Amps
[Top] [All Lists]

RE: [Amps] Line Isolators for RF feedback

To: "'Joe Isabella'" <n3ji@yahoo.com>, "'Amps'" <amps@contesting.com>
Subject: RE: [Amps] Line Isolators for RF feedback
From: "Joe Subich, K4IK" <k4ik@subich.com>
Date: Tue, 3 Aug 2004 23:26:28 -0400
List-post: <mailto:amps@contesting.com>

> I would imagine that the coax and/or PL-259 would be the weak 
> link in this case though, wouldn't it??  Even say RG-400 or RG-303 
> would give up before they get saturated, right?  Just curious --
> even if I ran my 3K-A at full bore, it wouldn't kill 'em 
> (given that the dipole is at it's resonant point).

Beware of the loss in the "beads" of the bead baluns.  While they 
may not saturate, if there is substantial current on the outside 
of the coax you can see significant heating ... to the point of 
exceeding the curie temperature of the beads resulting in their 
failure. 

I believe both W1JR and W8JI have written about the problem with 
bead baluns.  In order to keep the number of beads/length to a 
reasonable level, the beads have to be high mu but the high mu 
beads have higher loss characteristics ... and the loss seems 
to increase faster than the inductance. 

73, 

   ... Joe, K4IK 
 

_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps

<Prev in Thread] Current Thread [Next in Thread>