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swr problem 4104 beams

nosratt

Member
Mar 5, 2011
8
0
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I have a set of Shakespeare 4104 4 element beams...
they have no Gama adjustment ...
Swr goes over 2.0 @ 27mz and up from there.
Fiberglass 18' boom and fiberglass elements ...
Have anybody heard of beams how to Shuster them...
Any help can't hurt
Thanks
 

If the antenna has telescoping elements I'm guessing you need to lengthen the elements slightly. Can you tell where antenna is resonant?

Also, what is "Shuster"..not an antenna term I'm familiar with.
 
update to 4104 swr saga

I was wondering how to set swr on the 4104 beam...
Have moved front and rear elements but doesn't seem to change
Help... thanks
 
shuster?

Not an antenna term... a fat finger moment. Sorry...
I think I was trying to say was ajust the swr.
also elements are one piece fiberglass...
Am I wasting my time?
 
I was wondering how to set swr on the 4104 beam...
Have moved front and rear elements but doesn't seem to change
Help... thanks

How does the feedline attach to the antenna and are you using balun? Pretty sure you need to start tuning with the driven element. Hopefully you have or have access to an antenna analyzer so you can see where it IS tuned so you have a starting point.

Also measure the reflector, driven element and one of the directors end to end and post the lengths in inches.
 
4104 element measurements ...

#1 191"
#2 183" driver. With transmission line on it
#3 179"
#4 171"
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"
The elements are two piece fiberglass with a steel threaded ends
The transmission/coax is attached to #2 element by splitting the coax and an eyelet put on the center lead and on shield attached to the top and bottom of #2 element
On #1 element is grounded between the top and bottom element
How do I set standing wave thanks
 
#1 191"
#2 183" driver. With transmission line on it
#3 179"
#4 171"
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"
The elements are two piece fiberglass with a steel threaded ends
The transmission/coax is attached to #2 element by splitting the coax and an eyelet put on the center lead and on shield attached to the top and bottom of #2 element
On #1 element is grounded between the top and bottom element
How do I set standing wave thanks

Someone can check this math but it looks like your antenna is cut to operate at about 30 mhz. Sorry to tell you but this is no where close to where you need it to operate so you can't set the swr on it. Curious where you got it and who was using it before you.

Here are some approximate lenghts for a yagi with a center freq of 27.185 (channel 19). You would need to lengthen all of the elements significantly to bring the resonant freq. down to center it on the CB channels.

Reflector - 18' 5.5" or 221"
Driven Element - 17' 4" or 208"
Director 1, etc - 16' 4.5" or 196.5"
 
Not an antenna term... a fat finger moment. Sorry...
I think I was trying to say was ajust the swr.
also elements are one piece fiberglass...
Am I wasting my time?

Where is this antenna supposed to be resonant?

How long are the 1/2 elements?

How did you do the spacing?

the AT is very narrow banded, just a bit over the CB bandwidth.
 
Like this:

free4-dim.jpg
 
Last edited:

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