The AM Forum

I have a WinRadio SDR receiver that requires an external 12 VDC power supply. In the last year I have gone thru 2 of the supplies that were included with the receiver. Both of them went south because of over heating. These supplies are 12VDC at .8 amps and are your basic power supplies....external little black plastic boxes that are fairly heavy.  
I decided to go the "The Shack" for a replacement. They list a multi volt supply on there web site so I decided to buy it. Its rated at 2.5 amps....so maybe it will last longer than the originals.  When I went to the store to pick it up I found out that its a switching supply, a lot lighter than the original and I figured the noise this thing would generate would be a problem. (I hate switching supplies). Got it home....set it up.......and somebitch it works great.........NO NOISE. I hear all these problems with low voltage switching supplies and I expected the same from this.
I was wrong!!!!!!
Bill  

BTW.........the supply cost me $40


http://www.radioshack.com/product/index.jsp?productId=3875404 (http://www.radioshack.com/product/index.jsp?productId=3875404)

ITs putting out hash somewhere.. Proabably way up high. 

Do yourself a favor.. Put a meter on that thing..  on the 12 volt postion mine put out 19!~!!!! volts..  It was not regulated and expected some load to pull it down..

I have a preamp that needs 12 v at 1 amp.  I went through four of these wall type supplys. Everyone of them was reading 16 to 20 volts.  We used three volt meters and then tested them against the astrong.. exactly 13.8 volts.

C

I will try what u say......I did notice that the led on the front of the receiver is rather bright.
Ill post what I find tomorrow.
Thanks,
Bill

I have some kind of power supply like that and it puts out 20 volts in the 12 volt position.

lost my wall wart for my 2 mtr ht a few years ago - got a replacement from mcm for 4.99 - works great and pays to shop around
Greg

Bill,

That is a switching type supply so the voltage should be very close to its rated value up to the current limit.  The typical "wall warts" have a voltage that varies greatly with load but that isn't the case with your supply.

It sounds like the RS unit has decent RFI filtering built-in but many do not.  The Dell adapter for my laptop is terrible while the switching supply for the charger for my Canon EOS-1 is dead silent on nearby radios.

Rodger WQ9E

Thanks for all posts guys.......
I measured the output and its 12.6 volts open ckt. The reason the led on the front of the receiver is brighter is because to old supply output voltage was going down until it finally quit.

Thanks again,
Bill

The wall wart for the DSL modem here is an SMPS type.  It's an RF nightmare but putting it into a metal box and grounding it shut the thing up.

CTR Surplus on ebay you could have bought a linear much cheaper.

I wish I knew about CRT before I went to Radio Crack.......but so far so good.......

It amazes me how RF dirty those little wall-warts can be. My DGL-4300 router and a D-Link powered USB hub each had their own 5vdc switchers, and they emitted dueling oscillations that slowly wandered and warbled up through the 160 meter and 75 meter bands. After applying pounds of ferrite to their leads and all kinds of filtering schemes to the power strip they resided in, I finally chucked them and built a 5vdc linear supply into a stripped out enclosure from an old HP VTVM. The huge meter looks cool and the bands are blissfully quiet again!

Rob,
CTR Surplus always has 5 ,12 and 15 volt modules on ebay cheap. I bought a 5 volt 9 amp linear supply module with crowbar for under $20.

I bought a Jetstream 12V 45A power supply. Very quiet.

Here's the power supply site:
http://www.jetstream-usa.com/powersupply.shtml

The supply was right next to an MFJ unit of the same ratings and features in the ham store.
MFJ was 6 lbs., Jetstream was 9 lbs and $10 cheaper! Yep, bought by weight. No regrets. I never knew this brand before.