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That will not produce the RF ground effect you want. They should be radials, a bunch of them, about the base and center of the antenna mount, just as MRAM has indicated for his system. If your metal conduit is somehow grounded to actual Earth, then bonding the set of radials to it might (I say ‘might’) work for you, provided there is no loop effect that could goof up your audio.
Generally, more radials are better. However, for a 10′ antenna, I think more than 12 or 16 at 20′ each would be entering an area of diminishing returns. What you want is enough to cover a reasonable portion of the near field. We concentrate there for broadcast frequencies above, say, 1600 kHz, because the higher BCB frequencies are more efficient for loading coils (more inductance with fewer turns, less resistance) and generate most field strength within about .17 wavelength. With no decent return (through the air) to ground, it will dissipate quickly after that.
To contrast, loading with a coil at low frequencies requires many more turns to get good inductance, you sacrifice with more resistance in the coil, and so less power … IOW, it isn’t as efficient. However, the near field at low BCB frequencies has a much larger near field, so, though it starts out much weaker, it remains with whatever it has for longer distance, i.e., the transition from near field to far field starts to lose definition … it just fades away. But at these miniscule power levels, penetration is poor in the lower part of the band, so you won’t get much anyway.
Most of the successful range attributes of inductance coil loaded antenna systems I’ve seen here as used with SSTRAN have been in the upper portion of the band with a good set of ground radials bonded to Earth with multiple ground rods.
A roof-mounted system only has the advantage of getting over buildings. Otherwise, AM radio travels by ground wave during the day, so the best ground system you can get is vital.
3 basic things, then:
1) Maximum loading on an empty frequency in the uppermost portion of the BCB.
2) Maximun resonance, which requires patient matching for most field strength.
3) Maximum RF ground.
These 3 all affect each other, so finding a balance that works for you is where your brains and elbow grease come together 😉