[UK-CONTEST] : A3S

[G0JKZ]

There is no 10m trap... it's a straight bit of tube isn't it... then the
trap for 15 then 20 or is it the other way round?

> -----Original Message-----
> From: Colin Wilson [mailto:colin at sheffield-live.co.uk]
> Sent: 01 February 2012 14:52
> To: G0JKZ; steve at m0bpq.com; uk-contest at contesting.com
> Subject: [UK-CONTEST] : A3S
> 
> George
> you might well be right on that one unless its the 10m trap thats gone?
> 
> 73
> 
> Colin CT7ACG/G3VCQ
> www.sheffield-live.co.uk
> e. colin at sheffield-live.co.uk
> t. +351912884618
> 
> ----- Original Message -----
> From: "G0JKZ" <g0jkz at terminalcomputers.com>
> To: <steve at m0bpq.com>; <uk-contest at contesting.com>
> Sent: Wednesday, February 01, 2012 2:33 PM
> Subject: Re: [UK-CONTEST] A3S
> 
> 
> > Hmmm... if it is useless on all bands the surely something else is
wrong.
> > The a3s is a full size half wave at 10m so surely the trap at the end of
> > the
> > first section should not affect the operation on 10, but only 15 and
20...
> > I'm probably talking crap but that's what is flying through my head with
> > this problem.
> >
> > George G0JKZ
> >
> >
> >> -----Original Message-----
> >> From: Steve Bunting [mailto:stephen.bunting at virgin.net]
> >> Sent: 01 February 2012 12:41
> >> To: uk-contest at contesting.com
> >> Subject: [UK-CONTEST] A3S
> >>
> >> Guys,
> >>
> >> The recent co-ax chat has reminded me of a problem that I have with a
> >> Cushcraft A3S (at www.gb2gp.org.uk) and I wonder if I can tap into the
> >> expertise on the list.
> >>
> >> The antenna was being used with 400W CW on 20m when the SWR shot
> up
> >> from
> >> 1.4:1 to over 10:1 whilst transmitting. I swept the antenna with a
> >> miniVNA
> >> and it is u/s on 10,15 and 20m. The antenna is fed with 60m of
> >> LDF5-50 and ecoflex 10 around the rotator to the co-ax choke. I use
> > N-types
> >> or 7/16 connectors throughout so don't really expect there to have been
> > any
> >> failure there and have tested at the bottom of the tower to rule out a
> > co-ax
> >> fault where possible. My hypothesis is that a trap has failed in the
> > driven
> >> element. Does anyone know if this is common with pre-MFJ A3S's? Apart
> >> from a failed connector at the feed point, the traps are the only thing
> > that
> >> can break - aren't they? Perhaps someone here has experience with this
> >> antenna they can share with me off list.
> >>
> >> In theory this is simple to solve, but the antenna is on top of a 30m
> >> tall
> > fixed
> >> tower so trips to the top need good planning and any substantial
> > mechanical
> >> work needs a posse assembling. I am trying to be as informed as I can
be
> >> before embarking on tower top troubleshooting and hopefully a repair.
> >>
> >> 73
> >> Steve
> >> M0BPQ
> >> _______________________________________________
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> >> UK-Contest at contesting.com
> >> http://lists.contesting.com/mailman/listinfo/uk-contest
> >>
> >>
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01/31/12
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> >
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> >
> >
> 
> 
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