[Elecraft] OT: Astron RS-35M Transformer Hum

[David Herring]

I just got the PS back together and online again. I was astounded to discover that the transformer bolts were actually just shy of hand tight. I tightened them up and found that that quieted the thing down a lot. Not completely, but to a very large extent.

The bolts holding the transformer to the chassis were already tight, but I loosened and retightened them anyway, JIC.

Testing with a cardboard shim between the transformer and the lid didn’t make a difference in this case, but I thought it worth a shot anyway.

I scoured the shack and the junque box and didn’t find anything such as rubber or anything else suitable for use a dampener under the transformer, so figured that could wait. But I did perform some more experiments and discovered that the desk itself was exacerbating the noise more than I realized. So, it took some doing but I managed to move the PS under the desk sitting on cinder blocks. I didn’t have to lengthen the power run or the ground doing it this way, and it’s now sitting on something with mass so that there is virtually no vibration transfer anywhere. 

Happy to report the thing is as quiet as a church mouse now.  ;-) 

Thanks everyone…some really good information here…

David, N5DCH