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

[Bill Coleman]

Curious. I’m doing a lot of antenna work right now. I had to remove my 12/17/30m trap inverted V to get my beam off the tower. 

In the meantime, I’m making due with a 20/40/80m trap dipole. 

If I use 12m on the 20/40/80m dipole using a tuner, I’m not having any HI CUR issues, even when running 100 watts.

I think what I’m seeing is an RF in the shack issue. The 20/40/80m antenna feed point is about 70 feet further away than the old 12/17/30m antenna. 

> On Sep 5, 2020, at 10:41 PM, Bob McGraw K4TAX <rmcgraw at blomand.net> wrote:
> 
> I suggest you perform a TX Gain calibration using the K3 Utility.   A known accurate dummy load is all that is required. 
> 
> I’d say that a 1 volt drop is excessive.  Check power cable connectors.  Also add a dedicated ground conductor between the ground terminal on the radio and power supply ground terminal.  
> 
> The displayed voltage on the radio should be about 0.5 volt difference between RX and TX, CW mode key closed.    These measurements should be made using a dummy load. 
> 
> 73
> Bob, K4TAX
> 
> 
> Sent from my iPhone
> 
>> On Sep 5, 2020, at 7:15 PM, Bill Coleman <aa4lr at arrl.net> wrote:
>> 
>> I checked this. Voltage was 13.8 volts no load, dropped about a volt under load.
>> 
>> I cranked it up to 14.4 volts no load, and it’s better, but still getting HI CUR indication above 90 watts.
>> 
>>> On Jan 11, 2020, at 11:43 AM, Bob McGraw K4TAX <rmcgraw at blomand.net> wrote:
>>> 
>>> Is the power supply at 14 volts or so?  And what does the radio show the voltage to be in key down transmit into a dummy load.   Low voltage will demand more current to produce 100 watts. 
>>> 
>>> I run my supply at 14.25 V no load and the radio shows 13.8V during 100 watts transmit.  Voltage drop should be 0.5 volts or less. 
>>> 
>>> Bob, K4TAX
>>> 
>>> 
>>> Sent from my iPhone
>>> 
>>>>> On Jan 11, 2020, at 10:31 AM, Bill Coleman <aa4lr at arrl.net> 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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>>> 
>> 
>> 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
>> 
>> 
> 
> 

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