[Milsurplus] [ARC5] Quieting A DC/DC Converter

[Bob kb8tq]

Hi

You will not *hear* the 75 KHz by ear, but it will get into your radios. It takes a bit of effort to 
filter *both* the input and output for RFI. That said, no, you can’t come close to anything like
this price on a roll your own basis.

Best guess on efficiency (based on similar units) is around 70%. Running 40W out you will have
almost 60W in. That cute little PCB could be trying to dump near 20W into the surrounding area ….. 
(yikes !!) …. they will get warm …. Even 80% and 10W off the board would get toasty without some
moving air. 

Bob

> On Jan 18, 2018, at 3:00 PM, Jim Whartenby <antqradio at sbcglobal.net> wrote:
> 
> These are interesting modules Dave.  Several are available for under $5 each with free shipping.  All seem to be rated for 40 watts so at the maximum 390 VDC output, one has 100 mA available.  Can't roll-your-own for twice the money!
> 
> Does anyone have experience in using this module with 28 VDC input and around 250 VDC output?  Wonder what the efficiency is in this condition?  Operating at 75 kc, it should be as quite as a church mouse and easy to filter.
> Jim
> 
> 
> From: Bob kb8tq <kb8tq at n1k.org>
> To: David Stinson <arc5 at ix.netcom.com> 
> Cc: ARC-5 <arc5 at mailman.qth.net>; milsurplus at mailman.qth.net
> Sent: Sunday, January 14, 2018 6:24 PM
> Subject: Re: [Milsurplus] [ARC5] Quieting A DC/DC Converter
> 
> Hi
> 
> One of the “interesting” things about boards like this are the empty slots on the board 
> for other parts. In some cases the performance can be improved by putting those parts
> on the board. In other cases the result is a pretty dramatic burst of smoke ……
> 
> Bob
> 
> > On Jan 14, 2018, at 5:35 PM, David Stinson <arc5 at ix.netcom.com <mailto:arc5 at ix.netcom.com>> wrote:
> > 
> > Here's a listing for these DC-DC thingies.  It's
> > 390 VDC max.
> > 
> > https://www.ebay.com/itm/142555893852 <https://www.ebay.com/itm/142555893852>
> > 
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