[Boatanchors] TRANSFORMER BUZZ

[K0DAN]

Hello group...

I have a couple Motorola power supplies (from MICOR Compa stations, I
think?) which I use in the hamshack to power 12VDC stuff. Big, heavy, "old
style" supplies (big transformer, big caps, big filter choke...no switching
supplies here), they work great and are battle tanks.

But the transformers buzz like crazy (and drive me crazy). This is NOT like
getting a good buzz. Does anyone have any tricks for reducing the sound
level of the xfrmr buzz???

These units are TPN1110B and a TPN1111B.

While I'm on the topic, does anyone know the differences between these two
supplies? Spec'd voltage/current output? Any reason I can't/shouldn't rack
mount two of them and wire their outputs in parallel?

Thanks and 73

Dan
K0DAN