[TenTec] TenTec Digest, Switching Supplies

[N4be_Jim]

> 
> Sorry to drag this out but its a problem.  Noise generated by switching supplies... I used the TenTec switcher that came with the Orion and it was clean.  The build in switcher in my Icom 775 is also very clean.  They are good design.  But go buy a network router or switch, or have a cable box installed in your house, or even in your neighbors house, and you may get a lot of noise across the HF spectrum, with strong warbly carriers at regular intervals. The switching supplies are basically an oscillator that drives the power devices to produce the output voltage.  Harmonics of that oscillator cover the spectrum.  Wall warts are terrible sources, such as those used to power routers or cable boxes.  I had to replace the wall wart on my router with a traditional DC supply to clean up one problem, but there are many other oriental wall warts elsewhere in the house, all creating hash. I have HF mobile and I can cruise the neighborhood and hear them as strong signals everywhere.  Nuff said.  73 Jim N4BE