[1000mp] Hi SWR on new MkV

[Brian Smithson]

Thank for the explanation. This seems like a reasonable approach, but what
concerns me most is that the SWR starts out really high and then settles
down to what it should be (as measured with my RF Analyst and FT990). 

I should be getting access to a dummy load yet this week so I'll be able to
try with a 'better known' quantity.

The power does fold back - almost to 0 as the 'HiSWR' light comes on.

Thanks for everyone's help - I'll let you know what ends up being the
problem!

73,

-Brian n8wrl

-----Original Message-----
From: 1000mp-bounces at mailman.qth.net [mailto:1000mp-bounces at mailman.qth.net]
On Behalf Of KB9GKC at aol.com
Sent: Monday, December 13, 2004 3:48 PM
To: 1000mp at mailman.qth.net
Subject: Re: [1000mp] Hi SWR on new MkV


 
In a message dated 12/13/2004 5:09:45 AM Central Standard Time,  
w9ol at billnjudy.com writes:

But an  old trick I was taught, add random lengths of coax. Especially on 10
and  12, this 'sometimes' has an effect.


This old trick expained how I understand it.
 
The SWR reading along a coaxial line will change when tested at different  
points, but the SWR reading will never read higher then what' actually at
the  
antenna.
Example:
SWR at antenna is 1:5:1
SWR reading with 90 feet of coax 1:2:1
SWR reading with 92 feet of coax  1:4:1
SWR reading with 94 feet of coax  1:5:1
 
This is where velocity factor of the feedline and cutting the coax at  
correct multiple wavelengths becomes important, it's so that you read at the
SWR  
meter what' actually at the antenna.
 
Chances are that if your new MkV says it's seeing a high SWR that the SWR
is 
high.  Having a low SWR is not really that critical for efficiency  (below 
3:1 is fine) the problem arises with modern solid state equipment  that has
cut 
back circuits to protect the PA.
 
Hope this helps with what we are experiencing.
73
Douglas
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