Before you purchase a HAL ST-8000A, it would be best for you or the seller to run the internal test procedures to check your firmware and to ensure that everything is still running correctly. These units are over 20 years old now, and the electronics could start to fail if they have been sitting in storage for too long. The good news is that this testing is very easy, and only takes the power cable to complete. So even a NOS unit can be powered up and tested with no technical knowledge about the unit.
Check on the back panel to make sure that the frequency and voltage match your power mains. Unlike most TNC’s, the 8000A uses about 30W of AC power and not 13.8 VDC. In the US this would be 115V and 50/60 Hz. Europe and Asia require it to be set to 220V and 50/60 Hz. The frequency switch can also be set to 400Hz for aircraft use in accordance with MIL-STD-704. If your 8000A has the accessory package, you should be supplied with two power cables, one that is a standard desktop computer cable, and a short adapter that allows the unit to be plugged into military power systems. The male plug is for the US standard, but adaptors or other cables with the proper female socket will work.
Once the unit is plugged in, flip the front power switch and the 8000A will go through the first diagnostic check. During this check the firmware version will be displayed. The newest firmware is version 1.9. Once the start up has ended, the unit will show mark and space frequency as well as baud rate, and you should get a slight flicker in the LED bar graphs. A few of the display LED’s might also be illuminated, depending on the settings. This is the first test, and the one most ignorant sellers will claim is all they can do.
The second test is called the BIT test, and this tests the internals of the ST-8000A by routing the modulator through the demodulator to check that the circuits are working correctly. To perform this test, turn the unit it on, and upon completion of the start up test, hit the “2nd” key, then hit “BIT” and finally “Enter.” This will run the machine through a 13 step self-diagnostics test, including testing all the LED’s and testing the demodulator at several audio levels. If all is well, the unit will end the test by putting “Pass” on the LED display and finally returning to standby mode. If there is a failure at any point, it will display the step of failure and say “FAIL” on the screen. The test will not proceed beyond the failure point.
Once the ST-8000A is verified to be functioning correctly by these tests, it is time to move onto the wiring to be able to get audio into the unit from the source, and then intelligence back out.