"Dave Platt" wrote in message ...

In article ,
Wayne wrote:
So, lets begin again, with no distractions.

What is the purpose (or benefit) of using a 1:4 unun on a 43 ft
vertical.

# http://www.eham.net/articles/21272 has a nice analysis.

# It looks to me as if:

# - Without a 4:1 unun, the antenna provides a very nice match at three
# frequencies with in the HF band. At other frequencies, the SWR is
# up over 10:1 much of the time - high enough that a coaxial feed
# can be rather lossy.

# - With a 4:1 unun, you do lose the excellent match at those three
# frequencies... but the match gets better at most other
# frequencies. The SWR across the HF band is much more uniform, and
# lower on average... low enough to cut the coax losses somewhat and
# (I think) within the matching range of many rigs' "line flattener"
# built-in autotuners.


Thanks Dave. I'll have to spend some more time studying it, but the article
is along the lines of what I was looking for.

I would assume that the 1:4 causes behavior just as you say....worse SWR at
nearly matched frequencies and better SWR elsewhere.

I'll have to pull out some textbooks and see how the math works out for a Z
seen through a 1:4 unun.

In practice, I've had good results with SWRs even in the 30:1 range with
short coax feeds.

More research...and thanks.