Re: NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

Posted by Peter W2IRT on Jun 01, 2020; 4:07am
URL: http://elecraft.85.s1.nabble.com/Re-NOT-the-feedline-was-KPA-1500-faulting-on-6m-SWR-issues-tp7661502p7661508.html

New coax and old coax behaved identically. HOWEVER, running into about 80 feet of old RG-213 and into the Cantenna dummy load and it doesn't fault. This is the only condition on 6m where there is no fault. Brand new coax, old coax, brand new antenna, old antenna, with balun, without balun. Always faults except when feeding the pure resistive dummy load. If there's any reactance it trips or gives false SWR info.

I would also add, why would a 2:1 SWR trip out the amp at 25 or 30 Watts of drive? On the regular HF bands I can use the internal tuner to take out a 2.5 or 3:1 SWR and it still sends 1400-1450 Watts up the pipe..

 - pjd

-----Original Message-----
From: Adrian <[hidden email]>
Sent: Sunday, May 31, 2020 11:05 PM
To: Peter Dougherty <[hidden email]>; 'Paul Baldock' <[hidden email]>; [hidden email]
Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

To remove any doubt, a 1.5kw or close dummy load at the end of the coax to replace antenna, would confirm the amp issue.

On 1/6/20 12:27 pm, Peter Dougherty wrote:

> Paul, please re-read what I wrote. The 90W figure is with the amp IN
> STANDBY! I wouldn't dream of putting more than about 35W into the KPA-1500.
> I generally like to run about 1200W on 6m, but even if I turn my K3s
> drive down to 20 Watts, it will STILL hard-fault regularly. NO AMOUNT
> OF DRIVE from the K3s will stop these problems. If the amp is set to
> deliver power it's going to fault on 6m, regardless of what the ATU is
> set for (bypass or inline), and the KPA will miss-read the SWR of the antenna system.
>
> The resistance figure is 50.8 Ohms, and the reactance is -11 according
> to the AA-230. The only difference between "works reliably" and
> "faults out all the time" is one is a resistive-only load, the other
> has a reactive component.
>
>   - pjd
>
> -
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]