AGC threshold adjustment (R28)

• Turn first the AGC threshold trimmer R28 to noise edge by listening the audio noise
• Feed -73 dBm (50 uV) with a RF signal generator into the antenna connector
• Adjust the trimmer R28 so that the S-meter shows S9 (midpoint in the LCD bar display)
• If a RF signal generator is not available you can use another HF receiver as a reference

• The purpose of this adjustment is to null the 2f spurious response
• Feed -30...-10 dBm 7 MHz with a RF signal generator into the antenna connector
• Tune the RX frequency to 3.500.50 MHz and identify the 2f signal response
• Adjust the signal generator level so that the 2f  signal is audible and there is S-meter reading
• Adjust the trimmer R68 so that the 2f response minimized in S-meter
• If a RF signal generator is not available you can locate a very strong BC carrier in 7 MHz band and listen it at half of the frequency

• NOTE the pa board must be adjusted before this adjustment and the relative power switch must be in forward position
• Connect a 50 ohm dummy load, use 13.8 V / 1.5 A power supply
• Switch to CW mode and key down and adjust the RF ouput to 5 watts by the trimmer R50
• Two bars below the maximum display in the relative output display corresponds 5 watt
• The power output can be verified wit an oscilloscope, 45 Vp-p corresponds 5 watts

• NOTE the pa board must be adjusted before this adjustment and the relative power switch must be in forward position
• Connect a 50 ohm dummy load, use 13.8 V / 1.5 A power supply
• Transmit in DSB mode, whistle with lips almost touching the microphone and adjust the RF PEP output to 5 watts by the trimmer R41
• Two bars below the maximum display in the relative output display corresponds 5 watt

• In CW mode during transmit the TX frequency is shifted 700 Hz down. Thus the side tone pitch can be used to tune to the same frequency
• Switch to the DSB mode, the side tone is heared from the speaker also in DSB mode but nothing is transmitted
• Key down and tune the side tone frequency to 700 Hz by trimmer R53
• You can use counter connected in the speaker line, this adjustment is not critical, ± 100 Hz accuracy is adequate
• Alternatively the side tone pitch can be compared by ear with a piano or other musical instrument, note F is 698.4 Hz