balun directly in the coax cable

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All descriptions I've seen of using a balun indicates that it is a discrete, separate device. Is there any reason that a 1:1 balun cannot just be wound at the antenna end of the coax that leads to the receiver? I am going to mount a horizontal dipole in my attic with a 1:1 balun between the coax and the antenna. Thanks.
 

prcguy

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If you can find a diameter and number of turns that give a few thousand ohms or more impedance to common mode currents then your good. This is usually only achievable on a single band where ferrite loaded choke baluns can cover 80 throu 10m or more with adequate common mode rejection.

Using an ugly balun of coiled up coax on all bands is usually nothing more than extra coax flapping in the wind with no benefit.
prcguy
 

LtDoc

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That so-called "ugly balun" isn't a balun at all, it's just a choke. A choke can certainly reduce CMCs on the feed line, but it will never do the 'transitioning' between a balanced antenna and an unbalanced feed line like a balun will. Close, but no cigar. If you need a 1:1 balun then use one. For a dipole/doublet where you'll be mounting one, I wouldn't bother with a balun at all. They are not absolutely necessary on HF and non-directional antennas.
- 'Doc
 

W2NJS

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The dipole (not a folded dipole) has a nominal impedance at the feed point of 75 ohms or so. If you use a good 75-ohm coax you have a pretty good match without any kind of transformer or matching device, so it might not be worth the time and trouble to add to the simple setup.
 

prcguy

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In free space or at least a couple of wavelengths off the ground at half wavelength intervals it may be 75ohms but for most hams our dipoles are much lower to the ground and the impedance will be closer to 50ohms and sometimes much less.
prcguy


The dipole (not a folded dipole) has a nominal impedance at the feed point of 75 ohms or so. If you use a good 75-ohm coax you have a pretty good match without any kind of transformer or matching device, so it might not be worth the time and trouble to add to the simple setup.
 
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