Interesting data, Cecil, but you don't give any measurement methodology..
The power to the antenna was measured using two Bird directional wattmeters. Power to the antenna equals forward power minus reflected power. The signal was measured in the far field with a ferrite loop antenna tuned to the test frequency. It was done by some very competent RF engineers from the LA area using a very accurate RF voltmeter.
I think the antenna tuner losses are smaller than everyone is claiming.
I haven't measured the loss, but here is the measured feedpoint impedance for my improvised dual resonance whip:
How does your whip exhibit a dual resonance on HF? Do you have a loading coil there somewhere? Everything I have said about the SGC+whip assumed a standard CB whip resonant on 11m or the 11.5 whip, resonant on 15m, that was used for the measurements.
So it looks, at first glance, like the loss in the tuner is going to be less than a dB.
difference between a base-loaded bugcatcher and an SG-230 with 11.5' whip is 7 dB. I don't see how that 7dB could be anything other than losses in the SGC tuner. Where else could that 7dB of loss be occurring?