Beyond confused

[338_MtRushmore]

One must never ignore a perfectly good myth when in pursuit of the Magical, Mystical 1:1 and all of the Mythical goodness it brings.

Here's wishing that RF would propagate as well as the myths do. No F2 layer required.

I could care less what my swr is in the short runs of coax in the mobile. The amps... that's a different story. The feedline losses are nothing at 1.6:1 compared to the db's lost when the amp blows up.

Low swr for the right reasons lol

 

[338_MtRushmore]

And those numbers are physical lengths and have nothing to do with the electrical lengths. You need to factor in the cable's velocity factor to arrive at the fabled magic length.

Wait a second, those are electrical lengths and the physical lengths are much shorter. Right? Unless you have some awesome coax with a vf of 1. Or am I screwed up once again?

 

[sp5it]

Yes, you need electrical length. 180°

 

[Captain Kilowatt]

Wait a second, those are electrical lengths and the physical lengths are much shorter. Right? Unless you have some awesome coax with a vf of 1. Or am I screwed up once again?

The actual physical length will always be shorter than the electrical length due to the velocity factor of the cable. For instance RG-213 has a Vf of 66% therefore a quarter wavelength of RG-213 would be approximately 9 feet times 66% or about 6 feet. A half wavelength would of course be twice that at 12 feet. Different cables have different velocity factors so you must use the proper numbers to correspond to that cable.

 

[338_MtRushmore]

With my icom the swr measured at the amp output is 1.1:1. I change nothing but the radio and the swr is now 2:1. Again, nothing makes sense