Hi all, I have a Galaxy Saturn (not turbo) and this evening when I went to transmit there is a pretty loud/buzz/hum. When I am not transmitting I can hear it a little when volume is turned down but when I transmit it's fairly loud. On AM it's loud and on SSB it's low until I modulate and gets louder as the output increases with modulation. I did not opened the radio but I will try to tomorrow so perhaps someone may be familiar and tell me what to look for? I know to be careful and I am fairly handy. Thanks for any help. Adam
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Galaxy Saturn (not turbo) power supply buzz/hum-Help?
- Thread starter Adamf
- Start date
That's been a common question here throughout the years and on those older base radios it usually circles around the power supply. Search the threads and you'll find the common theme amongst those older base rigs. The more savvy techs here have posted lengthy information in those threads.
Thanks, I did look around but hoping someone is perhaps familiar with the Galaxy Saturn and can help. Thanks Adam
A rectifier bridge that has a marginal fault can do this. Only way to check is to wire in a new one and compare before to after.
If you have a 'scope, probing the unregulated side of the power supply would reveal a lack of symmetry to the "sawtooth" ripple waveform while under load. If every other peak is bigger than the one before it, that suggests a faulty bridge rectifier.
73
If you have a 'scope, probing the unregulated side of the power supply would reveal a lack of symmetry to the "sawtooth" ripple waveform while under load. If every other peak is bigger than the one before it, that suggests a faulty bridge rectifier.
73
Typically about 1 inch square with one flat terminal at each corner, bolted to the chassis deck.
73
73
BJ radionut
Supporting Member and 6m addict
Adam: That whole series of base radios are NOTORIOUS for bad power supplies.
The major issue is if you wait till it blows, it takes a bunch more with it!!!
Most guys scrap that overstressed power supply and replace with a whole new switching module.
You keep using it till it blows, be prepared to put many $$$ in it.
Just my thoughts.
All the Best
Gary
Galaxy Saturn Power supply swap | WorldwideDX Radio Forum
You look around the net and the forum...MUCH recurring issues with those.
Even brand new ones have issues.
GL Merry Christmas
The major issue is if you wait till it blows, it takes a bunch more with it!!!
Most guys scrap that overstressed power supply and replace with a whole new switching module.
You keep using it till it blows, be prepared to put many $$$ in it.
Just my thoughts.
All the Best
Gary
Galaxy Saturn Power supply swap | WorldwideDX Radio Forum
You look around the net and the forum...MUCH recurring issues with those.
Even brand new ones have issues.
GL Merry Christmas
BJ radionut
Supporting Member and 6m addict
Hi all, I am not the best at this, can I do a simple test on the power transformer? It has 2 wires in and 2 wires out. On the 2 wires in I should get 120VAC give or take, yes? On the wires out BEFORE the bridge rectifier what should I see approx for VAC output? Thanks, Adam
BJ radionut
Supporting Member and 6m addict
Hey Gary, thanks for the response. Yes, agreed, I am trying to fix it before it explodes. The problem is that I don't see any clear information on how to install a switching power supply, etc and that is what I would need. Anyway, thanks, Adam
Exit...ANDY...Nomad...Any extra help here?
I have not done one of these for like 15 years, any recent info?
Thanks
All the Best
Gary
Exit...ANDY...Nomad...Any extra help here?
I have not done one of these for like 15 years, any recent info?
Thanks
All the Best
Gary
Couldn't I use a DVM and test the rectifier block for both AC vs DC output - too?
Thanks
The noise you hear from the transformer may be solely the fault of the transformer. If the layers of the transformer's core are not securely glued together, they will vibrate. The more current you draw, the louder it gets.
Could be you just have a noisy transformer. Sometimes squeezing one corner or another of the core with a vise-grip will tighten it up and reduce the volume of the hum.
And it could be you have a good transformer that makes noise because of an out-of-balance rectifier.
If squeezing the corners of the transformer case against the core makes a difference, this is as cheap as it gets. Good chance that the rectifier is not at fault if this is all it takes.
A rectifier bridge with a bad diode won't show you anything that a meter can easily measure. An oscilloscope might, but not a meter.
As a rule, squeezing a corner of the transformer's core won't reduce the hum if a bad rectifier is the culprit.
73
Could be you just have a noisy transformer. Sometimes squeezing one corner or another of the core with a vise-grip will tighten it up and reduce the volume of the hum.
And it could be you have a good transformer that makes noise because of an out-of-balance rectifier.
If squeezing the corners of the transformer case against the core makes a difference, this is as cheap as it gets. Good chance that the rectifier is not at fault if this is all it takes.
A rectifier bridge with a bad diode won't show you anything that a meter can easily measure. An oscilloscope might, but not a meter.
As a rule, squeezing a corner of the transformer's core won't reduce the hum if a bad rectifier is the culprit.
73