"JERD" wrote in
:

....
The function of the earth stake is to 'ground' my new HF ham rig and
also the AT-4 automatic antenna tuner.
....

Jerd,

Nothing here stated AC protective ground (which comes from the earth pin in
your three wire power socket) or lightning ground.

You have identified that you want to attach the second output terminal of
the AH4 to the electrode. The proposed electrode (whether or not it is
throught the path) is likely to have a resistance that results in a low
antenna system efficiency at frequencies where the radiation resistance of
the antenna is relatively low.

The article at http://www.vk1od.net/InvertedL/InvertedL.htm models a
scenario that is probably quite similar to that which you are considering,
and discusses points relevant to the design... could be worth a read.

Now, there will be a body of opinion that it doesn't matter what you do,
you will still get QSOs, that it therefore 'works'. It sounds from your
question that you are more interested in that shallow level of engagements,
so read around.

I wrote another article on a minimal setup again with an AH4 and end fed
wire, it is at http://www.vk1od.net/NaroomaEFW/NaroomaEFW.htm .

By all means, drive an earth electrode as you have proposed principally for
lightning protection (though I would use a 2.4m copper clad steel
electrode), but run at least a couple of (untuned) shallow buried bare
copper radial wires from the AH4. Locating the AH4 remotely from your shack
and house if you can will reduce the RF intensity in those places and
reduce EMC problems.

Catch you on air sometime.

Owen