[Elecraft] [K3] KAT3 and 160 with 40m long doublet

[Ken Roberson]

Stephen,

What is the SWR without the tuner ?

73 Ken K5DNL
----------------------------------------------------------


--- On Sun, 1/2/11, Stephen Prior <sjp at sjprior.fsnet.co.uk> wrote:

> From: Stephen Prior <sjp at sjprior.fsnet.co.uk>
> Subject: [Elecraft] [K3] KAT3 and 160 with 40m long doublet
> To: "elecraft" <elecraft at mailman.qth.net>
> Date: Sunday, January 2, 2011, 1:31 PM
> I have only just recently added the
> KAT3 and I'm very impressed with it, but
> given the praise heaped upon it by others I'm slightly
> surprised that the
> best VSWR I can get on 160m is about 8:1.  The antenna
> is approximately a
> doublet which is a half wave long on 80m ­ I say
> 'approximately' as it's
> slightly off-centre fed.  I have about 7m of 300 ohm
> slotted down from the
> feedpoint and then into a coaxial choke at roof level for
> the remaining 10m
> into the back of the K3.  Substituting the straight
> connection for a 4:1
> balun (Guanella) at the transition between the slotted
> feeder and the coax
> helps slightly but not by much.
> 
> Unfortunately I don't have a vector analyser,  so I
> have no idea of the
> nature of the reactance that the K3 is seeing. 
> However, given the
> wavelength involved, I would need to add a very significant
> length of
> coaxial cable if I were to swing the point around the Smith
> Chart.
> 
> I have tried to manually tune the KAT3,  but unless I
> am missing something,
> I am am not able to change the L and C values at the same
> time as
> transmitting, so it's a very tedious process.
> 
> Tomorrow I may well add some extra wire to hang vertically
> down from the
> ends of the doublet.  In the meantime I would be
> pleased to hear any
> comments.
> 
> Happy New Year!
> 
> 73 Stephen, G4SJP
> 
> 
> 
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>