[Elecraft] Local Noise Problem

[ab2tc]

Hi,

Clearly, a switch to 12 or 24VDC power distribution in homes is not going to
happen for all the reasons given by K9YC, Jim. Even in cars there is a move
to higher voltage, such as 36VDC. We are stuck with switchers for conversion
to the lower voltages required by many devices and they *can* be and *are*
made quiet. The trouble is the total lack of accountability by the cheap
offshore knock-off manufacturers and FCC's inability to enforce its rules.
Even if wall warts are exempt from the part 15 rules, they do have to meet
the standards for conducted emissions below 30MHz and the really bad one
clearly don't.

AB2TC - Knut


Jim Brown-10 wrote:
> 
> On 4/3/2011 10:12 AM, AB8XA wrote:
>> The sub-panel will also have a 30 amp circuit to my "shack," feeding a 24
>> VDC to 13.8 VDC converter for full nominal voltage to our 100 watt rig.
>> There are many advantages to 24 VDC over 12 VDC in residential use.
> 
> Yes, BUT -- that 24VDC to 12VDC converter is almost certainly some sort 
> of switching power supply, and you will need to carefully search to find 
> one that is not a source of RF noise..  AND the conductors are going to 
> need to be pretty large, because they're carrying a 10A load (at 24V) 
> just to run your 100W rig.  Multiply that current (and copper) by about 
> 9X if you also want to run a 500W amp. And the only one I know of that 
> runs on 13.8V is the Ten Tec Hercules II, a very nice amp that's been 
> out of production for about 20 years.
> 
> 73, Jim K9YC
> 
> 


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