"clvrmnky" wrote
On 15/03/2005 8:33 PM, Richard Clark wrote:
As for the Neutral connection of the mains NO THAT IS NOT GROUND!

Absolutely. I actually have home wiring experience (I don't have my
electrician's ticket, but I could wire my own home, and it would pass
inspection.) I'm surmising that the ground my receiver is seeing (at
least the DC components within it) is the neutral wire. My comment was
more of a rhetorical comment, not a threat to use the white wire on my
AC outlet as ground!

Hi OM, it's clear you understand that wal-warts have only two connectors to
AC (hot and neutral), and neutral is bonded to ground at the mains.

My question to Richard (and group) is whether there is any RF or DC link to
ground via a radio's DC-power connection to a wal-wart? I have never
examined the internal components of a sealed wal-wart, only seen the results
of surge voltages from lightning that exploded them and damaged radios they
were connected to. Nothwithstanding the forces of lightning that made that
connection, isn't there isolation from ground when a DC converter is used?

Cheap DC converters can add noise to an electrical system and affect radio
reception, but I didn't think there was any DC coulping across the
transformer wiring, and probably limited if any rf-coupling there either.
Can anyone comment on this?


This goes again to the common misunderstanding. You won't suffer a
ground loop until it occurs. Solving it will be one of life's
greatest struggles, and the solution, if stumbled upon, will appear to
be one of life's greatest mysteries. Again, battery operation creates
its own bubble of isolation from these issues - however, adding a
charger brings the prospects back into the equation.

It's my understanding that ground loops are most common from having serial
v. parallel connections to ground from various equipments. Daisy-chaining a
series of radios to the common ground would thus allow radios to exhibit
feedback through each other instead of only to ground. When a properly
bonded system is connected (each unit indivdually connected to the single
point ground) there is no ground loop. Others often ask what about multiple
bonding-points of the external ground system and it's connection to the AC
mains? Answer: These are not ground loops and are not the cause of equipment
interference from the series-connections of equipments described above.


I get a bit of a boost in signal running off the wall-wart, but it is
actually more convenient for me to run off batteries. I end up moving
the receiver around quite a bit. I can pick the big blowtorches and the
relays from Sackville quite nicely off the whip, so I often listen to
them in the kitchen or when doing chores around the house. For "DXing"
I settle in near the door where I've got my antenna experiments going.


That's interesting OM, as it implies you are seeing a counterpoise effect of
rf-coupling across the windings of the dc transformer, or perhaps just the
secondary side? If a wal-wart helps complete an antenna, it would seem
there may be a design component missing from the antenna somewhere ;-)

Best regards,

Jack
(fmr navy instructor of strategic weapons systems electronics, now a
plug-n-play operator for the uscg)