Difference between revisions of "Icom IC-A21"
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(Created page with " == Squelch circuit == Noise components of the signal are output from IC1004 on pin 9. This is marked IC4 on the board and is an MC3372P. This then goes through the squelch...") |
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== Squelch circuit == | == Squelch circuit == | ||
Noise components of the signal are output from IC1004 on pin 9. This is marked IC4 on the board and is an MC3372P. This then goes through the squelch control pot and is rectified to a DC voltage. When high enough, this voltage turns on Q1008 pulling its output low. For an active high signal monitor the output of inverter Q1009. This signal goes across the ribbon cable to the logic board and is called 'sql'. | Noise components of the signal are output from IC1004 on pin 9. This is marked IC4 on the board and is an MC3372P. This then goes through the squelch control pot and is rectified to a DC voltage. When high enough, this voltage turns on Q1008 pulling its output low. For an active high signal monitor the output of inverter Q1009. This signal goes across the ribbon cable to the logic board and is called 'sql'. | ||
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| + | {{pdf|Icom_ic-a21_service_manual.pdf|Service manual}} | ||
Revision as of 06:14, 27 August 2018
Squelch circuit
Noise components of the signal are output from IC1004 on pin 9. This is marked IC4 on the board and is an MC3372P. This then goes through the squelch control pot and is rectified to a DC voltage. When high enough, this voltage turns on Q1008 pulling its output low. For an active high signal monitor the output of inverter Q1009. This signal goes across the ribbon cable to the logic board and is called 'sql'.
