[50mhz] Cushcraft A50-3S Question

[Chris Boone]

Doing what Marv describes has LONG been standard practice for pretuning HF
yagis before they are hoisted in the sky.... and it WORKS!! George, do as
Marvin suggest and your antenna will come out much better....The tree can
cause SWR issues depending on the time of the year (when the sap flows, the
dielectric of the tree changes...and its effect on the antenna does too!)
Use a fiberglass or wooden LADDER (IE: something dead....hmmmm, bad analogy
there maybe ;)

Also I never trust Cushcraft's dimensions that closely......I use their
antennas but they have the nickname CRUNCHCRAFT and it sure came around
because of reasons that you are experiencing....Once in the air, the antenna
will work fine though...just check SWR with it pointed UP (reflector can be
on the ground) and you'll be set. I had a commercial CC version of the A50-3
on 48MHz and it worked great (thicker wall tubing, heavier clamping,
etc)...in fact, I need to go get it...its lying on the ground now
unused...and I know a club that would LOVE to have it on their tower recut
and tuned to 6.

See ya on six this season!
Chris
WB5ITT
EL39

> -----Original Message-----
> From: 50mhz-bounces at mailman.qth.net 
> [mailto:50mhz-bounces at mailman.qth.net] On Behalf Of Marvin L. Jones
> Sent: Monday, February 11, 2008 8:20 PM
> To: George McCrary
> Cc: 50mhz at mailman.qth.net
> Subject: Re: [50mhz] Cushcraft A50-3S Question
> 
> On Mon, 11 Feb 2008, George McCrary wrote:
> 
> >I'm getting ready to put a used (good condition) A50-3S up 
> at about 57 feet.
> >I currently have the antenna on an 8 foot mast leaning 
> against a pine tree.
> >
> >I've set the antenna up for resonance at 50.0 MHz according the 
> >measurements in the manual. When I measure the VSWR I actually get a 
> >dip at around 50.8 MHZ where the VSWR is about 1:1. The VSWR 
> at 50.0 is almost 3:1.
> >
> >Are the measurements in the manual that unreliable, or is 
> the antenna 
> >being affected by it's proximity to the tree and ground?
> 
> Maybe.  Probably.  No doubt.
> 
> Using a tall wooden or fiberglass step-ladder -- full clear 
> of any nearby structures, clamp the mast to the top platform 
> with the antenna pointing STRAIGHT UP.
> 
> Now (re)do your SWR measurements -- and insure that _you_ are 
> nowhere inside the antenna's capture area.