All posts by houstin

(Skip to the bottom for BOM and how to build)

Thingiverse Link:

Original Reddit Post:

After being frustrated with 3 element beams and towers during field days past, I wanted to build something that gives me most of the benefits of a beam, but fits in a hatchback and can be setup by myself.

After finding some inspiration online, I bought 6 13′ Shakespeare TPS13 fishing poles and fired up my 3d printer.

The center core fits on the top section of an MGS mast with 2 nylon set screws to hold it in place. 3 bolts with wingnuts clamp the rods into place.

I even added a choke/1:1 unun inside at the feedpoint to minimize external parts

After the core and poles are assembled, wire guides go on the outside of the poles. Shock cord is added between the open poles to act as a tensioner/shock absorber.

Right now I just have a 20m element cut, but intend to add 10 and 6 (maybe 15 and 17 too)

Balun – or 5943001601 or 2643803802, Connector AMP 083-878, Screwposts 111-2223-001, RG-316

6x Shakespeare TSP13 or B&M BW4

  • Qty 2(per wire element): Locking Spade Connectors 8007K56
  • Qty 3: Wingnuts 92001A321
  • Qty 3: Pan Head Screw 90604A541
  • Qty 3: Fender Washers 91525A129
  • Qty 2: Plastic Screw 94564A310

Sized to mount on MGS Mk-4-Ext Mast, but any 1.5″ OD mast should work.

With the current popularity of air core magnetic loop antennas in amateur radio, I thought it would be nice to build another uncommon type. Instead of having a large loop with air in the middle (or core) of the antenna, this antenna uses a ferrite, not entirely dissimilar to those clips that come on USB cables, as a way to minimize physical size while maximizing the RF energy that flows through it.

The ARRL’s Antenna Book mentions this style of antenna, but only gives about a paragraph and references to the “Antenna Compendium Volume 1” and a reference to DeMaw’s text “Ferromagnetic-Core Design & Application Handbook”

Online, Ferrite Rod Antenna information is mostly about receive-only antennas, both for direction finding and shortwave listening. This particular antenna’s trick, thanks to the sizable ferrite, is the ability to transmit.

Granted it is only capable of handling about 20 watts, for a portable QRP rig it is pretty great. Especially with digital modes. Not to mention, that like a normal air core magnetic loop, it has great e-field noise rejection for urban environments.

With the capacitor I have and 10 turns on the LC tank circuit, it is able to tune from below 1.8 MHz up to 17 MHz. Tuning is an experience. When turning the knob, the human body de-tunes the whole circuit, so one has to adjust, move away and check, adjust, move away and check, repeat… Since it has such a high Q, there will be a lot of repeats getting it center on where you want it.

As for the parts it is fairly simple.

  • The ferrite rod itself.
    • This one is from a custom batch a friend of mine commissioned about a dozen years ago. (If interested, I recommend Stormwise Ferrite Rods, no affiliation, I’ve just had good luck with their products on several other projects, including a stack of rods for transmitting 100W)
  • A Vacuum Variable Capacitor
    • This one is a used Jennings 7-1000pF that only gets down to about 80pF
  • Wire for completing the LC Tank Circuit
    • I used some cheap Litz wire from eBay I had laying around. Its effects at this frequency aren’t as important, but with how soft it is it coils well.
  • Coax or wire for the ‘primary’ winding
    • I used a two turn Faraday coupler. Two turns because it gave me a 50 ohm match. A BNC to banana post adapter could work in a pinch too (and what I started with…)
  • Structure to hold it all together
    • I 3D printed some quick shapes with undyed filament, because plastics make it possible

On one of my i3 clones based off of the brainworm from Tom’s 3D I upgraded to a genuine i3 and an Titan extruder.  Not only are these really well made (3:1 gearing seems to be magic on 1.75mm filament) but it gives me a lot more peace of mind.

The i3 mkII layout uses an inductive sensor for automatic bedleveling, and since I would like to upgrade to a mk42 bed clone eventually, I wanted to make sure to follow this scheme.  Sadly, the longer non-PINDA probe just doesn’t fit in the mounts bouncing around thingiverse.

Still, worked with this a bit and here’s my solution in a picture:

Inductive sensor fit into an e3d titan

What I did was drill a hole in the base for the probe, and a getaway hole out the side (yes, over the holographic film) for the wire.  My drill speed was a bit aggressive and it chipped off the corner, but once the top was screwed back on everything is solid.


So, hope this helps someone.  It’s been running for about a month and a half for me without issue.

Icom likes to play it a bit fast and loose when it comes to standards.  Normally when someone complains about this digital radio is usually the subject of the conversation.  Not today folks.  That’s right, I’m ignoring proprietary codecs today because I made a retaining clip for my IC-7000.

I love this radio and have had it in my daily driver for about 3 years now.  It’s been used for net control at a race, listening to CB, and boring repeater chatter too.  I’m not sure if in my haste to unwrap it when it first came or if it never came with, but I never had a retaining clip for the HM-151 mic that comes with.  Now normally losing a mic clip wouldn’t be a problem.  When I wanted a new one for my FTM-350R that’s in my rallycross car I just went on ebay and picked up a new one for less than a buck.  With Icom skirting around typical design standards for the stupid little clips that was not an option.

So, 3D printing to the rescue!  I opened up Fusion 360 and my faithful caliper and in about 15 minutes drew up this:

Mic Clip Model

From there I took the STL and printed one out.  Making sure to print the object at at 15 degree angle to make sure the sheer forces weren’t all in the same line, I got this!

Mic Clip Mic Clip Side

A cute little clip indeed.  So with a 1″ square of double sided tape I hung it on my car right by the map light and away I go.  (I’d get a picture of that too but it is too dark.)

If you’re interested in making one yourself, here it is!

Download locally here Or Thingiverse!

One year ago plus one week (to the day) I drove a 1985 Alfa Romeo GTV6 home.  I picked it up in running, driving, but rusting condition for a price I can’t really complain about.  Sadly, since I’ve pulled it off the road, I still haven’t gotten it back on the road…  So it takes up space in the garage without giving the fun back.

A lot of the work required is welding, and while I had every intention of spending lots of time with my MIG this summer, work and flooring tended to get in the way.  Not everything is a wash though, since all the time away from home gave me plenty of time to sit with a caliper and reproduce nearly impossible to find parts.

The first one that came up is the adjuster carriage for the headlights.  The GTV6 uses a typical 5.75″ circular light mounted in a half-cup brace.  These braces aim up/down by riding on a little plastic carriages.  If these things are even still sold, I haven’t been able to find them, so I fired up the 3D printer and made a few.


It’s an odd part, with a number of compound curves, but designed to be made out of plastic.


Okay!  Great.  Tested the fit and they came out well.  Only problem is I have to finish the bodywork on the front end of the car yet before I can actually use them…

So, next while I was away another hard to source part, and this is one that breaks easily.  Heck, even the seller warned me not to break it: The sunroof handle surround.

Someone online produces a machined aluminum replacement that looks great, and I imagines functions great, but it’s a bit pricier than I wanted to pay for the moment.  So back to the 3D printer.


This is an odd part.  Based on some of the measurements and what dimensions seemed to be referencing, I’m of the mindset that Alfa originally designed this part to be machined metal, not injection molded plastic.  Probably why they have such a high failure rate.

Based on the way it printed it’s a little rough.  Will need sanding or chemical smoothing before use, and probably a few other changes to get a better fit.


The last part broken/missing on my GTV6 is probably the most unique of them all.  Since this car was designed in the late 70s/early 80s there was still that obsession with circuit boards and how futuristic they were.  So the tail lights were all mounted directly on PCBs.  PCBs, that I should add, were really build with substandard materials, so inevitably they all corrode away…

I started with the left side light, designed them, and sent a set out to OshPark to print.


I designed the boards to use the OEM type bulbs, by using the cheapest sockets I could find on eBay.  Standoff height is a bit different, but in my test fitting it seems reasonable.  I still have to correct some dimensions, but it’s 95% there.  The OEM wiring/connector just fits right on!


So those are the parts I amused myself with while away from home.  Sadly I haven’t had time to go back and weld/paint more, and with Winter setting in I’m a bit distraught another year will go by, but all fun and games!

Instead of finding a lathe and taking a stab at making replacement parts for the 19th century Canadian production spinning wheel Kit picked up last year, I figured I’d take a stab trying to make the parts on the Lulzbot.  Normally, for a typical wheel that’s around now it’s just a 20 dollar or so purchase to pick up bobbins, but these wheels were never built to any real standard.  So after an hour with a caliper, I’ve come up with this bobbing and the tapered drive pulley.

New Parts Old and New Drive Pulley Comparison Bobbin Comparison


I still need to smooth the ABS and bond the bobbin together (it is designed as a center shaft and two end pieces.)  Once it’s all done I plan to put up the STLs on my github.  Having not actually measured another wheel in person I don’t know exactly how different they are, but hopefully it’ll help someone in the future.

I picked up a LulzBot Mini this week.  The printer’s specs and price point finally pushed me into getting one.  It requires a computer with USB to be able to drive it (there is no screen or SD slot.)  I rather like this because it means the interface can be what I want. After using it enough with my laptop that I was confident in taking the next step, I went looking around for smaller systems.

I had an Arndale Octa with Linaro laying about being unused.  The Octa is a really interesting board that I originally got for playing around with OpenCL and USB 3 on an ARM Cortex-A15. While it only has 1 USB port, it has a lot more computing power than the Pis that are usually used.  I followed the guide to install OctoPrint on Raspian (since it is similar enough to a generic Debian install,) but when all was told, I plugged the printer in, connected to the web interface, went to select the serial port….and nothing.

Here it turns out the bog standard Linaro builds don’t include the CDC-ACM module.

No problem, it’s easy enough to build a kernel module.

First find the kernel version you’re using with the command “uname -r”

I was on 3.15, which is fairly recent, so I went straight to the Linux kernel repo on github and found the folder that contained the module of interest.

Make a new folder on the Arndale and wget cdc-acm.c cdc-acm.m from the repo.  Then create a Makefile that contains:

obj-m += cdc-acm.o
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

(Cut and paste may make things fail.  If you get errors in the next step, just type it out)

Make sure you have the needed packages to build from apt (they were already on mine)

apt-get install linux-headers-$(uname -r) build-essential

Then you should just be able to type “make” and things should go.  Once it’s done there should be a cdc-acm.ko in the folder. Try to use “sudo insmod cdc-acm.ko” and the printer should show up!

I’ve started laying out the file server system using the node from my C6005 experiments.  The EK blocks need to have the outer portion of the ears cut off to fit the close quarters, but I’m pleased with things so far.  Now to lay out the copper tubing!



Beginning layout of components (PSU is not the final unit)



Chipset waterblocks installed



Waterblock close-up



Doing some more testing, this time with a the 20-pin connector adapter



Awesomely silent high efficiency Seasonic single 12V rail PSU



Adapter wire



Hard disk backplane

Charmander, the C6005 node, runs outside of its chassis!  A few pictures of what I’ve done.


I couldn’t find my pin extractor, so I used two staples. It took me a long time, but I only had to solder one wire.


Down the middle are the two “No Connection” pins, and the one in the outer corner is the brown line that I haven’t analyzed yet. The system runs fine without it for now.


All connected up


We have post!


Ubuntu LiveCD with up to test connectivity 🙂

This first node is going in a custom Backblaze-inspired chassis build.  I ordered a bunch of parts from FrozenCPU for it and have laid out what I can in the chassis.  Once I plan out how the hard drive cradles will work it’ll be time for playing with metal.  So far though everything is fitting together even better than I could have hoped!

This will be the first part of my 1980’s inspired rack build.  Hopefully it goes well since the others are counting on it.




I picked up a 3 node C6005 off of ebay awhile ago, and while I love the systems for their cost and ability, the chassis they are in leaves a lot to be desired for the home lab.  So I’ve been attempting to figure out how to run the nodes outside their nurturing cocoon.  Tyan lists on their datasheet that it uses a “Proprietary 20-pin (12V single input) power connector” so I pulled the server out of the rack and started taking some notes.
c6005 Power ConnectorOnce I had an idea of what the connector looked like I could measure the voltage at each pin.  First odd thing is that when each node is ‘off’ pins 1 through 8 are all at 1V.  Once powered they are all 12V.  The other Yellow wire (pin 18) is the only 5V line.  All of the black lines (11 – 17 & 19) are Ground.  Pin 20, the Brown line, I’m not quite sure what it is.  It goes to a 2 pin header on top of the power distribution board.  My current thoughts are either a fan speed indicator or a “PSU on” control.

Also!  Header “U15”  by the USB port on the board are the power switch pins.