An app such as Frequency Sound Generator by Aleksandar Mlazev can be run on an Android or Apple phone or tablet. When using such an application you must select a sawtooth output as the tests below rely on even harmonics being present.

Step 1 - LO-End :-

1. Set all controls their minimum (CCW) position
2. Set FSG to 16Hz (fast clicking sound)
3. Adjust P101 for an output of 16Hz. The clicks will seem to wander spatially when the FSG and VCO are in sync

Step 2 - Wave Shaper :-

1. Set P201 to its mid-position
2. Set the VCO to about 300Hz
3. Monitor the [SHAPED AC] output
4. Adjust P201 for best sine wave sound possible
5. Turn [WAVE SHAPE] to maximum and check that the waveform becomes rich in harmoni

1. Monitor the [SAW AC] output
2. Set [CV-B] pot to '0'
3. Apply 0.0V to [CV A]
4. Set the FSG to 300Hz
5. Adjust [FREQUENCY] and use [CV-B] pot for minimal beating
6. Apply 2.0V to [CV A]
7. Adjust 5K Lin pot for precisely 75Hz
8. Repeat steps (3) to (7) for best accuracy

Stage 2:

1. Apply 2.0V to [CV A]
2. Set [CV-B] pot to '0'
3. Adjust [FREQUENCY] for 300Hz using [CV B] pot for fine tuning
4. Apply 0.0V to [CV A]
5. Set FSG to 1200Hz
6. Adjust P102 for minimal beating
7. Repeat steps (1) to (6) for best accuracy

Calibration of the HF Trim is a series of successive approximations so stages 1 and 2 should be repeated several times for optimum accuracy.

NB: In analogue electronics, perfection is necessarily a beat away - but kept as small as humanly possible.