Interesting Nerdy Pictures and Videos Thread

ToddDubya

ToddDubya

NES Member
Joined
Dec 14, 2011
Messages
29,887
Likes
61,625
Location
Berkshires
Feedback: 18 / 0 / 0
My friend sent me this video and it does a really good job of illustrating how waves behave in transmission lines, the effects of impedance mismatches/opens/shorts, and how a transmatch (tuner) affects waves. I'll have to watch it a few more times to get all the subtle details, but it's really good.

I really liked the part on SWR.


View: https://www.youtube.com/watch?v=DovunOxlY1k
 
This is an interesting video on designing yagis. I'll admit I always thought there was black magic and voodoo behind the design effort, but this guy shows a very simple approach that is just as good as all the fancy designs out there. He shows some neat illustrations and animations to help visualize what the elements in a yagi are doing.

Basic design:
  • Driven element is 1/2 wavelength
  • Reflector is 5% longer than the driven element
  • All directors are 5% longer than the driven element
  • All elements are spaced 0.2 wavelengths apart

Build and tune:
  1. Mount the driven element and tune it
  2. Add reflector and directors
  3. Tune for low SWR
  4. Tune for center frequency


View: https://youtu.be/gabzyN22pg4
 
I've seen a few of these built and I think this might be a good project for my shack. I've got some noise just like everyone else has, and have the toroids on a bunch of wires like everyone else has, but lately I've been noticing a lot of noise coming from my appliances. When the fridge compressor and dishwasher valves cycle I get a big crash that presumably swamps out the AGC for a few seconds. It's mostly annoying, but can't be good for the radio. I think I'd add a MOV to the circuit to help with surge suppression.

My appliances are also pretty old so I should really be looking at new ones.


View: https://www.youtube.com/watch?v=styV63U5Yws

For reference, here are the main parts he used, but from the US Mouser.

Oval toroid (need 2): https://www.mouser.com/ProductDetail/Fair-Rite/2643167851?qs=MLldULe7zY0D6iHMqTKiOw==
Fair-Rite 2643167851

Clamp-on toroid: https://www.mouser.com/ProductDetail/Fair-Rite/0431177081?qs=KmHvPbTOE4RJzgtUylmsjQ==
Fair-Rite 0431177081

Inline EMI filter (16A): https://www.mouser.com/ProductDetail/Schaffner/FN2030-16-06?qs=fosVUi2b00wdWzH3EXn5lg==
Schaffner FN2030-16-06

Inline EMI filter (20A): https://www.mouser.com/ProductDetail/Schaffner/FN2030-20-06?qs=fosVUi2b00ylH7/7HnpkGw==
Schaffner FN2030-20-06
 
Last edited:

Similar threads

CA Fires and Ham Radio
Replies
3
Views
161
RubiconLJ
R
70cm Call and Car emissions
Replies
6
Views
337
ToddDubya
ToddDubya
I have a Yaesu FTM 200DR and need help
Replies
7
Views
327
FisherTech
F
Whoops Thread
Replies
20
Views
959
SpaceCritter
SpaceCritter
SWR and Losses
Replies
1
Views
279
ToddDubya
ToddDubya
Back
Top Bottom