Ameri-King АК-451-Series User Manual

Page 19

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Adjust the reference amplitude to place the peak of the carrier slightly above the top
graticule fine.
Enable the "fine" amplitude adjustment. Set the carrier peak to exactly the top of the
reference line.
Read the displayed amplitude.

Repeat for the 243.0 MHz harmonic (change the "Center Frequency" to 243.0 MHz.
All other settings remain the same).

The minimum allowed amplitude on 121.5 MHz and 243.0 MHz is 20 dBm, after 3
minutes of operation.

3.2.2.2

406.028 MHz Power Output:

Note:
The power output is approximately (35 – 39) dBm. Ensure adequate attenuation is
inserted in-line between the ELT's 406.028 MHz output and the input to the spectrum
analyzer to protect the analyzer's input circuitry.

Connect the equipment as shown below:

Set the Spectrum Analyzer as follows:
•

Center freq: 406.028 MHz

•

Span: 1 MHz

•

Resolution bandwidth: 1 MHz

•

Vertical display: 10dB/Div

•

Sweep: Auto

•

Peak/Avg: Peak

•

Reference level: 30 dBm

•

Time/Div: 20ms

•

Max hold: On

•

Attenuator (as required) on Input

Turn the ELT on and wait approximately 50 seconds for the 406.028 MHz transmitter
to turn on (transmitter sends out first signal at 50 seconds then every 50 seconds
thereafter). Determine the power output from the stored waveform.

The 406.028 MHz power output should be (35-39) dBm (3.16 W min to 7.94 W
max), after 3 minutes of operation.

ELT BNC
Connector

Applicable

attenuator

Spectrum

Analyzer

3.2.3

Frequency Test / Current Draw Test, Performance Testing:

NOTE: Using of ELT Test set TS-451 or equivalent test equipment is acceptable

The ELT Transmitter frequency may be measured as follows:

3.2.3.1 Connect the Frequency Counter as shown below:

3.2.3.2

Measure the 121.5 / 243.0 MHz frequency:

Select the Notch filter as appropriate, i.e. 243 notch when measuring 121.5 MHz.
The ELT should be within 50ppm (± 6.075 KHz) of 121,500,000 Hz.

Repeat with the 121.5 MHz Notch Filter. The ELT frequency should be within 50
ppm (± 12.150 KHz) of 243,000,000 Hz, after 3 minutes of operation.

3.2.3.3

Measure the 406.028 MHz frequency:

Ensure that adequate attenuation rated for 406.028 MHz, 37 dBm and 5 Watts is
installed between the ELT's 406.028 MHz output and the input to the frequency
counter to prevent damaging the frequency counter's input circuitry.

Set up the equipment as shown below:

Verify an initial frequency of 406.028 MHz +/- 1 KHz, after 3 minutes of operation.

Note:
Allow the unit to run 3 minutes, before making the measurement to allow the
oscillator to stabilize.