Power Supply Hum

Things that make you go hum…  Or maybe bonkers.  I have a Astron RM-50A that I have been using to power two Motorola units that I use for VHF/UHF.  Yes, overkill, but I have been planning on putting it in a console that will also house my Seinna and my Icom IC-746Pro.Astron RM-50A

This last week I finished constructing the console, so now comes the fun part of taking everything apart and putting it back together.  Since I got the PS, it has always had a pretty annoying hum to it, so I thought now would be the time to work on it.

I took the cover off of it, dreading the possibility of what I would find.  I have read too many Amateur Radio horror stories about de-laminated transformers and such.  You know, best to just pretend it doesn’t hum.  Anyway, I found the transformer to be in decent shape, so I checked the nuts and found a few loose and one on the big capacitor missing.  I tightened them up and replaced the missing one.

It seems to be better, but I do still hear some hum when it is on.  The top cover really deflects right over the transformer when I first turn it on.  It doesn’t help to apply pressure to the top cover, so I don’t think that is it.  I guess I will just see what happens.

BTW, I did let the capacitors discharge before working on it.  That’s why I am able to make this post.

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