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RE: [TowerTalk] Re: narrowband filters

To: <towertalk@contesting.com>
Subject: RE: [TowerTalk] Re: narrowband filters
From: "Lau, Zack, W1VT" <w1vt@arrl.org>
Date: Wed, 21 Jul 2004 09:18:58 -0400
List-post: <mailto:towertalk@contesting.com>
  Someone asked whether the filters I designed will handle 
200 watts.  No they won't--the losses are too high. 

   However, if someone wants to tackle some new territory in
filter design--may I suggest coupling two small transmitting 
loop antennas?  A transmitting loop can be used as a very high
Q resonator that will handle lots of power.  Ideally, these
would be rigidly enclosed in shielded enclosures.  Walking near
an unshielded loop will detune it--not to mention the RF safety
issues.

        Good mechanical construction is essential with high Q filters.
A little bit of coil wobble can cause serious problems in a narrow
filter--this is why I mounted the coil on a PVC form.  You should 
also take into account thermal stability issues.

73--Zack Lau W1VT
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