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2) Use the up arrow key to light each LED in turn. Only a single LED
should be on at a time. The down arrow key will step backward
through the sequence.
3) After lighting the REM LED, pressing the up arrow key again will
enter keyboard test mode. Now pressing a key will display the
name of the key on the display.
4) Turn the FS700 off and then on again to restore normal operation.
Record the results of this test.
RF Bandwidth Test
These tests check the shape of the FS700's 100 kHz bandpass filter,
and the overall gain of the receiver.
Note: dB = 20 log10 (v2 / v1)
1) Connect the function generator to the antenna input through the
antenna terminator. Set it to sine wave, 10 mV amplitude, 100 kHz.
2) In CAL MENU 1 (press BSP and TIME key simultaneously), set the
attenuators to 64 dB. Look at the FS700 LORAN OUTPUT on the
scope, and measure the amplitude with the AC voltmeter. The
amplitude should be 0.4 vrms ± 0.3. This is the "nominal"
amplitude. Record this number on the test sheet.
3) Set the frequency to 90 kHz and record the voltage. Calculate the
voltage ratio in dB. This reading should be nominal ±2 dB. Record
this number.
4) Repeat step 3 with a frequency of 110 kHz.
5) Set the frequency to 80 kHz and record the voltage. Calculate the
voltage ratio in dB. This reading should be between nominal -1 dB
and nominal -6 dB. Record this number.
6) Repeat step 5 with a frequency of 120 kHz.
7) Set the frequency to 50 kHz and record the voltage. Calculate the
voltage ratio in dB. This reading should be at least -25 dB below
nominal. Record this number.
8) Repeat step 7 with a frequency of 150 kHz.
9) If the readings are out of range, the bandpass filter may need to be
calibrated.
Internal Self-Tests
The self-tests test the functionality of the system ROM and RAM, the
pattern RAM, the DAC/ADC combination, the rf attenuators, and the
gated integrators.
