It is possible to perform several preliminary test on the completed boards with no radio, antennas, or test equipment other than a 12 volt power supply and a wire jumper. If a voltmeter is available, it would be wise to check the +5 and +10 volt supply outputs, before proceeding. An oscilloscope is the preferred tool, if any "serious" problems occur.
The Doppler generates all the signals ( internally ) that are needed for basic tests. Connecting a wire jumper from U6 ( pin 11 ) to the audio input should "light up" a single LED on the readout. Adusting the CALIB trimpot should "move" this LED around the entire dial. Removing the jumper from U6 pin 11 and moving it to U9 ( pin 8 ) should yield a display which is located 180 degrees away from the previous display.
The antenna board can be tested by feeding the antenna output directly into the
audio input of the D/F unit. Grounding any antenna input with a clip lead should
yield a specific LED display. By sequentially moving the jumper to the other
antenna inputs, the display should advance 45 degrees, ( two LED positions )
for each antenna "step". This test can also be done by connecting the audio input
directly to each antenna terminal... the DC switching pulse for the RF diodes will
drive the D/F display unit.