2 EL Delta Match Yagi

[HomerBB]

I built a workable 2 el yagi with a gamma match. http://www.worldwidedx.com/home-brew-mods/33847-home-made-2-element.html
Now i am trying to get this one right: Using Delta Matching on HF Beams by dxzone.com.
I am close. I want to center resonance on 27.185, but currently the SWR is 3.0:1. I get a SWR of 1.4:1 on 28.755. Clearly I am centered too high. I have followed the formulas as exactly as I know how converting all metric units to inches.
What I need is some input on what may help to bring it down. I am inclined to adjust the RG58U 4:1 balun length, but am not sure which way to go.

Any help is appreciated.

Driver length 18' 0.5"
Director length 16' 8"
Boom length 2' 10"
Darm length 2' 5.25"
Darm spacing 3' 7"
Mbalun length 12' 10.1"

 

[mrgumby]

seems to be tuned for 10 m maybe the elements are a bit too short

 

[HomerBB]

seems to be tuned for 10 m maybe the elements are a bit too short

I believe you're right.

 

[Captain Kilowatt]

seems to be tuned for 10 m maybe the elements are a bit too short

That was my first thought as well. If you used any dimensions on DXzone they would surely be for 10m unless you compensated for 11m. Either way there is usually a bit of adjustment necessary.

 

[HomerBB]

That was my first thought as well. If you used any dimensions on DXzone they would surely be for 10m unless you compensated for 11m. Either way there is usually a bit of adjustment necessary.

I did the math based on centering on 27.185 operating frequency. Not used to doing a delta match I thought something else may be off. Duh. Okay, I'll lengthen the elements and see what happens.

Thanks.

 

[HomerBB]

Got the SWR down to 1.0:1 on ch 19. Don't know if the antenna's any good. No Skip, no analyzer, and gotta go to work. Details later. . .

 

[Marconi]

Got the SWR down to 1.0:1 on ch 19. Don't know if the antenna's any good. No Skip, no analyzer, and gotta go to work. Details later. . .

What did you do to fix the problem? I just left you a response on Grumpies site.

 

[HomerBB]

What did you do to fix the problem? I just left you a response on Grumpies site.

Thanks!

Here is a little info:


Driver length 19' 6"
Director length 17' 6"
Boom length 3' 2 1/2" Through Space 2' 10"
Darm length 3' 2 1/2"
Darm spacing 4'
Mbalun length 12' 10.1"

Boom 1 1/2" aluminum tube
Elements 1/2" x 10' EMT centered and 3/8" x 6' coated plant stakes adjustable rods for ends of elements.
Delta arms #12 solid steel wire


SWR:

28.855 2.1:1
27.405 1.1:1
27.205 1.0:1
26.965 1.3:1
26.515 2.1:1

Here is a little info:


Driver length 19' 6"
Director length 17' 6"
Boom length 3' 2 1/2" Through Space 2' 10"
Darm length 3' 2 1/2"
Darm spacing 4'
Mbalun length 12' 10.1"

Boom 1 1/2" aluminum tube
Elements 1/2" x 10' EMT centered and 3/8" x 6' coated plant stakes adjustable rods for ends of elements.
Delta arms #12 solid steel wire


SWR:

28.855 2.1:1
27.405 1.1:1
27.205 1.0:1
26.965 1.3:1
26.515 2.1:1


[img]http://www.cirilo.net/cac/2el/2el002.JPG

 

[HomerBB]

Mark, Jan 14 2010, 06:20 AM
Nice looking beam there .... any chance of some close ups where the feeder connects to it ...cheers Homer

Okay on the photos of the feedline connection.
Here you go:

this is the coax entering the box with a CMC choke at the antenna feedpoint

this is a shot of the coax 4:1 balun entering the box (bottom of the box)

inside the box showing the connections

A full shot of the connections including the delta match on the driven element

this is the construction of the 4:1 coax balun