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

Posted by Eric Norris-2 on Jun 01, 2020; 9:24am
URL: http://elecraft.85.s1.nabble.com/Re-NOT-the-feedline-was-KPA-1500-faulting-on-6m-SWR-issues-tp7661502p7661514.html

Is there any chance RF is getting in to the KPA1500 via an alternative
route, like one of your HF antennas, a faulty switch, loose bonding/ground,
or even a change in house wiring or wifi router, antenna rotator cable,
picking up the RF and radiating/routing it to the KPA1500 from the
antenna?  It's a shot in the dark, I know, but cut out everything but the
direct signal path originating from the K3, pull all the house breakers not
used, turn off everything--make only the 6m path active and see what
happens if this makes sense to you.

I feel your frustration--the same thing in reverse took out my 2m EME
station. I replaced every single thing, sent the K3 to Elecraft, the XV144
to Don...GUD LUCK OM!

VY 73 Eric WD6DBM

On Sun, May 31, 2020, 9:07 PM Peter Dougherty <[hidden email]> wrote:

> 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
> >
> > -
> >
>
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