[Elecraft] KAT 500 and open wire

[Bob McGraw K4TAX]

They are a voltage type, 4:1 designed to feed a folded dipole. There are 
actually 4 windings, 2 on each coil.

If you want to see the best in balun usage and efficiency, a folded 
dipole typically has some 200 to 300 ohms impedance when constructed 
from open wire line or like materials.    Thus the upper radiator and 
lower radiator are equal diameters.  Of course it basically a single 
band antenna and  when used with a 4:1 balun provides,  a 50 to 75 ohm 
load for the transmitter.   For that reason, I believe hams {not me for 
one}, have gotten away from the design.  There is a lot of merit to the 
folded dipole antenna, relatively broadband, less noise on receive, low 
loss, high efficiency and etc.   I use one for my 160M and another for 
my 75M AM stations.    Both of mine are constructed from heavy 300 ohm 
transmitting feed line.  One must pay special attention to end support 
means {and not by the conductors with an insulator}  and center support 
where the feed line is attached.

73

Bob, K4TAX

On 1/6/2019 10:17 PM, Charlie T wrote:
> I should probably know this, but what is the old dual air coil Heathkit B-1
> balun, a current or voltage type?
> If I remember correctly, they are 4:1 ratio.
> Would this be a better choice for open-wire feed to a dipole intended for
> use on several bands?
>
> 73, Charlie k3ICH
>
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