On Mon, 28 Jan 2008 11:27:20 -0000, Richard wrote:
I have an ex AM PMR radio that I wish to use on 144Mhz. I need a PSU
feeding 24V @ about 300mA.

You are almost talking about a wall-wart there, aren't you?
Or, possibly, a desktop 'brick' PS.

Are switch-mode powers supplies alright or are they too noisy to be
used for receivers? TIA.

Just make sure the PS is enclosed. And, use ferrite beads/doughnuts on
_all_ input\output wiring. And, it wouldn't hurt to put .001 uF bypass
capacitors on that wiring, too, betwix the ferrites and the PS.

My venerable IC-551's (6M) internal power supply went kah-kah and I
replaced it with a switched-mode PS from Marlin P Jones:

http://www.mpja.com/

That was some time ago, but what I bought was similar to:

http://www.mpja.com/prodinfo.asp?number=16001+PS

My original requirement was _size_. I wanted to stuff the new PS into
the same cavity in the IC-551 where the old PS came out. So, having
installed the new switched-mode PS _inside_ the rig -- with all the
install 'details' I listed above -- I saw no appreciable rise in the
no-antenna-connected noise floor.

Plus I could 'tweak' the output voltage -- setting it at 13V -- and "amp
up" that IC-551 to a blistering 11W or so. HI!HI!

I encouraged a feller in Kansas to do likewise with his IC-251 (2M) that
had a dead PS, and he reported similar success.

Of course, YMMV
gl es 73
Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
38.24N 104.55W | @ config.com | Jonesy | OS/2
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