[Elecraft] [K3] Issue with HI CUR on 12m

[Robin Szemeti]

Antenna feed impedance under 50R?  Take some measurements with a cheap VNA

On Mon, 12 Oct 2020 at 01:55, Bill Coleman <aa4lr at arrl.net> wrote:

> Don,
>
> I finally got around to running my K3 into a dummy load.
>
> I had no problem running 100w or even 110w with a dummy load. Current draw
> from the power supply was 22 A and 23 A, respectively, on the K3 display.
> No HI CUR indications.
>
> External wattmeter validates the output.
>
> I was getting the HI CUR indication on a trap 30/17/12m inverted V. I had
> to take it down, and now I’m using a trap 80/40/20m dipole through the
> tuner. No HI CUR indication on that antenna, either.
>
> Even though I have current baluns on both antennas, I’m thinking that my
> HI CUR problem may be related to RF feedback in the shack.
>
> Do you concur?
>
> I’m in the process of a number of shack improvements, including antenna
> replacements and grounding and bonding, so that might take care of it.
>
> > On Jan 11, 2020, at 11:29 AM, Don Wilhelm <donwilh at embarqmail.com>
> wrote:
> >
> > Bill,
> >
> > Is this into a dummy load (bypass the ATU or tune the ATU into the dummy
> load).
> > If it is into an antenna, there are a whole lot of guesses about how the
> antenna behaves with higher power levels than your antenna analyzer shows.
> So check it with a dummy load to eliminate the possibility that the problem
> is in the antenna.
> >
> > Put an external wattmeter in line with the dummy load to eliminate
> questions about the calibration on the K3 wattmeter.
> >
> > If you can measure the actual current drawn, that would also be helpful.
> >
> > 73,
> > Don W3FPR
> >
> > On 1/11/2020 11:18 AM, Bill Coleman wrote:
> >> Back in early December, I installed two KSYN3As in my K3 SN 7071.
> Sometime after that, I noticed that on 12m, I’m seeing a HI CUR indication
> when I set the power level to more than about 80-85 watts. The K3 will back
> off on the power level, then slowly ramp back up until it hits HI CUR again.
> >> I don’t remember seeing this before. After the KSYNC3A install, I ran
> the transmit gain calibration at both 5 and 50 watts, as specified in the
> instructions. Just in case something went awry, I ran it again.
> >> I’m still seeing this problem. What causes HI CUR at 85 watts? The K3
> ought to be able to produce over 110 watts on 12m.
> >> I’m not seeing this issue on other bands.
> >> No issues with calibration
>
> Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
> Web: http://boringhamradiopart.blogspot.com
> Quote: "Not within a thousand years will man ever fly!"
>             -- Wilbur Wright, 1901
>
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