Kenwood CO-1506 Instruction Manual

A L I G N I N G A M R E C E I V E R SA typical adjustment of A M receivers is that of the I Ftransformers. Connections are made from the sweepgenerator to the receiver at the rotor and stator of thereceiver variable capacitor. T h e leads from CO-1506 areconnected across the volume control variable resistor ofthe detector circuit observe the detector output.T o CO-1506 E X T S Y N C / H . I N P U TFig. 11 Adjusting AM receiverMODULATION MEASUREMENTT h e CO-1506 works if the measured modulated carrier isbelow 1.5MHz. Connect the modulated carrier to V .I N P U T (1) and adjust with V E R T A T T (4) and V . G A I N(11) to produce an envelope as shown in Fig. 12.This modulation envelope is a result of constant modulatingfrequency which will be displayed with stability on thescope when synchronized with controls (6) and (10).T o find the degree of modulation, measure maximum andminimum values A and B .A ^ x 1 0 0 . . . Modulation in %A + BAnother method of modulation measurement is the use of atrapezoidal pattern. In this method, the modulated radiosignal to be measured is fed to A C terminal (1) with S W E E PR A N G E (6) set to E X T position. In this set-up, themodulating signal applied to H. I N P U T (8) will produce atrapezoid or rectangular pattern on the scope. Assume thelonger side as A and the short side B, then the above sameequation applies to find the degree of modulation.Common terminalConnect this lead toappropriate terminalFig. 13 Method of selecting power supply voltage10Fig. 12 How to measure modulation degreeA - B .Sweeping outputfrom the generatorTuning circuitVolume control variable resistorin the detector circuitT o CO-1506V E R T I C A LI N P U TSweep generator connected at the 4 5 5 kHzI F input or R F output