Yeah, I tried one of those.Â* It was worth a shot, but what a racket it
caused in the radio!Â* It's not just the wire(s) being an antenna, but
the switching circuit creates a square wave which, using a transformer,
is reduced from ~12v to ~5v.Â* As all EEs know, a square wave is a mix of
an infinite number of sine waves (can you say RF emissions?) and
therefore the entire box should also be shielded.

Just for fun, I looked up the Fourrier Transform
https://betterexplained.com/articles/an-interactive-guide-to-the-fourier-transform/
and was pleasantly surprised to find a layman's description.Â* So much
easier to understand than in an electrical engineering class so many
decades ago...

Cheers!

On 9/26/2017 6:46 PM, wrote:
On Tuesday, September 26, 2017 at 7:47:52 PM UTC-4, wrote:
Perhaps this?
Not sure if it emits noise for the vhf.

https://powerwerx.com/usbbuddy-power...device-charger
These things all have a 3.7V lithium ion battery inside, and a "switching" circuit to convert that to 5V for the output. Thus they are all potential noise makers. Put the output cable 2 or 3 times through a ferrite ring if you notice too much noise in the radio. Since the pack has no other connections, that cable is the main "antenna" for the noise, so that should fix it.

--
Dan, 5J