A while back I showed a homebrew antenna rotator design I found on Youtube. This works well for lighter loads but I am concerned that the hexbeam is too heavy to perch on top of the motor shaft. I remixed a thrust bearing design I found on Printables and am encouraged that with some further tweaking it will work. It uses 6mm airsoft BB’s as balls that are captured on the lower race.
The Hexbeam structure survived just over 48 hours on a test tripod and up about 6 feet. It has been breezy with gusts this morning reaching 30mph. This was enough to topple the tripod dropping the hexbeam frame to the ground. The only casualty was the center adapter I 3D printed to attach the hexbeam to the tripod. It (predictably) snapped.
No cracking or other damage was noted on any of the other Hexbeam parts. I took the whole thing down and stowed the components. I could probably improve the setup time by sliding the spreaders into their mounts rather than tightening them down in the blocks and then installing onto the hub. Twenty-four wing nuts are time consuming to put on and off.
While the antenna was up I tested the location of the wires against the height of the center post. I’ve now developed simple clips to hold the feedline and element wires at the proper point.
So overall good progress. I plan to do some additional modeling before I start cutting wires. I’ll need at least one more visit to Home Depot for some hardware. Next time I set this up it will be with the wire elements so getting close.
Hexbeam 1.0 began structural testing today. I set it up on a short tripod with the spreaders and stretcher cords. The stretcher cords are made from 150lb test Kevlar string. It is quite wobbly until the perimeter cords are all put in place but appears to form up nicely once under tension:
Winds here today are about 12mph and likely to increase so I’ll see how the structure holds up. I’ll also take some measurements of both the yard (for turning radius) and or location of the three band elements and their relative positions on the center post.
Only findings so far are that the pole tips need to be adjusted a bit to ensure they fit correctly. Unwinding the stretchers is a bit fiddly and installing the spreaders on the hub needs some space and is a bit time consuming.
Next up are cutting the wire elements, setting up the center post and installing ferrites on the feedline. I’m also working on the rotator to add a thrust bearing to stress relive the motor a bit.
I have decided to build the hexbeam as a 3-band version for 20m-15m-10m bands. I need to use 5 sections of fiberglass tent poles for the spreaders. Here is my status:
Will use flagpole mast, guyed at the base and the last section. Height should be close to 25ft.
Dacron Guy Cords. I’ll use CamJam tensioners.
I’ll use 1.7mm Kevlar cord for the stretchers.
The hub is cut from an HDPE cutting board about 10″ in diameter made very similar to the one on the Moxon.
I’ll use the home made rotator that I have been working on for the Moxon.
The antenna elements will be from #14 THHN house wire. I’m scaling the lengths down by a factor of 0.98
I’ll make the feedline post out of PVC pipe.
I’ll likely 3D print the tip spacers as was done on the Moxon.
I have completed the spreader clamps, center hub and wire clamps.
I still need the rod tips, stretcher clamps, center pole connections and cut all three wire elements. I’m estimating the final antenna will weigh in at about 12lbs.
I am looking at using many of the items that went into building the single band Moxon antennas to build a Hexbeam. I originally had in mind to build a 3 band (20m-15m-10m) version but rather than spend some additional cash for more spreaders I’ve decided to use as much of what I have in order to build a 2-band (15m-10m) version that I can use in some upcoming contests. I am planning to try and use the tent poles I originally intended for the Moxon on the Hexbeam. I have four sets already built and will only need to add two more. If everything works as planned, I can always size it up to add the 20m band. Some of the features:
Will use flagpole mast, guyed at the base and the last section. Height should be close to 25ft.
Dacron Guy Cords. I’ll use CamJam tensioners.
I’ll use Kevlar cord for the stretchers.
The hub will be HDPE cutting board about 10″ in diameter made very similar to the one on the Moxon. I have already designed a new clamp to test out on the tent poles
I’ll use the home made rotator that I have been working on for the Moxon.
The antenna elements will be from #14 THHN house wire.
I’ll make the feedline post out of PVC pipe and use coax to connect the two drivers together.
I’ll likely 3D print the tip spacers as was done on the Moxon.
I’m hoping to have this ready by the end of the month and in time for the North American QSO party.
Fiberglass fishing poles used to be fairly easy to find on Ebay or AliExpress. These have been largely replaced with Carbon Fiber types which are largely unsuitable for use as spreaders. I mentioned in my last post breaking a spreader on my Moxon. I did find a spare without having to use one of the two extras I have reserved to try and build a hexbeam with. I also have collected a complete other set of fiberglass poles to use on future projects so I should be covered for now.
I used the 15m Moxon in the CQ WW DX contest this past weekend. I made two changes to the setup vs. my last deployment. First, I added a guy ring on the first section of the spiderpole. This helped stabilize the pole mount greatly. Another change was to use 4 guy lines instead of 3. The new guy rings I 3D printed seemed to do a better job of keeping the antenna positioned correctly in the breeze at least on Saturday when we had 20 mph gusts. Sunday was windier and resulted in pole collapse at least once and a bit more difficulty keeping the antenna pointing in the right direction.
The main guy lines were up about 6m and I found them to get loose perhaps due to the tensioners I was using. I also noticed that the pole would collapse when tensioned too much on even one line. This something I need to experiment with.
I did one band change by replacing the wire set for 15m band with one cut for 10m. The 10m antenna worked just as well if not better than the 15m version. What is clear from the contest is that having at least a 2 band beam results in better performance. I’ve worked out through EZNEC modeling that if I increase the size of the 10m wire set by about 3% I should be able to run both antennas on one feedline. This will be my next experiment.
There was one casualty after bringing the antenna down. I broke one of the spreader arms. I have a spare that I was going to use to try a hexbeam so I can repair it. I believe I clamped down too tightly on the wire clamps piercing the fiberglass. I am finding that fiberglass fishing pole are now really hard to find, and expensive as most Chinese manufacturers have moved to carbon fiber which is unsuitable for this kind of antenna. I did find a set of set for $120 on Amazon may try a last time buy .
I have been using the Creality CR-10S to print some antenna parts this week and ran into a problem as I was replacing the filament spool. The new filament would not feed into the Micros Swiss Direct Drive extruder. After some troubleshooting, I found that the short PTFE tube that feeds into the hot end had developed a slight deformity preventing the filament from feeding into it. Fortunately, I had some replacements and had to partially disassemble the extruder to remove the old tube and install the new one. This tube has some small, angled bevels on the input that had worn out. After re assembly I have had to check the bed levelling sensor, manually level the bed corners and reset the z-offset. Looks like after running an XYZ calibration cube that I am back in business.
I recently posted some experiments using two JPC-12 vertical dipole antennas a vertical beam. I went ahead an bought the hub for the JPC-7 which allows me to use both sets of JPC-12 antennas in a horizontal dipole configuration. The hub resembles a Buddipole VersaTee Hub and has a 1/2″ NPT threaded hole for attaching to a mast of some type. I 3D printed an adapter to mount the hub at the top of the 7m pole section of a Spiderpole.
I posted the build files in Thingiverse if anyone wants to build one of their own. I have included the STEP files so it can be modified for other mast diameters. Will try this on 15m this weekend weather permitting.
My upgraded Creality CR-10S 3D printer has been working flawlessly since April 2022. It was at that time that I detailed installing a Micro-swiss direct drive extruder and all metal hot end along with a TH3D Studios bed leveling sensor. Last week I had a print fail about halfway through. Filament just stopped coming out of the extruder. I usually address this type of problem by heating up the hot end and pushing through some filament manually. When I tried this nothing came out. Next step was to pull out the filament completely. This did not work either as the filament was stuck in the extruder.
Doh!
This was a very unusual problem as there was clearly a jam but I could not tell where it was occurring. I removed the fan cover and leveling sensor to gain access to the hot end. There was no sign of plastic leakage around the nozzle. I loosened the grub screw holding the titanium heat break to the heat sink and found the path to that point was clear. I figured the most likely culprit was a clog at the nozzle itself, so I removed it breaking off the bit of filament that was in the nozzle. the filament was still stuck! I removed the heat break from the heat block and cut off the remaining filament. Sure enough the bit of filament going through the heat break was jammed tight. Not sure if the material had melted a bit or if there was some imperfection on the filament itself. I managed to pop out the bit of stuck filament using a hex key and a hammer. Inspecting the inside of the heat break I noticed some plastic residue stuck to the inside walls. This proved difficult to remove without using a torch to soften the material first. After cleaning it off completely I reassembled the hot end with a new nozzle.
Now that the hot end and extruder were reassembled, I next had to relevel the bed manually and reset the z-offset. After having struggled a bit with this, I found the best way to do this was with everything cold. I printed several xyz calibration cubes and everything seems to be working great again.
I apologize for the long post on this subject but I hope this info is useful to anyone who runs into a similar problem someday and to remind me what I did if it happens to me again. I will likely also order a few spare parts incase something more significant happens. I have a spare heat break, heat block, heat sink and nozzles already but I should get a replacement set of heaters and thermistors.
I have had the CR-10S now since 2018 and printers have continued to advance in functionality and a reduced cost. Today, the CR-10S Pro V2 has all the features that I have had to upgrade to at about the same cost as my new CR-10S 5 years ago. Creality has just released their new K1 Max printer at a price point of $999 (the smaller K1 is $599).
This fully enclosed printer comes assembled out of the box and has numerous sensors built in to make the printing process about as plug and play as possible. It is also much faster to print than the CR-10S and with a 300°C hotend capable of more types of materials. It will be interesting to see what kind of reviews for this printer look like. 3D printing has come a long long way from my early days in 2011 with the Makerbot cupcake:
Adventures in Amateur Radio 