[Antennas] inverted L and trap

[G B]

Hello,

Laid down a dozen radials so I could test the inverted L on 80 meters.

First test with analyzer excellent, or so I thought, with nearly 1.1, 48
ohms and 5 ohm
X.  I know, that means the ground is not that great.

But resonance point was at 3.68Mhz, and very narrow 2:1 swr bandwidth at
70Khz.

So, added nearly 3 feet, and rechecked.  Resonance only dropped 40Khz to
3.64.

This does not make sense to me, so my question is:
Is the trap tuned wrong, to about 3.65Mhz instead of the intended 3.55Mhz?
What effect on resonance will the trap have?

Also, even though there are no 160M radials at this time, I cannot find the
resonance point
for 160M.  It looked like the analyzer was going from infinite to something
lower at 1.7Mhz,
it's lowest freq.

The trap was made from internet program Coaxtrap I think is the name of it.
8 turns, rg-8X
foam coax on a 4.2" PVC drain pipe.

Any suggestions?

TIA

73's

Glen K4KV