I have had bad luck with multiband yagi's with traps also. I managed to
burn up traps as you are describing on several tribanders. Several things
might have happened. Normally there is a drain hole in the bottom of the
trap to let it drain the condensation and moisture out that collects. If
the drain hole gets dirty and plugged then the trap will arc over inside.
This is what usually goes wrong. Note that it is important when assembling
the antenna to make sure all the trap drain holes are on the underside.
Another possibility that happened to me one time is tiny spiders nesting in
the trap causing arc over !
My recommedation for anyone that is selecting a multiband yagi is to buy one
that uses a linear loading design rather than traps. I now avoid trapped
antennas. Linear loading does not have the arcing problems that traps have.
You can run high power with out worrying about smoking a trap. Several
excellent antenna lines that utilize linear loading are KLM's KT34, and
Force 12's multiband yagi's. I have used both lines with excellent results.
Presently I am using Force 12 yagis. I remember one contest when I was in
the middle of a nice run on twenty meters, at around 2 AM ,and the swr went
very high on the Hy Gain TH6DXX I was using. I looked out the shack window
up at the beam and saw an orange glow coming from one of the traps !
I had smoked the trap. I switched over to a Butternut vertical and finished
the contest. (the Butternut verticals also have linear loading rather than
traps by the way)
Bob, K6UJ
----- Original Message -----
From: "Massimo IZ5ASZ" <iz5asz@libero.it>
To: <towertalk@contesting.com>
Sent: Thursday, October 24, 2002 11:08 AM
Subject: [Towertalk] mosley trap failure
Hello ,
I am Massimo IZ5ASZ I write this E-mail for a friend of mine.
My name is Patrizio, I own an antenna Mosley PRO 57 B
Now, after one year one trap is burnt on 20 meters and even the others one
has suffered.
I have opend it and with disappoint I have seen that the wire is complitely
melted
Comparing the trap of the PRO 57 B with one of my old antenna CL33 the
gauge wires are the same.
I wonder. How can be possible that? When the PRO57B is rated for 5 Kw and
the other one is 2.5 Kw?
Maybe the traps were faulty?
The amplifire that I use mount two tubes 4CX800A7. I operate only SSB mode I
am not a contester
no RTTY and neither CW.
I have seen on the technical sheet that They rated the TA series and the PRO
series for the same power 600 W RTTY. and the 2.5 Kw for the TA and 5 Kw
for PRO. Very strange.
Has anybody experience things like this?
I have sent 2 e-mail to Mosley no replay yet.
Best Regards
I5ZSS and IZ5ASZ
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