Re: KPA3 output erratic


Brian K0DTJ
 

Hi Chuck,
I would say that 1.2v is excessive.  I started out with the 60 inch or so #12 Elecraft standard power lead and had a slow power hunting problem.  It varied by band but each time I changed the power setting or bands it go to max and then drop down and slowly come to set power.  The power calibration ran OK but didn't solve the problem.

I changed to about 3 ft of #10 stranded automotive wire in a twisted pair setup.  I set the RS-35A Astron supply to about 14.2v.  With that I get 14v at the K3 on receive and 13.3v on transmit at 100w (80m).  Measuring the voltage at the PS under load I get less than 0.1v sag in the Astron regulator.  Then ran the K3 Utility TX gain calibration _twice_ and all is OK now.

Note, in all cases the high current K3 power lead was connected directly to the Astron terminals, not though the RigRunner I use for low current 12v distribution in the shack.

Hope this helps.  Good luck.

73,
Brian, K0DTJ

On 8/9/2020 16:23, Chuck Miller wrote:
What amount of sag is useable? I removed the inline fuse from the power cable, and cranked the 35 amp Astron up to 14.2 volt according to the K3. It drops to 13 volts at 100w watts. The power cable is about 6 feet long as the Astron is a rack mount, and sits on the floor. The power is slow to rise mostly on 160 and 80, and to a less amount on 60 meters. 30 meters and up don't have that lagging power. Still got to check all my coax jumpers
.
73, Chuck
N0NC

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