Hum from astron power supply

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  • Updated 3 weeks ago
  • (Edited)
I have an Astron 50 amp supply that i use with My 640, with nothing on the supply there is no hum, when 6400 is on have a slight hum and increases when 6400 in in transmit mode quiet a bit. The 6400 runs full power on the supply.
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Don

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Posted 3 weeks ago

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Joe N3HEE

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Were do you hear the hum ?  On the radio or coming from the power supply ?
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Don

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Power Supply got speaker muted
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Don

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In transmit  mode i can press on the power supply the buzz  gets louder. 
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George Molnar, KF2T, Elmer

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IF it's coming from the power supply, that's pretty normal. Under load, the supply is working harder, and any small effects will become larger. You could try tightening down the internal hardware, if it's a real bother.
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Don

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George it's coming from P/S and goes from hum to more like a buzz i noticed it when on ft8 but does on SSB also and it is more than likely being heard with my audio.
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Don

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In transmit  mode i can press on the power supply the buzz  gets louder.
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WX7Y

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Hi Don,
As George said, that is pretty normal BUT If it's coming from the radio then you need to change the BIG electrolytic Capacitor in the Power Supply.
If it's coming from the Power supply then that is just the big power transformer vibrating and working harder and you can try tightening it down or even put a peace of rubber mat under the transformer and bolt it back down to help absorb the vibration from the transformer.
Check the power supply voltage drop during Transmit and if it drops more then normal then you have lost 1 or more 2N3055 type Transistors on the heat sinks. 
Unless you loose voltage regulation that is about all that can go wrong with the astron P.S. 

73's
Bret


(Edited)
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Don

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In transmit  mode i can press on the power supply the buzz  gets louder.
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Paul

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Hi Don, if it's a linear power supply it's more than likely the transformer laminations vibrating under load. Since tightening the mountings didn't fix it
you could try getting a centre punch and centre-punching the framework of the transformer at several points on each side. I have done this successfully with several buzzing linear supplies. Obviously turn it off and unplug it first but turn it on after each "punch" and you will know if/when it's fixed. Worth a try - at your risk of course.
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Don

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Paul i a astron  rs 50 i will give it a try and let you know
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Paul

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OK Don - I should perhaps emphasise you should NOT be punching the laminations themselves but the framework that squeezes them together. Sorry if that's already obvious to you. 
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Lucas - W6AER

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It is not uncommon for linear power supply to hum a little or even vibrate. I used the Astron 70Amp unit for a while and I always knew when it was on. As it was mentioned above, things to come a little loose, so some preventive maintenance will likely improve it. If you are hearing it via the radio or via the audio system, then you may have bigger issues but that is very hard to troubleshoot without seeing it.
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Burt Fisher

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Same issue, it turned out to be the screws to the pass transistor was loose.
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Don

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Fellows thanks for help, it turned out to be one of the diodes( 1n1184a)
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Clay N9IO

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Congrats on the troubleshooting Don.
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Clay N9IO

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I found on my RS35A a small tightly rolled piece of paper jammed in between the cover and face of the PS fixed the issue. Been there probably 25 years.