HyGain TH-11 15 Meter element length. Which is right?

[WB4KZI]

I bought my TH-11 in 1992 and it's been a good antenna ever since, except on 15 meters. The SWR is lowest at the bottom of the band, around 21.025 and is 1.6:1. In the phone part of the band its 3:1. I wanted to set my element lengths for the phone portion of the band according to the HyGain specs. Looking back at the manual that came with the antenna (the one I used to build it in 1992) the element lengths in Figure 5 (page 3-6) show 55", 26" and 62" for the lenghts that make up the element for the 15 meter driven element (15DE). The next figure (Figure 6 on the next page) shows 55" 24" and 61" for the 15 meter driven element (15DE). I just looked at the HyGain web site to download the latest manual for the TH-11 and Figure 5 (page 3-6) now shows 55", 26" and 68" for the lengths of the 15 meter driven element (15DE). Figure 6 on the next page doesn't even show a length for the section of the 15 meter DE closest to the boom. Since its the first and larger piece of the element I guess they thought it wasn't necessary to label that one. The old drawing shows 55" for it. My question is, does anywone know what the end piece of the 15 DE is suppoe to be for the phone part of the 15 meter band? All of the other bands have low SWR in the phone portion just like its suppose to be.
 73

[K2DC]

Hard to tell what the correct design dimensions are.  But based on what you're seeing, here's a suggestion:  Measure whatever you have now, and shorten all three dimensions by about 2%.  That should move your current performance at 21.025 up to 21.250.

GL & 73,

Don, K2DC

[AB4D]

I bought my TH-11 in 1992 and it's been a good antenna ever since, except on 15 meters. The SWR is lowest at the bottom of the band, around 21.025 and is 1.6:1. In the phone part of the band its 3:1. I wanted to set my element lengths for the phone portion of the band according to the HyGain specs. Looking back at the manual that came with the antenna (the one I used to build it in 1992) the element lengths in Figure 5 (page 3-6) show 55", 26" and 62" for the lenghts that make up the element for the 15 meter driven element (15DE). The next figure (Figure 6 on the next page) shows 55" 24" and 61" for the 15 meter driven element (15DE). I just looked at the HyGain web site to download the latest manual for the TH-11 and Figure 5 (page 3-6) now shows 55", 26" and 68" for the lengths of the 15 meter driven element (15DE). Figure 6 on the next page doesn't even show a length for the section of the 15 meter DE closest to the boom. Since its the first and larger piece of the element I guess they thought it wasn't necessary to label that one. The old drawing shows 55" for it. My question is, does anywone know what the end piece of the 15 DE is suppoe to be for the phone part of the 15 meter band? All of the other bands have low SWR in the phone portion just like its suppose to be.
 73

Hi, I just installed a new TH-11DX. I also have an issue with 15 meters, but I am still working on that one.  Nevertheless, to answer you question.  Figure 5 in the manual does not give the installed element measurement length.  That drawing gives the size and length of tubing that is used to make each element.  Figure 6 gives the actual installed length.  So using both drawings, the element for 15 meters consists of the following pieces of tubing.  The piece of tubing closest to the boom is 7/8 inches in diameter that is 55 inches long.  The next piece is 5/8 tubing 26 inches long, once inserted into the 7/8 inch piece there should be 24 inches exposed, the final piece is 7/16 inch, 68 inches long.  Once inserted into the 5/8 piece, 61 inches of tubing should be exposed.

There is no phone setting specified for the 15 meter driven element.  Only the 20 meter, 17 meter, 10 meter driven elements, the 20 meter reflector, and the directors for 15 and 20 meters has settings specified in the manual for Phone, DX, and MARS.

Jim, 73