[Elecraft] Noise with KX1 and Powerwerx supply

[Chip Stratton]

If you start looking for an alternative, try the TDK Lambda LS25-15 (for
1.7A), LS35-15 (2.4A) or LS50-15 (3.4A). These are switch mode power
supplies that I've found to be fairly well shielded, light weight,
conservatively rated, and not expensive from Newark Electronics. They are
nominal fixed 15V supplies, but their output can be set from 13.5V to
16.5V. The supply is contained within a metal cage, but you will probably
want to mount it in another enclosure with an on/off switch and banana or
Powerpole terminals, and to protect the 120v input terminals.

These are especially good for the KX1, since maximum output comes with a
14V power input, which most small 12V supplies can't quite deliver. Is the
K1 the same way? They are also good for the K2 with internal battery, since
you need 14V for proper charging.

It might be hard to find any switch mode power supply that won't put some
noise into an antenna that is sitting right next to, though. If you can
move the antenna feed point 5 or 6 feet away from the PS with some coax you
might have better luck. You might also get a copy of the current issue of
QEX. There is an article in which the author details his quest to turn a RF
noisy switch mode PS into a very quiet one.

73
Chip