I am working on this amp for a friend when I received amp had a bad vibrating type hum from transformer when just turned on I replaced power rectifier diodes and amp has no hum and is very quiet when power on. Amp is working fine power output wise also but when keyed has a small hum coming from it this does not show up to anyone I am transmitting to unless they hear it thru my microphone. Any suggestions on what to do or is this normal for this amp. Thanks Jimbo
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Siltronix LA-550 amplifier has small hum when keyed.
- Thread starter Jimbo165
- Start date
How much carrier / DK are you putting out. I'm not familiar with that amp. But if the amp only hums when keyed wondering if pulling too much. Or maybe something off on biasing. I'll have to look up amp and see what tubes are in it.
the transformer is vibrating and/or causing other components to vibrate due to stray magnetic fields.
check the mounting bolts and rubber vibration dampers (if any are installed)
As road squaker posted could be
TR humming.
I have had luck loosening the nuts or bolts on the TR then re tighten them, eliminates the hum, sometimes. Also check mounting bolts to chassis, go through the whole amp tightening any hardware and usually the hum goes away.
TR humming.
I have had luck loosening the nuts or bolts on the TR then re tighten them, eliminates the hum, sometimes. Also check mounting bolts to chassis, go through the whole amp tightening any hardware and usually the hum goes away.
Found problem one of the 100mfd 150v capacitors was bad replaced both and now amp has almost no hum when keyed. I had did a quick check when they were in line but the one did not show bad until I removed and checked it out of amp. Thanks for the help. Jimbo