[ARC5] Adventures in Battery Ops

[Scott Robinson]

Folks,

There are lots of filters that isolate line noise from loads or 
vice-versa.  Look at

<http://www.te.com/catalog/menu/en/27685?BML=10576,16356>

for many examples.

Now, the thing is that most of them don't work well below 20 MHz. 
However, some do, and if you look around the website you'll find them.

Their type 3EC2, for instance, looks promising.

The power supply needs to be in a shielded enclosure, and the filter 
gets mounted to the sheet metal to make a proper Faraday cage.

I would *never* use a switcher near any radio receiver. Linear supplies 
(transformer/rectifier/filter L's and C's) work fine. If you use a 
bridge rectifier topology, bypass the diodes with 0.05 uF caps of 
adequate voltage rating.

Regards,

Scott

On 4/9/15 9:32 PM, Leslie Smith wrote:
>    Hello Bill,
>    I'm interested in the symptoms of mains-borne noise in your set and
>    reduction in noise when operating from batteries.
>
>    I'm considering the problem of noise here too.  I have some
>    interesting stuff "going on" here.
>    One particular switch mode supply (for an MP3 player) thinks it's role
>    in life is perimeter duty.
>    The switching noise rampages up and down the band, incrementing the
>    frequency in steps as it marches over everything.
>
>    Do you know (in your set-up) how the noise gets from the mains into
>    your receiver?
>    You seem to be saying that you can't connect a
>    transformer/rectifier/regulator to a battery + receiver without
>    increasing mains-borne noise.
>    In other words the mains-noise isn't 'filtered' by the battery.
>
>    In the notional system I WAS considering (until I read your posting) I
>    had a power supply trickle-feeding a 12V battery.
>    The battery would feed the filaments AND an inverter.  The inverter
>    can produce any B+ from 45 to 180 volts.
>    I have the inverter - but haven't listened to see how noisy it is in a
>    well shielded box.
>
>    It seems (from your description) I can't run the power supply AND
>    receiver at the same time without the penalty of noise.
>    At the same time it seems remarkable that there isn't some filter that
>    can remove mains-bourne noise.
>
>    Comments?
>
>    73 de Les Smith
>    vk2bcu at operamail.com
>