[MrFixr55]

Hi Martin,

First off, welcome to the Phorum.

If you are still using a UPS, it may, in fact not isolate you from the AC line. Only true "On Line" UPS units where the power is rectified, batteries are in line, and then inverted back to AC will isolate.

Your set has a power transformer and full wave rectifier. I tried running an "AA5" radio (AC - DC Set with 12SA7, 12SK7, 12SQ7, 50L6 and 35W4 half wave rectifier) on a portable 120V AC supply with "modified sine wave" output. It was not listenable due to the "hum" which was very raw. A set with a full wave rectifier fared much better, but not like the power line.

Unfortunately, there is so much noise pollution in a house nowadays. Between the Internet of Things (IoT), WiFi, Cellular, CFLs, LEDs, Computers, etc., AM is almost unlistenable. This is worse in areas where the house is wired with Type NM (Romex) cable as opposed to jurisdictions requiring Type AC (incorrectly referred to BX), actual BX (God help you) or all wiring to be in metallic conduit.

AM reception in my house is horrific, even with an outdoor long wire and even with battery power. My house is wired with NM cable, no conduit, recent service equipment upgrade, performed by me, fully in line with the 2014 NEC and inspected both by the power company and an Underwriters inspection service. All water pipe is coper and system ground is at water service inlet to house. 38ft of copper pipe from house to water main, buried 6ft in sandy loam, bonded around the water meter. Second ground as required by NEC. No change in noise between new service and previous service. However all lighting is CFL or LED, office computer, LED display, WiFi, etc. in house. I need to get outside the house to have good reception on line powered or battery powered radios. Even the car radio reception is sketchy in my neighborhood (typical suburban development from the mid 1950son Long Island NY.

Most of my radios do not have EMI filter caps, and those that had them, I removed them, but that's me. Those that do have EMI caps do not seem to work better in my house than those that don't. Seems that the best performing radios in my house are those with loopstick antennas. The worst "hum" in my house occurs "on station" as opposed to off station. On sets with Aux inputs, audio from audio sources, like MP3, CD, etc., are very clean. I am a big fan of adding "Aux inputs as they allow "Divide and Conquer" troubleshooting. If audio is good on an aux input but bad on radio, you have eliminated the audio amps, speaker and power supply as the source of hum, distortion , noise, etc.

The best thing I can suggest is that if you have a set from a similar period, compare performance between that set and the set that you are restoring.

Hope this helps.