[RFI] A note from Sangean about switching power supplies

[Jim Brown]

On Sat,1/7/2017 6:18 AM, David Robbins wrote:
> It is interesting that they warn you about that... but a company making a radio should at least try to choose a wart that is quiet.

Since it has been posted by others that the radio DOES hear weak signals 
12 inches from the wart, it strongly suggests that they DID do their 
best with choosing the one they did. Some mfrs are more careful than 
others in this regard. I've not done exhaustive studies, but the SMPS 
units supplied with Thinkpads both before and after IBM sold the line to 
Lenovo are generally pretty quiet. I should look at the PSUs supplied 
with my Motorola cell phone. The few Apple products in our home also 
seem fairly clean. The 33V PSU shipped by SteppIR to run their 
controller was a HORRIBLY noisy beast, and not even the most massive 
choking could make it acceptable. I replaced it with a home brew linear 
supply from the estate of a neighbor ham, whose Rohn 25 sections are 2/3 
of what's holding up that antenna.

As to "government regs" and "individual choice:"

1) People are not CHOOSING a power supply, they are choosing an 
appliance, and the PSU comes with it. Choice was made by the seller, not 
the buyer.

2) The mandate for efficiency came, I believe, from the Dept of Energy, 
and is in same spirit as that for high efficiency lighting -- to reduce 
our carbon footprint.

3) EMC regulations come from the FCC. Different branch of government. 
Left hand does not know what right hand is doing -- or, more to the 
point, left hand does not know that the right hand is there.

4) FCC regs are not enforced because the FCC has been seriously 
underfunded for several decades. It is Congress that sets funding.

73, Jim K9YC