AMERITRON ATP-100 Manuale di istruzioni - Pagina 8

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ATP-100 Instruction Manual

Tuning Pulser

APPENDIX

Testing QSK Systems

The Ameritron ATP-100 Tuning Pulser can be used to evaluate QSK systems.

In one test configuration, a continuous signal source is loosely coupled to the

dummy load. The receiver is tuned to this signal source, and the Ameritron ATP-

100 Tuning Pulser controls are adjusted until the test signal is clearly audible.

The maximum QSK receive speed is found by measuring the PULSE RATE, and

multiplying the PULSE RATE by 2.4. The DUTY CYCLE should be set for

normal sounding CW dots during this test, or a 1:1 ratio.

The transmission waveshape can be checked by looking at the RF output on a

scope, with the scope triggered or synchronized to the keying line signal. A

normal CW signal has a smooth rise and fall time of about one millisecond, with

no overshoot or undershoot. Switching from manual operation to full QSK

should not disturb the keying waveform, or change the on and off time period.

Testing Wattmeters

Wattmeters can be tested by measuring the single tone power with a barefoot

exciter running off of a regulated supply, and adjusting an oscilloscope to read

near full screen with that carrier. By activating the ATP-100 with the PULSE

RATE set approximately mid-range, and adjusting the DUTY CYCLE control

until the full peak envelope voltage is just displayed on the scope, the meter can

be evaluated. A good peak reading meter should indicate the same amount of

peak power with the ATP-100 pulsing the carrier as it indicates with a

continuous carrier, as long as the maximum scope deflection remains the same.

RFI and TVI Troubleshooting

The Ameritron ATP-100 Tuning Pulser can be used to activate the transmitter

with a pulsed signal of full peak power, without undue equipment heating. This

will allow you to move to the location of the device being interfered with, while

safely operating the transmitter at high power.

You can add filters, grounds, and move cables on the device being interfered

with without fear of overheating your transmitter. The short duty cycle also

reduces interference to other amateur operators.

Be sure to have a licensed operator attending your station, and to conform to all

FCC rules regarding CW emissions.