Top View Showing Board Mounting and Shielding Arrangement

    The boards are sized to fit a 3x4x5" minibox as shown.  The RF amp and its controls are on the left side of the shield.  The shield is essential to keep 3496Hz LO signals from reaching the input of the RF amp.  The two battery holders are mounted outside on the left and the phase-lock alarm is on the right.  The 10 turn "knobpots" for RF Gain and Null are old surplus units I had on hand.  The rest of the layout is not critical.