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[TowerTalk] ferrites & fires

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Subject: [TowerTalk] ferrites & fires
From: (Martin Ewing)
Date: Sat Jun 28 10:58:10 2003
I appreciated W1HIS's tale about his line isolator burn-up.  I was thinking 
about getting some of these products, so the timing was propitious.

A few thoughts in response:

-Life is simpler with QRP. :-)

-Unless you have high confidence in the product you are buying _and_ you 
understand the your operating conditions, you need to over-rate your 
  That means that a $30-40 PVC thingy might not be a good idea for your 
transmmission line. [In a conservative system design, you might require that 
components should survive a serious fault, like an open or shorted antenna 
connection - or at least fail safely.]

-Everybody uses PVC, but PVC is not known for its ability to dissipate heat, 
it makes pretty nasty smoke.  Is there a better design?  Open air? Water 
cooled? :-)

-Some 3rd party should be doing destructive testing on QRO items.  This could 
fun for the right person! Burning attic anecdotes are nice, but it's an 
inefficient way to learn about products.

-The line isolator product is available from at least 3 vendors at about the 
same price.  MFJ's product info says _nothing_ about power handling ability. 
The W2DU unit ( claims 10 KW PEP at 10 MHz and 2:1 VSWR. What's 
fella to do?



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