[TowerTalk] LP vs SteppIR

[jim Jarvis]

I made comments directly to Doug, at his first posting, and said that this thread would
again get legs.  :)   

So let me repeat some of my comment, for those who didn't see it the last time.

1)  I've had several LPDA's,  the T8 being the best of them.    It's head and shoulders
above most trapped tribanders on short booms.  The F12 C3S may be an exception,
It's pretty good.

2)  I changed from LPDA to a 3 el SteppIR, and was extremely pleased with its performance.
It was a 3 el,  and sure enough, results were like going from a 2 el yagi with the lpda
to a 3 el with the steppIR.   No magic there.

     Band change, with the Icom interface, was very fast.   It took approximately 
2-3 seconds for the computer to command the rig, amp, and antenna to switch over.
Barely enough time to get a sip of coffee, before calling the station I was chasing.
(I like to use the bandmap in small station contesting,  in a point & click mode.)

3)  Stacking Log Periodics:

	An interesting topic.   And one which seems worth experimenting, to me.
I started to, but got wrapped around the axle:

With two T8's, each with  16' booms,  you can put the front elements half wave apart 
at 28MHz,  and the rear elements half wave apart at 14 MHz.   The upper antenna
tilts downward and the lower antenna tilts upward.   I don't recall the angle, at this point,
something like 22.5 degrees.   My plan was to mount the lower antenna with the longest
20m element at 36',  and the upper 20m reflector at 70'.   

I went so far as to buy two blank mast-boom plates from Tennadyne, and have them 
locally drilled for the calculated tilt angles.    I was in process of designing the In/Out of
phase system,  which can be done fairly simply with a single relay, given the transmission line boom
feed system for the T8.    

Somewhere in there, I got bogged down trying to model the thing.   Cebik also got
bogged down modelling it.   Healthy discussion followed.   I was about to buy the second
LPDA and get on with my empirical approach,  when a hurricane blew through,  took out
a big oak tree, which took out my tower.   Then I got transferred.    

The feeling was that tilting the antennas would tend to raise the radiation angle, at the
heights we were talking about.   If I could have put the lower one at 70' and the upper
at 100, it might have been different.   That's what we had hoped to model.

I still think this would be a worthy experiment--but not one I can pursue in suburbia.

N2EA