[Elecraft] KPA-1500 faulting on 6m; SWR issues

[Jim Miller]

I run 1500w for JT65 EME. No problems. My antenna measures 1.4:1 on the
KPA1500 swr meter and therefore never engages ATU.

Have you vetted your feedline at 1500w? Many times something might be good
at low power and fail at 1500. neither the AA230 or K3s will stress such a
feedline.

I believe the AA230 will do TDR. What does that show? Have you inspected
each connector for corrosion?

jim ab3cv

On Sun, May 31, 2020 at 12:47 PM Peter Dougherty <lists at w2irt.net> wrote:

> Hi all (and sorry about the blank post-I don't know what happened there).
>
>
>
> I am experiencing a continuing and repeatable problem with my KPA-1500 on
> 6m. With the amp in bypass I am able to operate normally with my K3s, but
> the amp's meter is showing a 1.8 to 2:1 SWR on that band, despite
> measurements on an AA-230 analyzer and the SWR meter on the K3s itself
> showing it virtually flat (no more than 1.2:1).
>
> Once the amp is placed set to operate it's still showing SWR measurements
> of
> 1.8:1 to 2.1:1 consistently when delivering power. If the tuner is bypassed
> I can't run more than about 600W out before it faults. If I put the tuner
> in
> and click it to tune, it will deliver power just fine at 1200 or 1300 Watts
> for ONE FT8 transmit cycle. When it goes to transmit again it hard-faults
> with too much reflected power. Using 100W straight from the K3s there is no
> issue whatsoever, but *any* level of power from the KPA is liable to trip
> the excess reflected power sensor on the amp.
>
> At first I thought I had an antenna problem, but yesterday I put up a brand
> new 6m LFA and it's doing the same thing. This coming week I plan to
> replace
> the feedline with LMR-400--it's got a combination of 3/8" hardline and
> RG-213 at the moment. Any thoughts on what might be going on here? Is there
> a known-issue on 6m with the KPA?
>
>
> ---------------------------------------------
> 73 and Good DX
> Peter, W2IRT
>
>
>
> President, North Jersey DX Association
>
> DXCC Card Checker
> Letter O Manager, ARRL Incoming 2nd District QSL bureau
>
>
>
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