[Milsurplus] Re: switcher noise

Wed Jun 29 15:03:43 EDT 2005

That seems to work well with switching mode supplies, as long as their
outputs are isolated from the chassis.  I have three 5V 200A switchers, one
by Sorenson and two by Chloride.  Since the outputs are isolated, setting
them up for series operation was no problem other than finding heavy
cables.  With three fans blasting away they are very noisy so I've only
used them so far when testing large dynamotors.  Electrically they seem
very quiet.  I've operated a BC band transistor radio inside a loop of wire
carrying 10 amps from the Sorenson with barely discernable interference.
Mine were $5 for one and $10 each for the others....

When I tried this series trick with three PC power supplies It also worked,
but only after I removed their PC boards and cut away the grounding land
from each one.  I even managed to get my seriesed 14V at 20A and 12V at a
few amps but could only connect to the 12V from the PS at the "bottom" of
the stack since the 2M amp and the transceiver were sharing a common ground
through the coax.

Have any of you ever tried the PC power supply conversions that have been
in QST and other magazines?

73,  Clare Owens  N2RJB

             "Ralph Cameron"                                               
             <ramcam at magma.ca>                                             
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                                       [Milsurplus] Re: switcher noise     

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I've series connected three regulated crowbar protected 5V (nom.) 35 A
switching supplies to get 12V @35A and they run cool as acucumber at 40A
continuous for over 2 hours and they barely get warm. There is no  switcher
noise I can discern and shouldn't be if properly designed.

Before series "ing" I carefull adjusted the voltage from each to 4.3V I
can't discern any voltage drop at full load. They were a bargain at a buck
apiece.

Ralph VE3BBM
----- Original Message -----

> Message: 4
> Date: Wed, 29 Jun 2005 10:32:25 -0400
> From: flood at Krohne.com
> Subject: [Milsurplus] T-195 power supply
> To: milsurplus at mailman.qth.net
> Message-ID:
> <OF29E09354.0216C5F2-ON8525702F.004E967E-8525702F.004FDF65 at Krohne.com>
> Content-Type: text/plain; charset="US-ASCII"
>
> Greetings,
>
> I have come into a large number of 24-28VDC 60 amp power supplies.  These
> are switching supplies pulled out of 250-500 Watt 900MHz paging
> transmitters.  My thoughts went to using these as a power supply for the
> T-195 transmitter I picked up this spring.  Have any of you out there
used
> something similar.  I was worried about switching noise.  I have a very
> quiet switcher running the R392 now.
>
> Also, it's a bit off track but is anyone interested in 500 watt Glenair
> PA's for 900MHz?  Perhaps you could use them to cook birds nesting on
your
> hf arrays?
>
> John Flood KB1FQG
> TASC Department
> KROHNE, Inc
> 7 Dearborn Rd.
> Peabody, MA   01960
> Tel.:  978-535-6060 / 800-356-9464
> Fax:   978-535-8180
>