[Elecraft] ASTRON RS-20A

[Alan WB6ZQZ]

ARRL performed extensive testing on a number of modern switching supplies. 
Several of them were found to be adequately low noise for HF use - at or 
below the receiver noise floor.

The Astron RS-20 is a great supply. The Astron SS-30M is one of the 
supplies that ARRL tested and found to be excellent for HF. I have had good 
luck with both of them. The SS-30M also seems to operate fine connected 
directly across a deep cycle battery with the intrinsic switching diode 
protecting it from reverse currents, so I've used it in portable operation 
on a generator across a group 27 deep cycle, which works well for 
'uninterruptible power'.

With or without a battery I have not noted any interference from the 
SS-30M. Portable operation puts us in low noise areas (usually without 
computers), so power supply noise would be more noticeable than at home.

If you want a lightweight supply check the ARRL for the QST article 
reviewing the switchers. There are some good ones and some not so good.

I believe the MFJ also tested well.

-- Alan WB6ZQZ