[TowerTalk] KC1XX's 8 10M yagis

[Ian White, G3SEK]

Tyler Stewart wrote:
>Bill Fisher - W4AN wrote:
>> 
>> I have to question the logic of 8 10M yagis stacked vertically.  Unless
>> Matt is using hardline between the antennas for phasing lines, I would
>> guess that much of the gain he gets with 8 yagis is lost in 8 very long
>> feed lines.  Of course Matt never does anything half____.  So he must
>> know something (probably a lot) I dont know.
>> 
>
>What's the problem?  1 or 8, the feedline loss is the same...well,
>almost.  It depends on if the runs end up being a longer overall. 
>HOwever, for all practical purposes, it's close.  Now if it were 2304
>Mhz, we could talk!
>

We can certainly talk 144 or 432, where contesters use 8-high stacks to
increase the gain without narrowing the beamwidth. For the simplest
system, feeding all antennas through equal line lengths, the maximum
length is no more than it would take to reach the top antenna. The main
distribution point is half-way up the stack, so 6 out of the 8 feedlines
have to be coiled up to "lose" some length.

Bottom line: even at 432 (and using higher-loss flexible feedlines such
as 9913 to permit rotation) stacking gain still comes out ahead of
feedline losses for an 8-high stack.


73 from Ian G3SEK          Editor, 'The VHF/UHF DX Book'
                          'In Practice' columnist for RadCom (RSGB)
                           http://www.ifwtech.demon.co.uk/g3sek

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