[TowerTalk] Force12 mag 2/2 yagi (2el 80 2el 40 linear loadedcombination)
regates at hughes.net
Wed Feb 14 20:57:10 EST 2007
I believe you'll find that F12's stated gains are based on a height of 74' on 40M and 140' on 80M. Try these heights in EZNEC and see if the results are closer. Just doing a real quick look using HFTA, I see as much as 5dbi difference between 2ele at 72' and 140'.
73, Bob W7BJ
The Force12 uses both relay switched coils (for moving resonant frequency in the band) and linear loading for the 80m on both elements. Using Eznec I have not been able to get gain when the linear loaded is placed at the center of the elements but I can get about 3.5 db gain when the loading is moved to the end of the elements similar to the Steppir 40m dipole addition. (I didn't model the coils). Force12 specifies about 4 db gain with their center loading installation. It may be that my model is inaccurate. The height that I have modeled is 72' which is the height that I would install it on a LM470 crankup.
So far I have only heard from on other "user" of the Mag2/2. He bought it used and decided not to install it! I will appreciate comments.
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