Mike,
The original issue was whether to ground the Astron negative bolt DC
connection. That is done if you connect the Astron, as built, to the Scout
negative, black power wire, for it goes directly inside the Scout to the
chassis and the Ground stud that has the wing nut, and if you have grounded
that stud to a single point earth connection for your station. To ground at
Both Astron end and Scout end creates the loop of wire that can pick up RF.
The Astron chassis is normally grounded via its AC power plug as you state,
and that is fine.
EMC is electromagnetic compatibility, which is something ARRL has touched
the tip of the iceberg with a short manual I heartily suggest you read,
since your experience is in the ham field. It does not tie one up with
math, formulas, but suggests practical fixes and standard rules to avoid
ground loops.
Just for info, I have repaired Astrons and the most usual failure in them
from lightning is the 317 voltage regulator chip, which makes an excellent
lightning dissipator!
The MOV across the line (Metal Oxide Varistor), that looks like a ceramic
disk cap of blue, black or red case color, is the next thing to go, in most
lightning events, a good reason to not leave AC plugged into the wall when
not operating your station. I think I have had to replace about six of the
MOV protective devices. They bulge and sometimes char and crack when hit.
However, if you know of a close by surge, you should replace them anyway, as
they are only good for a few hits, and the voltage protection threshold will
raise, making them less protective of the device to which they are attached.
Cheers,
Stuart K5KVH
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