Typically you will see a trap self resonate just below
the band it is designed for, i.e., a 15 meter trap should
show a dip somewhere 20.500 <> 21.000 MHz. KL7HF is correct
in saying that it is highly unlikely a 20 meter problem would
be a trap. There are no 20 meter traps on a tribander. The
entire element resonates on 20 meters.
73 de Bob - K0RC
At 07:16 AM 7/21/96 -0700, you wrote:
>> Message-Id: 1169_zs1ctc
>> From: zs1afz@zs1ctc
>> To: firstname.lastname@example.org
>> Hi Folks,
>> MOSELEY TA-33 JR TRIBANDER BEAM ANTENNA
>> My friend is experiencing problems with his antenna. It does work
>> 100% on 10 and 15 meters, but doesn't want to work on 20 meters.
>> He suspects that the traps are burnt.
>> Please can someone advise from where he can order replacement
>> driver traps?
>> Your help will be much appreciated! Many thanks in advance.
>> 73/88 Maria (email@example.com)
>Hi Maria. It is doubtful that the traps are to blame. If a trap goes bad,
>it affects all bands due to detuning. They can be "Grid-Dipped' to check
>What you describe could be the balun arrangement.
>Before removing the traps to check resonance, try bypassing the balun
>and feeding element direct with the transline and see what happens.
>If you don't see an improvement, then you can check with Mosley for the
>proper resonant frequency of each set of traps, and continue from
>Good luck. de KL7HF