If you're asking for schematics I would presume you may be referring to the 3 element Yagi? Those should be available from MFJ/Maco or on line.
The simple blue-green Archer Crossbow omni simply threaded together in the center (albeit a reverse thread, if I recall correctly) and mounted on a mast. It's basically a 100w pep 16' big stick. Why they decided to use a reverse thread at the center junction I'll never understand.
I gleaned one of the 96" blue fiberglass whips from a friend's Crossbow (which fell and splintered near the base) and rethreaded it for correct thread direction 3/8" x 24 and it makes a real nice mobile antenna on the 4-magnet mount.
It's a 100w antenna at best. It uses a small capacitor up inside to match the 72ohm center-fed dipole back down to 50ohms, and that capacitor tends to fry with any real power. - That's why you see so many of them not in use above homes, but in the landfill.
It's a center-fed dipole, and is basically a unity gain antenna. If you live in an area surrounded by hills or mountains, change out the 96" whip for a 7 foot Firestik, (which you'll have to rethread wackbirds) but it will help your signal to get up over and above the hills. I had success doing this in 1986 near Bodega Bay in the Ca coastal mountains and saw a marked improvement into town (Santa Rosa) using the 7' Firestik.
If it were me, I'd ebay it for as much as someone more nostalgic than knowledgeable (antenna-wise) will pay, then spend the cashola for a metal 5/8 like a Maco or equivalent.
