2 EL Delta Match Yagi

[lamplighter]

I built a workable 2 el yagi with a gamma match.
Now I am trying to get this one right: www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=7512
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"

[lamplighter]

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. . .

[marconi390]

Jan 9, 2010 23:07:17 GMT -5 lamplighter said:

I built a workable 2 el yagi with a gamma match.
Now I am trying to get this one right: www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=7512
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"

Looks like you have fixed the problem, but I would check your boom length. The length you show is very narrow. In the documentation it is shown the author using .12% wavelength as a starting point of boom length. I have not checked the formula math for DR/D1 setup, but the typical 11 meter spacing for DR/D1 is in the range of 42" - 55" I think.

11m WL = 36' x .12 = 4.32' feet

[lamplighter]

I may have to go at the boom again, but I tried his formula for what I've got.

Even my solutions doesn't make much sense.


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

[lamplighter]

[lamplighter]

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