to Menu 08.
3. Turn the big knob to get it to "BAND-25" (i.e., 25 kHz deviation).
4. Press P5 to confirm setting & get back to operating mode.

There.  The TYT-900D is a weird, cantankerous beast to set up, but the price is right and they work pretty well once programmed.  Good luck.  And if you leave the digital noise reduction on, tell Aquaman I said hello.

A Beautiful Mess of a Plane

It was designed for but arrived a year too late to make it into WWII, so it was re-forged into the bridge between the Prop Era B-29s and the Jet Age B-52s.  Somewhat forgotten today, the B-36 Peacemaker was in service for less than fifteen years before it was phased out.  Seventy six years ago yesterday, one fell out of the sky over Canada; you can read about the incident here at This Day in Aviation.

Anyway, it's a beautiful plane in its own ungainly way.  Glad we never had to use them for their main purpose.

Beast of a plane, but I'd love to have gone up in one.  Once.

With the retractable gun turrets, it has a certain sci-fi vibe.

This Explains So Much

Over at SMBC.

It also goes a long way towards explaining why we now have string theory and techno-pop.

Kessler... Maybe?

A couple of years ago I posted a little piece on the Kessler Syndrome here (includes a brief discussion one the topic at hand, if you need a reminder), and the bottom line was "yeah, don't worry about it – yet."

Now Kessler and a co-author have recently revisited the topic, and their results are not so sunny.  You can read the abstract and download the paper here, or listen to Sabine Hossenfelder's take on the matter here.  It's going to be interesting to see this one batted around over the next few years.  With such wildly divergent results, there's going to be a good academic catfight.

My advice: Enjoy your Starlink while you can, but brush up on your HF skills too.  And if it comes to it, enjoy the light show.

Protip: Never exceed any limit labeled "Runaway Threshold."  Don't, just don't.