An excellent point missed by many of the desktop tuner and high feedline
SWR advocates who insist on using coax fed antennas. Typically, they
blame their failures on cheap coax.
73,
Bill - NA5DX
On 4/21/2017 11:32 AM, Alan Bloom wrote:
With 1500W of power, if the SWR is greater than 3:1 you may be
exceeding the ratings of the feedline. For example, Belden 9914 is
rated at a maximum of 300 VRMS, which is 1800W with a 50-ohm feedline
or only 600W with a 3:1 SWR. At 30 MHz, RG-8/213 style coax is
typically rated at 1500W with a 1:1 SWR.
It's true that you can do more than that with low-duty-factor modes
like CW and SSB, but if you are running much more than 3:1 SWR you may
be in danger of damaging the feedline.
Alan N1AL
On 04/21/2017 06:28 AM, Jim Miller wrote:
Wes
Can you describe your affected antennas?
73
Jim ab3cv
On Apr 21, 2017, at 8:56 AM, Wes Stewart <wes_n...@triconet.org>
wrote:
A couple of points.
If you believe that an SWR of >3 necessarily degrades the efficiency
of an antenna, you are simply wrong.
If the "tuner" components have to be derated to this extent then
perhaps it should be called a line flattener rather than a tuner
because a lot of guys are still going to need a tuner.
On 4/21/2017 4:34 AM, j...@kk9a.com wrote: The KPA1500 tuner range
is fine. If your antennas have >3:1 SWR you need to do some work
outside. It will help your signal much more than the amp. Even when
I operated the RTTY Roundup in January after an ice storm my
antennas were within this amplifiers SWR range.
John KK9A
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