[TowerTalk] "Magic" length from tower to first insulator

[StellarCAT]

I used the ARRL AB values and found that the distance recommended from the tower out was problematic. I had quite severe interaction to the guys with only about 6’ from the tower to the first insulator. My guess is that they weren’t taking into account that it is connected to the tower at the center and there are 3 of these 6’ lines going out ... the impact was seen in the SWR so as noted below the FB would have been severely impacted. This was solved by placing clamp on ferrites just at the end of the Big Grips at the tower (3 on each leg). 

As for divorcing the first section and not having any interaction beyond that – not a chance! I’ve modeled guy lines with yagis and they interact considerably. The first hit is to the FB ratio where it can reduce it by 5+ db (it can also enhance it in some directions)... the second hit is the SWR ... the gain is rarely impacted. 

I personally am going with 50% philly and then EHS. This works very well in eliminating interaction at least in the models I’ve done for the bands I’ve done. 

Gary 
K9RX


A friend of mine told me that someone, somewhere had calculated a "magic"length for guy cable. If you went down 10 or 11 or 13 feet (or whatever itis) off of your tower and installed your first insulator there, your guyswould be sufficiently 'non-resonant' so that they wouldn't interfere withthe pattern of the antenna(s) above.What is this magic length and where is it documented? Larry WO7R_______________________________________________