Re: KAT2 with EFHW antenna

Posted by Guy, K2AV on Aug 24, 2011; 5:49am
URL: http://elecraft.85.s1.nabble.com/K3-S-meter-oddities-tp6676870p6718956.html

An EFHW is a very efficient antenna, but the usual tuner needs help.  One
way to use the EFHW is to put a toroidal winding at the base of the antenna,
between the tuner and the antenna. Bifilar or trifilar or quadrifilar
windings configured as a tapped winding will reduce the tough impedance to
something that the tuner will handle easily.

The 80 meter version of this, an end-fed half-wave L fed against ground is
probably the best single wire antenna for 80 meters that there is.

73, Guy.

On Tue, Aug 23, 2011 at 11:50 PM, Phillip Shepard <[hidden email]> wrote:

> Thanks for all of the great advice.  This reflector is a fountain of
> knowledge!  I checked the 33' antenna/16' counterpoise combination with an
> MFJ259B, and it indicated over 25:1 SWR.  Extending the antenna to 39' and
> adding a second "radial" of 6' gave an SWR reading of about 11:1 with the
> antenna analyzer.  The KAT2 seems to handle that much better.  This will
> get
> me through one or two SOTA peaks at Crater Lake later this week; and I can
> look for better solutions after that.  Thanks again.
>
> 73,
>
> Phil, NS7P
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]]On Behalf Of Phillip Shepard
> Sent: Tuesday, August 23, 2011 4:00 PM
> To: [hidden email]
> Subject: [Elecraft] KAT2 with EFHW antenna
>
>
> I have been using my K2 with an MFJ tuner to feed an end fed halfwave wire
> for portable use (like SOTA).  The 20m antenna is 33' long and I use one or
> two 16' counterpoise wires.  It seems to work well for what it is and 10W.
> I just built and installed the KAT2 ATU into the K2 to lighten my pack by
> the loss of the MFJ.  The KAT2 tuner checked out fine on the bench, but it
> had a very hard time getting a good match to the antenna.  In AUTO mode, it
> only got the SWR down to about 5:1.  I put it in ALT mode, and it spent a
> long time searching before it got down to between 3:1 and 4:1, depending on
> the 20m frequency.  I added about 2" of wire to the antenna, and the tuer
> got down to about 2:1 to 2.5:1.  I added another foot of wire (now 36'),
> and
> it got down to about 1.5:1.  Five or six feet added yielded a perfect match
> (1:1).  So I now have a 39' wire for 20m use.
>
> Is this normal?  Should the KAT2 be able to more easily match the 33'
> halfwave antenna?  Thank you.
>
> 73,
> Phl, NS7P
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html