[Elecraft] 12-V power supply caution

[Julian (G4ILO)]

I observed the same effect with an FT-817 sat on top of a small power
supply that was the exact same footprint and looked like it was made for
it.

The PSU I recently built for the K2 inside an EC2 enclosure uses a toroidal
transformer and, presumably because of the lower magnetic field produced by
this type of transformer, I haven't observed any problems. If so, it's a
happy accident rather than good design, because I couldn't find a
conventional transformer with a high enough VA rating that would fit inside
the EC2.

73,
--
Julian, G4ILO. (K2 #392)
Homepage: http://www.qsl.net/g4ilo

Ron D'Eau Claire rondec@easystreet.com wrote:

It is common practice in the "land mobile" business in which a "mobile"
transceiver is mated to an AC power supply for use as a "base station".
I did it countless times working in that field with no ill effects. So I
did it when I built my K2, putting it on top of a linear power supply
that had the same "footprint". 

I started getting reports of HUM on my signal (and, yeah, I've heard all
the comments about my call sign...<G>). Traced it to the 60 Hz magnetic
field from the power transformer frequency-modulating PLL reference
oscillator in the K2. Moving the K2 off of the power supply fixed the
problem.

The K2 is not the only HF transmitter that needs to be kept away from
strong a-c magnetic fields. Since that experience I've noted a number of
manufacturers warning users to keep the rig away from the power supply.

My 20 Amp Astron is under the desk, several feet from the K2/100 <G>.

Ron AC7AC
K2 # 1289