The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

Category: Amateur Radio

Using and building radio gadgetry

Vacuum Tube LEDs: Platter Chassis

Given that Greenlee chassis punches fit the ersatz vacuum tube sockets, this makes a certain perverse sense:

Greenlee puch on hard drive platter

This set of punches is probably worth its weight in, uh, tool steel, because Greenlee got out of the Radio Chassis Punch business quite a while ago:

Greenlee 730 Radio Chassis Punch Assortment

As far as a Greenlee punch is concerned, a hard drive platter looks a lot like thin aluminum sheet:

Greenlee punched drive platter

I lathe-turned that white bushing to align the hard drive platter around the screw inside the punch. The right way to make that bushing in this day & age definitely involves 3D printing, but I was standing next to the lathe and spotted a nylon rod in the remnants bucket underneath.

The inner ring crumples around the bushing inside the die, while the platter outside remains flat & undamaged through the entire experience.

I match-marked the socket & “plate cap lead” holes on the punched platter and introduced it to Mr Drill Press, but the right way to do that for more than one socket / plate involves a Sherline mill fixture and some CNC.

And then It Just Worked:

Vacuum Tube LEDs – IBM 21HB5A drive platter socket

That’s obviously a proof of concept; the socket rests on the desk with the rest of the tubes / sockets / Neopixels tailing off to the right. The plate cap lead should pass through a brass tube fitting on the platter, just for pretty.

The 7- and 9-pin sockets have a raised disk that’s slightly smaller than the 25 mm hard drive hole; the easiest fix involves slightly enlarging the disk to match the hole. Although CDs / DVDs have a 15 mm hole and Greenlee punches work surprisingly well on polycarbonate, if I’m going to CNC-drill the screw / wire holes anyway, CNC milling the middle hole should go quickly and eliminate a messy manual process.

Come to think of it, that big tube would look better in the middle of a DVD amid all those nice diffraction patterns from the RGB LEDs in the cap…

2016-02-25
Bike Helmet Earbud Replacement

A bag arrived from halfway around the planet, bearing five sets of cheap earbuds. There was no way to tell from the eBay description, but they’re vented on the side:

Cheap earbud – side vent detail

And also to the rear, down inside those deep slots below the chromed plastic cover:

Cheap earbud – back openings

The raised lettering is a nice touch; the other earbud has a script L.

The PET braid over the fragile wire should withstand a bit more abuse than usual. The strain relief isn’t anything to cheer, though, consisting of that rectangular channel with the wire loose inside. I figured I’d start minimal and fix whatever crops up; I have nine more earbuds to go.

The motivation for all this was having the Gorilla Tape peel off the helmet, leaving a hardened mass of glue behind, then snagging the earbud wires. This is the new, somewhat better protected, wiring:

Bell Helmet – mic-earbud wire – hardened tape adhesive

In a triumph of hope over experience, I applied more Gorilla Tape:

Bell Helmet – re-taped mic-earbud wiring

The helmet may need replacing after another iteration or two.

My solid modeling hand has become stronger these days, so I should gimmick up a flat-ish wart anchoring the mic boom and all the wiring to the helmet shell.

2015-12-30
Family Christmas Ride

This doesn’t happen very often nowadays:

The Family That Rides Together – DCRT near Parker – 2015-12-25

That’s in the rock cut just east of the tunnel under Parker Avenue. In a normal winter, that rock wall completely shadows the asphalt and preserves an icy layer through March.

We rode out-and-back over the Walkway, with a few digressions along the way:

Christmas Ride 2015 – APRS track

A good ride was had by all; we could get used to those empty roads…

2015-12-27
Monthly Science: APRS Coverage Near Red Oaks Mill

APRS tracks for my rides around Poughkeepsie in early November 2015:

APRS Coverage – Highland to Hopewell – 2015-11

Turning on the topo data and squinting at the Red Oaks Mill area:

APRS Coverage – Red Oaks Mill area topo – 2015-11

The topography isn’t in my favor, with two ridgelines between Red Oaks Mill and the two APRS nodes near Poughkeepsie. APRS coverage southwest of Red Oaks Mill along the Mighty Wappingers Creek (basically, Vassar Road) ranges from spotty to nonexistent, because that route has even worse topography.

Seems to me an APRS iGate in Red Oaks Mill, running Xastir (perhaps headless) on an RPi, conjured from my heap (perhaps with a shiny new TNC-Pi atop the RPi, rather than an ancient Kantronics KPC-9612), and using a vertical VHF antenna in the attic (because lightning), might improve the situation.

That whole project continues to slip into the future, but at least I have more motivation and linkies…

2015-12-01
APRS Electronics Case Power Contacts

Mary reported hearing occasional beeps during a recent ride that indicated the Wouxun KG-UV3D radio on her bike was rebooting. It turned out that the nut soldered to the lug atop the screw contacting the radio’s battery contacts had turned itself slightly loose on the stud:

HT-GPS Case – PCB and battery contacts – end view

Snugging it up against the PCB made everything happy again.

However, while I had the APRS box off, I added strips of copper tape to enhance the connection to the radio:

KG-UV3D APRS interface – power contacts

Mostly, those gadgets just keep working…

2015-08-19
Bicycle GPS Track: Diggin’ Deep and Flyin’ High!
At first glance, I thought Mary had taken a tour of The Great Swamp south of the Vassar Farm gardens:

APRS Bicycle Tracking – Flying High

Having helped put the fence up, I’m absolutely certain nothing growing in the garden could get her to 4373 feet, much less boost the bike that high.

Before that, it seems she did some high-speed tunneling:
```
2015-05-10 18:17:31 EDT: KF4NGN-9>T1TP4X,WIDE1-1,WIDE2-1,qAR,KB2ZE-4:`eP}nAIb/"/k}
   type: location
   format: mice
   srccallsign: KF4NGN-9
   dstcallsign: T1TP4X
   latitude: 41.67466666666667 °
   longitude: -73.88283333333334 °
   course: 345 °
   speed: 42.596 km/h
   altitude: -371 m
   symboltable: /
   symbolcode: b
   mbits: 101
   posresolution: 18.52 m
   posambiguity: 0
```
The bike’s altitude began falling while she was on the way to the garden, from a reasonable 66 meters on the entrance road, bottoming out at -371 m as she hit 42.6 km/h (!), rising to 1341 meters with the bike leaning against a fence post, and returning to 53 meters as she started riding home.

Obviously, you shouldn’t trust consumer-grade GPS tracks without verification: it can get perfectly bogus numbers from fixes with poor satellite geometry. Altitude values tend to be only close, at best, even when you’re not too fussy about accuracy.

We experienced small-scale jitter in New Jersey and a friend carrying a commercial satellite link experienced similar randomization. Trust, but verify.
2015-05-17
Monthly Image: Bootleg Bell Ringers

MHVLUG meetings end around 8 pm and, depending on this-and-that, the bell atop Old Main on the Vassar College campus will be tolling the hour as we emerge. Here’s a scene-setting photo from Wikimedia, taken from about where I parked the car:

Vassar College Old Main Building

Although the bell didn’t have its usual steady rhythm after the most recent meeting, I didn’t expect this:

Bell Ringers atop Vassar Old Main

The tree grows in the near foreground, not over Old Main.

Two of them realized the risk of permanent hearing damage, but do you see the real hazard?

Take a closer look:

Bell Ringers atop Vassar Old Main – detail

No, it’s not the guy leaning against the historic-but-flimsy railing. That folded-dipole antenna over on the right side most likely connects to Vassar’s 45 W UHF EMS repeater; at that range, RF can burn deeply.

Obviously, the student body needs more amateur radio operators…

Taken with the Canon SX230HS braced on the side of the Forester and zoomed all the way.

2015-05-15