CVARS WA7UHD

CVARS
The Chehalis Valley
Amateur Radio Society
WA7UHD

ARRL special service club




Electronics Workshop - May 30, 2019

Time & Location:

Topics:
  1. Wire Dipole Antennas
  2. Baluns and Ununs
  3. 3D printers

Notes:
Half-wavelength dipoles:
  1. Wavelength(λ) * Frequency(f) = Speed of light(c) * Velocity factor
  2. Speed of light in free space (velocity factor = 1) = 299,792,458 meters per second = 983,571,056 feet per second
  3. For wire dipoles, velocity factor ≈ 0.95
  4. Half-wavelength dipoles are also resonant at odd harmonics of the base frequency
  5. Current baluns try to make current at the balanced terminals equal and are used to keep unbalanced current flowing on the coaxial shield which can cause RFI in the ham shack
  6. Voltage baluns try to make voltage at the balanced terminals equal

3D printing:
  1. Mike has an Ender3 3d printer: https://www.creality3d.shop/collections/3d-printer/products/creality3d-ender-3-pro-high-precision-3d-printer
  2. Shared 3D printable things at: https://www.thingiverse.com/
  3. Free Fusion 360 3D CAD, CAM, and CAE tool: https://www.autodesk.com/campaigns/fusion-360-for-hobbyists
  4. OctoPrint, a web interface for 3D printers: https://octoprint.org/

Reference:
  1. LDG Electronics ad for baluns and ununs: http://nutsvolts.texterity.com/nutsvolts/201902/MobilePagedReplica.action?pm=1&folio=3#pg3
  2. "A Ham's Guide to RFI, Ferrites, Baluns, and Audio Interfacing:" http://audiosystemsgroup.com/RFI-Ham.pdf
  3. DX Engineering balun article: https://www.dxengineering.com/techarticles/balunsandfeedlinechokes/baluns-choosing-the-correct-balun

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