[Elecraft] OT 20M Moving QRM (Video)

[Jim Brown]

On Thu,3/3/2016 2:57 PM, W2RU - Bud Hippisley wrote:
>> Is there any way to easily determine if a wall wart is a SMPS?
> Weigh it.

Yes -- switch-mode supplies are a lot lighter for the same power rating. 
Another way -- tune a portable AM radio to the high end of the AM band 
and listen for noise as you hold the ferrite loopstick antenna next to 
the unit. Linear supplies will be dead quiet, SMPS units will be noisy. 
I use a Kenwood TH-F6A, which uses a ferrite loopstick in the base below 
10 MHz, and I tune it to about 2 MHz.

73, Jim K9YC