Mike,
The reason is that for small 4:1 baluns, you need more turns of wire
on them to get the necessary inductance, more turns means a smaller
wire to fit, and a smaller wire means the impedance of the two wire
transmission line is not optimum for a 4:1 balun. You will have a
high SWR just due to the balun. However, I have made many small 1:1
baluns using several turns of RG-174 on a toroidal core, by placing
ferrite beads (12 FB43-801 beads work nicely) on the outside of a
piece of RG-174, or just winding a bifilar pair of #22 enamel
insulated magnetic wire on a toroidal core. You need a F114-43 or a
F140-43 core to get enough impedance for 80 meters, although a
smaller core will work for 40 up. Palomar sells a BA-58 bead kit for
RG-58. Actually, a 1:1 balun works as well on a random length
transmission line as a 4:1 balun. Unless the load is a predictable
200 ohms or there about like you get on an OCF antenna, the impedance
of an open wire feed line is just as likely to be near than 50 ohms
as it is near 200 ohms. You also can use a Low Power balun for 100
watts like the Elecraft balun kit, or the one on the NJQRP web site.
DXE baluns are for high power, are large and heavy, and cost a lot of money.
73, Chas W1CG
At 06:04 PM 10/11/2005, mc wrote:
trying to get a little more out of this KX1 , I found a site on
baluns, is anyone else listening in to the eham.net. there is
comment on the balun pages that says there is no real good balun
for low power, my question is why not, is it not the purpose to
keep everything in balance to get the best out of your antenna no
matter the power. the eham site does not offer any explanations on
this but one HAM operator says DXE balms claim to fame is high power out puts.
mike
kb7dpc
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