讨论：EF340型天线有问题吗？该如何来修整？ [复制链接]

拼了老命调340，最好的结果只有6db fb，如果照他们通常流行的尺寸调，就接近于一个巨型dp，当然比dp还是好，因为8字的腰很细。我觉得还是放弃这个的好。如果舍不得扔，最好改成cl40b的形式，改造方案有，回头有可能在by5cd上试试看。

谁想谋杀我啊。我现在终于有人要杀了。太高兴了。

this is a 2 element yagi design similar to the ef-240 except for a 24' boom length. the linear loaded elements are approximately 1/3 wavelength. the parasitic element can be configured as a director or reflector by changing the resonance of the loading wires. this is a plus if you like to experiment. mechanically, this antenna is sturdy. the majority of joint connections are riveted. additional boom support is provided by a mast mounted cable. the linear loading wires double as supports for the elements. force 12 supposedly upgraded the boom to mast mounting bracket so be aware if shopping for a used model. mine was acquired used but is equipped with a heavy duty, 2-piece mounting bracket. the only problem encountered mechanically to date has been thread galling between the stainless wire retaining bolts and the aluminum threaded couplers used at the wire coupling points of the elements. anti-seize compound should prevent this problem commonly encountered between dissimilar metals from reoccurring. electrically the antenna performs as advertised. the 2:1 bandwidth is about 250khz. the forward gain is very evident as compared to a dipole at same height – especially for stateside contacts. my vertical will some times offer a slightly better signal from dx stations coming in at low wave angles due to the limitations of my installed height (50ft).

这也真是辛苦你了，先不要放弃，看看能否简便改造一下结构，从上面照片中看到了ef240的结构是有些小问题，但是，ef340还是缺少很多资料，其中关键的是三根铝振子的总长度是否一样长（不包括折线在内）？不是的话，它们之间各差额多少？
ps:
上图的ef340的引、反振子折线是否反错位了。 [表情]

.......先按理论计算值调三根不同频率的dp（计算下来三根都和中心频率不一样的），最后组装成八木，加发夹调到最终工作频率。

这个方法我想过好久,第一次玩转软件后就一直这么想,能不能这样去调八木,不过没有试验过,所以希望大佬搞定这个方法后传授一下 [表情]

alc啊，你看ef240s的资料就知道了，，
两个天线振子中心都断开，，各自调准频率后中，其中一个振子短接。

alc啊，你看ef240s的资料就知道了，，
两个天线振子中心都断开，，各自调准频率后中，其中一个振子短接。

那就好了,我的想法也完全成立,我计划的小八木可以再搞下去

先按理论计算值调三根不同频率的dp（计算下来三根都和中心频率不一样的），最后组装成八木，加发夹调到最终工作频率。

为啥340没有这个图，有了就不用瞎调了

那你干脆把大八木也调了吧，调三根阵子对你来讲是小菜一碟。

这也真是辛苦你了，先不要放弃，看看能否简便改造一下结构，从上面照片中看到了ef240的结构是有些小问题，但是，ef340还是缺少很多资料，其中关键的是三根铝振子的总长度是否一样长（不包括折线在内）？不是的话，它们之间各差额多少？
ps:
上图的ef340的引、反振子折线是否反错位了。 [表情]