There are many designs on the web for ugly baluns. But I particularly like that of John Portune, W6NBC, and Jim Bailey, W6OEK (QST Magazine – February 2024; pg. 30).  A PDF copy of their article can be downloaded here.  It gives a nice clean looking balun, it fits on standard 2” or 4” PVC pipe and it has an incorporated coax holder. The end-caps and brackets can be 3-D printed at a reasonable cost. Jim Bailey made the needed .stl files available to me for 3D printing.

Here is my experience with the 3D printing of the un-ugly balun pieces by the Bonner County Library.  As of June 2024 (the name matches the file names from Jim Bailey): The price to print (1) each of:

A: ENDCAP_dovetail_mount_A: $0.98+tax (this is one side of the mounting bracket)

B: ENDCAP_dovetail_mount_B: $0.76+tax (this is the other side)

C: ENDCAP_dovetail_RING_4: $2.26+tax (this is for the 4” ring that utilizes the dovetail mounts A & B)

D: Mini_Cap_2: $0.51+tax (this is for the 2” ring that does not use A & B above)

You have to pay in advance at the Tech Desk which is located on the second floor of the library and they will add your prints to the printing queue. Note: there is a limit of 10 pieces (items) per each customer.  So, if you have more than 10 it requires 2+ trips and payments.

However, for clubs such as ours, I convinced them that it is easier to deal with 1 person with 1 set of prints than multiple people with multiple sets of the same print.  Depending on who you speak with you may get the 10 limit rule.  To avoid this you need to contact: Brenden Bobby at brenden@ebonnerlibrary.org, who seems to be the 3D print guru, and make arrangements through him.  The caveat is that to keep from holding up other users, if their printing Q is large, they may break the print job into multiple jobs scheduled at different times and advise when the total job is complete.  With my order plus one other person’s, there were 24 items which I got in less than 10 days after payment.

To have the library, or someone else, to print the items, you need to:

• Furnish the library with the appropriate .stl files. I used a thumb drive which they downloaded and gave back to me at the time of payment.
• 2 of C + (2 of A&B, if you want to use the mast mount) for 4” PVC pipe. Or, 2 of D if you are using 2” PVC pipe. (one of which one you use for each end)

 

All in all, I think the prints came out great.  One thing to be aware of is that they will have extraneous material that will have to be removed.  This usually comes off easily by hand but an “exacto” knife helps pry some of the more stubborn off.  This is especially true around the coax openings.

If you are interested in learning 3D printing they hold an “Intro to 3D printing with Tinkercad” at various times throughout the year and a lab every Wed. at the Sandpoint Library Lab on the first floor.

As our website doesn’t allow .stl files, if you want a copy of the files Email me or contact me at our monthly meeting.