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[TowerTalk] Smoking Rotor Box

To: towertalk@contesting.com
Subject: [TowerTalk] Smoking Rotor Box
From: jmltinc@aol.com
Date: Mon, 29 Dec 2008 17:05:29 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Hello all,

I have a friend (without computer) who has a Yaesu 2800 that has given him good 
service for a couple years. He works all bands from 160 meters through 10GHz. 
All of his amplifiers are QRO homebrew, of the highest quality.

He recently constructed 2KW+ amp for 160 meters. All has been well since he put 
it on the air. The other day, he keyed up on 160 SSB and as he started to 
speak, he got a 'poof' from the Yaesu control box and a little puff of smoke. 
He immediately stopped. The rotor still works OK, so he opened it up and sees 
no visible burnt components (but has the tell-tale smell).

He scoped each rotor cable wire at the control box and there is plenty of RF on 
each wire on 160 and 75 meters at 100 watts. The amplifiers are separate for 
each band. The (smoking) rotor is for the?10 GHz?dish and the only commonality 
is that all coax (there are dozens) and?rotor cables all are routed together to 
the outside. There is one other Yaesu 2800 and two Tailtwisters that are not 
affected.

Our thought was to choke out the 160 (as no other band has any effect) using a 
toroid on the rotor cable before it enters the box.

Any suggestions as to core and turns?

All suggestions are appreciated.

-John, N9RF
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