Antennaware
[Top] [All Lists]

[Antennaware] to Paul G0HWC abt 20m Moxon

To: <antennaware@contesting.com>
Subject: [Antennaware] to Paul G0HWC abt 20m Moxon
From: "Andreja Todorovic" <muzikant@sezampro.yu>
Date: Mon, 21 Apr 2008 18:31:01 +0200
List-post: <antennaware@contesting.com">mailto:antennaware@contesting.com>
Hi Paul, simple answer on Your question is: 2 feeders; multi-band Mox in square 
shape only; 1 to 1 balun is recomended, and contact me on muzikant@sezampro.yu  
for picture and construction details. I prefere my 3L/3b Moxon 20/15/10m,
 73 to all Andra YU1QT
  ----- Original Message ----- 
  From: antennaware-request@contesting.com 
  To: antennaware@contesting.com 
  Sent: Monday, April 21, 2008 6:00 PM
  Subject: Antennaware Digest, Vol 54, Issue 7


  Send Antennaware mailing list submissions to
  antennaware@contesting.com

  To subscribe or unsubscribe via the World Wide Web, visit
  http://lists.contesting.com/mailman/listinfo/antennaware
  or, via email, send a message with subject or body 'help' to
  antennaware-request@contesting.com

  You can reach the person managing the list at
  antennaware-owner@contesting.com

  When replying, please edit your Subject line so it is more specific
  than "Re: Contents of Antennaware digest..."


  Today's Topics:

     1. 20m Moxon beam (Paul Young)
     2. Re: building a TAK-Tenna ??? (Terry Conboy)
     3. OT XM240 Loading Coils (Gedas)
     4. Grounding needs (Howard W3CQH)
     5. Re: Grounding needs (K9AY)


  ----------------------------------------------------------------------

  Message: 1
  Date: Sun, 20 Apr 2008 18:18:42 +0100
  From: "Paul Young" <paul@g0hwc.com>
  Subject: [Antennaware] 20m Moxon beam
  To: <AntennaWare@Contesting.com>
  Message-ID: <83356CB27EF5414996385AB3100A58DE@PaulPC>
  Content-Type: text/plain; charset="iso-8859-1"

  Hi all,
          I am going to be building a Moxon beam for 20m.
  I have got 4 fiberglass poles for the spreaders and trying to find the best 
way to fix them to the 2 inch mast.
  I have looked on the moxon project website but would like to see other ways 
of mounting.
  http://www.moxonantennaproject.com/


  Also would like to hear what others think about fitting a 1 to 1 balun or not 
?
  And how will it affect things if I add a 15m loop within the 20m loop?
  Would I be best to have 2 feeders or the one ?

  Many thanks for your time

  Paul G0HWC

  Check out my website  www.g0hwc.com / www.sstv.org.uk

  ------------------------------

  Message: 2
  Date: Sun, 20 Apr 2008 11:06:34 -0700
  From: Terry Conboy <n6ry@arrl.net>
  Subject: Re: [Antennaware] building a TAK-Tenna ???
  To: Paul Young <paul@g0hwc.com>
  Cc: Antennaware@contesting.com
  Message-ID: <7.0.1.0.2.20080420104247.04a98e20@arrl.net>
  Content-Type: text/plain; charset=us-ascii; format=flowed;
  x-avg-checked=avg-ok-5D193B82

  At 04:03 PM 2008-04-12, Paul Young G0HWC wrote:
  >I have been reading up on the TAK-Tenna and would like to build one
  >for 20m and 40m. Anyone for the details for this ?
  >
  >Also, anyone tried building a 80m TAK ?

  There has been some discussion about the Tak-tennas on the TowerTalk 
  list.  Start at 
  http://lists.contesting.com/archives//html/Towertalk/2008-04/msg00319.html
  The comments from K4SAV are especially pertinent.

  The conclusion is that the "antenna" serves to drive currents down 
  the shield of the feedline, which actually does the vast majority of 
  the radiating.  Tapping the two "pancake" coils asymmetrically 
  adjusts the coupling to the coax shield and lets you get a good match.

  On 40m, the radiation resistance of the antenna itself is only a few 
  ohms, most of which is copper loss, since the radiation resistance of 
  such a small dipole is less than an ohm.  The bandwidth is also very 
  narrow, which is typical of small antennas, regardless of the loading 
  method.  If a choke balun were used at the feedpoint of the Tak-Tenna 
  so the feedline isn't part of the radiating system, the SWR would be 
  very high, even at resonance.

  On the good side, for a very small antenna, this is a relatively 
  efficient design, since capacitive/inductive hats of this type do 
  tend to raise the radiation resistance near the maximum possible for 
  a 30 inch radiator.  But the reality is that the bandwidth will still 
  be very narrow even after matching (with a hairpin, etc.) and 
  decoupling the coax shield.

  I have some EZNEC models for 40m, which include the coax shield, if 
  anyone is interested.

  73, Terry N6RY



  ------------------------------

  Message: 3
  Date: Sun, 20 Apr 2008 15:42:40 -0400
  From: "Gedas" <w8bya@mchsi.com>
  Subject: [Antennaware] OT XM240 Loading Coils
  To: <AntennaWare@Contesting.com>
  Message-ID: <00e901c8a31e$b1bb5610$0401a8c0@ham>
  Content-Type: text/plain; format=flowed; charset="iso-8859-1";
  reply-type=original

  Does anyone have handy the inductance value for the loading coils on the CC 
  XM240?

  Gedas
  W8BYA
  http://gedas.cc
  http://www.w8bya.com 



  ------------------------------

  Message: 4
  Date: Mon, 21 Apr 2008 10:10:54 -0400
  From: "Howard W3CQH" <hsgorden@comcast.net>
  Subject: [Antennaware] Grounding needs
  To: <antennaware@contesting.com>, <antennas@mailman.qth.net>
  Message-ID: <016401c8a3b9$850d0780$6401a8c0@HAMSHACK>
  Content-Type: text/plain; format=flowed; charset="iso-8859-1";
  reply-type=original

  I live in a 1 story home with a accessible attic.

  I have an Icom AH-4 tuner mounted in the attic, and need to run a real 
  ground to the 8' ground rod we just pounded in.

  My question is - should the ground wire coming from the AH-4 be of a wire 
  gauge of #12, or should I consider running 1/4" copper tubing?  The total 
  length of the run is approximately 30'

  73's 




  ------------------------------

  Message: 5
  Date: Mon, 21 Apr 2008 09:41:27 -0500
  From: "K9AY" <k9ay@k9ay.com>
  Subject: Re: [Antennaware] Grounding needs
  To: "Howard W3CQH" <hsgorden@comcast.net>,
  <antennaware@contesting.com>
  Message-ID: <015c01c8a3bd$c802eb00$6401a8c0@SUMMIT1>
  Content-Type: text/plain; format=flowed; charset="iso-8859-1";
  reply-type=original

  >I live in a 1 story home with a accessible attic.
  >
  > I have an Icom AH-4 tuner mounted in the attic, and need to run a real
  > ground to the 8' ground rod we just pounded in.
  >
  > My question is - should the ground wire coming from the AH-4 be of a wire
  > gauge of #12, or should I consider running 1/4" copper tubing?  The total
  > length of the run is approximately 30'
  >

  Howard,

  At a length of 30 feet, there is no RF "ground" -- it's nearly 1/4 
  wavelength at 40M and will always be part of any antenna connected to the 
  attic-mounted tuner. If you include the ground wire in a computer model of 
  the antenna, this will be quite obvious. I have three suggestions:

  1. Install the ground wire as short as possible, with as large a conductor 
  as is practical. If the tuner and antennas work as you expect, you are 
  finished.

  If the antennas fail to perform as expected, or if the tuner behaves 
  erratically, the new wire has created an unwanted resonance and/or increased 
  the RF levels at the tuner. One of the two other options may work:

  2. Add an RF choke in the power/control wires of the tuner -- ferrite beads 
  or a few turns of all wires through a large toroid. This will "disconnect" 
  the wires at RF.

  3. Run multiple ground wires (e.g. 3) of different lengths to different 
  ground rods. This will create different RF paths with different resonant 
  behavior. Odds are that this will change things enough to reduce the 
  problem.

  73, Gary
  K9AY 



  ------------------------------

  _______________________________________________
  Antennaware mailing list
  Antennaware@contesting.com
  http://lists.contesting.com/mailman/listinfo/antennaware


  End of Antennaware Digest, Vol 54, Issue 7
  ******************************************

_______________________________________________
Antennaware mailing list
Antennaware@contesting.com
http://lists.contesting.com/mailman/listinfo/antennaware

<Prev in Thread] Current Thread [Next in Thread>
  • [Antennaware] to Paul G0HWC abt 20m Moxon, Andreja Todorovic <=