[MrFixr55]

One would think that switchers would put out a lot of noise, but a lot of audio equipment use them. I was a field engineer and technical specialist for a well known manufacturer of Clinical Laboratory chemistry and hematology analyzers, where quiet power was an absolute must for the photometric and Ion Selective Electrode analog circuits and instrumentation amplifiers. we started out with analog supplies, but "switched" to switch mode power suppies in the mid 1080s. It is what happens after the switching circuit, how well they are filtered and how well the supply is shielded. In fact, shielding may be a very big part of it.
Power supplies for analog instrument amplifiers, Hi Fi, Mic amps and audio mixers must be rock solid. Computer power supplies must be free of noise too. Computers themselves generate enough on their own.

I have tried to build switching power supplies for B+ using 2 different e-pay power supply modules meant for "nixie clocks", and yes, mucho noise, but have not had any issue with commercial power supplies. I may just not have the correct caps in the output, or maybe did not shield the supply well enough. Electrolytics, for some strange reason, have a high resistance (impedance?) to high frequency. Electrolytics on the "other side" of the high frequency transformer are usually bridged by other types of caps of much lower capacity in the filter circuits. Shielding may be an issue.

If you have one kicking around, firing up the radio with the 5V section won't blow anything and won't cost you anything.

I have 2 farm sets that I powered from a 3Volt "wall wart" switching power supply with no issue. I have powered a 1920s radio using the 5V section of the computer PS and a bunch of 9V batteries successfully. I have not tried to use the -5 or -12V sections for bias yet, but bias batteries last a real long time.

When one looks at an old school tube auto radio, or farm sets with vibrator power supplies, these are essentially "switchers" also, just usually at a lower frequency.



Granted, I eventually bought an ARBE III, but more out of frustration and the need to bust a move on fixing and demonstrating several 1920s battery sets.