[Amps] High SWR

[Fuqua, Bill L]

  I have used RG-59 for DC over 5000volts and the larger RG-8 type over 20kV.
But the ratings in the catalogs have more to do with UL and CSA classifications and in some cases
may be real voltage limits but with RF AC voltage applied to the coax (dielectric loss limitations).
But dielectric losses are a function of frequency so you rarely see that sort of limitation listed.  

73
Bill wa4lav
________________________________________
From: amps-bounces at contesting.com [amps-bounces at contesting.com] On Behalf Of Alex [alexeban at gmail.com]
Sent: Saturday, April 25, 2009 4:03 AM
To: 'Rex Lint'; dezrat1242 at yahoo.com; amps at contesting.com
Subject: Re: [Amps] High SWR

... sorry, but something really doesn't fit!
RG 213 has a withstand voltage closer to 6000 (six thousand) volts rather
than 600!
Alex    4Z5KS


-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Rex Lint
Sent: Thursday, April 23, 2009 4:02 AM
To: dezrat1242 at yahoo.com; amps at contesting.com
Subject: Re: [Amps] High SWR

Huh?  600 Volts?  Where did that figure come from?

      -Rex-

       K1HI
       Rex Lint
       Merrimack, NH


-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Bill, W6WRT
Sent: Wednesday, April 22, 2009 7:53 PM
To: amps at contesting.com
Subject: Re: [Amps] High SWR

ORIGINAL MESSAGE:

On Wed, 22 Apr 2009 17:39:22 -0400, Pete Smith <n4zr at contesting.com>
wrote:

>, but SWR, per se, is not
>something to worry yourself about, so long as the amplifier can match the
load.

REPLY:

I agree up to a point. The main villain with SWR, IMO, isn't loss, it
is the excess voltage present on the line. Most coax, even the RG-213
size, is rated for only 600 volts. If you have a 2:1 SWR at 1500 watts
you are living on the edge already. Go to 3:1 and you have crossed the
line.

I won't say it can't be done, but a wise op won't.

73, Bill W6WRT
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