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Re: [TowerTalk] Was "43ft Vertical Feeding

To: Pete Smith <>
Subject: Re: [TowerTalk] Was "43ft Vertical Feeding
From: jimlux <>
Date: Mon, 24 Nov 2008 06:33:05 -0800
List-post: <">>
Pete Smith wrote:
> What am I missing here.  You need to cover 8 bands - surely a set of 
> switched L networks, including several for band segments on 160, 80 and 40, 
> could be built for much less than any automatic tuner capable of handling 
> the power.  You're not looking for continuous coverage 1.8-30 MHz, after all.
> 73, Pete N4ZR

A couple years ago I ran through a design exercise on just this 
approach, and it turns out that it's about the same, either way.  The 
typical L network autotuner has 7 or 8 L's (and their relays) and 7 or 8 
C's (and their relays) (the SGC with a pi network has more C's, total).

Now consider 8 L networks.. 8 Ls, 8 Cs, 8 relays (if you use DPDTs) or 
16 relays (if you use SPST).

So it's almost the same parts cost (the cost of the microcontroller is 
negligible compared to big Ls, Cs, and relays)

There IS an advantage to the switched tuning networks, rather than the 
generic L/C tuner..  you *might* be able to get lower overall loss by 
optimizing the network for a specific antenna, etc.  With the generic 
tuner, there are some Zs that won't be efficiently matched.  It's pretty 
installation dependent, though.


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