[Elecraft] Wiring 101 question

[Don Wilhelm]

Tim,

Your question may not be as elementary as you surmise.

My guess (and it is only a guess) is that your power supply is the cause of
the 'noise'.  I would wager that you have a switcher supply there, and the
effective length of your new power cord that you stumbled on may be the
right length for some noise generating circuits in the supply to radiate.

Actually it could be any number of things - all related to the power supply
capabilities.  Oscillations can happen even with power wiring - rare, but
possible, or you may be creating just the right ground loop for strange
things to happen.

Describe for us your power supply particulars and the entire power wiring
stucture including any grounding wires and perhaps we can offer better help.

73,
Don W3FPR

----- Original Message ----- 

| Hi folks -
|   The nice thing about this reflector is that nobody calls you an idiot
when
| you ask REALLY simple questions - at least so far hi hi!
|   So here is the simple question. I just made a second power cord for my
| K2/100 so that I could locate the antenna tuner on a different shelf
rather
| than right under the K2/100.
|   Both the old and new cord have a "Y" joint which takes power from the
main
| lcord and runs it to the ATU. The second power cord has a much longer ATU
| line though. It's about 6 feet long. There is a "Y" joint about 2 feet
from
| the radio end of the cable and the fuse is about a foot from the opposite
| end. The ATU cord length is about 2 feet. Before plugging this new cable
in
| I checked the voltage at the radio and and on the ATU jack end - all was
| fine. Also tested for any shorts - all was fine. The problem is that when
I
| turn on the rig with this power cord I get a loud noisey, steady hum -
which
| made me turn the rig off immediately. It occurs regardless of whether the
| ATU section is plugged into the ATU. When I put the original power cable
| back on and no problem.
|   I'm just a solder jockey that could not troubleshoot his way out of a
| paper bag - but the cable delivers proper voltage and has no shorts - fuse
| is OK - what could I have done wrong? How can I determine the cause of
this
| kind of issue? Thanks for any help folks!
| 73/Tim NZ7C