Welcome to theradioboard! I've enjoyed your posts in the other Yahoo group, that many of us seem to visit as well.
Thanks for your detailed reply. A couple of more questions:
When building a shield box out of double-sided copper-clad circuit board, is the outer foil surface electrically separate from the inner foil surface? Is there any reason a slab of medium-density fiberboard with copper foil on both sides can't be used exactly like a double-sided copper-clad circuit board for building a shield box?
Also, is it feasible to homebrew an openable, but still RF-tight, lid for the enclosure? If so, I could keep the power supply (battery) and tuning controls for the measurement receiver all inside the box, tune the receiver with the lid open, and close the lid only when measuring. I would prefer an openable lid for convenience; if however that's not easily possible, then I have to run all the receiver control lines and power supply lines outside the box, which seems more complex with drilling holes, using feedthrough capacitors (which I don't have), chokes, etc.
Finally, your comment about outside vs. inside shielding raises another question - I now wonder if I may be doing the front-panel shielding wrong on my current wooden-box regen serving as my station receiver. I've got the circuitry mounted on the inside side of a wooden box lid:
I added shielding on the inside of the lid by taping copper foil to the inside and soldering the corners together:
The shield foil is grounded to the main circuit ground at the tuning capacitor. There is no shielding foil on the outside side of the lid, where the knobs are mounted. Now, in this case, should the shielding, located on the inside of the lid, help against hand capacity effects when touching the knobs, or must the shielding be on the outside?