The Metro

This is my creation called the "Metro". It features 5.75 coils, one inboard wave trap based on the wave trap on Owen Pools site, one ferrite rod outboard wave trap, multiple hookups for detectors, multiple hookups for phones and a volume control, believe it or not. The volume control is necessary when I tune in the local band master. Without the vc, my earphones literally rattle. The two switches allow me to switch the wave trap in or out of the circuit on those rare occasions when the trap's not necessary, and the other switch bypasses the antenna tuning cap, some stations tune better without it. All of the components feature banana plugs which makes for easy switching in and out of detectors, phones, antenna & ground hookups.

It's a simple double tuned set with loose coupled parallel Inductor/Vcap's for both the antenna and detector circuits.

The philosophy behind the rig is simple for my area. I have 3 band masters beaming over me at all times. I wanted the advantage the larger coils give me, but even at thier farthest separation they are way too over coupled for the strong locals, so I built in the wave traps. This allows much closer coupling of the coils for the very weak signals where the large coils shine. Normal coupling for the very weak signals is about two to three inches, six inches for the medium locals.

Before I mounted the coils, I tested just how far apart I could get them and still detect the local band master. I could still hear the local torch plainly with the coils separated over four feet apart.

This is my complete rig. Along with the Metro, to the right, there's the impedance matching circuit, the "UltiMatch" designed by Steve Bringhurst. That circuit truly makes a HUGE difference. On top of the Ultimatch is my very comfortable, very sensitive Stromberg Carlsons mounted in the highest rated shooters muffs I could find at Wally World. You can see the ferrite rod wave trap on the right in the unused position.

In front of the Ultimatch you can just barely see the 1SS98 Schottky diodes that slide in and out of the detector's banana plug mounts. These are easily and quickly traded in and out with the rock stand in the fore ground.

Close up of the rock stand

The inline wave trap, mounted inside the chassis.