X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 24 Feb 2011 11:09:22 -0500 Message-ID: X-Original-Return-Path: Received: from elasmtp-banded.atl.sa.earthlink.net ([209.86.89.70] verified) by logan.com (CommuniGate Pro SMTP 5.4c2o) with ESMTP id 4880031 for lml@lancaironline.net; Wed, 23 Feb 2011 11:31:32 -0500 Received-SPF: none receiver=logan.com; client-ip=209.86.89.70; envelope-from=colyncase@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=CgPpvN042Ay6kZYxF8C2bO0cGSnHZilsDcWHqrNnUcsrFy5DvNQhCgbqCF4n3/e4; h=Received:From:Mime-Version:Content-Type:Subject:Date:In-Reply-To:To:References:Message-Id:X-Mailer:X-ELNK-Trace:X-Originating-IP; Received: from [216.57.118.194] (helo=[192.168.1.100]) by elasmtp-banded.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1PsHc8-00046P-Ln for lml@lancaironline.net; Wed, 23 Feb 2011 11:30:57 -0500 From: Colyn Case Mime-Version: 1.0 (Apple Message framework v1082) Content-Type: multipart/alternative; boundary=Apple-Mail-380-196393189 Subject: Re: [LML] Antenna type and placement X-Original-Date: Wed, 23 Feb 2011 11:30:56 -0500 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: <2941BEC7-FA5A-408C-B165-E9B0A8F1CBDE@earthlink.net> X-Mailer: Apple Mail (2.1082) X-ELNK-Trace: 63d5d3452847f8b1d6dd28457998182d7e972de0d01da940edc49b1e1957670bdff1493cde77ba15350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 216.57.118.194 --Apple-Mail-380-196393189 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii Hi Tom, based on my experience with Nav antennas and carbon, I would say your = chances of getting a com antenna to work inside carbon are about nil, = even with NO paint over the top. In fact, I have yet to hear (although I hope it's possible ) that = someone got really good (e.g. 100 mile line of sight) range out of a Bob = Archer com antenna in a glass vstab. What seems to work is a whip (monopole) on the belly with either a sheet = metal ground plane or a star of copper tape. The RADIUS of the ground = plane should ideally be 22" although people have done well in the high = teens. ...so placement is an issue. You can build your own whip out = of fiberglas and copper tape and make it more aerodynamic if you wish. = Length is critical and seems to come out to 20.8" with 1/2" copper tape = (as predicted by Jim Weir). You want to get the ferrite donuts from = Jim Weir if you go that route. Colyn On Feb 23, 2011, at 9:09 AM, TOM GARDINER wrote: > Folks > =20 > I am experiencing a dreadful time getting my COM radios to perform to = their full (or even half) potential in my LNC2. I have two Bob Archer's = mounted in the tailcone and in the proper orientation with a VSWR of = around 1.5 with RG 400 cable. The antennas are fed by two Garmin 430s = with a measured output of 8 watts each. The thing is that ATC and my = flying friends report a consistently weak signal and the same applies on = reception on my end. My airplane has the carbon tail and I built the = seat bench using carbon on foam (bad idea in hindsight). I have tried = another type of antenna that is a dipole with a balun mounted in the = center of the baggage section in a vertical orientation but with little = or no improvement in results. > =20 > =20 > I am beginning to suspect the Lancair supplied Gray epoxy primer which = I understand contains aluminum oxide in the base > =20 > I am now considering mounting an external antenna but thought I would = ask if anybody had experienced similar issues and subsequently corrected = them. Any help/advice would be very much appreciated > =20 > Thanks > =20 > Tom > =20 > LNC2 > 24 hrs >=20 >=20 --Apple-Mail-380-196393189 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii Hi Tom,

based on my experience = with Nav antennas and carbon, I would say your chances of getting a com = antenna to work inside carbon are about nil, even with NO paint over the = top.

In fact, I have yet to hear (although I = hope it's possible ) that someone got really good (e.g. 100 mile line of = sight) range out of a Bob Archer com antenna in a glass = vstab.

What seems to work is a whip (monopole) = on the belly with either a sheet metal ground plane or a star of copper = tape.   The RADIUS of the ground plane should ideally be 22" = although people have done well in the high teens.   ...so placement = is an issue.   You can build your own whip out of fiberglas and = copper tape and make it more aerodynamic if you wish.   Length is = critical and seems to come out to 20.8" with 1/2" copper tape (as = predicted by Jim Weir).   You want to get the ferrite donuts from = Jim Weir if you go that = route.

Colyn

On Feb 23, = 2011, at 9:09 AM, TOM GARDINER wrote:

Folks
 
I am = experiencing a dreadful time getting my COM radios to perform to their = full (or even half) potential in my LNC2.  I have two Bob Archer's = mounted in the tailcone and in the proper orientation with a VSWR of = around 1.5 with RG 400 cable.  The antennas are fed by two Garmin = 430s with a measured output of 8 watts each.  The thing is = that ATC and my flying friends report a consistently weak signal and the = same applies on reception on my end.  My airplane has the = carbon tail and I built the seat bench using carbon on foam (bad idea in = hindsight).  I have tried another type of antenna that is = a dipole with a balun mounted in the  center of the baggage section = in a vertical orientation but with little or no improvement in = results.
 
 
I am = beginning to suspect the Lancair supplied Gray epoxy primer which I = understand contains aluminum oxide in the base
 
I am now considering mounting an external antenna = but thought I would ask if anybody had experienced similar issues and = subsequently corrected them.  Any help/advice would be very much = appreciated
 
Thanks
Tom
LNC2
24 hrs



= --Apple-Mail-380-196393189--