Jim Kelley wrote:
2. The current on a 75m mobile antenna is at least 90%
standing wave current.

And what's the other 10% supposed to be?

The other 10% is the traveling wave that gets radiated
of course (neglecting losses).

Please explain how one would
go about getting "standing wave current" to flow through something -
anything - like a measuring instrument for example.

Opps, standing wave current doesn't flow so you must
have meant how does one eliminate reflections so that
nothing except traveling wave current is present.
Do you need that explained to you?

Have you tried pulsing a current through one? I can't imagine there
wouldn't be a delay in getting from one end to the other and back.

Exactly, but some would say that's digital, not RF,
or that is not steady-state conditions.

4. Yet, this is exactly the current that w7el and w8ji
used in their measurements

No, it is not.

Sorry, you are wrong about that. w7el described in detail
what he had measured and it was "total current" which was
about 90% standing wave current. Here's what he said:

"The result from the second test was a current difference
of 5.4%, again with no measurable phase shift." All using
the total antenna current which is about 90% standing
wave current. What he didn't realize is that a current
difference of 5.4% is a calculated phase shift of ~19
degrees, i.e. ARCCOS(1-.054) = ~19 degrees, to which
you have previously alluded.

Here's a question for you: What is the phase shift
in the current in 90 degrees of an ideal lossless
1/4WL stub?

I'm reminded of the troll at the bridge.

I'm reminded of people who refuse to answer simple questions.
One wonders why? The answer is zero degrees.

To what phase shift do you refer? With respect to voltage, from one
point to another, out and back - you need to be considerably less
imprecise if you expect someone to bother to answer (to) you.

The context was specified as current. Here is an EZNEC simulation
which should help you.

http://www.w5dxp.com/stub_dip.EZ

Click on currents. You will see that the current phase
varies by ~2 degrees end to end in 90 degrees of stub
just as it does in a 1/4WL monopole over ground.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com