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[K3S] K3S High SWR Shutdown on FT8?

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MaverickNH

[K3S] K3S High SWR Shutdown on FT8?

I'm using a K3S/100 with ATU to drive a 43ft vertical with remote ATU at base. To operate, I typically bypass the K3S ATU, tune the remote ATU to 1:1 on 20m, then turn the K3S ATU to auto and tune again to 1:1 reading on the K3S. Running WSJT-X FT8 digital mode at 63W, all is fine, but if I run 100W too long I sometimes hear an alarm and turn power back to 63W (the alarm stops) or the K3S just shuts down. I'm not sure where the high-pitch alarm is coming from - I have a nearby Yaesu FP3010A Linear PSU but the manual mentions nothing about an alarm. Nor does the K3S mention an alarm. I see no High SWR warning on the K3S display. The PSU does not turn off.

Any thoughts appreciated!

Bret/N4SRN

Don Wilhelm

Re: [K3S] K3S High SWR Shutdown on FT8?

Bret,

As far as I know, the K3S does not have any audible alarm.
So that leaves 2 elements in your setup that could be producing that
alarm - the remote ATU control unit, or the computer you are using.
The "alarm" could also be the result of some sort of feedback and is
'just something that happens' but is not really intended to be an alarm.

If you find your remote ATU is causing the problem, check all
connections at the antenna. It is quite common for a connection to be
OK at lower powers, but when the power is increased, something breaks
down causing the problem. If you can verify that it is an SWR problem,
then look carefully at the antenna for the solution.

73,
Don W3FPR

On 7/30/2017 9:16 AM, MaverickNH wrote:
> I'm using a K3S/100 with ATU to drive a 43ft vertical with remote ATU at
> base. To operate, I typically bypass the K3S ATU, tune the remote ATU to 1:1
> on 20m, then turn the K3S ATU to auto and tune again to 1:1 reading on the
> K3S. Running WSJT-X FT8 digital mode at 63W, all is fine, but if I run 100W
> too long I sometimes hear an alarm and turn power back to 63W (the alarm
> stops) or the K3S just shuts down. I'm not sure where the high-pitch alarm
> is coming from - I have a nearby Yaesu FP3010A Linear PSU but the manual
> mentions nothing about an alarm. Nor does the K3S mention an alarm. I see no
> High SWR warning on the K3S display. The PSU does not turn off.
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MaverickNH

Re: [K3S] K3S High SWR Shutdown on FT8?

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Re: [K3S] K3S High SWR Shutdown on FT8?

In reply to this post by MaverickNH

Why on earth bother with the tuner in the radio, when you've matched the
antenna to the feeder at the feed point?

All your doing is adding extra loss to both the TX and RX path.

If the match (indicated by VSWR at the rig end of things) is changing
during the 15 second FT8 transmission period, that could be stressing a
PA and or PSU, and you're hearing an over-temp warning from something,
if that's what it is.

Either case, the cause of the wandering VSWR (if that is it) or the lack
of cooing to the PA/PSU needs sorting out.

Lastly, most people running JT (and other digi) modes, don't run the rig
at full power, but between 25 and 50%. 50W is half an S point down on
100W. Those that do run QRO on those modes, do so with a "Large" PA,
also under run, to keep it very linear (for the modes that need it)
and/or within it's dissipation/duty cycle ratings.

73.

Dave G0WBX.

On 30/07/17 20:26, [hidden email] wrote:

> On 7/30/2017 9:16 AM, MaverickNH wrote:
>> I'm using a K3S/100 with ATU to drive a 43ft vertical with remote ATU at
>> base. To operate, I typically bypass the K3S ATU, tune the remote ATU to 1:1
>> on 20m, then turn the K3S ATU to auto and tune again to 1:1 reading on the
>> K3S. Running WSJT-X FT8 digital mode at 63W, all is fine, but if I run 100W
>> too long I sometimes hear an alarm and turn power back to 63W (the alarm
>> stops) or the K3S just shuts down. I'm not sure where the high-pitch alarm
>> is coming from - I have a nearby Yaesu FP3010A Linear PSU but the manual
>> mentions nothing about an alarm. Nor does the K3S mention an alarm. I see no
>> High SWR warning on the K3S display. The PSU does not turn off.

MaverickNH

Re: [K3S] K3S High SWR Shutdown on FT8?

In reply to this post by Don Wilhelm

That alarm turned out to be my USP - the sound was hard to track down as it's on the floor. The USP is a CyberPower CP1500PFCLCD which is giving an Overload alarm on typically the last TX of a QSO at 100W. The specs are Output 1500VA 900W.

I'm curious why power consumption increases with each 15sec FT8 TX, when I have a SWR 1:1 with a SG-235 antenna coupler at the base of my 43ft Vertical. PA Temperature runs about 40-42C when the overload alarm goes off.

Bret/N4SRN