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

[Herb Schoenbohm]

Earl.

I have a Rohn 25 foot tower with a 204BA which you sent me the model 
parameters and it matched right down to the foot on 1.828 Khz with the 
data you sent.  When K6VVA wanted to operate this station in the ARRL CW 
last spring I put up a home built 26 foot boom plumbers delight 
interlaced 4 element 15/10 with a Force 12 type driven element matching 
structure so I could use a single 7/8 inch heliax feed for this new 
antenna.  The effect of adding the antenna below the 204BA was not even 
noticeable on the "sweet point" on 160.  The 204BA with the longer 
elements above make the 10/15 antenna below essentially invisible.  I 
probably have some interaction on the upper bands that I did not take 
into account because they are closer than the book recommends.  But for 
top band it did not hurt one bit.  Is it safe to say that a close spaced 
upside down Christmas tree is acceptable if you originally plan for the 
big antenna to match at the onset? (Eric did well in the contest after a 
return of being QRT for 10 years, I think he was #4.  So the setup is 
not all that bad.)

Herb Schoenbohm, KV4FZ


Earl W Cunningham wrote:

>I've never modeled an "upside-down Christmas tree" like that, but I agree
>that the difference will be even more pronounced in that case.
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