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swr problem 4104 beams

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  #17  
Old 03-06-2011, 06:00 PM
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Quote:
Originally Posted by nosratt View Post
I got it!!!!
I switched the shortest details of
elements to the driver and swr went to
1.1 @ 27.605... so I put next longest
set on the driver and swr went to
1.1 @ 26.965.
The element order is now 1 3 2 4 and
spacing is the same...

Thanks guys
Wrong.

The REFLECTOR is the longest element at one end of the beam.

Next to that, the DRIVEN element is the next longest element (this is where the Gamma match/coax is attached to). Because it DRIVES the whole beam.

Next, the 1st DIRECTOR has the 2nd to the shortest length and mounts next to the DRIVEN element.

The 2nd DIRECTOR is the shortest element - and is at the long end of the beam.

Look at the picture I previously posted above.
Notice the larger spacing between the 1st and 2nd DIRECTOR?
That proportion should be consistent with most beams.
They lengths should be in descending order of lengths from the REFLECTOR (longest) on one end, down to the 2nd DIRECTOR (shortest) at the other end.

Because the elements lengths are shorter; the antenna HAS to tune in the ~28.400mhz - or higher - range. The elements MUST be longer to tune on the CB band. No if's, and's, or but's . . .

The "Gamma Match" is how the SWR is adjusted. If the lengths of the elements are SHORT; then they have to tune to a higher frequency. That is just the nature of antennas.
Just because the SWR look acceptable by no means that it will radiate as it should/as designed!
Looks to me that someone modified the lengths for the 10m Ham band - IMO . . .

You stated that:
#1 191"
#2 183" driver. With transmission line on it
#3 179"
#4 171"


But to tune PROPERLY on the CB band, they NEED to be:
#1 - 215.35"
#2 - 203.875" With transmission line on it.
#3 - 202.5"
#4 - 186.75"

If you can lengthen them to these lengths and THEN reset the Gamma match to a decent SWR, then it should be fairly RESONANT on 27.555 and below (the CB band). In truth, to be fully resonant on the CB band - it would need to have the REFLECTOR ~225" and the other elements "scaled" proportionally to that length.

boom 188 1/2"
distance between #1 and #2. 68. 3/4"
between #2 and center of boom 22 1/2"
between #2 and #3 55 1/2"
between #3 and #4 61 3/4"

Compare your spacings to the diagram at the top of this page. Spacings change how the beam will focus and the "gain" it will have. But the LENGTHS of the elements HAVE TO BE CORRECT! The spacing between the REFLECTOR and the DRIVEN elements are critical.

Keep tryin; don't give up!
We are on your side and pulling for you!!!
__________________
BASE: Kenwood TS-2000, GAP Titan DX, Diamond X50A, Sirio SY27-4, and IMAX 2000.
MOBILE: Galaxy DX99V w/RF Limited CR-577 mic, Sirio Z-180. Yaesu FT-8800R & Diamond NR-770.

Last edited by Robb; 03-06-2011 at 06:43 PM.

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  #18  
Old 03-06-2011, 06:40 PM
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Quote:
Originally Posted by Robb View Post
Wrong.

The REFLECTOR is the longest element at one end of the beam.

Next to that, the DRIVEN element is the next longest element (this is where the Gamma match/coax is attached to). Because it DRIVES the whole beam.

Next, the 1st DIRECTOR has the 2nd to the shortest length and mounts next to the DRIVEN element.

The 2nd DIRECTOR is the shortest element - and is at the long end of the beam.

Look at the picture I previously posted above.
Notice the larger spacing between the 1st and 2nd DIRECTOR?
That should be consistent with ANY beam.
They should be in descending order of lengths from the REFLECTOR (longest) on one end, down to the 2nd DIRECTOR (shortest) at the other end.

Because the elements lengths are shorter; the antenna HAS to tune in the ~28.400mhz range. The elements MUST be longer to tune on the CB band. No if's, and's, or but's . . .

The "Gamma Match" is how the SWR is adjusted. If the lengths of the elements are SHORT; then they have to tune to a higher frequency. That is just the nature of antennas.
Just because the SWR look acceptable by no means that it will radiate as it should/ as designed!
Looks to me that someone modified the lengths for the 10m Ham band - IMO . . .

You stated that:
#1 191"
#2 183" driver. With transmission line on it
#3 179"
#4 171"


But to tune PROPERLY on the CB band, they NEED to be:
#1 - 215.35"
#2 - 203.875" With transmission line on it.
#3 - 202.5"
#4 - 186.75"

If you can lengthen them to these lengths and THEN reset the Gamma match to a decent SWR, then it should be fairly RESONANT on 27.555 and below (the CB band). In truth, to be fully resonant on the CB band - it would need to have the REFLECTOR ~225" and the other elements "scaled" proportionally to that length.

boom 188 1/2"
distance between #1 and #2. 68. 3/4"
between #2 and center of boom 22 1/2"
between #2 and #3 55 1/2"
between #3 and #4 61 3/4"

Compare your spacings to the diagram at the top of this page. Spacings change how the beam will focus and the "gain" it will have. But the LENGTHS of the elements HAVE TO BE CORRECT! The spacing between the REFLECTOR and the DRIVEN elements are critical.

Keep tryin; don't give up!
We are on your side and pulling for you!!!
This antenna has no gamma match.

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  #19  
Old 03-06-2011, 09:14 PM
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Quote:
Originally Posted by nosratt View Post
I got it!!!!
I switched the shortest details of
elements to the driver and swr went to
1.1 @ 27.605... so I put next longest
set on the driver and swr went to
1.1 @ 26.965.
The element order is now 1 3 2 4 and

Thanks guys
This antenna was designed to cover 23 ch only. The elements are shakespeare 10-3 style fiberglass mobile whips the lengths are correct due to the small dia wire in the whips. If i remember the thing used some type of coax matching section to feed it. After you changed the whips around and got low swr around ch 1 your on the right path . as others have commented you must have the lengths in decreasing order starting with the reflector. If you need to have low swr higher in the band try shortening the driven elements only an inch at a time. Have a couple of old fg whips you may want to replace the driven element whips and try tuning those first, Keep in mind this antenna is only going to cover a limited portion of the band. I played with several of these and they are touchy. They even made a stacked pair.

Good luck RCB

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  #20  
Old 03-06-2011, 09:25 PM
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Quote:
Originally Posted by regencycb View Post
This antenna was designed to cover 23 ch only. The elements are shakespeare 10-3 style fiberglass mobile whips the lengths are correct due to the small dia wire in the whips. If i remember the thing used some type of coax matching section to feed it. After you changed the whips around and got low swr around ch 1 your on the right path . as others have commented you must have the lengths in decreasing order starting with the reflector. If you need to have low swr higher in the band try shortening the driven elements only an inch at a time. Have a couple of old fg whips you may want to replace the driven element whips and try tuning those first, Keep in mind this antenna is only going to cover a limited portion of the band. I played with several of these and they are touchy. They even made a stacked pair.

Good luck RCB
Jusr re read this antenna has no gamma match . It has a shorted stub coax matching section. Post some pics if you can so others can see how it's constructed.

RCB

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  #21  
Old 03-06-2011, 09:38 PM
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Hello,


1/2 inch elements
Desing frequency : 27,5 Mhz.
Gain 8,2 dBi
Front to Back : 21 dB

Using a split radiator. 1 piece of the coax to one end and one piece to the other...
No matching needed in anyway...direct feed..

A 50 ohms impedance with a real wide SWR bandwidth. (26,6 to 28,3 Mhz)
Direct feed, a rf choke is recommended.

This is a so called "owa" design.


Reflector: 5,46 meter
Radiator : 5,3 meter
Director 1 : 5,04 meter
Director 2: 4,8 meter

Distance radiator reflector: 1,33 meter
Distance Director 1 to reflector : 1,835 meter
Distance Director 2 to relfector : 3,82 meter


Drop me a email on 19sd348@planet.nl and i ll forward you the eznec file.


Regards,

Henry

11 meter Dx antenna systemx

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  #22  
Old 03-07-2011, 06:06 AM
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I got it...
I switch the shortest set of elements to the
Driver and swr went to 1.1 @ 27.605@
So I put next longest set on driver and
Swr went to 1.1 @ 26.965...
Now element order is 1 3 2 4
thanks guys

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  #23  
Old 08-03-2013, 12:54 PM
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4104 got two but can,t seem to be able to point or no difference east west north or south no direction so been looking for shematics or manual any help will be appreciated thx guys

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  #24  
Old 08-03-2013, 05:28 PM
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Is the conductor in those elements just a straight wire, or are they wound? By any chance did you get instructions with this thing?
- 'Doc

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