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Megawatt Power Supply Spewing Noise on Portions of HF

Are you using it to charge a typical 12V battery

From the PDF...

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Some SPS contain a variable output trim feature, you might want to investigate that so you can provide the proper voltage rise to overcome the resistance and drop across the cells of the battery.
 
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The MegaWatt's are only slightly better than some others.They all make noise depending on which frequencies/ bands you're on.They all, including the MegaWatt's seem to deteriorate over time and get noisier.
 
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Hello All: Yes the Megawatt supply will slowly drain the battery as when its turned off, another "Oh how wonderful" thing to bite ya. I installed a heavy duty switch then turns off the power supply when not needed. That fixed it when it was off. It keeps the batteries up and charged when heavy load to the batteries is used when I fire up the generator.

I turned up the Megawatt 50 Amp supply up14 VDC, which is max, same voltage as the alternator, the supply is just a foot away from the #2 auxiliary truck battery so line loss isn't a problem. The Battery on my radio table is connected to the #2 Aux Battery by 50 foot 6 gauge jumper cable. This allows the solar system to lightly charge the radio battery next to all the radios and have the #2 Aux Battery as a helper supply when CB Radio activity is busy. The 200 watt amp probably draws 20 to 25 amps Iam thinking.

I contacted Megawatt and asked if there was a mod to increase the 50 amp models output voltage by half a volt to 1 volt. Answer: Install 10 gauge wire instead of 14 gauge wire. Ok I see a crystal ball calibration problem here.

During night time we use the radio battery to power 12 volt lights for use in the kitchen area of the old building. So when morning comes the solar cell charges the #2 and Radio batteries. Even with a hang over.

The trucks main starting battery is kept out of the loop as to allow starting the trucks engine if necessary, and the 150 amp alternator comes on line. A contactor relay can be switched on connecting the Trucks main starting battery to the #2 aux battery and Radio Battery charging all of them if needed. Kind of a neat option I think.

Jay in the Great Mojave Desert

Oh yeah Handy Andy #6 posting shows a circuit to reduce noise, this works quit well Thanks Andy
 
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Not to help the Reader, I have to do a lot of editing due to time and job constraints.
It limits my abilities to proofread what Google tends to think I typed...
Click to expand...

Don't thank me, I'm surprised with all the copy-cats on the issue of Switching power supplies, not many are offering this type of circuit to support, or as a support add-on for those that need that level (or range) of noise removed. I would think of it as being like an accessory as AC for a car, don't always need it but it's nice to have it as an option for those using such units for the filtering and extra protection it can provide.

As for the "Gleaned knowledge" - my experiences began on a Field Day Here>>excessive<<Here (It really should be Exercise but it's autokorrected) back in the early 2000's dealing with mobile setups on generators with switching power supplies to handle the various radios.

Quite the mess back in the day and hitting the ground running, you had to think fast - so the common mode chokes concept is not new, just not well utilized and since linear takes care of much of the ripple/noise being common point tied, the issues of SPS and lifted grounds to buck-up the voltage becomes the source of much of the noise you hear,

Not many linear power supplies need that type of regulation - they just need current more than voltage to handle the wall-wart output stuff a lot more quietly. It's their inefficiency at best, but the quieter level of operation - takes precedence.

Now if the powers that be raised the AC cycles from 60 to say, 120 Hz, we'd have a much different ballgame...

Epilogue...
Excessives? Well, it was a Day out in a Filed - er FIELD somewhere :)
There are times I just can't make this stuff up!
 
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I was just looking at buying another Megawatt today. I've had my 36A for such a long time and it's just been a workhorse but looking for a 50A or 100A.

Wish someone would make a really clean PS. I've had no problems with the Megawatt over the years but I did notice some noise this last week which is the first time I've ever noticed anything.
 
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quality power supplies have a set of terminals marked remote sense.
these go to the load.
heavier leads are better but the remote sense helps.
look at those megawatt units and post back.
Jay Mojave said:
Hello All: Yes the Megawatt supply will slowly drain the battery as when its turned off, another "Oh how wonderful" thing to bite ya. I installed a heavy duty switch then turns off the power supply when not needed. That fixed it when it was off. It keeps the batteries up and charged when heavy load to the batteries is used when I fire up the generator.

I turned up the Megawatt 50 Amp supply up14 VDC, which is max, same voltage as the alternator, the supply is just a foot away from the #2 auxiliary truck battery so line loss isn't a problem. The Battery on my radio table is connected to the #2 Aux Battery by 50 foot 6 gauge jumper cable. This allows the solar system to lightly charge the radio battery next to all the radios and have the #2 Aux Battery as a helper supply when CB Radio activity is busy. The 200 watt amp probably draws 20 to 25 amps Iam thinking.

I contacted Megawatt and asked if there was a mod to increase the 50 amp models output voltage by half a volt to 1 volt. Answer: Install 10 gauge wire instead of 14 gauge wire. Ok I see a crystal ball calibration problem here.

During night time we use the radio battery to power 12 volt lights for use in the kitchen area of the old building. So when morning comes the solar cell charges the #2 and Radio batteries. Even with a hang over.

The trucks main starting battery is kept out of the loop as to allow starting the trucks engine if necessary, and the 150 amp alternator comes on line. A contactor relay can be switched on connecting the Trucks main starting battery to the #2 aux battery and Radio Battery charging all of them if needed. Kind of a neat option I think.

Jay in the Great Mojave Desert

Oh yeah Handy Andy #6 posting shows a circuit to reduce noise, this works quit well Thanks Andy
Click to expand...
 
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Reactions: Rwb and Shadetree Mechanic

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