Topband: invL experiments

[armin.ficza at nsn.com]

Finally my 160m invL is ready. Successfully tested yesterday, worked the
big guns: VE7CC, W5UN and W8JI with 100w. Thanks for the QSO guys! And
with 400w : JA1HQT, K7LAY, K9DX
Antenna is an invL with 19m vertical section, 21m horizontal. Have two
elevated radials ( 2m height) 42m long. It was resonating on 1.700 Mhz,
so I installed a series capacitor and moved the resonance to 1.830.
We have too much rain here, and moisture is always a problem, so
capacitor could be a problem, so today I restored the original situation
( resonance at 1.7) and started to trim the radials. Finally I achieved
resonance on 1.83, SWR 1:1.25 Bandwidth is 100 KHz (SWR<2) . Had to cut
8 meters, so the two radials are 34m long each.

Could somebody explain to me:
Which one is the better option. 
Next thing is that theoretically 3m trim would be needed, but had to cut
8m. Why? Is there some coupling active?
Does this antenna act as a vertical dipole ( with capacity hats) now? 

Unfortunately cannot use my SWR analyzer (strong AM transmitter not so
far away), and because of the terrain ( very sloping up and down (
valley), plus small creek in the middle) ground radials are not an
option...