A 10 15 20 tribander antenna like TA33, unless a 40m kit is installed, has
no traps for 20m...
The existing traps are for 10 and 15 meters and their inductance (minus trap
capacitance) acts like a loading coil for the 20m elements.
If the antenna has no problems on 10 and 15 meters, the traps can't be
faulty, otherways problems should appear on 2 or 3 bands.
Concerning 20 meters, elements tips and their connection to the 15m traps
can be a failure reason instead.
Before opening traps looking for strange things, it's wise to check
continuity between tips and the tube where they are fixed.
We have often found totally isolated between each other, sliding aluminium
tubes threated with the so called "conductive paste" furnished by Mosley and
That material apparently transformed, slowly but irreversibly, in a sort of
strong non conductive film.
The only solution we found is to scratch it away from tubing and never use
again that paste.
Directors or reflectors faults greatly change resonance and feed point
impedance so it's incorrect to focus on driven element only.
Last but not least TA33 has a single enclosure for both 10 and 15 m traps.
Da: Fred Hopengarten <email@example.com>
A: firstname.lastname@example.org <email@example.com>; firstname.lastname@example.org
Data: lunedì 7 giugno 1999 16.22
Oggetto: Re: [TowerTalk] Check me Please!
>Fred Hopengarten K1VR 781/259-0088
>Six Willarch Road
>Lincoln, MA 01773-5105
>permanent e-mail address: email@example.com
>if sending attachments: firstname.lastname@example.org
>On Mon, 07 Jun 1999 08:46:37 -0500 Lee Buller <email@example.com>
>>I am thinking that a trap is gone in the Driven Element. But, Mosley
>>says it could be any trap in either the reflector or the director that
>>could cause it to act funning. Before I run off and buy a lot of parts,
>>what do you "august" experts think?
>K1VR: First thing I'd do is to take down the driven element and get it
>to the ground. Then open up the two 20 meter traps. Look closely closely
>closely at the wires connecting the trap to the element and the screws
>holding those coils (wires) in place. Why start with the driven element?
>Because it is easy, quick and cheap, and you can do it alone. It is one
>of only a few things you can do without taking the beam down.
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