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

[Gary J Ferdinand]

Rule out or in the feed line. Put the amp into a dummy load and see if it trips.  Good Luck.

73/Gary W2CS

> On May 31, 2020, at 12:54 PM, Jim Miller <jim at jtmiller.com> wrote:
> 
> 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 <mailto: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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