This program write alternate two low frequency or three high frequency tones to the tape recorder.
Record this for a couple of minutes.
When reading this tape the PLL should convert this to a symmetric block pulse.

This program shows on the first two digits on the KIM-1 LED display the number of ‘1’s read, on the second two digits the number of ‘0’s read.
When all is well this should 80/80 but anything between 60/A0 and A0/60 is fine.