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Re: KPA1500 Operation on 6 Meters

Posted by Paul Baldock on Jun 16, 2020; 3:33pm
URL: http://elecraft.85.s1.nabble.com/KPA1500-Operation-on-6-Meters-tp7662211p7662285.html

At 07:30 AM 6/16/2020, you wrote:
>So, summary question for the KPA1500 amp designers: With 5 watts
>drive and the amp in STBY, the KPA1500 display reads the correct 1.3:1 SWR.


I think the designers will tell you that the SWR meter does not read
well until you have about 20-30 watts passing through it.

Here's what mine reads in STBY, in to precision 100W dummy
load  connected on the back of the Amp (no coax involved) at 50.1MHz.

60W 1.3
30W 1.3
24W 1.3
18W 1.2
12W 1.2
6W  1.0

Here's what mine reads in OPER, in to a "cantenna" 1000W dummy load at 50.1MHz.

106W 1.3
314W 1.3
447W 1.2
693W 1.2
1071W 1.2

You will see that the AMP SWR  meter reads 1.2-1.3 all the way from
12W  to 1071W.
It should of  read ofcourse 1.0 in to the precision dummy load, not
1.3. It has worked this way since being born about 2 years ago. I
called Elecraft to ask if there was an adjustment for this, and they said no.

By the way on 29MHz in to the precision load the internal SWR meter
reads 1.1, and then from 24.9MHz to 1.8MHz reads 1.0.

Assuming your LP100 sensor is connected directly to the back of the
AMP (no coax involved) and always reads the same at all power levels
then I agree your AMP has an internal problem.

Good luck

- Paul KW7Y





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