[TowerTalk] Trap Resonance

[Fred Hopengarten]

From:
Fred Hopengarten  K1VR               617/259-0088
Six Willarch Road
Lincoln, MA 01773-5105
permanent e-mail address:  fhopengarten@mba1972.hbs.edu

On Tue, 12 Aug 1997 14:13:52 +1000 (EST) Peter Cattell
<p.cattell@qut.edu.au> writes:

> I bought a few weeks ago a Hy-Gain
>TH6 DXX Thunderbird Yagi.  I have disassembled it, cleaned all 
>overlapping
>sections of tubing, coated them with Aluminox conductive paste and
>reassembled it.  Prior to raising it on the tower, I would like to 
>check
>that all traps are OK.


I've brought two TH6's back to life in my career.  So I thought I'd throw
in some remarks.

During manufacturing, a "dimple" or two is created to keep the trap
sleeve in place.  The dimple is the equivalent of taking a dull nail and
punching down on the aluminum so that it sticks to the plastic coil form
below.  If you are clever with wood, you can create a "tool" that you can
pound on to get the sleeve off.  That way you won't be hammering the
aluminum, which is a bad idea.

There are are only a few things which can go wrong with a HyGain trap:

	Debris and detritus.  Bugs get in and leave stuff behind.  This
should be blown out with compressed air.

	Screw problems.  The screw holding the end of aluminum wire can
rust.  Replace it.  Use an antioxidant at the joint between screw and
aluminum wire.

	Carbon tracks.  If a prior user has blown up the trap with high
power out of resonance, you may find a carbon track.  Use a magnifying
glass to look for one.  If you find one, use a sharp knife and cut out
the carbon track.  Get rid of that carbon physically.

	End caps. Too many years in the sun and they will crack.  Don't
bother fiddling.  Call the woman at the factory who talks to hams and
takes their orders for parts all day long.  She doesn't know radio, but
she does know TH6 parts! And she's friendly.  Replace all traps.  When
installed, drill a weephole for water to escape from the side facing
down.

	Good luck!		Fred K1VR

		

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