[Elecraft] 75 ohm coax

Josh Fiden josh at voodoolab.com
Wed Apr 1 19:32:58 EDT 2020


This all reminds me of the difference between when I was a young teen getting started as a ham vs now. 

As a kid I would put things together or throw em up. Only worried about it after it didn’t work. Nowadays, I plan & overthink things to death before getting anything accomplished. I prefer the old way. 

73,
Josh W6XU

Sent from my mobile device

> On Apr 1, 2020, at 4:20 PM, Frederick Dwight <kl7cw at mtaonline.net> wrote:
> 
> If you have 75 ohm coax, I would just try it.  If the Z of the antenna is in fact around 35 ohms, the Z at the shack end may be close to 35 ohms on some bands, but on others the Z will be transposed to well over 100 ohms with an SWR probably over 3 to one.  One of my dipoles has a SWR at the top of 75 meters of approximately 4:1, and I occasionally venture up there, but my K3S with internal tuner does not complain and quickly matches it to about 1:1.  Not ideal and this is not the way I usually build my antennas, but the loss is not too bad.  If you can build a unun with approximately a 1:2 ratio this should solve your problem.  If it does not cover all the way from 80 to 10 with low loss, I would not worry too 



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