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Re: [TowerTalk] upper/lower/both box

To: towertalk@contesting.com
Subject: Re: [TowerTalk] upper/lower/both box
From: "Joe Subich, W4TV" <lists@subich.com>
Date: Fri, 18 Jun 2010 11:29:06 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
For monoband stacks I like the N4TZ "Invisible Stub" design
from NCJ a few years back.  You will need to add an extra
box/relay with half-wave coax for the out of phase condition.

The N4TZ design avoids the un-un and/or L/C networks and
is arguably more reliable due to the lack of discrete parts
that can break down.

73,

    ... Joe, W4TV

On 6/18/2010 10:22 AM, Jim Thomson wrote:
> does anybody remember how these box's were configured ?
>
> Buried some where in mu old W2PV material... there is a diagram of
> one. Think it used a pair of P+B DPDT relays.    This is for 2 x
> identical 40m yagi's... that's it.  It only has to be configured for
> one band.
>
> Last time round... I designed a simple LC box for a buddy who has 2 x
> 40m yagi's. The 2 x ant's  were always drioven in phase.  The LC box
> was simple.. just a mess of shunt NPO 5 kv doorkno caps at left end.
> [ hot to grnd]   followed by  a series cu tubing coil.    50 ohms
> in... and 25 ohms out.  The 25 ohms consisted  2 x  coax connectors..
> wired in parallel.    2 x identical length 50 ohm cables... one per
> yagi.
>
> I was going to suggest adding bip/bop capability... since that only
> involves adding 1 x spst vac relay.. and one  x  1/2 wave of coax.
>
> IMO... I think BIP /BOP would be plenty.    However.. there maywell
> be cases where the top ant by itself would be louder than both in
> phase..... and ditto with bottom yagi [vs BOP]
>
> Is the U/L/B box in one of the books ?   If it is..it's  buried good.
> This is just for one band... no broadband xfmr's required.
>
> Tnx........ Jim  VE7RF
> _______________________________________________
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>
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