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Remote antenna selection

Subject: Remote antenna selection
From: W8FN@aol.com (W8FN@aol.com)
Date: Mon Aug 28 23:34:07 1995
I switch the (soon to be replaced) 115VAC Dow-Key relays in my antenna
switching assembly using solid state relays I got at a local electronic
surplus store for about $4 each. These things are readily available and
accept TTL or CMOS logic levels to switch AC. Been using them for about 8
years with nary a failure.

GL & 73... Randy, W8FN

>From km9p@is.net (Bill Fisher)  Tue Aug 29 04:30:10 1995
From: km9p@is.net (Bill Fisher) (Bill Fisher)
Subject: Contest Free Zones
Message-ID: <199508290330.XAA09954@mail1.is.net>

>As a little pistol, sometimes the upper parts of the bands are the only
>place I can occupy without being run off by a BIG GUN. 

Little pistol...  Heck you don't need to start this sentance that preface....

A good friend of mine and active contester was rumored to be favoring such a
contest free zone on 20M SSB from 14300 to 14350 with the league.  Take
those frequencies away from me, and you take away 20m SSB.

I operate once, maybe twice a year on SSB.  They can put up with me for the
VERY little time I spend on "their" frequencies.  


>From n3rr@cais.cais.com (Bill Hider)  Tue Aug 29 05:33:53 1995
From: n3rr@cais.cais.com (Bill Hider) (Bill Hider)
Subject: Antenna question
Message-ID: <199508290433.AAA28088@cais.cais.com>

At 10:20 PM 8/28/95 -0400, Randy Thompson wrote:
>Here is one for the technical wizards among us...
>Yesterday I installed a Cushcraft 40-2CD for a local contester.  The 
>tower is 90' of Rohn 25G with an LTA 7-el 10m beam at the top, and the 
>new 40-2CD about 8' above that.
>The antenna was built to have the SWR minimum around 7080.
>We first applied RF when the antenna was 1' above the 10.  SWR minimum is
>somewhere below the band (about 1.5:1 at 7000 and goes up in smooth curve
>as you move up the band).  Raised the antenna up to final position hoping
>it would get better -- it didn't change at all. 
>So...looking for ideas on why this antenna is resonant below the band 
>(>100 khz below where it should be).
>Here is the interesting part.  The person who built the antenna used a 
>Line Isolator instead of the suggested roll of coax choke.  He put the 
>Isolator about 12-15" of coax back from the actual feed point.  Could it 
>be that the coax between the isolator and the feed point is radiating -- 
>making the antenna appear longer than it should be?
>            +-----+      /
>============+     +------
>            +-----+      \
>coax        isolator     feed
>                   12"coax
>Randy Thompson, K5ZD


I installed my 40-2CD (134 Ft.) in February and am building another to stack
(67 Ft) with this one. 

During the construction of my first one, I noticed that if I followed the
instructions in the Cushcraft manual, I could not install the LCA (loading
coil assembly) the way they intended.  The heat-shrink on the LCA would not
allow me to install the LCA into the larger diameter previous (inward) tube
as far as the directions stated. (The error due to the heat-shrink was
approximately 3/4" ).  Since this is the case, the tip section (the next
section outward from the LCA) length must be increased to compensate for
this.  Both elements and all four LCAs experienced this problem.  

Secondly, with 12 to 15 inches of coax (you don't say how much of that coax
was "peeled back" and not actually coax, but actual radiating wire) if it is
not in its coaxial state, indeed it could be adding excessive length to the
driven element and lowering its effective resonant frequency.  <The
Cushcraft manual says to "peel back" 4 inches of center conductor and 4
inches of shield off of the coax.>

I use the HiGain BN-4000 Balun on all of my Yagis. (In lieu of the coil of
coax suggested by Cushcraft).

By the way, I wouldn't expect the 10 M beam to interfere with the 40-2CD (my
105CA is @ 141 Ft) and the few feet of height change you made for the
comparison would only cause a negligible effect on VSWR at the 90 ft level.
A better check would have been on the ground with the beam pointed straight
up, in the clear, at a height of 4 ft or greater.  That would have shown you
the problem on an analyzer (the MFJ or AEA type).  I have an AEA HF analyst
analyzer and it sure has come in handy in building/installing my new antennas.

Be glad to answer any Qs you may have.


Bill, N3RR

n3rr@cais.com OR n3rr@cais.cais.com

>From n3rr@cais.cais.com (Bill Hider)  Tue Aug 29 05:46:21 1995
From: n3rr@cais.cais.com (Bill Hider) (Bill Hider)
Subject: Antenna question CORRECTION
Message-ID: <199508290446.AAA28983@cais.cais.com>

>To: Randy Thompson <k5zd@iconics.com>, CQ-Contest Reflector
>From: n3rr@cais.com (Bill Hider)
>Subject: Re: Antenna question



> ...Since this is the case, the tip section (the next section outward from
the LCA) length must be DECREASED to compensate for this.  Both elements and
all four LCAs experienced this problem.  
>Sorry for the "typo" 

>Bill, N3RR
>n3rr@cais.com OR n3rr@cais.cais.com

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