[TowerTalk] Stacked KT34XA's vs The Competition?

StellarCAT RXDesign at ssvecnet.com
Tue Mar 28 13:31:50 EST 2006

I have three f12 C31XR's here - up since Dec of last year. Not 
that it is anything spectacular but in 11 weeks I have managed 
to work over 200 countries from out here in AZ (no contests 
included) - not an overly easy task at this time of the sunspot 
cycle as well as from out west. [Heights 121', 81', 41']

I can say MOST of the time the stack is the best of the bunch - 
on 20 rarely is there much difference between it and the single 
antennas. But that is to be expected. Some of the times it is 
indeed stronger - as much as an S unit on 20 and I have seen 
three S units on the other bands (for the stack versus the worst 
antenna). The "best" differential I have seen was on 10 - where 
the stack and top antenna were as much as 20 db down from the 
LOWEST antenna (to the Caribbean). Height is indeed more 
important than gain. Being able to select various heights is an 
advantage - not all the time - but an advantage nonetheless that 
comes into play. I remember once in a DX contest I temporarily 
installed a 6 el KLM 15 at 28' ... it was WAY below the "main" 
antenna (Hygain 5 el at 85') in signal strength except when the 
band was going out - all of a sudden there was as much as a 20 
db difference with the lower antenna being stronger!

Phasing IS critical - when I first installed it, using Unadilla 
baluns (junk in my opinion due to mechanical construction) I 
found that whenever the center antenna was included the signals, 
even the noise level, went down. We suspected (and WX0B had 
said) bad phasing but all were constructed the same. We checked 
it out and sure enough the center balun was wired differently 
INTERNALLY! Changing this made a big difference.

As far as being competitive - hard to say definitively at this 
point but I can say it holds its own even going east - breaking 
through the east coast wall to EU or AF often with just 100W is 
a great feeling!


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