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

[Bill Coleman]

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
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