Topband: Tophat? Does it have to be at the top?

[Guy Olinger, K2AV]

I agree with Earl.

Much of the difference in opinion on this subject has to do with what
is really a fairly complex situation. It is convenient if a whole
category of proposed construction is defined by a nice simple rule,
but towers with all the stuff hanging off are anything but simple.

The only good way to get a handle on the kind of behavior a tower and
all it's attachments will display is to put all the metal in a model
and let the program add up all the vectors and impedances.

Sometimes small changes on the tower make huge changes in behavior,
other times adding a beam might not change anything. Sometimes the
intuitive behavior is what happens, other times something else. It
just depends.

Trying to figure out how a tower will load without a model usually is
shooting in the dark. Other times you get lucky.

Model it. It will give you a good idea what YOUR situation will do.

73, Guy.


From: "Earl W Cunningham" <k6se at juno.com>


> I changed my opinion
> after modeling numerous shunt-fed towers