Jim Lux wrote:

Or, easier.. put a choke around the feedline where it comes
into the shack, so that there's no appreciable RF current
through the chassis and green-wire ground.


Okay, I'm adding a balun. Now the question is what and where. The
assembly instructions for the antenna say...

The antenna is "..designed to be used with
50 ohm coax cable. No balun is required for
proper operation.

If RF on the coax is a problem, simply wind
a "choke balun" with the coax that's used for
your feedline. Wind approx 8 turns, at about
an 8 inch diameter and tape (with outdoor rated
black electrical tape), like a donut, and place
this "donut" near the feedpoint of the antenna.
You should leave about 2 foot of your coax
sticking out of this "donut" for connection to
the antenna. Then attach the end of your
coax to the antenna connector on the center
insulator, with the coax connector that is
already on your feed line."

In other words, a scramble-winding choke near the antenna's feedpoint.
The alternative is an MFJ-915 in-line balun with 50 ferrite core beads
on coax (cheaper than I can buy the ferrites), which MFJ says should
be installed closer to the radio (3 feet) as opposed to the antenna
feedpoint at the other end of the coax as described above.

Which of the two options is most sufficient for the task and which is
the correct placement for this - or are they both right depending on
the type?

stewart / w5net