10k223,
"The antenna has much gain and receives as well as the quad." - If you would change that just a tiny bit, to the quad you had up, I'd sure be willing to believe it. As it stands, though, 'fraid not.
As for the guy who designed it, he may very well know what he's talking about. But, since we're getting things sort of 'second-hand', there might also be some 'fudge-factor' in the relaying. Not hard to do at times, and not always necessarily intentional.
And the part you won't want to hear, and won't agree with...
Coils always introduce loss. May not be much, but it's always there. Just a matter of physics. The only good reason to use a coil as a load in an antenna is to make that antenna shorter. There are some very good reasons to do that, especially for a mobile antenna for HF. That shortening of an antenna does change it's radiating characteristics. If that change isn't much, if the antenna isn't shortened a great deal, there will probably not be any readily apparent noticeable difference in what you hear. If that change in length is very much, there will probably be as much reduction in what you can hear with it. Just another fact of life about antennas (provable, by the way, just as the coils/loss thingy is).
Does any of this say there's something wrong with your antennas? I don't think so, if they are used for what they should be used for. And with any antenna, if it isn't used to the best of it's characteristics (what it ought'a be used for), it's like putting one 13" Goodyear tire on a large 'John Deere' tractor. It may work, but not very well.
- 'Doc