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

[Bill Breeden]

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_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
>>>
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