[Elecraft] K2/100 - voltage drop across DC cable
ON4WIX
on4wix at skynet.be
Thu Feb 22 12:56:14 EST 2007
Hi all
This afternoon, just out of curiosity, I put a DVM across the DC input terminals of my K2/100. The power supply I'm using is a Kenwood PS-53 and the cable between the PS and my K2 is the "Elecraft issue" cable.
Upon hitting the "tune" button (with the K2 connected to a known good dummy load) I noticed that the voltage across the input dropped to 12V. Getting curious I rotated the "Power" knob so the tune mode would go to full power out. Much to my surprise the voltage across the K2's input terminals dropped to a meagre 9,2 volts when the K2 was putting out 105 watts. I ran the same tests again, this time with the DVM connected across the PS's terminals. As you probably can guess this voltage was rock solid (around 14 volts).
So I guess I've got myself a suspect DC feed cable which dissipates a *lot* of power across the 5V voltage drop when running the rig at full throttle. I need to check the Powerpole connectors and the fuse holder. Knowing that several of you have run into the same problem before, are there any telltale signs of bad connections? Sometimes the simple things are the hardest to spot... I know I could try reflowing the solder on all connections but maybe some time an be saved...
FWIW, DC resistance across the red lead is 0.2 ohms, DC resistance across the black lead is slightly less at 0.1 ohms when measured out of circuit.
Thanks in advance for any suggestions.
CU this weekend in the UBA CW DX contest
Glenn ON4WIX/OR4W
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