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Author Topic: DC power supplies  (Read 1202 times)
AB4D
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« on: October 08, 2007, 08:41:50 PM »

Hello all, I'm seeking opinions concerning the level of physical and RF noise generated from several different DC power supplies that I am considering. I've looked though the eham power supply reviews, but it seems that not to many people comment on physical noise from power supplies, except fan noise. I'm considering several different supplies to power my station, such as the Astron RS-70M, which is my first choice.  However, I have a smaller Astron (RS-20M) and it gives off some minor, but somewhat annoying physical low frequency vibration.  I keep my DC supplies in a cabinet so any minor noise is amplified, therefore I would like to know if the RS-70 also vibrates.  My second choice is a Daiwa SS-505, I've heard that the switching supplies are physically quieter, but I am concerned with RF hash so I am also seeking opinions about any RF or physical noise from the Daiwa switching supplies. I have an older Daiwa supply (PS-304) which is fairly quiet, but I need something larger in the 50-75 amp range.  My third choice is the new MFJ/Ameritron SPS-75, 75 amp switching supply. If anyone has used this supply, I am very interested in reading comments about any physical/RF noise that the SPS-75 may generate. If anyone has suggestions about other supplies I should consider, I would also like that information.

Thanks, 73 Jim AB4D.


     
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KE3WD
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« Reply #1 on: October 09, 2007, 09:50:17 AM »

Vibration noise can be solved with a bit of damping.  

As little as a board placed on top of some foam of aprox 1 - 2" thickness, maybe less, can do the trick, place the PS on top of the board.  Don't place the PSU directly onto the foam, though, for it can prevent breathing in the form of air convection, etc.  

Or you can purchase vibration isolators for a really snazzy setup...

Things are looking up for switching supplies, rule of thumb would be the newer the design, the less likely it will emanate RFI/EMI -- considering designs intended for use with communications gear.  Astron has a good track record.  

Of course, the all out champ as far as radiation goes will still be the heavier and less efficient linear supply, for weak signal work it still would be my first choice, eliminating any possility of problems along those lines from popping up.  And if you already have some switchers, a good linear supply would make a good addition to your lineup, yielding more possibilities, say there is one rig or band where the noise can be problematic, use the linear supply there, things like that.  


Hope this helps,


--KE3WD
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KE5MXA
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« Reply #2 on: October 14, 2007, 02:36:56 PM »

I have an Astron RS-70a sitting next to me.. and i dont hear a peep.
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AB4D
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« Reply #3 on: October 20, 2007, 06:37:30 PM »

Thanks to all who responded here and by e-mail.  I ended up purchasing another Astron (VS-70) to power my station.  I also modified my Astron RS-20 which reduced the vibration/noise down to almost a whisper.  For those who are interested in the modification, I give the details on my amateur radio web site/blog at www.ab4d.blogspot.com

73 Jim AB4D
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