Before you need go further, here are two very useful and related documents. They are reproduced here with permission of Tom, N0SS.

  Samlex 1223/Kenwood KPS-15/Yaesu FP-1023 Service information.

  Samlex 1223 RFI mods from ZL2DF

Let the saga begin:  I used the FP-1023 for about seven years total, and it spent the last five of those years running 24/7/365. It survived a lightning strike in 2002 that killed my radio, and it trudged along valiantly for another five years of full time service. But it finally "let the smoke out" during the 2008 January NAQP CW. After taking a quick look at the supply, the fuse was toast, as well as capacitor C24, a .1uf capacitor across the output terminals(an RFI bypass?). C24 was a charred cinder that fell away as ash when touched.

That set me on a search that lead me to conclude that the Yaesu FP1023, the Kenwood KPS-15 and the Samlex 1223 are all essentially the same device. Tom, N0SS has a schematic of the Samlex. That document also includes a couple of photos that show the striking similarity. The ARRL(members only) January 2000 review of switchers states "The Yaesu and the Samlex are very similar".  That seems a bit of an understatement. If the schematic from one can be used for the other.... Hmmmm. "Very Similar", indeed. The review's oscilloscope traces and spectral plots taken on the output of the two are also "Very Similar". Go figure.

You can go straight to the mountain to see N0SS's web site which has loads of other useful information. Or you can go directly to his documentation on the Samlex 1223 and a document that describes a simple mod by ZL2DF to reduce 1223 RFI.  

My FP-1023 photos page has photos of my supply after it gave up its smoke. The page has lower resolution photos with links to the high res shots. The high resolution photos are 2MB each, so they maybe slow to load.

ZL2DF refers to another interesting article, a document by XQ2FOD describing a 40 amp power supply design.

Personally, I never noticed any RFI from this supply. But I live in the shadow(about a mile) of a 50KW AM station, and and also very near another strong station. I have harmonics from each, mixes of the two, mixes of the harmonics,etc., etc., and general RF overload. A few birdies are hard to find in all of that mess.  In short, the switcher worked fine in this environment. So I'm tempted to go with another, because they are just so light and easy to pack up for field day.  For me the convienience is a big factor.

If I get another switcher, it will be the Samlex, and I plan to test it for RFI before and after the mods.  If that happens, the results will be posted here.  Lacking the equipment needed, it will be a rather subjective test using the S-meter and the attenuator pad in my FT-920 to determine signal levels of any birdies. But thats probably sufficient for a ballpark impression.