Will probably try a coax feed, and a Balun, to the random length wire
running around the four sides of
my attic to reduce noise, hopefully. Do listening only, up to 30 MHz.

a. For a receiving 9:1 Balun (coax to a random length wire in attic),
does the Balun have to be grounded ?

Or, is it grounded "adequately" via the coax - to the radio chassis -
to an earth ground from the radio chassis ?

[If the Balun Does require a ground (also), wouldn't this possibly
cause a ground loop in that it would be grounded at both ends ?]

b. Anyone have any experience with, or opinions on:

-the 9:1 Balun by RF Systems in the Netherlands
(termed a magnetic balun, how it's different from a normal toroidal
transformer coupling, I have no idea ?)

-or the unit by Win Radio (WiNRADiO WR-LWA-0130 Long Wire Antenna Adapter
$39.95 ADP35)

c. Any significant difference in the type of coax used for listening
only,
with a run of about 50 feet.
Used LMR 400 for my attic scanner, but would like to avoid the hassle
of stringing the large diameter coax again, and possibly
just use a small diameter coax. Would one likely notice any
difference
up to 30 MHz ?

Thanks,
Bob

Forget the balun for receiving. For under 30 mhz you will not notice any
differance in the smaller coax cables. You may want to look at some of the
cable TV (RG-6 size ) 70 ohm coax. Cost less than most other coax and for
under 30 mhz has low loss. Don't worry about the 70 ohm impedance for
receiving. YOu may have a problem dealing with the shield not being able to
take solder in some cases.