Hum from astron power supply

DonE

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.

Joe N3HEE

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

George KF2T

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.

WX7Y

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

DonE

Power Supply got speaker muted

DonE

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.

DonE

Bret it's coming from P/S and goes from Hum to more like a buzz . noticed it when on ft8 but it also is there on ssb and could be heard along with audio. I checked the voltage it goes fpr 14.01 to 13.90 on transmit. I have tightened up all the hardware. I just notice it last night but had been hearing it since be on ft8 but has gotten a lot worse

DonE

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

DonE

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

DonE

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

DonE

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

Lucas - W6AER

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.

Burt Fisher

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

DonE

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

Clay N9IO

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.

Clay N9IO

Congrats on the troubleshooting Don.

Glenn Gray

Don, could you comment on how you determined one of the diode was the problem?

Tim - W4TME

Astron linear supplies all vibrate when used.  This vibration can lose the screws inside the supply leading to poor ground connections.  About every 2 years, I shut down my supplies, bleed off the filter cap voltage and tighten every nut and **** I can easily get to.