Radio Shack 21-513 Antenna Tuner

 Found an Archer branded Radio Shack antenna tuner in a box.  The 1973 catalog describes it this way:  Antenna Tuner.  Matches any antenna impedance between 10 and 1000 ohms.  To 500 watts of RF power.  $9.95

I don't know where the manual is, couldn't find one or a schematic online.  The two knobs control compression caps.  There is a somewhat complicated tri-filar air-core coil resulting in an unusual tuner circuit configuration.  I suppose that unlike most ham antenna tuner circuits, this one could concentrate on one band (CB).  I was hoping to use it on 10 meters to help with receiving but can't get an audible peak.

I tried tracing out the circuit schematic:

I measured the output winding to the antenna as 0.128 uH.  The  windings are side by side, wire is about 1 mm diameter (#18 ?).  The coil is air-core, about 12 mm in diameter, 6 turns.  The compression caps are marked 200 - I assume that means 200 pF ?  I tried measuring the left cap, got a maximum of 288 pF (tight) and a minimum of 87 pF (loose).

I will have to look around for the manual, I must have had some kind of documentation to write ant. and radio on the back.

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm