Test a Balun? - Carolina Windom Problem

[Carl WA1KPD]

Hi Stu,

Unfortunately I cannot tell you the manufacturer. He is an older retired gentleman, one man shop who is usually at Nearfest. I know he lives a town or so west of Worcester as I stopped by his shop on the way to bring my daughter back to school. As I also recall he spends winters down south. He usually sets up a table at Nearfest with a bunch of his wire antennas. I can't find the small amount literature  nor some emails we exchanged. Figures.

I have found the same thing you have when I was trying to find an example of the antenna.

One of the selling points of the design he had was that the ground side of the single balun is grounded right at the balun. In other words, the 22 ft of 320 ohm ladder line come down to about 6"inches from the ground and are attached to the balun. The ground side of the coax is literally attached to an 8 ft ground rod.  
This set up dramatically reduced some local noise I had from the house etc and it returned a very low and flat SWR across all  bands from 160 up to 6. In fact I stopped using my antenna tuner and the tuner in my 756 could easily handle any small matching. I am no engineer so I can't tell you the how and why of it all, and I am embarrassed to say I bought a wire antenna after 40+ years in the hobby, but it did all he claimed.


When I got the Flex I used the ATU in it and did not really pay attention to the initial readings. I decided to get a linear for AM use and before I used it I wanted to check what the SWR was. Much to my surprise it had climbed quite a bit. When, I do not know as the ATUs may have been masking it.

Things have been busy so I have not had a chance to check the coax but will get to it this weekend.
73
Carl

[Carl WA1KPD]

Stu

http://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/1990/08/page28/index.html

The second 1/2 of this page descibes the antenna as designed
http://188.182.100.158/The%20Traditional%20Carolina%20Windom.html

And finally here is a 40 meter version

Carl

[WD5JKO]

A single 1/2 wave long antenna on 80m usually has a 2:1 SWR point at something like +/- 150Khz. It is very hard to make an antenna that is 2:1 or less across 3.5 to 4.0 Mhz unless the designer incorporates some form of trickery. Feeding at the center, or off center fed, or end fed all have the same problem since 500Khz is a big percentage of any 80m frequency. One example would be multiple elements in parallel with each a different length such that there are staggered resonances. Another would be very wide elements such that the length to diameter ratio is not so large.

I once was involved into why a UHF AM aircraft setup had only 10KM line of sight range. The antenna had a special "tuning" network to "match" the antenna to the transmitter over the range of 225 to 400 Mhz. It turns out that the network was ~100' of 1/8" coax, RG-174. Lots of loss in line to make nice low SWR.  

No doubt the antenna at question in this thread involved some sort of trickery if it was 2:1 or less across 3.5 to 4.0 Mhz. That said, I bet the original balun was part of it, and substituting another design would yield different results.

Jim
Wd5JKO