[Elecraft] [Elecraft_K3] New from Elecraft: KPA1500 amplifier with built-in ATU, separate power supply

[Alan Bloom]

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_n7ws at 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, john at 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
>>